NASA Astrophysics Data System (ADS)
McCullough, Bob
2007-03-01
Professor H Winter. It was with great sadness that we learnt of the death of colleague and friend Professor Hannspeter Winter in Vienna on the 8 November 2006. In memory of him and the contribution he made both to our conference and to the field of the physics of highly charged ions we dedicate these proceedings. Hannspeter was one of our distinguished invited speakers at HCI2006 and gave a talk on the status of the ITER programme. His invited paper on the subject is included in these proceedings. Hannspeter will be particularly remembered for his pioneering work on ion-surface interactions that, together with his colleagues at the Vienna University of Technology (TUW), has stimulated a worldwide experimental and theoretical interest in this field. He was appointed Director of the Institut fuer Allgemeine Physik at TUW in 1987 and using both his scientific and management skills has made it one of the leading university physics laboratories in the world. His research publications, of which there are 270, have inspired many others to work in the field of atomic and plasma physics. He was also a great European playing a major role in the EURATOM fusion programme, the European Physical Society and the International Union of Pure and Applied Physics and was an evaluator and advisory board member for many national and international institutions. Hannspeter was also an interesting and friendly social companion with interests in current affairs, music and fine wines and will be greatly missed both on a scientific and social level. Our condolences go to his wife Renate, son Dorian and his relatives. R W McCullough Co-chair HCI2006
ERIC Educational Resources Information Center
Rice, Kathryn; Scott, Paul
2005-01-01
This article presents a brief biography of Johann Carl Friedrich Gauss. Gauss was born on April 30, 1777, in the German city of Braunschweig (Brunswick). He was the only child of Gebhard Dietrich Gauss and Dorothea Benze. Neither of Gauss's parents had much education, his father could read and write, but earned his living doing menial jobs such as…
[Georg Friedrich Händel's eye disease].
Evers, S
1993-09-01
In his last years Georg Friedrich Händel suffered from a loss of sight not definitely to be defined. Based on primary sources, this disease, often mentioned in his biographies, is described and analysed. Altogether, Händel's eye-disease can be best interpreted as a central vascular disorder with degeneration of retina or with ischemic changes in the corresponding nuclei or tractus, complicated by a simple senile or post-traumatic cataract. Händel's profile of risk factors points most probably to a vascular degeneration of macula or a damage of choroidal vessels. Händel's eye-disease must be seen in relation to his cerebro-vascular disorder. His most probable strokes as well as his loss of sight were of vital importance in his biography, as is reflected even by his compositions. However, both disorders did not fundamentally influence his creativity. Only in a few compositions a reference to the loss of sight can be found. Apart from changes in concert-practising during his last years Händel's eye-disease, however, had no direct effect on his musical work. PMID:8264215
Obituary: Ludwig Friedrich Oster, 1931-2003
NASA Astrophysics Data System (ADS)
Sofia, Sabatino; Altschuler, Martin D.
2003-12-01
Ludwig Friedrich Oster died at the Anchorage Nursing and Rehabilitation Center in Salisbury, MD on 28 February 2003, of complications from advanced Alzheimer's disease. He is survived by his wife Cheryl M. (Oroian) and his two children by a previous marriage, Ulrika and Mattias Oster. He had a distinguished career both as a researcher in solar physics and as a science administrator in the National Science Foundation. Ludwig was born on 8 March 1931 in Konstanz, Germany and emigrated to the U.S. in 1958, acquiring American citizenship in 1963. His mother and father were Emma Josefine (Schwarz) and Ludwig Friedrich Oster. He got a BS degree in physics at the University of Freiburg under the guidance of Prof. K. O. Kiepenheuer in 1951, and a MS (1954) and PhD from the University of Kiel in 1956 under the guidance of Prof. A. Unsold. From 1956 to 1958 he was a Fellow of the German Science Council at Kiel and, upon his arrival to the US in 1958, he became a Postdoctoral Research Associate in the Physics Department of Yale University. He became an Assistant Professor of Physics and Astrophysics at Yale in 1960 and five years later he was promoted to Associate Professor. In 1967 he became an Associate Professor of Physics and Astrophysics at the University of Colorado and a Fellow of the Joint Institute for Laboratory Astrophysics; he was promoted to Full Professor in 1970. In 1981 he was a Visiting Professor at Johns Hopkins University, and shortly thereafter became a National Research Council Senior Associate at NASA/Goddard Space Flight Center in Greenbelt, MD, where he worked on solar variability. He joined the National Science Foundation in 1983, where he became the Program Manager for the National Radio Astronomy Observatory in the Division of Astronomical Sciences of the Foundation; he remained there until his retirement in 1996. His early work, started in Germany and continued at Yale, concerned radiation mechanisms related to solar phenomena. His works on
Stereotyping in "Damals war es Friedrich" and "Brandstiftung."
ERIC Educational Resources Information Center
Moffit, Gisela
2000-01-01
Discusses the use of young adult books in teaching high school and college-level German, particularly "Damals war es Friedrich" and "Brandstiftung." The didactic intentions of these books are to inform younger adults about the Nazi periods of the past and the Neo-nazi resurgence of the present, encourage them to confront the issues, and to take a…
[God is dead--Friedrich Nietzsche's Oedipus complex].
Wilkes, J
1997-04-01
The early psychoanalysts were influenced by the philosophical ideas of FRIEDRICH NIETZSCHE. The work of SIGMUND FREUD was partly based on NIETZSCHE'S literary world. Just before his mental disaster NIETZSCHE radically destroyed once precious ideals. The roots of this provocative development will be elucidated by analyzing NIETZSCHE'S childhood. A main aspect is NIETZSCHES close mother-tie and especially his father's early death. The father-image of NIETZSCHE'S late years is an essential of this paper. PMID:9206788
Friedrich Nietzsche and his illness: a neurophilosophical approach to introspection.
Perogamvros, Lampros; Perrig, Stephen; Bogousslavsky, Julien; Giannakopoulos, Panteleimon
2013-01-01
There are some arguments that Friedrich Nietzsche suffered from the autosomal dominant vascular microangiopathy: Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL). Here, a hypothesis is formulated supporting that CADASIL presenting with symptoms of bipolar disorder and Gastaut-Geschwind syndrome would contribute to the increased insight and creativity of a philosopher whose perceptions and intuitions often bear out the results of modern neuroscience. Alterations of the brain default and reward networks would account for such an increased level of introspection and creativity. A new framework on approaching illness is proposed, which, in conformity with Nietzsche's positive view, outlines the enabling aspects of some otherwise highly disabling neuropsychiatric disorders. PMID:23586545
NASA Astrophysics Data System (ADS)
Rompe, Robert
Friedrich Möglich, ein Schüler von Max von Laue und Erwin Schrödinger, übernahm 1947 die Chefredaktion der Annalen der Physik.Translated AbstractFriedrich Möglich - His Contributions to the Formation of Physics in GDRFriedrich Möglich a student of Max von Laue and Erwin Schrödinger took over as editor in chief of Annalen der Physik in 1947.
Heidland, August; Klassen, André; Sebekova, Katarina; Bahner, Udo
2009-01-01
In Rudolf Virchow's concept of inflammation, the basic alterations were derived from connective tissue cells, which underwent a marked metamorphosis. This cell-based and static conception was fundamentally broadened and, in part, refuted in the ensuing decade by 2 of his scholars. Friedrich Daniel von Recklinghausen characterized the pus cells in acute inflammation and made the seminal observation of their contractility and mobility. He was the first who described the wandering leukocytes which were demonstrated in particular in experimental keratitis. He also showed that pus cells could migrate from the places of their origin in the interstitium to other tissues and epithelial cells. Von Recklinghausen in addition contributed to the concept of phagocytosis. The work of Julius Friedrich Cohnheim was focused on the mechanisms involved in the extravasation of leukocytes from the blood vessels in the inflamed mesentery of the frog and carefully described the time-dependent alterations: dilatation of the arteries and veins, adhesion of colorless cells to the endothelial cells, and the subsequent transmigration from the capillaries and venules into the interstitial space. In the last few decades, experimental and clinical studies using modern techniques have fully confirmed and extended these basic observations made by von Recklinghausen and Cohnheim more than 100 years ago. PMID:20013736
Friedrich Nietzsche: the wandering and learned neuropath under Dionisius.
Gomes, Marleide da Mota
2015-11-01
Friedrich Nietzsche (1844-1900) was a remarkable philologist-philosopher while remaining in a condition of ill-health. Issues about his wandering/disruptive behavior that might be a consequence and/or protection against his cognitive decline and multifaceted disease are presented. The life complex that raises speculations about its etiology is constituted by: insight, creativity and wandering behavior besides several symptoms and signs of disease(s), mainly neurological one. The most important issue to be considered at the moment is not the disease diagnosis (Lissauer's general paresis or CADASIL, e.g.), but the probable Nietzsche's great cognitive reserve linked to the multifactorial etiology (genetic and environmental), and shared characteristics both to creativity and psychopathology. This makes any disease seems especial regarding Nietzsche, and whichever the diagnostic hypothesis has to consider the Nietzsche's unique background to express any disease(s). PMID:26517222
Albert Einstein and Friedrich Dessauer: Political Views and Political Practice
NASA Astrophysics Data System (ADS)
Goenner, Hubert
In this case study I compare the political views of the physicists Albert Einstein and Friedrich Dessauer between the first and second world wars, and I investigate their translation into concrete political practice. Both departed from their roles as experts in physics in favor of political engagement. The essence of Einstein's political practice seems to have been a form of political participation in exerting moral influence on people and organizations through public declarations and appeals in isolation from political mass movements. Dessauer exerted political influence both through public office (as a member of Parliament for the Catholic Center Party) and by acquiring a newspaper. The different political practice of both Einstein and Dessauer were unsuccessful in thwarting the Nazi takeover.
Karl Friedrich Zollner and the historical dimension of astronomical photometry
NASA Astrophysics Data System (ADS)
Sterken, C.; Staubermann, K. B.
This book results from presentations and discussions of a group of astronomers and historians during a one-day workshop held at Archenhold Observatory, Berlin-Treptow, on April 4, 1997. This meeting was the first forum in a series dedicated to historical aspects of observational astrophysics in the nineteenth and early twentieth century. The basic principle of these meetings is to reflect during one or more days on the work and personality of a single individual or of a group of persons, at the same time avoiding the really dominant figures that typify the age. By focusing on key people who epitomize a way of thinking and working that has formed many of the ideas by which we do astrophysical research today, we also attempt to evoke the scientific spirit of the era under consideration. In 1858, the German physicist Karl Friedrich Zoellner introduced a new type of astronomical photometer which became a bestseller in the second half of the nineteenth century and which led him to the first German professorship in astrophysics. His type of photometer allowed most accurate photometric measurements and was used at several observatories for almost half a century. This book outlines four major themes. The first part describes the observing instruments that were used by Zoellner and his contemporaries: photometers and spectrographs that complemented his original design, but also competed with his most versatile prototype photometer. The description also includes an account of technical aspects associated with the replication of such a photometer today. The second part analyses the astrophysical data that were obtained with Zoellner's tools, and extracts information hidden in the published data --- scientific information as well as diverse aspects related to the observer himself. These nineteenth-century data are now published for the first time on a modern magnitude scale and are directly accessible in tabular form, and are thus fully applicable to archeophotometric studies
[Recollections of Carl Friedrich von Weizsäcker].
Gottstein, Klaus
2014-01-01
Reminiscences and a diary of the author allow a report on meetings, conversations, experiences and joint undertakings with Carl Friedrich von Weizsäcker during five decades. They began in the winter of 1948/49 in Göttingen in the Max Planck Institute for Physics where Werner Heisenberg was the director and Weizsäcker head of the Theory Division and where the author was graduate and post-graduate student and later group and division leader. In the 1960s a close cooperation with Weizsäcker resulted from common membership in Working Committee and Board of the Federation of German Scientists (VDW). As Science Attaché at the Embassy in Washington from 1971 to 1974 the author prepared for Weizsäcker the programme of his visits to the U.S. From 1974 to 1977 he cooperated closely with Weizsäcker, preparing the sessions of the Advisory Committee to the Federal Minister of Research and Technology of which Weizsäcker was Chair. Also in later years there were illuminating discussions and correspondences. PMID:24974623
[Friedrich Mauz: T4 assessor and military psychiatrist].
Silberzahn-Jandt, G; Schmuhl, H-W
2012-03-01
Friedrich Mauz is one of the medical perpetrators of the second tier whose biography is difficult to comprehend. Autobiographies from three different political systems exist - Weimar Republic, the Third Reich, and postwar Germany in which he constantly reinvented himself. While after 1933 he suddenly emphasized his participation in the civil war turmoil during the early period of the Weimar Republic and his patriotism, he then depicted himself after 1945 as an apolitical person characterized by Württemberg pietism who inwardly rejected the Nazi State but had found himself prepared to accept "all sorts of humiliating concessions." He claimed that he had always remained true to his scientific code of conduct and had distanced himself from psychiatric genetics. In point of fact, Mauz was among those exonerated in the denazification trial in 1946 and was able to pursue his career in the Federal Republic of Germany. However, if the sources are read against the grain, a different picture emerges. Mauz's career stalled in the 1930s, not because he had been politically offensive, but because his scientific work was flimsy and considered lacking originality, particularly since he had chosen constitution research and psychotherapy as his main fields of interest, which were overshadowed by research in genetic psychiatry in the 1930s. Mauz tendered his services to the Nazi policy of genetic health, served as a medical assessor in proceedings based on the "Law for the Prevention of Genetically Diseased Offspring," permitted himself to be recruited for the T4 program as a medical expert, even participated in the deliberations on a future "Law on Euthanasia," and as a consulting psychiatrist for the German Armed Forces contributed to military medicine. PMID:22399061
Friedrich Wilhelm Bessel (1784-1846) and the Russian Astronomy
NASA Astrophysics Data System (ADS)
Ichsanova, Vera N.
In the first half of the 19th century the foundations of stellar astronomy were established thanks to the German astronomer, geodeticist and mathematician Friedrich Wilhelm Bessel. Internationally estimed and in close relationship with scientists in many countries, especially in Russia, Bessel (although not yet 30 years old) in 1814 became a foreign member of the Petersburg Academy of Sciences. Wilhelm Struve, director of the Dorpat observatory, was in close contact with him. Together they discussed problems of observational procedures and the use of instruments. In 1817 Struve bought the same Reichenbach meridian circle as Bessel used in Königsberg. Both ordered their refractors from the famous Fraunhofer workshop in Munich. %(9-inch for Dorpat). Bessel was also involved in the high precision Russian geodetic survey which started in 1816 and which succeeded in connecting the Russian and western European triangulation networks. Struve tried to measure parallaxes using the bright star Vega (α Lyrae); his results were published in 1837. Also in 1837 Bessel, using his Fraunhofer heliometer and the star 61 Cygni, found a result close to modern values, later acknowledged with the Gold Medal of the Royal Astronomical Society. In 1834 Struve was named director of the new Russian observatory in Pulkovo, St. Petersburg. Struve discussed the plans with Bessel and both acquired a Repsold meridian circle. The next aim, begun in the 1840s -- after the first determination of stellar distances -- was the distribution of stars in space (in the Milky Way). For this, catalogues with not only accurate stellar positions but also brightnesses were necessary. Thanks to Bessel's thorough reformation of measuring and reduction methods, making possible high accuracy telescopic observations, Struve was able to produce important results in stellar astronomy.
NASA Astrophysics Data System (ADS)
Glassmeier, K.-H.; Tsurutani, B. T.
2014-02-01
This is a translation of the Allgemeine Theorie des Erdmagnetismus published by Carl Friedrich Gauss in 1839 in the Resultate aus den Beobachtungen des Magnetischen Vereins im Jahre 1838. The current translation is based on an earlier translation by Elizabeth Juliana Sabine published in 1841. This earlier translation has been revised, corrected, and extended. Numerous biographical comments on the scientists named in the original text have been added as well as further information on the observational material used by Carl Friedrich Gauss. An attempt is made to provide a readable text to a wider scientific community, a text laying the foundation of today's understanding of planetary magnetic fields.
"Dancing Cannot Start Too Soon": Spiritual Education in the Thought of Jean Paul Friedrich Richter
ERIC Educational Resources Information Center
Pridmore, John
2004-01-01
Johann Paul Friedrich Richter (1763-1825) adopted the pen-name "Jean Paul" in honour of Jean Jaques Rousseau. His "Levana or the doctrine of education" ("Levana oder Erziehlehre") was once a standard text and required reading in teacher education. Outside Germany the name of Jean Paul is now little known and the seminal educational text for which…
ERIC Educational Resources Information Center
Provenzo, Eugene F., Jr.
2009-01-01
Friedrich Froebel, the German educator and founder of the Kindergarten Movement, developed a series of play materials including geometric building blocks and pattern activity blocks designed to teach children about forms and relationships found in nature. Froebel's notions about using activity and play in preschool education complement many…
Friedrich Durrenmatt's Tragicomedy of the Grotesque "The Visit" in an Intermediate German Course.
ERIC Educational Resources Information Center
Modzelewski, Jozef A.
A description is provided of "Der Besuch," a written companion to the Houghton Mifflin Company's standard edition of the drama "Der Besuch der alten Dame (The Old Lady's Visit)," written in 1956 by the distinguished Swiss playwright Friedrich Durrenmatt. The drama is an excellent choice for any intermediate or advanced language course that seeks…
ERIC Educational Resources Information Center
Friedrichs, Terence Paul; Shaughnessy, Michael F.
2015-01-01
In this reflective interview with Terry Friedrichs--a hands-on academic-learning specialist and researcher with gifted students with Asperger Syndrome--he defines these pupils, describes their "straightforward" and confusing traits, and recounts his initial and later instructional experiences with them over several decades. The piece…
Two Rival Conceptions of Vocational Education: Adam Smith and Friedrich List.
ERIC Educational Resources Information Center
Winch, Christopher
1998-01-01
Examines and discusses two views of political economy: (1) the classical model of Adam Smith; and (2) the social capitalist model associated with Friedrich List. Explores two varieties of vocational education and training that emerge from a comparison of Smith's and List's ideas. (CMK)
ERIC Educational Resources Information Center
Vinterbo-Hohr, Aagot; Hohr, Hansjorg
2006-01-01
Friedrich Schiller (1759-1805), German poet, dramatist, philosopher and publisher, was a prominent contributor to the educational neo-humanistic concept of Bildung at the threshold to Romanticism. Schiller assigns a pivotal role to the aesthetic education arguing that aesthetic activity reconciles sensuousness and reason and thereby creates the…
NASA Astrophysics Data System (ADS)
Zimmermann, Bernhard
At the suggestion of the Prussian military geodesist Johann Jacob Baeyer, the government of Mecklenburg decided in 1853 to undertake an ordnance survey on a trigonometric basis. It appointed Friedrich Paschen (1804-1873) as the scientific and technical head of this survey. Paschen was a lawyer, but visited Gauss' lectures on mathematics, astronomy and geodesy during his student years in Göttingen. This paper gives an account of the astronomical-geodetic works. For the first time also parts of Paschen's correspondence with Gauss and other scientists is published.
Wilkes, J
2000-04-01
The philosopher Friedrich Nietzsche was one of the most famous patients in the psychiatric hospital Jena. Between 1889 and 1890, Otto Binswanger und Theodor Ziehen treated the progressive paralysis of Friedrich Nietzsche whose 100th anniversary of death is on 25th August 2000. After Nietzsche's death, an animated discussion about his disease arose. Many objected against the syphilitic diagnosis of the disease. Nietzsche's medical fill became a popular object of science, although it ended as a very odd story. PMID:10812640
Werner Heisenberg and Carl Friedrich Freiherr von Weizsäcker: A Fifty-Year Friendship*
NASA Astrophysics Data System (ADS)
Cassidy, David C.
2015-03-01
This paper follows Werner Heisenberg and Carl Friedrich von Weizsäcker during their fifty-year friendship from 1926, when they first met in Copenhagen, to Heisenberg's death in Munich in 1976. The relationship underwent profound changes during that period, as did physics, philosophy, and German society and politics, all of which exerted important influences on their lives, work, and interactions with each other. The nature of these developments and their impact are explored in this paper.
["Living with the bomb" - Carl Friedrich von Weizsäcker's path from physics to politics].
Walker, Mark
2014-01-01
Carl Friedrich von Weizsäcker spanned a spectrum from physics to politics, with philosophy in-between. This chapter surveys the most controversial part of his career, including his work on nuclear weapons and participation in cultural propaganda during the Second World War, his subsequent active political engagement during the postwar Federal German Republic, in particular the role of nuclear weapons, and his participation in myths surrounding Hitler's Bomb". PMID:24974611
[Carl Friedrich von Weizsäcker's philosophy of the mind].
Lyre, Holger
2014-01-01
The paper deals with Carl Friedrich von Weizsäcker's position within the philosophy of mind. It turns out that Weizsäcker's ontology is based on an unorthodox conception both in the philosophy of physics and in the philosophy of mind. His quantum information theoretic reductionism is based on a subtle combination of atomism and holism, his philosophy of mind connected to this is a neutral monism, which proposes a bold intertwining of mind, matter, and space. PMID:24974603
NASA Astrophysics Data System (ADS)
Lakaev, Saidakhmat; Darus, Maslina; Kurbanov, Shaxzod
2013-05-01
A family Hμ(p), μ > 0, p\\in {T} of the generalized Friedrichs model with perturbation of rank 1, associated with a system of two particles, moving on the one-dimensional lattice {Z} is considered. The existence of a unique eigenvalue E(μ, p), of the operator Hμ(p) lying below the essential spectrum is proved. For any p from a neighborhood of the origin, the Puiseux series expansion for eigenvalue E(μ, p) at the point μ = μ(p) ⩾ 0 is found. Moreover, the asymptotics for E(μ, p) is established as μ → +∞.
[Carl Friedrich von Weizsäcker and the Bethe-Weizsäcker cycle].
Wiescher, Michael
2014-01-01
The Carbon- or Bethe-Weizsäcker Cycle plays an important role in astrophysics as one of the most important energy sources for a quiescent and explosive hydrogen burning in stars. This paper presents the historical background and the contributions by Carl Friedrich von Weizsäcker and Hans Bethe who provided the first predictions of the cycle. Furthermore, it discussed the experimental verification of the predicted process in the following decades. Also discussed is the extension of the initial Carbon cycle to the CNO multi-cycles and the hot CNO cycles which followed from the detailed experimental studies of the associated nuclear reactions. Finally discussed is the impact of the experimental and theoretical results on our present understanding of hydrogen burning in different stellar environments and on our understanding of the chemical evolution of our universe. PMID:24974598
Friedrich Berthold Reinke (1862-1919): brilliant yet troubled anatomist of the vocal fold.
Senior, A
2015-11-01
Reinke's space is a critical laryngeal structure, and the eponym remains in current use in both clinical and research settings. However, little is known about the life of the German anatomist Friedrich Berthold Reinke. His name is missing from the otolaryngological histories, despite his work on the structure he described being responsible for a fundamental advance in our understanding of the larynx. Although brilliant, Reinke was described as impetuous and coarse by his colleagues, resulting in his academic career being cut short. Reinke's relative anonymity is thought to derive from the fact that he never defined himself as a laryngologist. Without question, Reinke's observations of the human vocal fold are substantive contributions, without which modern laryngology could not have evolved. This article aimed to summarise this brilliant yet troubled man's life and achievements, allowing appreciation for his singular genius and fundamental contribution to laryngology. PMID:26521816
[The ambivalence concept by Carl Friedrich von Weizsäcker - attempt at an exegesis].
Laitko, Hubert
2014-01-01
Carl Friedrich von Weizsäcker treated the problematic implications of scientific-technological progress, emerging in the lifetime of his generation, under the key-word "ambivalence". Obviously it means a proto-theoretical, fuzzy concept that cannot be introduced explicitly per definition; starting with an intuitive perception, "ambivalence" should gradually gain meaning by using it in different argumentative contexts. Following a circular course (Kreisgang)--a procedure typical for Weizsäcker's style of thought--, he moves successively from explicit ambivalence in the application sphere of science through ambivalent features in scientists' behaviour and action up to the general ambivalence of human existence, disclosed only at an anthropological level of deliberation. The given paper delineates the ambivalence concept used by Weizsäcker during the 1960s and 1970s. PMID:24974609
[Friedrich Nietzsche: life and work in the struggle against his suffering].
Kaiser, Otto
2005-01-01
This paper examines the connection between the life, sense of mission and suffering in the work of Friedrich Nietzsche. It shows that, as early as his Basel years, he wanted to become a philosopher who was willing to transmit without fear what he considered to be true to everybody, even if he would have to suffer and remain unappreciated. He was afflicted with increasing numbers of headaches and bouts of nausea from the mid-1870s and was further handicapped by constantly deteriorating vision. The ten years before his breakdown were spent as a traveller searching for a place where his suffering could be eased. The isolation imposed on him by the illness gave him the inner freedom to break the old certainties and to offer a new myth as an alternative. His failure as a writer was compensated by an intensified and, finally, gross sense of mission which ended in mental derangement in early January 1889. PMID:17144613
Triarhou, Lazaros C
2012-01-01
This article highlights the life and work of Bernhard Pollack (1865-1928), a pioneer neurohistologist, ophthalmologist, and world-class pianist. In 1897, Pollack published the first standard manual on staining methods for the nervous system. Born into a Prussian-Jewish family, he received his piano education from the composer Moritz Moszkowski and his pathology education from Carl Weigert. Pollack worked in the Institutes of Wilhelm Waldeyer (anatomy), Emanuel Mendel (neuropsychiatry), the later Nobel laureate Robert Koch (infectious diseases), and the Eye Policlinic of Paul Silex (ophthalmology), becoming a Professor of Ophthalmology at Berlin's Friedrich-Wilhelms-Universität in 1919. The study also chronicles the founding by Pollack of the Berlin Doctors' Orchestra in 1911. PMID:22572721
Carl Friedrich Richard Foerster (1825-1902) - the inventor of perimeter and photometer.
Grzybowski, Andrzej; Sobolewska, Bianka
2015-09-01
Carl Friedrich Richard Foerster (1825-1902) was a German who was born in the Polish city Leszno. He studied medicine at the Medical Faculty of Breslau (now Wroclaw, Poland) University, and later in Heidelberg and Berlin. From 1855, he worked in Breslau, where he established in 1857 the first ophthalmology clinic. Later, he became a professor in ophthalmology, the first director of the Department of Ophthalmology at the University of Breslau, and even the rector of this University. Forster did many pioneering works on visual fields, invented a photometer and the first perimeter, known for many years as the Foerster perimeter. Moreover, he studied night blindness, visual field changes due to different pathologies, and many eye diseases, including glaucoma, cataract, retinal and choroidal diseases. PMID:25833059
Vital forces and organization: philosophy of nature and biology in Karl Friedrich Kielmeyer.
Gambarotto, Andrea
2014-12-01
The historical literature on German life science at the end of the 18th century has tried to rehabilitate eighteenth century vitalism by stressing its difference from Naturphilosophie. Focusing on the work of Karl Friedrich Kielmeyer this paper argues that these positions are based on a historiographical bias and that the clear-cut boundary between German vitalism and Naturphilosophie is historically unattested. On the contrary, they both belong to the process of conceptual genealogy that contributed to the project of a general biology. The latter emerged as the science concerned with the laws that regulate the organization of living nature as a whole. The focus on organization was, at least partially, the result of the debate surrounding the notion of "vital force", which originated in the mid-eighteenth century and caused a shift from a regulative to a constitutive understanding of teleology. PMID:25168014
Friedrich Berthold Reinke (1862-1919): anatomist of the vocal fold.
Dräger, Désirée Louise; Branski, Ryan C; Wree, Andreas; Sulica, Lucian
2011-05-01
Although Reinke's space, or layer, is a critical laryngeal structure, and the eponym is in current use in both clinical and research milieus, little is known about the life of the eponymist, German anatomist Friedrich Berthold Reinke. Extensive investigation of the archives at the University of Rostock and other sources, as well as multinational collaboration, has yielded unique insight into the personal and professional life of this pioneer who, among other things, identified and characterized the subepithelial space of the vocal fold and structures in the Leydig cells of the testicles and ovaries. This breadth of investigation reflects Reinke's intellectual curiosity and broad-ranging interest as well as his scientific environment. Without question, Reinke's observations of the human vocal fold are substantive contributions, without which modern laryngology could not have evolved. In 2009, at the 90th anniversary of Reinke's death, we summarize his achievements to express our appreciation for his singular brilliance and fundamental contribution to laryngology. PMID:20488661
NASA Astrophysics Data System (ADS)
Schembor, Friedrich Wilhelm
The Urania Observatory in Vienna and the life and workings of the Viennese astronomer Friedrich Viktor Schembor are the topics of this volume. The first part deals with the history of the Urania Observatory and its significance as the oldest popular observatory in Vienna for the education of adults. After a short digression on the development of popular educational activities in the 19th century, the efforts are traced that led to the establishment of the Urania Observatory. The second part deals with the biography of the astronomer Friedrich Viktor Schembor (1898-1942). Already at an early age he committed himself as a volunteer for popular education in astronomy. In his time as director of the Urania Observatory, he was able to guide the “Astronomische Gemeinde” (Astronomical Congregation) to scientifically useful results. Because of a vicious disease, he was given only a short time of scientific work at the Vienna University Observatory.
NASA Astrophysics Data System (ADS)
Mori, Takashi
2015-02-01
The Floquet eigenvalue problem is analyzed for periodically driven Friedrichs models on discrete and continuous space. In the high-frequency regime, there exists a Floquet bound state consistent with the Floquet-Magnus expansion in the discrete Friedrichs model, while it is not the case in the continuous model. In the latter case, however, the bound state predicted by the Floquet-Magnus expansion appears as a metastable state whose lifetime diverges in the limit of large frequencies. We obtain the lifetime by evaluating the imaginary part of the quasienergy of the Floquet resonant state. In the low-frequency regime, there is no Floquet bound state and instead the Floquet resonant state with exponentially small imaginary part of the quasienergy appears, which is understood as the quantum tunneling in the energy space.
[Carl Friedrich von Weizsäcker and the Society of German Scientists].
Bieber, Hans-Joachim
2014-01-01
The Federation of German Scientists (VDW) was founded in 1959 as West-German pendant of the Federation of American Scientists and as West-German group of the Pugwah Conferences. From the beginning, Carl Friedrich von Weizsäcker played a leading role in the VDW and pleaded for influencing politicians by scientifically and politically uncontestable studies, in the 1960s mainly of the effects of nuclear war and world food affairs. These studies were conducted by a research institute in Hamburg funded by external funds, industry and banks. It was the nucleus of the "Max Planck Institute for living conditions of the technical-industrial world" founded in Starnberg in 1969. Due to a "super inheritance", the research institute was continued in addition to the Starnberg institute. Young Marxist social scientists published several studies here which the executive board of the VDW disapproved of. Numerous prominent members left the VDW, donations decreased rapidly. In 1975, the research institute was closed down. PMID:24974613
Model building with wind and water: Friedrich Ahlborn's photo-optical flow analysis.
Hinterwaldner, Inge
2015-02-01
Around 1900, several experimenters investigated turbulences in wind tunnels or water basins by creating visualizations. One of them, the German zoologist Friedrich Ahlborn (1858-1937), was familiar with the works by his contemporaries but he struck a new path. He combined three different kinds of photographs taken at the same time and showed the same situation in his water trough-but each in a different way. With this first basic operation, Ahlborn heuristically opened up a previously non-existent space for experimentation, analysis, and recombination. He generated an astonishing diversity of information by adopting the tactics of 'inversions' in which he interpreted one part of the experimental setup, or its results, in different ways. Between the variants of the 'autographs' which he developed, he defined areas of intersection to be able to translate results from individual records into each other. To this end, Ahlborn created other sets of visual artifacts such as drawn diagrams, three-dimensional wire frame constructions, and clay reliefs. His working method can be described as a cascading array of successive modeling steps, as elaborated by Eric Winsberg (1999), or of inscriptions in Bruno Latour's words (Latour, 1986). By examining Ahlborn's procedures closely we propose conceptualizations for the experimenter's various operations. PMID:26109406
Vitalism and synthesis of urea. From Friedrich Wöhler to Hans A. Krebs.
Kinne-Saffran, E; Kinne, R K
1999-01-01
In 1828, Friedrich Wöhler, a German physician and chemist by training, published a paper that describes the formation of urea, known since 1773 to be a major component of mammalian urine, by combining cyanic acid and ammonium in vitro. In these experiments the synthesis of an organic compound from two inorganic molecules was achieved for the first time. These results weakened significantly the vitalistic hypothesis on the functioning of living cells, although Wöhler, at that time, was more interested in the chemical consequences of isomerism than in the philosophical implications of his finding. However, the chemical synthesis observed by Wöhler does not represent the reaction which is employed in the mammalian liver for urea synthesis. The mechanism of this process was elucidated by the German physician Hans A. Krebs and his medical student Kurt Henseleit in 1932 and was shown to include the ornithine cycle. This 'urea cycle' is only observed in living cells; this apparently vitalistic phenomenon is caused by the compartmentalization of the various enzymatic reactions in mitochondria and cytosol, respectively. PMID:10213830
[Carl Friedrich von Weizsäcker and the interpretations of quantum theory].
Stöckler, Manfred
2014-01-01
What are 'interpretations' of quantum theory? What are the differences between Carl Friedrich von Weizsäkcker's approach and contemporary views? The various interpretations of quantum mechanics give diverse answers to questions concerning the relation between measuring process and standard time development, the embedding of quantum objects in space ('wave-particle-dualism'), and the reference of state vectors. Does the wave function describe states in the real world or does it refer to our knowledge about nature? First, some relevant conceptions in Weizsäcker's book The Structure of Physics (Der Aufbau der Physik, 1985) are introduced. In a second step I point out why his approach is not any longer present in contemporary debates. One reason is that Weizsäcker is mainly affected by classical philosophy (Platon, Aristoteles, Kant). He could not esteem the philosophy of science that was developed in the spirit of logical empiricism. So he lost interest in disputes with Anglo-Saxon philosophy of quantum mechanics. Especially his interpretation of probability and his analysis of the collapse of the state function as change in knowledge differ from contemporary standard views. In recent years, however, epistemic interpretations of quantum mechanics are proposed that share some of Weizsäcker's intuitions. PMID:24974602
[Carl Friedrich von Weizsäcker's design of a unity of physics].
Görnitz, Thomas
2014-01-01
As I learned in many conversations with Carl Friedrich von Weizsäcker, he saw his place in the history of science deriving from his "Theory of Urs". This theory will establish the unity of science on the basis of quantum bits. Any attempts to find some "fundamental bricks"--of whatever kind--must fail because of the antinomies of atomism. An abstract quantum bit is a structure quantum that cannot be conceived as a particle in space and time. However, it is clear, solely for logical reasons, that a quantum bit is an ultimate and indecomposable entity. Weizsäcker's revolutionary goal was--already 50 years ago--to unite quantum theory with cosmology and, on these grounds, proceed to a theory of elementary particles. The article gives a short overview of Weizsäcker's approach to the unity of physics, ending with a brief summary of what has been achieved in that endeavour up to now. PMID:24974600
Friedrich Albert Lange on neo-Kantianism, socialist Darwinism, and a psychology without a soul.
Teo, Thomas
2002-01-01
Friedrich Albert Lange was a German philosopher, political theorist, educator, and psychologist who outlined an objective psychology in the 1860s. This article shows how some of the most important worldviews of the nineteenth century (Kantianism, Marxism, and Darwinism) were combined creatively in his thought system. He was crucial in the development of neo-Kantianism and incorporated psycho-physiological research on sensation and perception in order to defend Kant's epistemological idealism. Based on a critique of phrenology and philosophical psychology of his time, Lange developed a program of a psychology without a soul. He suggested that only those phenomena that can be observed and controlled should be studied, that psychology should focus on actions and speech, and that for each psychological event the corresponding physical or physiological processes should be identified. Lange opposed introspection and subjective accounts and promoted experiments and statistics. He also promoted Darwinism for psychology while developing a socialist progressive-democratic reading of Darwin in his social theory. The implications of socialist Darwinism on Lange's conceptualization of race are discussed and his prominence in nineteenth century philosophy and psychology is summarized. PMID:12115788
Generalized Eigenvectors for Resonances in the Friedrichs Model and Their Associated Gamov Vectors
NASA Astrophysics Data System (ADS)
Baumgärtel, Hellmut
A Gelfand triplet for the Hamiltonian H of the Friedrichs model on ℝ with multiplicity space { K}, dim { K}<∞ , is constructed such that exactly the resonances (poles of the inverse of the Livšic-matrix) are (generalized) eigenvalues of H. The corresponding eigen(anti)linear forms are calculated explicitly. Using the wave matrices for the wave (Möller) operators the corresponding eigen(anti)linear forms on the Schwartz space { S} for the unperturbed Hamiltonian H0 are also calculated. It turns out that they are of pure Dirac type and can be characterized by their corresponding Gamov vector λ → k/(ζ0 - λ)-1, ζ0 resonance, k∈ { K}, which is uniquely determined by restriction of { S} to { S} cap { H}+2, where { H}+2 denotes the Hardy space of the upper half-plane. Simultaneously this restriction yields a truncation of the generalized evolution to the well-known decay semigroup for t ≥ 0 of the Toeplitz type on { H}+2. That is: Exactly those pre-Gamov vectors λ → k/(ζ - λ)-1, ζ from the lower half-plane, k in { K}, have an extension to a generalized eigenvector of H if ζ is a resonance and if k is from that subspace of { K} which is uniquely determined by its corresponding Dirac type antilinear form.
[Carl Friedrich von Weizsäcker's language, rhetoric and habitus].
Hentschel, Klaus
2014-01-01
Carl Friedrich von Weizsäcker was not only an exceptional physicist, philosopher and peace scholar, but also a skilled and articulate speaker and a highly successful author. Dozens of his books were published in tens of thousands of copies despite their highly nontrivial content. This wide impact was only possible--this at least is one of the claims made in this paper--because of his sophisticated style and rhetorics. The analysis here is based on hand-picked samples from all kinds of Weizsäcker texts (talks, scientific and popular papers and books, poems and Limericks). Strangely enough, this interesting stylistic and rhetorical facet of his oeuvre has hitherto not been analyzed in any detail despite its crucial importance in the broad impact on his multifarious audience. My paper starts out from a collection of striking features of his language and structural specialties in his published talks and speeches, and explore findings from sound recordings and film tapes which offer further insight into his manner of emphasis, usage of pauses and intonation. On the basis of these stylistic traits and their often subcutaneous, but nevertheless clever rhetorics, I close with a few remarks on the habitus of this scholar and his positioning within the ensemble of German-speaking physicists of that generation. PMID:24974596
Cabello C, Felipe
2013-04-01
Georg Friedrich Nicolai (1874-1964) was a German physician and physiologist whose pacifism during the First World War led him in 1914 to cosign with W. J. Foerster, A. Einstein and O. Bueck a "Manifesto to the Europeans" against the entry of Germany into the war and the invasion of Belgium. As a result of this appeal and his strong pacifism, Nicolai lost his positions as cardiologist to the German royal family, professor at the University of Berlin and chief of laboratory at the Charite hospital also in Berlin, and was sent as a garrison physician in Graundenz, in today's Poland. There he began to write his book, The Biology of War. It managed to avoid censorship and was published in Leipzig in 1916. He was court-martialed in Danzig in 1916 but escaped to Denmark. Nicolai was reinstated to his faculty positions by the Weimar Republic after the war but was subsequently forced to emigrate from Germany to South America by the pressure of right wing student groups who accused him of being a deserter and a traitor. From 1922 to 1932 Nicolai lived in Argentina, and from 1932 until his death in 1964, in Chile. In this later country Nicolai was professor in the University of Chile and interacted with members of the Chilean intelligentsia, including the poets Vicente Huidobro, Gonzalo Rojas and Pablo Neruda. Through his friendship with Chilean psychiatrist Agustin Tellez, Nicolai influenced the development of phenomenological psychiatric school in Chile. The Chilean novelist Fernando Alegria compared him favorably with Robert J. Oppenheimer and Linus Pauling. PMID:23900377
[Carl Friedrich von Weizsäcker: nuclear disarmament and the search for freedom].
Neuneck, Götz
2014-01-01
Carl Friedrich von Weizsäcker's comprehensive contributions to nuclear disarmament and arms control, as well as his peace policy impulses are to be understood primarily in the context of his family origin, his comprehensive thinking and the historical circumstances of the emerging nuclear age. They have a scientific, political and a strong philosophical-moral component. Beside the factual problems (nuclear energy, military strategy) he was interested in political power issues and their ambivalence and perception. His actual work is not only based on general academic knowledge, but also serve the immediate political influence on a scientific basis. Weizsäcker was not committed to nuclear disarmament or arms control per se, but about creating a lasting peace policy in the nuclear age. The paper discusses in chronological order of Weizsäcker's work within the policy field peace and disarmament. Family origin, study and work on the nuclear programme by Nazi-Germany laid the foundations for his later career. As a young physicist, he was directly involved in the political and ethical dilemma of the military and civilian use of nuclear energy. After the war, in Göttingen and Hamburg the reflections of the Nazi phase and the discussion of ways out of the dangers of the Cold War followed. The Max-Planck Institute in Starnberg dealt with the science-based treatment of global world problems, including the dangers of nuclear proliferation. Finally, Weizsäcker initiated a Peace Council in 1985. He urged both the perception of the moral responsibility of scientists as well as an ethics of the scientific-technological age. According to him, a general and profound change in the consciousness of humankind is needed to solve the existing power problems and the problem of war. PMID:24974615
NASA Astrophysics Data System (ADS)
Djoufedie, George Noel; Felaco, Elisabetta; Rubino, Bruno; Sampalmieri, Rosella
2016-03-01
This paper is devoted to the compactness framework and the convergence theorem for the Lax-Friedrichs and Godunov schemes applied to a {2 × 2} system of non-strictly hyperbolic nonlinear conservation laws that arises from mathematical models for oil recovery. The presence of a degeneracy in the hyperbolicity of the system requires a careful analysis of the entropy functions, whose regularity is necessary to obtain the result. For this purpose, it is necessary to combine the classical techniques referring to a singular Euler-Poisson-Darboux equation with the compensated compactness method.
Rummler, S
2004-06-01
This article is dedicated in remembrance of Friedrich Wilhelm von Halem, a former student of the University Frankfurt-on-Oder (Viadrina) in later eighteenth-century Germany. Friedrich Wilhelm von Halem from Aurich, was the first physician in the period of the German Enlightenment, who had introduced the thalasso-therapy as a part of a new health-conception. His pioneering achievement led to the foundation of the first health resort on the german coast of the North-Sea in Norderney (East Frisian Islands), May 1797. PMID:15236096
Nogaller, Alexander
2005-01-01
Adalbert Friedrich Markus (1753-1816) was one of the most eminent doctors of his time. His name was given not accidentally to one of the largest squares, a street and a bridge across the river Regnitz in Bamberg, the town where he worked more than 40 years. Markus was well-known among the population as an excellent doctor, he also was a personal doctor of Kurfürst bishop Franz Ludwig von Erthal. Markus was the first principal to found a hospital affordable to everyone, where medical personnel was taught and many professors worked. He was also founder and principal of the medico-surgical school, whose program of studies was equal to those of an university. On Markus' initiative a birthhouse was founded, as well as a sheltered housing complex for the elderly and a school, as well as a social system for poor citizens. In January 1803 Markus became the head of the health department of the principality of Frankonia. On his initiative a free smallpocks vaccination for all new born was carried out. Markus brought up an annual report of medical science and numerous magazines on therapy. In his scientifical articles in different magazines he wrote about diseases of respiratory tract, skin, liver, as well as typhus and feaver. In many of his published works he appears to be a philosopher supporting a naturalistic philosophy and disagreeing with its idealistic attitude at the same time. He was the head of a literature society called "Harmony", and he supported the construction of the first theatre where E. T. A Hoffmann worked who was a friend of Markus. A. F. Markus' death 1816 put his friends and supporters into a deep grief. According to the newspapers of that time, the whole town followed the funeral procession and all the churches rang their bells goodbye. The name of A. F. Markus has an important place among the extraordinary German physicians of the late 18th and early 19th century. PMID:17153321
NASA Astrophysics Data System (ADS)
Schwemin, Friedhelm
Friedrich Wilhelm Tönnies' name is hardly found in the major histories of astronomy. This is not surprising since he died before the age of twenty-one. Nevertheless, and perhaps because he knew at heart that not much time was granted to him, he left an astonishingly prolific oeuvre which indicates his rich talents. His contemporaries also testify that this son af a wealthy textile merchant had a great talent. But it is idle to speculate whether he would have become a second Bessel, or just an inconspicuous high school teacher in some remote Prussian province. He experienced a decisive career advancement by the Berlin astronomer J.E. Bode, obtained his Ph.D. already at the age of nineteen, published, among other things, about the large solar eclipse of November 19, 1816, and corresponded with several professional astronomers, before he succumbed to a pulmonary disease.
[A failed experiment - Carl Friedrich von Weizsäcker, Jürgen Habermas and the Max-Planck Society].
Leendertz, Ariane
2014-01-01
From 1970 to 1980 Carl Friedrich von Weizsäcker headed the Max-Planck-lnstitut zur Erforschung der Lebensbedingungen der wissenschaftlich-technischen Welt (MPI for the study of the living conditions of the world of science and technology) in Starnberg, jointly with Jürgen Habermas since 1971. From the start, the Max Planck Society regarded the new institute as an experiment that might perhaps be aborted a few years later. This is exactly what happened. With the retirement of Weizsäcker, his section was closed and the whole institute was renamed. In 1981. Habermas resigned, and then the institute was closed. This paper focusses on some of the problem constellations within the institute that partly explain its development and eventual closure: its birth out of the idea of scientific policy advice, the debates within the Max Planck Society and the complex relationship between Weizsäcker and Jürgen Habermas. PMID:24974605
Meyer-Abich, Michael
2014-01-01
(1) Quantum theory deals not just with reality but with the physical (scientific) reality of its objects. Carl Friedrich von Weizsäcker understood this to imply that scientific knowledge of objects converges with philosophical knowledge of their objectivity but did not succeed in rounding off physics. (2) We are actors as well as spectators not only in scientific knowledge but in political processes as well, particularly by means of science. It is, therefore, not justified to deny political responsibility even in 'basic research'. Carl Friedrich von Weizsacker identified classical physics as the venture of knowledge without love but believed that this boundary could be transcended. The apparent neutrality of science must not be tolerated by the churches, however. (3) In religion Weizsäcker felt most at home in Buddhist spirituality, this being akin to Christian spirituality which has been more or less lost by the Christian churches. Yet he tried to support his church and to participate in its actions. (4) Lack of love corresponds to an excess of power in the religious critique of science. In both respects Weizsäcker presented the mirror to industrial society but people in general did not recognize their image. The Max-Planck-Society, however, shut up Weizsäcker's "Institute for the study of the conditions of life in the modern world" (Starnberg 1970-1980) as soon as possible. (5) Weizsäcker always refrained from exerting any power except that of reason or truth. According to Lao Tse this is the power least perceived as such. In politics he generally followed the mainstream after once having been tempted to action in 1941/42. His influence on German society was based on his charismatic spirituality. PMID:24974621
Brückner, Burkhart
2016-01-01
Friedrich Krauß (1791-1868) is the author of Nothschrei eines Magnetisch-Vergifteten [Cry of Distress by a Victim of Magnetic Poisoning] (1852), which has been considered one of the most comprehensive self-narratives of madness published in the German language. In this 1018-page work Krauß documents his acute fears of 'mesmerist' influence and persecution, his detainment in an Antwerp asylum and his encounter with various illustrious physicians across Europe. Though in many ways comparable to other prominent nineteenth-century first-person accounts (eg. John Thomas Perceval's 1838 Narrative of the Treatment Experienced by a Gentleman or Daniel Paul Schreber's 1903 Memoirs of my Nervous Illness), Krauß's story has received comparatively little scholarly attention. This is especially the case in the English-speaking world. In this article I reconstruct Krauß's biography by emphasising his relationship with physicians and his under-explored stay at the asylum. I then investigate the ways in which Krauß appropriated nascent theories about 'animal magnetism' to cope with his disturbing experiences. Finally, I address Krauß's recently discovered calligraphic oeuvre, which bears traces of his typical fears all the while showcasing his artistic skills. By moving away from the predominantly clinical perspective that has characterised earlier studies, this article reveals how Friedrich Krauß sought to make sense of his experience by selectively appropriating both orthodox and non-orthodox forms of medical knowledge. In so doing, it highlights the mutual interaction of discourses 'from above' and 'from below' as well as the influence of broader cultural forces on conceptions of self and illness during that seminal period. PMID:26651186
Brückner, Burkhart
2016-01-01
Friedrich Krauß (1791–1868) is the author of Nothschrei eines Magnetisch-Vergifteten [Cry of Distress by a Victim of Magnetic Poisoning] (1852), which has been considered one of the most comprehensive self-narratives of madness published in the German language. In this 1018-page work Krauß documents his acute fears of ‘mesmerist’ influence and persecution, his detainment in an Antwerp asylum and his encounter with various illustrious physicians across Europe. Though in many ways comparable to other prominent nineteenth-century first-person accounts (eg. John Thomas Perceval’s 1838 Narrative of the Treatment Experienced by a Gentleman or Daniel Paul Schreber’s 1903 Memoirs of my Nervous Illness), Krauß’s story has received comparatively little scholarly attention. This is especially the case in the English-speaking world. In this article I reconstruct Krauß’s biography by emphasising his relationship with physicians and his under-explored stay at the asylum. I then investigate the ways in which Krauß appropriated nascent theories about ‘animal magnetism’ to cope with his disturbing experiences. Finally, I address Krauß’s recently discovered calligraphic oeuvre, which bears traces of his typical fears all the while showcasing his artistic skills. By moving away from the predominantly clinical perspective that has characterised earlier studies, this article reveals how Friedrich Krauß sought to make sense of his experience by selectively appropriating both orthodox and non-orthodox forms of medical knowledge. In so doing, it highlights the mutual interaction of discourses ‘from above’ and ‘from below’ as well as the influence of broader cultural forces on conceptions of self and illness during that seminal period. PMID:26651186
Pospischil, Andreas
2015-08-01
Karl Friedrich Meyer (KF) was born and educated as a veterinarian in Europe; he researched infectious diseases in Europe, South Africa and the United States. He is one of the true forefathers of the 'one health-one medicine' concept. The broad scope of his research covered botulism, leptospirosis, brucellosis, plague, ornithosis, Western equine encephalitis, mussel poisoning and clostridia. This manuscript adds some more details of his early biography. PMID:26032783
Zigman, Peter M
2009-01-01
This article for the first time provides an edition and commentary of the letters of Friedrich Ratzel to his older colleague, teacher and mentor, Ernst Haeckel, which are kept in the archive of the Ernst-Haeckel-House (memorial museum) in Jena. Altogether fifteen letters and one postcard are presented. Haeckel's letters to Ratzel are considered to be lost. The edition is prefaced with a detailed description of Ratzel's life, career and work, as a part of the edition. PMID:20509448
Dräger, D L; Protzel, C; Hakenberg, O W
2014-08-01
The 95th anniversary of the anatomist Friedrich Berthold Reinke's death is 19 May 2014. This an excellent moment to remember his anatomical research. Two structures which he discovered and first described continue to be associated with his name: Reinke crystals of testicular Leydig cells and Reinke's space in the larynx. Reinke's crystals are crystalline protein aggregates within interstitial Leydig cells which are probably associated with testosterone production. They are pathognomonic for Leydig cell tumours. PMID:25027714
NASA Astrophysics Data System (ADS)
Sterken, C.; Staubermann, K. B.
This book results from presentations and discussions of a group of astronomers and historians during a one-day workshop held at Archenhold Observatory, Berlin-Treptow, on April 4, 1997. This meeting was the first forum in a series dedicated to historical aspects of observational astrophysics in the nineteenth and early twentieth century. The basic principle of these meetings is to reflect during one or more days on the work and personality of a single individual or of a group of persons, at the same time avoiding the really dominant figures that typify the age. By focusing on key people who epitomize a way of thinking and working that has formed many of the ideas by which we do astrophysical research today, we also attempt to evoke the scientific spirit of the era under consideration. In 1858, the German physicist Karl Friedrich Zoellner introduced a new type of astronomical photometer which became a bestseller in the second half of the nineteenth century and which led him to the first German professorship in astrophysics. His type of photometer allowed most accurate photometric measurements and was used at several observatories for almost half a century. This book outlines four major themes. The first part describes the observing instruments that were used by Zoellner and his contemporaries: photometers and spectrographs that complemented his original design, but also competed with his most versatile prototype photometer. The description also includes an account of technical aspects associated with the replication of such a photometer today. The second part analyses the astrophysical data that were obtained with Zoellner's tools, and extracts information hidden in the published data --- scientific information as well as diverse aspects related to the observer himself. These nineteenth-century data are now published for the first time on a modern magnitude scale and are directly accessible in tabular form, and are thus fully applicable to archeophotometric studies
Schirrmacher, Arne
2014-01-01
Both Carl Friedrich von Weizsäcker und Max Born belong to the most active scientists, which have raised their voice for peace in the 1950s. While Born, senior to Weizsäcker by one generation, engaged in peace movements at an early stage, which was also due to his emigration, and was a driving force for the Einstein-Russell memorandum, Weizsäcker entered the stage essentially with the Göttingen declaration but quickly dominated the discourse. The comparison of their different engagements for peace sheds new light on Weizsäcker. Unlike the German emigrant with a British passport, who was mainly influenced by EInstein and Russell as well as some socialist thoughts he had encountered at an early age, the son of a noble diplomat and the physicist, who was saved from military duties because of his work in the German wartime nuclear project, had quite a different perspective on the postwar atomic threat. The relation of Born and Weizsäcker remained marked by a certain distance even when both took up very similar roles of 'public scientists' active for peace, be it as delegates at Pugwash conferences, on the air, or as speakers in the Frankfurt Paulskirche. PMID:24974612
Georg Friedrich Händel: a case of large vessel disease with complications in the eighteenth century.
Bäzner, Hansjörg
2015-01-01
Georg Friedrich Händel was not only one of the greatest musical giants ever but also he was probably the first composer who was also the manager and promoter of his own works. Various myths embellish his various biographies. This is also true for his pathography: several articles written by authors from various specialties suggested him having suffered from psychiatric diseases, like cyclothymia or mania, and rheumatologic disorders, like arthritis, while others tended to interpret his recurrent palsies as typical sequelae of ischemic strokes. More recently, reports proposing lead poisoning as the main source of disease in Händel gained the attention of musical and lay press. During his last years of life, Händel was struck with blindness, which in his era had been interpreted as being due to cataracts. This led to three "coucher" operations, all of them without any lasting effect. Although a definite diagnosis cannot be proven from the original sources, the most plausible explanation for Händel's palsies and visual impairment may be based on one single context, i.e., cerebrovascular disease. The possible differential diagnosis will be discussed in this chapter. PMID:25684296
Gal, Joseph
2007-02-01
Enantiomorphism and enantiomorphous were the first enantio-based terms, introduced 150 years ago, by Carl Friedrich Naumann, a German crystallographer, to refer to non-superposable mirror-image crystals. The terminology was not adopted by Pasteur, the discoverer of molecular chirality, and was not embraced at first in the stereochemical context, until it was accepted in 1877 by Van't Hoff in the German edition of his proposal for the tetrahedral asymmetric carbon atom. In the 1890s the use of enantio terms began to spread in the research literature, and many new derivatives of Naumann's original two terms were subsequently introduced. Problems in the usage of some of the terms are often found in the literature, e.g., enantiomorphism is sometimes confused with chirality; enantiomeric is often misused; the meaning of some of the many derived terms, e.g., enantiosymmetric, enantioposition, etc., is unclear. All in all, Naumann should be remembered as the creator of essential terminology in the realm of chirality. PMID:17096375
[A utopian episode - Carl Friedrich von Weizsäcker in the networks of the Max-Planck Society].
Kant, Horst; Renn, Jürgen
2014-01-01
Carl Friedrich von Weizsäcker was a key figure in the history of the Max Planck Society (MPS). This essay contextualises his work with the development of the MPS, highlighting the institutional and personal networks upon which it was based. Some of the stations addressed in the following are his role in the German Uranium Project, in preparing the Mainau Declaration, the Göttingen Manifesto, and the Memorandum of Tübingen as well as his involvement in the foundation of the Max Planck Institute (MPI) for Human Development and his own MPI for the Research of Living Conditions in the Modern World located in Starnberg. The relationship between Weizsäcker and Hellmut Becker, long-time friend and founding director of the MPI for Human Development, will be of particular interest. Another issue broached here is the connection between natural science and the humanities in Weizsäcker's work, and subsequently the relation between these two science cultures in the MPS. Finally, we look at the challenges Weizsäcker's work could present to the MPS today. PMID:24974604
Honigsbaum, Mark
2016-04-01
The Swiss-born medical researcher Karl Friedrich Meyer (1884-1974) is best known as a 'microbe hunter' who pioneered investigations into diseases at the intersection of animal and human health in California in the 1920s and 1930s. In particular, historians have singled out Meyer's 1931 Ludwig Hektoen Lecture in which he described the animal kingdom as a 'reservoir of disease' as a forerunner of 'one medicine' approaches to emerging zoonoses. In so doing, however, historians risk overlooking Meyer's other intellectual contributions. Developed in a series of papers from the mid-1930s onwards, these were ordered around the concept of latent infections and sought to link microbial behavior to broader bio-ecological, environmental, and social factors that impact hostpathogen interactions. In this respect Meyer-like the comparative pathologist Theobald Smith and the immunologist Frank Macfarlane Burnet-can be seen as a pioneer of modern ideas of disease ecology. However, while Burnet's and Smith's contributions to this scientific field have been widely acknowledged, Meyer's have been largely ignored. Drawing on Meyer's published writings and private correspondence, this paper aims to correct that lacuna while contributing to a reorientation of the historiography of bacteriological epidemiology. In particular I trace Meyer's intellectual exchanges with Smith, Burnet and the animal ecologist Charles Elton, over brucellosis, psittacosis and plague-exchanges that not only showed how environmental and ecological conditions could 'tip the balance' in favor of parasites but which transformed Meyer thinking about resistance to infection and disease. PMID:26612760
Triple differential cross sections for the ionization of water by electron impact
NASA Astrophysics Data System (ADS)
Tóth, Istvan; Nagy, Ladislau; Campeanu, Radu I.
2014-12-01
Calculated triple differential cross sections are presented for the ionization of the 3a1 orbital of water by electron impact. The cross sections are determined for symmetric coplanar and non-coplanar geometrical arrangements. The obtained results show reasonable agreement with experimental data for both geometries. Contribution to the Topical Issue "Elementary Processes with Atoms and Molecules in Isolated and Aggregated States", edited by Friedrich Aumayr, Bratislav Marinkovic, Stefan Matejcik, John Tanis and Kurt H. Becker.
Koszka, Christiane
2009-08-01
Friedrich Nietzsche was one of the most influential and profound German philosophers. After prolonged illness, he died at the age of 55 in Weimar, Germany. The interest in his medical biography has always been strong while the cause of his illness and death has remained a mystery, intriguing philosophers as well as physicians. The diagnosis of syphilis proposed in the 19th century has been controversial until today and many other diagnoses have been discussed. This paper suggests that Nietzsche suffered from mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes syndrome. PMID:19723969
Kästner, Ingrid
2005-01-01
In 1906, Dr. med. Georg Friedrich Nicolai, a young specialist in the field of electrocardiography from the university of Berlin, spent some months in the laboratory of Pavlov, where he was one of the first German visitors. Two letters written by Nicolai to Pavlov are a mirror of Nicolai's admiration for the brilliant Russian Nobel prize winner, but also of Nicolai's remarkable insight into the perspectives of Pavlov's physiological method for "objective" psychological investigations. Nicolai regarded himself a pupil of Pavlov until his death in South America, where he was forced to emigrate after World War I due to his pacifist activities. PMID:17153304
Krohn, Wolfgang
2014-01-01
In the Starnberg Max-Planck Institute one of the working groups was concerned with science as the formative condition--or "hard core"--of societal modernity, and with science as potential resource for solving social problems and addressing future goals. More precisely, the group intended to differentiate between phases in which scientific disciplines predominantly care for their own paradigmatic completion and those allowing their theoretical potential resonate with external needs. The conceptual model was coined "finalization in science". It soon provoked a heated controversy on the dangers of social control of science. The paper analyses Carl Friedrich von Weizsäcker's views on the relation between philosophy and policy of science including his interpretation of Thomas Kuhn and reconstructs the impact of his ideas on the finalization model. It finally reflects on the relationship between science development and change of consciousness in the context of scientific responsibility for (the use of) research outcomes. PMID:24974608
Schäfer, Wolf
2014-01-01
In a letter to his wife from October 14, 1943, Werner Heisenberg describes a fierce clash with Carl Friedrich von Weizsäcker. The sudden conflict raises numerous questions, two of which are tackled here. First: How is now the friendly relationship between Heisenberg and Weizsäcker in the postwar years to be understood? The answer is: as a strategic performance. Second: How are the radical opinions to be explained that Weizsäcker expressed at the time? A thorough reconstruction of the lifelong connection that Weizsäcker maintained with Martin Heidegger and Heidegger's philosophy gives the answer: the young Weizsäcker was fired up by the "utopian" National Socialism with which Heidegger trumped the real existing. PMID:24974620
Bartosch, Ulrich
2014-01-01
The intention of this article is to show the suitability of "Weltinnenpolitik" (world domestic policy) as an analytic and programmatic view on contemporary policy. A full reconstruction or comparison of Carl Friedrich von Weizsäcker's concept is not at the focus. As mentioned in other contributions to this volume, Weizsäcker did not refer to the disciplinary discourses in detail. His approach is particularly 'unique' since he set about in 1963 to study the conditions of peace in a very general way. By doing so, he was able to circumscribe the conditions of peace realistically: those valid for us today and apparently also in the future. Weizsäcker probably did underestimate the complexity of the transformation to sustainable politics for preventing climate change. Vice versa one should hope that we today do not discount the prevention of atomic war as a sine qua non for sustainable climate-saving policy. Both could mark the quintessential conditions for peace. PMID:24974610
Seefried, Elke
2014-01-01
Carl Friedrich von Weizsäcker crossed the boundaries separating science, politics and the public sphere. In this he was led by the conviction that scientists in the modern 'technical age' are responsible for consequences resulting from their applied knowledge. Weizsäcker tried to introduce his knowledge into the policy process by advising politicians or by using the public sphere, thus applying pressure on politics. This was not only true for the 'Göttinger Erklärung' in 1957 but also for his engagement in the nuclear energy debate of the 1970s. Influenced by the 'Limits to Growth' discourse, Weizsäcker more and more gravitated towards an ecological world view and increasingly questioned material growth as well as a techno-scientific based understanding of progress. Weizsäcker thought about risks of the technical age in general and of the use of nuclear energy in particular. In the light of a growing fragmentation of scientific authority, Weizsäcker revealed uncertainty as he became fully aware that expertise cannot be based on scientific reason and cannot code the problems in terms of truth, but is inextricably linked with value spheres and contingencies. Nevertheless, his expertise was utilized as he encouraged parts of the Social Democratic Party (SPD) around Erhard Eppler to think about alternatives in energy policy. PMID:24974614
Forsbach, R
2012-03-01
The psychiatrist Friedrich Panse (1899-1973) was a T4 assessor during the Nazi era who sent mentally disabled and mentally ill people to their deaths. In the German Armed Forces he used higher galvanic currents to cure "war neurotics" and expose "malingerers." As a National Socialist he was a committed teacher of racial hygiene. Nonetheless, after the end of the Nazi regime many supporters quickly surfaced who were prepared to exonerate Panse. Panse himself was not among those who indignantly repudiated the accusation of any contact with the Nazi Party. He did not deny that he had openly embraced the Nazi measures for preserving the genetic integrity of the populace, but he did let it be known that he had suffered incredibly under the heavy burden. The State Government of North Rhine-Westphalia refused to allow Panse to continue in his capacity as an extraordinary professor. Panse successfully contested this decision at the State Administrative Court in Düsseldorf. He became the Director of the Institution in Düsseldorf-Grafenberg, the Psychiatric Clinic in Düsseldorf, a member of the German Council of Medical Advisors for questions regarding care for war victims of the German Federal Ministry of Labor, and President of the German Society for Psychiatry and Neurology. PMID:22399062
Hernigou, Philippe
2016-04-01
The national achievements of the orthopaedic school of Germany became international in the second part of the 19th century, and from 1860 through 1914 its educational system attracted many physicians and surgeons from all over the world. During this period of 50 years, German surgeons asserted their dominance in orthopaedic surgery, particularly with four famous surgeons: Richard von Volkmann, Julius Wolff, Albert Hoffa, and Friedrich Trendelenburg. They held annual meetings, during which papers were read and discussed. We also present contributions to orthopaedic sciences of the other German authors during 19th century according to different cities. PMID:26585866
Two-electron exchange interaction between polar molecules and atomic ions — Asymptotic approach
NASA Astrophysics Data System (ADS)
Karbovanets, Oleksandr M.; Karbovanets, Myroslav I.; Khoma, Mykhaylo V.; Lazur, Volodymyr Yu.
2015-05-01
We have described the asymptotic approach for calculation of the two-electron exchange interaction between atomic ion and polar molecule responsible for direct double electron transfer processes. The closed analytic expression for matrix element of exchange interaction has been obtained in the framework of the semiclassical version of the asymptotic theory and point-dipole approximation for description of the polar molecule. Contribution to the Topical Issue "Elementary Processes with Atoms and Molecules in Isolated and Aggregated States", edited by Friedrich Aumayr, Bratislav Marinkovic, Štefan Matejčik, John Tanis and Kurt H. Becker.
Electron-impact-induced tryptophan molecule fragmentation
NASA Astrophysics Data System (ADS)
Tamuliene, Jelena; Romanova, Liudmila G.; Vukstich, Vasyl S.; Papp, Alexander V.; Snegursky, Alexander V.
2015-01-01
The fragmentation of a gas-phase tryptophan molecule by a low-energy (<70 eV) electron impact was studied both experimentally and theoretically. Various positively charged fragments were observed and analyzed. A special attention was paid to the energy characteristics of the ionic fragment yield. The geometrical parameters of the initial molecule rearrangement were also analyzed. The fragmentation observed was due to either a simple bond cleavage or more complex reactions involving molecular rearrangements. Contribution to the Topical Issue "Elementary Processes with Atoms and Molecules in Isolated and Aggregated States", edited by Friedrich Aumayr, Bratislav Marinkovic, Stefan Matejcik, John Tanis and Kurt H. Becker.
Krietsch, P
1990-01-01
An account is given in this publication of the activities of Robert Friedrich Froriep (1804-1861), Prosector at Charité Berlin. He headed the Prosector's Department from 1833 through 1846. Froriep had come to Berlin in 1831 with intentions to do research, primarily on cholera with which the city had been afflicted in those years. When the position of a "Provisional Prosector" of Charité became vacant, after withdrawal of Philipp Phoebus, autumn 1832, the officials of the Hospital Affairs Curatory decided to continue the provisional arrangement, and five candidates applied for the office. Froriep was accepted primarily for two reasons: He had just completed service as an extraordinary professor at the Berlin Faculty of Medicine, and he was capable of producing evidence to the double-track education desired for the job, anatomy and scientific drawing. The Prosector's office was a low-salary side job. Therefore, to ensure his own livelihood, he went into two additional occupations, teaching of anatomic drawing at the Academy of Fine Arts and running of a private clinic. Froriep did extremely well in firmly establishing the Prosector's Department by enhancement of its scope and enlargement of its collection of pathologic-anatomic specimens. He failed, on the other hand, in his attempts to establish pathological anatomy as a subject in its own right at the Berlin Faculty of Medicine. That failure together with insecurity regarding the Prosector's office and position in the hierarchic system of Charité, compounded by protracted disputes between him and Johannes Müller on the Prosector's collection of specimens were causes for Froriep's aggravating frustration towards the late thirties. He also failed in trying to stabilize his scientific and financial positions by accepting directorship of a surgical department. The totality of problems in Berlin and illness of his father in Weimar prompted him to move to Weimar, in spring 1846, to take over as a manager of the
Gebhardt, Gerd
2014-01-01
The luminosity of Carl Friedrich von Weizsäcker's holistic thinking in the former German Democratic Republic (DDR) is reviewed. Broad-minded academics sought, in accordance with the modern paradigm of self-organization, beyond the ideological template for ways out of the dead end of incrustations of society and innovation blockages under the constraints of a dictatorship. Right after the fall of the wall, Weizsäcker willingly backed a "community of free researchers for self-organization" (Freie Forschungsgemeinschaft Selbstorganisation, FFGSO). This group, conceived as a nonpartisan "think tank" of civil activism, is also discussed. At a number of its meetings Weizsäcker debated the dangers of ideologically influenced science. The effectiveness of the dual leadership at his own Starnberg Institute, for instance, was stymied by the tensions arisen out of such conflicting aims. Against the voluntaristic anticipations of the mainstream in sociology, precisely that system proved to be more viable that was meant to be overcome: faulty and purportedly futureless capitalism. Weizsäcker repudiated social prognoses made in the absence of rules for their falsification resp. verification. Weizsäcker acted as a leading figure at the FFGSO's Potsdam conference, opened on 30 Mar. 1990, on the "DDR--and afterwards?". Its intention was in order to trigger a nationwide discussion of scientific scenarios in designing German unification in the face of gross practical disparities between East and West Germany. The Trust Agency inspired by the FFGSO at the Round Table between opposition and old government was supposed to transfer the national public property "Volkseigentum" of the DDR into private property of the East German citizens, to enable them to realize a role as subject through self-organization. At the group's request, Weizsäcker mediated the readiness by the Lutheran World Federation to assume the role of ombudsman in anticipation of conflicts of interest within the
Bessel, Friedrich Wilhelm (1784-1846)
NASA Astrophysics Data System (ADS)
Murdin, P.
2000-11-01
Astronomer, geodesist, mathematician, born in Minden, Westphalia, Germany. At the age of 26, became director of Frederick William III of Prussia's new Konigsberg Observatory, where he remained for the rest of his life. Published (1838) the first recognizedly accurate stellar parallax (of 61 Cygni), the earliest accurate method for measuring stellar distances (10 light years for 61 Cygni) (but see...
Argelander, Friedrich Wilhelm August (1799-1875)
NASA Astrophysics Data System (ADS)
Murdin, P.
2000-11-01
Astronomer, born in Memel, East Prussia. Director of the Bonn Observatory, where he organized a survey of the position of all 324 198 stars of the northern hemisphere above the ninth magnitude, published as the star charts and catalogs of the Bonner Durchmusterung (BD). His assistant, Eduard Schönfeld (1828-91), made the extension (BDE) into the southern sky. It is staggering to think about this ...
An unrecognized renal physiologist: Friedrich Wöhler.
Richet, G
1995-01-01
Wöhler, in 1828, was the first chemist to synthesize urea. In 1824, towards the end of his medical studies, he had already published an important article on the renal excretion of some 41 substances administered orally or parenterally and on the links between their renal excretion and their metabolism: salts of potassium are excreted either reduced or oxidized, urine can be acidic when the blood is alkaline, the rate of water excretion is influenced by the rate of substances excreted in the same form as they are administered. He adumbrated the general concepts on the role of the kidney in the maintenance of the composition of the body. Had he continued in this direction, Wöhler would have been recognized not only as a remarkable chemist but also as a great physiologist. PMID:8546178
Zöllner, Johann Karl [Carl] Friedrich (1834-82)
NASA Astrophysics Data System (ADS)
Murdin, P.
2000-11-01
German astronomer, born in Leipzig, was a pioneer solar astronomer, classifying solar prominences. He first suggested that the spectral types of stars represent an evolutionary sequence, starting hot and cooling. This idea was taken up with variations by H C VOGEL and NORMAN LOCKYER....
NASA Astrophysics Data System (ADS)
Fürst, Dietmar
This contribution illuminates a hitherto unknown side of the famous astronomer Bessel: his delight in occasionally writing poetry. These poems were thought to be of private use only, in particular as rhymed answers to his intimate correspondent Heinrich Christian Schumacher.
Electron-induced ionization and dissociative ionization of iron pentacarbonyl molecules
NASA Astrophysics Data System (ADS)
Lacko, Michal; Papp, Peter; Wnorowski, Karol; Matejčík, Štefan
2015-03-01
Electron ionization (EI) and dissociative ionization (DI) of Iron pentacarbonyl molecule (Fe(CO)5) was studied using a crossed molecular and electron beam mass spectrometry technique. Positive ions FeO(CO)+, FeC(CO)2+ and CO+ of Fe(CO)5 were detected for the first time. We have determined the experimental appearance energies of positive ions, the thresholds for dissociative reactions, the experimental bond dissociation energies for (CO)nFe+-CO bond breaks (for n = 4,..., 0) and their average value for Fe-C bond energy 1.25 eV in Fe(CO)5+. We have performed extensive density functional theory (DFT) studies of the ground states of neutral molecule and fragments 1 A1' Fe(CO)5, 3B1 Fe(CO)4, 3A1Fe(CO)3, 3∑g Fe(CO)2, 3 ∑FeCO as well as positive ions 2A1 Fe(CO)5+, 4A1 Fe(CO)4+, 4A1 Fe(CO)3+, 4∑g Fe(CO)2+ and 4 ∑ FeCO+. The structures and energies of the states have beendetermined and the calculated bond dissociation energies (BDEs) were compared with present experiments as well as with previous works. Contribution to the Topical Issue "Elementary Processes with Atoms and Molecules in Isolated and Aggregated States", edited by Friedrich Aumayr, Bratislav Marinkovic, Stefan Matejick, John Tanis and Kurt H. Becker.
Dissociative excitation study of iron pentacarbonyl molecule
NASA Astrophysics Data System (ADS)
Ribar, Anita; Danko, Marián; Országh, Juraj; Ferreira da Silva, Filipe; Utke, Ivo; Matejčík, Štefan
2015-04-01
The processes of dissociative excitation (DE) and dissociative ionisation with excitation (DIE) of iron pentacarbonyl, Fe(CO)5, have been studied using a crossed electron-molecule beam experimental apparatus (Electron Induced Fluorescence Apparatus, EIFA). Using EIFA we were able to record the emission spectrum of the molecule in the UV-VIS range, as well as the photon efficiency curves initiated by electron impact. The emission spectrum of Fe(CO)5 initiated by impact of 50 eV electrons was recorded in the spectral range between 200 nm and 470 nm. It shows a high density of emission lines and bands (mainly iron lines and carbonyl bands). Additionally, we have measured photon efficiency curves (PECs) as a function of the electron impact energy for several lines and bands. On the basis of the PECs we have discussed the reaction mechanism and the energetics of the reactions associated with the DE and DIE processes. Contribution to the Topical Issue "Elementary Processes with Atoms and Molecules in Isolated and Aggregated States", edited by Friedrich Aumayr, Bratislav Marinkovic, Štefan Matejčík, John Tanis and Kurt H. Becker.
Photoionization dynamics of the C2+ ion in Rydberg states
NASA Astrophysics Data System (ADS)
Stancalie, Viorica
2014-11-01
The goal of this work is to examine in detail the ionization dynamics of Be-like C ion in Rydberg states. An initial calculation has been done to output the lifetime due to spontaneous decay for unperturbed 1s22sns (1Se) Rydberg states using the multi-configuration Dirac-Fock (MCDF) method with configuration interaction option implemented in the general-purpose relativistic atomic structure package (GRASP). Both the C2+ ground state and the C3+ target state energies have been carefully calculated. We report results from a detailed and systematic study of the behaviour of complex photoionization amplitudes, the lifetime due to spontaneous decay for unperturbed 1s22sns (1Se) Rydberg states, the `resonant' phase shift and the rapidly increasing of this shift from well below to well above the resonance position. The sum-over-state method is used to calculate the static dipole polarizability, while the frequency-dependent polarizability values of C2+ ion in these Rydberg states are obtained from two-state model calculation results. Contribution to the Topical Issue "Elementary Processes with Atoms and Molecules in Isolated and Aggregated States", edited by Friedrich Aumayr, Bratislav Marinkovic, Stefan Matejcik, John Tanis and Kurt H. Becker.
ERIC Educational Resources Information Center
Weber, Barbara
2011-01-01
Philosophy for Children claims to foster not only critical thinking, but also creative and caring thinking. However, its theoretical foundations draw mainly on the analytic and pragmatist philosophical tradition. Consequently, and made evident by the choice of the terms "caring thinking" and "creative thinking", it seem to reduce these concepts…
Going to School with Friedrich Nietzsche: The Self in Service of Noble Culture
ERIC Educational Resources Information Center
Yacek, Douglas W.
2014-01-01
To understand Nietzsche's pedagogy of self-overcoming and to determine its true import for contemporary education, it is necessary to understand Nietzsche's view of the self that is to be overcome. Nevertheless, previous interpretations of self-overcoming in the journals of the philosophy of education have lacked serious engagement with…
Peters, U H
1990-01-01
Nietzsche's autobiography gestates neither conflicts, nor life problems, nor matter suppressed from his subconscious, nor are the speech distortions of the schizophrenic patient to be found. In all, analysis allows with certainty the conclusion that is was written by a sick person suffering from a psycho-organic disorder of the kind Bonhoeffer referred to by the general term "symptomatic psychosis". PMID:2184449
What Friedrich Nietzsche Cannot Stand about Education: Toward a Pedagogy of Self-Reformulation.
ERIC Educational Resources Information Center
Bingham, Charles
2001-01-01
Examines Nietzsche's rejection of mass education, arguing that it was based on his desire for education to be more self- reformulative than he thought possible, and concluding that education in schools is beneficial because it can foster radical forms of selfhood. This process can begin by listening to Nietzsche's philosophy while ignoring his…
The relationship of Carl Friedrich Gauss with his Hungarian scientist friends
NASA Astrophysics Data System (ADS)
Vargha, Magda
Gauss had been in close contact with four Hungarian astronomers: Farkas Bolyai, Franz Xaver von Zach, János Pasquich and Pál Tittel. All these friendships were different from each other, if only because of the various ages and social standings in which these Hungarians lived. Gauss had always shown great interest in the latter. With the exception of Pasquich, all three friendships had started out as close, and in the end Gauss had repaid poorly what he received. His correspondence with Pasquich was quite different. Towards the end of his contact with Pasquich, Gauss had lifted himself above his usual indifference. With the help of his German astronomer friends, Gauss did everything he could to vindicate Pasquich, who had been accused in front of the whole astronomical community of publishing invented observations.
Ernst Florens Friedrich Chladni (1756-1827) and the origins of modern meteorite research
NASA Astrophysics Data System (ADS)
Marvin, Ursula B.
1996-09-01
In 1794, Ernst F. F. Chladni published a 63-page book Über den Ursprung der von Pallas gefundenen und anderer ihr änlicher Eisenmassen und über einige damit in Verbindung stehende Naturerscheinungen in which he proposed that meteor-stones and iron masses enter the atmosphere from cosmic space and form fireballs as they plunge to Earth. These ideas violated two strongly held contemporary beliefs: (1) fragments of rock and metal do not fall from the sky, and (2) no small bodies exist in space beyond the Moon. From the beginning, Chladni was severely criticised for basing his hypotheses on historical eyewitness reports of falls which others regarded as folk tales and for taking gross liberties with the laws of physics. Eight years later, the study of fallen stones and irons was established as a valid field of investigation. Today, some scholars credit Chladni with founding meteoritics as a science; others regard his contributions as scarcely worthy of mention. Writings by his contemporaries suggest that Chladni's book alone would not have led to changes of prevailing theories; thus, he narrowly escaped the fate of those scientists who propose valid hypotheses prematurely. However between 1794 and 1798, four falls of stones were witnessed and widely publicized. There followed a series of epoch-making analyses of fallen stones and "native irons" by the chemist Edward C. Howard and the mineralogist Jacques-Louis de Bournon. They showed that all the stones were much alike in texture and composition but significantly different from the Earth's known crustal rocks. Of primary importance was Howard's discovery of nickel in the irons and the metal grains of the stones. This linked the two as belonging to the same natural phenomenon. The chemical results, published in 1802 February, persuaded leading scientists in England, France, and Germany that bodies fall from the sky. Within a few months, chemists in France reported similar results and a new field of study was inaugurated internationally—although opposition lingered on until 1803 April, when nearly 3,000 stones fell at L'Aigle in Normandy and transformed the last skeptics into believers. Chladni immediately received full credit for his hypothesis of falls, but decades passed before his linking of falling bodies with fireballs received general acceptance. His hypothesis of their origin met with strong resistance from those who argued that stones formed within the Earth's atmosphere or were ejected by lunar volcanoes. After 1860, when both of these hypotheses were abandoned, there followed a century of debate between proponents of an interstellar vs. a planetary origin. Not until the 1950s did conclusive evidence of their elliptical orbits establish meteorite parent bodies as members of the solar system. Thus, nearly 200 years passed before the questions of origin that Chladni raised finally were resolved.
My favorite aromatic compounds--a tribute to friedrich August Kekulé.
Hopf, Henning
2014-10-01
[For a discussion of this picture, please see the Editor's postscript at the end of the paper] Note from the Editor: We are all collectors. All one needs to do is explore a flea market, an antique fair or especially a weekend street market to understand the range of human collections. Tetsuo Nozoe, whom this project celebrates, collected autographs as well as the friendship of those who signed his books! What we collect doesn't necessarily have to be tangible. We all collect memories, stories, and anecdotes. We chemists are particularly privileged: we also collect molecules and reactions. In the essay that follows, Professor Henning Hopf shares with us his collection of favorite aromatic compounds. Hopf is the perfect chemist to have undertaken this sharing, for he has been active in the field of novel aromatic compounds for over four decades. Furthermore, Hopf is a deeply philosophical scientist. I very much admire his 2008 paper with Roald Hoffmann, "Learning from Molecules in Distress" published in Angewandte Chemie, a journal from the same pubilshers as The Chemical Record. As you read the paper that follows, imagine that Professor Hopf has just welcomed you to his home and is giving you a tour of his artwork. The walls are covered with works of Boekelheide, Cram, Fittig, Hückel, Kuck, Müllen, Newman, Scott, and Willstätter among others. Oh, yes, there's a Hopf or two! Enjoy your time in this very special museum. -Jeffrey I. Seeman Guest Editor University of Richmond Richmond, Virginia 23173, USA E-mail: jseeman@richmond.edu. PMID:25205433
Karl Friedrich Meyer (1884-1974): His ambitions, approach and achievements.
Gessner, Urs
2016-02-01
Karl Meyer was one of the outstanding scientists in the areas of medical and veterinary microbiology, infectious diseases, pathology, epidemiology, ecology, academic education and public health during the first half of the 20th century. He was an exceptional scientist with an enormous drive to deepen knowledge and understanding, in the interest of the people, to improve diagnosis and treatment of many zoonoses including prevention and improvement in health laws. This paper presents a survey of the extraordinarily wide-ranging achievements of Meyer and his systems approach. PMID:24585625
VizieR Online Data Catalog: DB white dwarfs from the Hamburg/ESO survey (Friedrich+, 2000)
NASA Astrophysics Data System (ADS)
Friedrich, S.; Koester, D.; Christlieb, N.; Reimers, D.; Wisotzki, L.
2000-11-01
We present an analysis of 40 cool helium-rich white dwarfs found in the Hamburg/ESO survey. They were selected for follow-up spectroscopy because of their U-B colour below -0.18, the absence of strong absorption lines, and a continuum shape similar to that of a quasar. Effective temperatures for individual stars were determined by fitting model atmospheres of nearly pure helium with a small admixture of hydrogen. As a consequence of the selection criteria all but one sample stars have Teff below 20000K. Four stars clearly show helium and hydrogen lines in their spectra. In the spectra of another three, helium, hydrogen, and metal lines can be detected. For these stars hydrogen and metal abundances were also determined by fitting appropriate model atmospheres containing these elements. Seven sample stars most likely have helium-rich atmospheres but do not show any helium lines. They either have featureless spectra or show calcium lines. (4 data files).
Schlumbohm, Jürgen
2014-01-01
The problem of anonymous or confidential deliveries, a subject of current controversy, has a long history. Some maternity hospitals offered the possibility for "clandestine" births as early as the 18th and 19th century. A recently emerged source about the maternity clinic of Göttingen University allows insight into the motives that led to keeping a birth secret and the consequences of such a clandestine birth for mother, father and child. The director of the institution, a professor of obstetrics, wrote case reports on the women, who paid a handsome sum for his help and the in-patient care they received. In return, these women could be admitted under a pseudonym, and thus falsify their child's birth certificate; moreover they were not used as teaching material for medical students and midwife apprentices, whereas "regular" patients had to give their names and, in return for being treated free of charge, be available for teaching purposes. The ten cases that have been painstakingly investigated reveal that the reasons that led the women and men to opt for an anonymous birth were manifold, that they used this offer in different ways and with different consequences. All of these pregnancies were illegitimate, of course. In one case the expectant mother was married. In several cases it would be the father who was married. Most of the women who gave birth secretly seem to have given the professor their actual details and he kept quiet about them--with the exception of one case where he revealed the contents of the case report many years later in an alimony suit. Only one of the men admitted paternity openly, but many revealed their identity implicitly by registering the pregnant woman or by accompanying her to the clinic. If the birth was to be kept secret the child needed to be handed over to foster parents. By paying a lump sum that covered the usual fourteen years of parenting, one mother was able to avoid any later contact with her son. In most cases contact seems to have been limited to the payment of this boarding money. One of the couples married later and took in the twins that had been born clandestinely out of wedlock. One mother kept close contact with her son through intermediaries. All of the women who gave birth in this clandestine fashion received practical as well as financial support, often from the child's father or from a relative. Few of them came by themselves. In those days, only women who used the maternity hospital free of charge would have been as isolated in the difficult perinatal period as are women today who choose to deliver their babies anonymously. PMID:25134255
NASA Astrophysics Data System (ADS)
Staubermann, K. B.
Using my training as an astronomer and drawing on resources such as museums, instrument collections, and archives, I have rebuilt Zoellner's astro-photometer designed by Zoellner in the late 1850s when he was working for his doctoral thesis at Basel University. The photometer was designed to compare an artificial star with a real star by means of a half-transparent screen which allowed simultaneously observation of the two together. The brightness and colour of the artificial star could be matched those of the real star by means of polarisation. After completing his instrument Zoellner observed with it at Berlin for almost two years. I have both replicated the instrument and carried out observations following Zoellner's own records. The replication of the instrument included all its optical components, the brass and wooden parts and the town gas used to produce the artificial star. This dissertation will follow the line of investigation of historical practice. The beginnings of nineteenth-century photometry will be presented, followed by a description of the Zoellner photometer, its replication and the observations carried out with the replica. I will contextualize my work based on my insights with the photometer, and then trace its career through the second half of the nineteenth century.
Hernigou, Philippe
2016-02-01
In orthopaedic medicine in Germany, Lorenz Heister, practicing in the eighteenth century, is considered one of the fathers of German surgery and is renowned for his books on management of hemorrhage, wounds, fractures, bandaging, instrumentation and surgery. After Heister, at the beginning of the nineteenth century, orthopaedic medicine in Germany developed uniformly. In a period when few doctors were interested in a separate discipline of orthopaedics, Germany led in this field. Heine devoted himself to the development of the new profession of orthopaedics, and in 1816, he opened the first orthopaedic institute on German soil in the former monastery of St. Stephen, which later became known as the Karolinen-Institut. Along with Heine and his family, the special development of orthopaedics in Berlin may be attributed to the work of Dieffenbach who, in 1832, became professor at the University of Berlin and in 1840 director of the Clinical Institute for Surgery at Charité Hospital. PMID:26294002
Izaurralde, E
2001-07-01
The distinguishing feature of eukaryotic cells is the segregation of RNA biogenesis and DNA replication in the nucleus, separate from the cytoplasmic machinery for protein synthesis. As a consequence, messenger RNAs (mRNAs) and all cytoplasmic RNAs from nuclear origin need to be transported from their site of synthesis in the nucleus to their final cytoplasmic destination. Nuclear export occurs through nuclear pore complexes (NPCs) and is mediated by saturable transport receptors, which shuttle between the nucleus and cytoplasm. The past years have seen great progress in the characterization of the mRNA export pathway and the identification of proteins involved in this process. A novel family of nuclear export receptors (the NXF family), distinct from the well-characterized family of importin beta-like proteins, has been implicated in the export of mRNA to the cytoplasm. PMID:11529502
ERIC Educational Resources Information Center
Popplow, Marcus
2012-01-01
This essay contributes to a recent strain of research that questions clear-cut dichotomies between "scientists" and "artisans" in the early modern period. With a focus on the exploitation of agrarian resources, it argues for the appreciation of a more complex panorama of intersecting knowledge systems spanning from botany as part of natural…
ERIC Educational Resources Information Center
Jaura, Ramesh, Ed.; And Others
The discussion presented in this booklet was organized to foster international understanding by encouraging a genuine dialogue between the industrialized nations of the northern hemisphere and the developing nations in the southern hemisphere. The first section of the booklet presents introductory statements by the chairperson of the North-South…
Achenbach, T M; Dumenci, L
2001-08-01
L. Lengua et al. (2001) proposed scoring the Child Behavior Checklist (CBCL; T. Achenbach, 1991b) on dimensions that "correspond to current conceptualizations of child symptomatology," (p. 695) embodied in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; 4th ed., American Psychiatric Association, 1994). They concluded that their "results support the use of the new dimensions." Yet, their regressions and diagnostic efficiency statistics showed that DSM diagnoses were predicted less well by their dimensions than by CBCL syndromes that reflect actual patterns of problems. Not only these findings, but also the high correlations of their dimensions with CBCL syndromes and the lack of norms and validated clinical cutoffs for their dimensions, argue against use of their dimensions. To advance assessment and taxonomy, new national samples have been used to construct DSM-oriented scales and to revise cross-informant syndromes. PMID:11550735
When One Biographer "Borrows" from Another, the Dispute Gets Philosophical
ERIC Educational Resources Information Center
Shea, Christopher
2012-01-01
Mark Anderson, a professor of philosophy at Belmont University, publishes an account of Nietzsche's life and work. He remembered liking "Friedrich Nietzsche" (Overlook Press, 2005), by the late independent scholar Curtis Cate, so he started rereading that one. But then he had second thoughts. After all, "Friedrich Nietzsche: A Philosophical…
NASA Astrophysics Data System (ADS)
Murdin, P.
2000-11-01
Struve, Friedrich Georg Wilhelm (1793-1864); Struve, Otto Wilhelm (1819-1905), son of Friedrich; Struve, Karl Hermann (1854-1920), elder son of Otto Wilhelm, brother of Gustav; Struve, Gustav Wilhelm Ludwig (1858-1920), younger son of Otto Wilhelm, brother of Karl; Struve, Otto (1897-1963) [Otto Struve II], son of Gustav....
Neuronal Spoken Word Recognition: The Time Course of Processing Variation in the Speech Signal
ERIC Educational Resources Information Center
Schild, Ulrike; Roder, Brigitte; Friedrich, Claudia K.
2012-01-01
Recent neurobiological studies revealed evidence for lexical representations that are not specified for the coronal place of articulation (PLACE; Friedrich, Eulitz, & Lahiri, 2006; Friedrich, Lahiri, & Eulitz, 2008). Here we tested when these types of underspecified representations influence neuronal speech recognition. In a unimodal…
Lawrence Cardman
2006-09-01
The Continuous Electron Accelerator Facility, CEBAF, located at the Thomas Jefferson National Accelerator Facility, is devoted to the investigation of the electromagnetic structure of mesons, nucleons, and nuclei using high energy, high duty-cycle electron and photon beams. Selected experimental results of particular interest to the MAMI community are presented.
Nietzsche in Basel: Writing Reading.
ERIC Educational Resources Information Center
Miller, J. Hillis
1993-01-01
Explores the tight relationship between reading and writing, and discusses the implications of this central relationship for departments of English. Discusses Friedrich Nietzsche's early writings on rhetoric as challenging Western metaphysical tradition and providing a new model of writing. (HB)
Killing Initial Data on spacelike conformal boundaries
NASA Astrophysics Data System (ADS)
Paetz, Tim-Torben
2016-08-01
We analyze Killing Initial Data on Cauchy surfaces in conformally rescaled vacuum space-times satisfying Friedrich's conformal field equations. As an application, we derive the KID equations on a spacelike ℐ-.
NASA Astrophysics Data System (ADS)
Langkavel, Arno
When Bremen and Lilienthal are mentioned, people interested in the history of astronomy will first of all remember Wilhelm Olbers (1785-1840) and Johann Hieronymus Schroeter (1745-1816). In addition to them, Friedrich Wilhelm Bessel (1784-1846) and Carl Friedrich Gauß (1777-1855) have also left their traces. Two walks describe the main memorial sites, which are all outdoors and easily accessible to the general public.
Generation of inflow data for inhomogeneous turbulence
NASA Astrophysics Data System (ADS)
Johansson, Peter S.; Andersson, Helge I.
2004-11-01
Inflow boundary conditions for turbulent plane channel flow are generated by solving evolution equations only for the most energetic eddies. The dynamical systems are derived by Galerkin projecting the Navier-Stokes equations onto the subspaces spanned by various sets of the most energetic modes from a proper orthogonal decomposition (POD) of the same flow. Low-energy small-scale POD-modes are added randomly in order to impose some energy in the high wave number range. This is found to be crucial in order to more rapidly establish the correct level of dissipation and achieve a more realistic distribution of energy between the velocity components. The method is tested on a DNS of R*=180 and a LES of R*=400. Statistics such as mean velocity, rms-profiles, turbulent shear-stress and energy spectra become close to the fully developed state within 1500 wall units downstream the inlet.
NASA Astrophysics Data System (ADS)
Albeverio, Sergio; Lakaev, Saidakhmat N.; Djumanova, Ramiza Kh.
2009-06-01
A model operator H associated to a system of three identical quantum particles on the three-dimensional lattice ℤ 3 is considered. The existence of eigenvalues lying below the essential spectrum of a family of Friedrichs models under rank-one perturbations h μα(p) , p∈T , α = 1, 2, is established. The essential spectrum of the operator H is described by the spectrum of the family of the Friedrichs models h μα(p) , p∈T , α = 1, 2. The following results are proven: The operator H has a finite number of eigenvalues lying below zero, if at least one of the Friedrichs models hμα(0), α = 1, 2, has a zero energy resonance. The operator H has infinitely many eigenvalues lying below zero and accumulating at zero, if both operators hμα(0), α = 1,2, have zero energy resonances.
Two-dimensional shallow water equations by composite schemes
NASA Astrophysics Data System (ADS)
Liska, Richard; Wendroff, Burton
1999-06-01
Composite schemes are formed by global composition of several Lax-Wendroff steps followed by a diffusive Lax-Friedrichs or WENO step, which filters out the oscillations around shocks typical for the Lax-Wendroff scheme. These schemes are applied to the shallow water equations in two dimensions. The Lax-Friedrichs composite is also formulated for a trapezoidal mesh, which is necessary in several example problems. The suitability of the composite schemes for the shallow water equations is demonstrated on several examples, including the circular dam break problem, the shock focusing problem and supercritical channel flow problems. Copyright
ERIC Educational Resources Information Center
Beatty, Barbara
2011-01-01
Background/Context: More than a century before modern controversies over scripted instruction, the Froebelian kindergarten--the original kindergarten method designed by Friedrich Froebel--and Maria Montessori's pedagogy were criticized for rigidly prescribing how teachers taught and children learned. Today, scripted methods such as Direct…
A discretization of the multigroup PN radiative transfer equation on general meshes
NASA Astrophysics Data System (ADS)
Hermeline, F.
2016-05-01
We propose and study a finite volume method of discrete duality type for discretizing the multigroup PN approximation of radiative transfer equation on general meshes. This method is second order-accurate on a very large variety of meshes, stable under a Courant-Friedrichs-Lewy condition and it preserves naturally the diffusion asymptotic limit.
The First Treatise in Comparative Education Rediscovered
ERIC Educational Resources Information Center
Lenhart, Volker
2016-01-01
The Latin essay "De re Scholastica Anglica cum Germanica Comparata" (English and German school education compared) published in 1795-1798 by the Freiberg/Saxony grammar school principal Friedrich August Hecht is the first treatise in comparative education. The rediscovery of the text, its earlier mentioning in the history of comparative…
Payback Time? Discourses of Lack, Debt and the Moral Regulation of Teacher Education
ERIC Educational Resources Information Center
Beighton, Chris
2016-01-01
This paper analyses recent policy and discourse in the UK lifelong learning sector to identify a tension in discourse which positions teacher educators as essential to the knowledge economy while simultaneously insisting on the deficits they represent. Drawing on critical analyses from Friedrich Nietzsche, Maurizio Lazzarato and Gilles Deleuze, I…
Froebel and Early Childhood Education in America.
ERIC Educational Resources Information Center
Sniegoski, Stephen J.
The idea of a special type of education for young children emerged in the United States in the mid-nineteenth century, with the kindergarten movement. The kindergarten was created by Friedrich Froebel, the German educator whose ideas, although no longer popular, can be traced to contemporary early childhood education. Froebel explicitly rejected…
Learning through Literature: Historical Fiction, Autobiography, and the Holocaust.
ERIC Educational Resources Information Center
Short, Geoffrey
1997-01-01
Argues against the common-sense view that children's literature dealing with the Jews in Nazi Germany is necessarily useful as an aid to studying the Holocaust. Finds a number of significant issues overlooked in the classroom. Discusses the novel "Friedrich" by H.P. Richter. (PA)
The Origin of the s, p, d, f Orbital Labels
ERIC Educational Resources Information Center
Jensen, William B.
2007-01-01
The theory of s, p, d and f dealing with the line spectra of the alkali metals during the period 1881 based on analogies with the harmonic ratios of sound is described. Friedrich Hund followed Bohr's practice of labelling the various shells and subshells by replacing the secondary quantum number with the series notations (s, p, d, and f), which…
ERIC Educational Resources Information Center
Tyson, Ruhi
2014-01-01
In the present article I will be discussing the importance attributed to aesthetic experiences in the vocational education of bookbinding master Wolfgang B. using the philosophy of Friedrich Schiller both to understand what constitutes these processes and to examine Schiller's thoughts in the light of his recollections. By doing this I hope…
The "Hard Problem" and the Quantum Physicists. Part 2: Modern Times
ERIC Educational Resources Information Center
Smith, C. U. M.
2009-01-01
This is the second part of a review of the work of quantum physicists on the "hard part" of the problem of mind. After an introduction which sets the scene and a brief review of contemporary work on the neural correlates of consciousness (NCC) the work of four prominent modern investigators is examined: J.C. Eccles/Friedrich Beck; Henry Stapp;…
Sand Face: Humanism after Antihumanism
ERIC Educational Resources Information Center
Arcilla, René V.
2015-01-01
Have the critiques of humanism of the 1960s and 1970s buried this idea once and for all? Or is there a way that humanism can absorb some of this antihumanist thinking and thereby renew itself? Drawing on writings of Michel Foucault, Charles Taylor, Friedrich Nietzsche, and Martin Heidegger in order to illuminate artworks by Robert Smithson and…
Froebel and the Rise of Educational Theory in the United States
ERIC Educational Resources Information Center
Baader, Meika Sophia
2004-01-01
This contribution compares entries on Friedrich Froebel and the kindergarten in German and United States' histories of education from 1857 to 1933. In the American histories, Froebel appears as the great "hero" of education of the 19th century, whereas in the German histories, Pestalozzi is the "hero." This difference in the perspectives goes back…
Over Two Years, What Did Froebel Say to Pestalozzi?
ERIC Educational Resources Information Center
Adelman, Clem
2000-01-01
Argues that Friedrich Froebel used essential principles of Heinrich Pestalozzi, related to pedagogy and curriculum. Investigates two periods when Froebel and Pestalozzi might have conversed to gain information about the other person. Believes that the educational principles of child-centered education originated from Pestalozzi, not Froebel. (CMK)
Nietzsche among the Scholars. A Bibliometric Analysis and Study of Nietzsche Scholarship.
ERIC Educational Resources Information Center
Lynn, Matthew T.
This paper addresses the literary canon surrounding the nineteenth century philosopher Friedrich Nietzsche, in order to inform philosophy librarians as to the nature of the particular body of literature. Using the "Philosopher's Index" database to locate all the Nietzschean literature published between 1986 and 1995, defining characteristics of…
Impossible Geometric Constructions: A Calculus Writing Project
ERIC Educational Resources Information Center
Awtrey, Chad
2013-01-01
This article discusses a writing project that offers students the opportunity to solve one of the most famous geometric problems of Greek antiquity; namely, the impossibility of trisecting the angle [pi]/3. Along the way, students study the history of Greek geometry problems as well as the life and achievements of Carl Friedrich Gauss. Included is…
Child-Centered Education for Pacific-Rim Cultures?
ERIC Educational Resources Information Center
Jackson, Peter W.
1998-01-01
Argues for a cautious approach to transplanting theory from one culture to another, particularly considering the case for applying Friedrich Froebel's child-centered theory to early childhood education in Pacific Rim cultures. Uses a historical approach to distinguish three distinct versions of the theory, the Christian, the Progressive, and the…
Changing Images of Childhood. Issues in Education.
ERIC Educational Resources Information Center
Goellner, Lydia A.
2000-01-01
Examines the changing images of childhood throughout history, focusing on how changes are reflected in beliefs and educational and social practices toward children with special needs. Describes impact of a painful childhood on Friedrich Froebel and actor Cary Grant. Suggests ways to enhance children's lives, including government subsidized…
The Riemann Zeta Zeros from an Asymptotic Perspective
ERIC Educational Resources Information Center
Grant, Ken
2015-01-01
In 1859, on the occasion of being elected as a corresponding member of the Berlin Academy, Bernard Riemann (1826-66), a student of Carl Friedrich Gauss (1777-1855), presenteda lecture in which he presented a mathematics formula, derived from complex integration, which gave a precise count of the primes on the understanding that one of the terms in…
"Like Sending Coals to Newcastle": Impressions from and of the Anglo-American Kindergarten Movements
ERIC Educational Resources Information Center
Nawrotzki, Kristen D.
2007-01-01
Developed by the German pedagogue Friedrich Froebel (1782-1852), the Kindergarten offered a revolutionary educational program for young children. In the mid-nineteenth century, after several decades of limited success in the German states, Froebel's Kindergarten began to be transplanted to other countries, including the USA and England. The…
NASA Astrophysics Data System (ADS)
Oestmann, Günther
The paper deals with contemporary assessments of Johann Hieronymus Schroeter's (1745-1816) astronomical works - especially by Wilhelm Olbers and Carl Friedrich Gauß - and also later judgements of the scientific importance and significance of his observations voiced by astronomers and historians.
Reprint Series: Memorable Personalities in Mathematics: Nineteenth Century. RS-11.
ERIC Educational Resources Information Center
Schaaf, William L., Ed.
This is one in a series of SMSG supplementary and enrichment pamphlets for high school students. This series makes available expository articles which appeared in a variety of mathematical periodicals. Topics covered include: (1) Laplace; (2) Carl Friedrich Gauss; (3) Wolfgang and Johann Bolyai; (4) Evariste Galois; and (5) Josiah Willard Gibbs.…
Explorations in Regional Variation: A Variational Pragmatic Perspective
ERIC Educational Resources Information Center
Barron, Anne
2015-01-01
The present article introduces the Special Issue entitled "A Variational Pragmatic Approach to Regional Variation in Language," a collection of papers which celebrates the work of Klaus P. Schneider (Rheinische Friedrich-Wilhelms-Universität Bonn, Germany) on the occasion of his 60th birthday.
Validating a Psychology as a Helping Profession Scale
ERIC Educational Resources Information Center
Gervasio, Amy Herstein; Wendorf, Craig A.; Yoder, Natalie F.
2010-01-01
We developed an 11-item Psychology as a Helping Profession (PHP) scale that measured aspects of personal growth/helping skills and applied helping. The scale was only weakly correlated with Friedrich's (1996) Psychology as Science (PAS) scale, implying that the 2 scales measure different conceptions of the nature of psychology. Psychology majors…
LAYER DEPENDENT ADVECTION IN CMAQ
The advection methods used in CMAQ require that the Courant-Friedrichs-Lewy (CFL) condition be satisfied for numerical stability and accuracy. In CMAQ prior to version 4.3, the ADVSTEP algorithm established CFL-safe synchronization and advection timesteps that were uniform throu...
Art, Water, and the Environment: Hundertwasser and Ukiyo-e
ERIC Educational Resources Information Center
Stephens, Pam
2005-01-01
This brief article explores the work of Friedrich Stowasser (1928-2000), an Austrian artist who modified his name throughout his career, eventually settling upon the invented name of Friedensreich Hundertwasser. Both Hundertwasser's original Slavic surname and his invented surname mean about the same: hundred waters. Both names illustrate the…
Seminar on the Role of Communication in the Euro-Arab Dialogue, Cairo, December 18-21, 1983.
ERIC Educational Resources Information Center
Friedrich Ebert Foundation, Bonn (West Germany).
Presented in this booklet are descriptions of the sessions at a seminar on the role of communication in European-Arab relations, organized by the German Friedrich Ebert Foundation in collaboration with the Ministry of Information of Egypt. Following an introduction and a list of items on the seminar agenda, the booklet describes the opening…
None So Blind: Early Childhood Education and Care--The Connective Tissue
ERIC Educational Resources Information Center
Gammage, Philip
2007-01-01
The author makes sense of the story of his professional life through the eyes of several important writers and teachers on education and says that, for him, Bridget Plowden ranks alongside John Dewey, Friedrich Froebel, Ben Morris and A.S. Neill.
Pre-School Education in Egypt, Oman and Japan: A Comparative Perspective.
ERIC Educational Resources Information Center
Dahawy, Bayoumi Mohamed
This paper examines preschool education in Egypt, Oman, and Japan in the light of the comparative education approach developed by George Bereday utilizing description, interpretation, juxtaposition, and comparison. The literature of early childhood education is surveyed, beginning with the three most influential pioneers: Friedrich Wilhelm…
ERIC Educational Resources Information Center
Jonas, Mark E.
2009-01-01
In this paper, I argue that Friedrich Nietzsche's concept of self-overcoming has been largely misinterpreted in the philosophy of education journals. The misinterpretation partially stems from a misconstruction of Nietzsche's perspectivism, and leads to a conception of self-overcoming that is inconsistent with Nietzsche's educational ideals. To…
Schopenhauer, Nietzsche, and the Aesthetically Sublime
ERIC Educational Resources Information Center
Vandenabeele, Bart
2003-01-01
Much has been written on the relationship between Arthur Schopenhauer and Friedrich Nietzsche. Much remains to be said, however, concerning their respective theories of the sublime. In this article, the author first argues against the traditional, dialectical view of Schopenhauer's theory of the sublime that stresses the crucial role the sublime…
Burke, Nietzsche, Lacan: Three Perspectives on the Rhetoric of Order.
ERIC Educational Resources Information Center
Thomas, Douglas
1993-01-01
Examines the complex relationship between rhetoric and order in the works of Kenneth Burke, Friedrich Nietzsche, and Jacques Lacan. Argues for three differing, yet complementary, views of rhetoric and order, each having a corresponding epistemology and axiology. Concludes with an analysis of the construction of order in Thomas Hobbe's "Leviathan."…
ERIC Educational Resources Information Center
Rosenow, Eliyahu
2000-01-01
Examines the pedagogical interpretations of Friedrich Nietzsche published during the past two decades in German and English comparing the pedagogical characterizations in these publications. States that German researchers exclude him from educational theory and philosophy. Reveals the cultural differences in pedagogical reflection. (CMK)
The Use and Abuse of Education for Culture; Lesson from Nietzsche.
ERIC Educational Resources Information Center
Maratos, John
2000-01-01
States that Friedrich Nietzsche identifies three ways the past is used. Using examples from ethnic, cultural, and political projects, considers the three abuses of education for culture: (1) the need for monumental history; (2) antiquarian uses of education for culture; and (3) critical uses of education for culture. (CMK)
Nietzsche contra Burke: The Melodrama in Dramatism.
ERIC Educational Resources Information Center
Desilet, Gregory
1989-01-01
Examines Kenneth Burke's and Friedrich Nietzsche's similar understanding of the hortatory nature of language-using, weighed against their radically differing conceptions of the negative, which allows a distinction between two genres of dramatism, and illustrates contrasting orientations toward symbolic activity in general. (SR)
The madness of Nietzsche: a misdiagnosis of the millennium?
Cybulska, E M
2000-08-01
This article represents a personal discussion about Nietzsche's mental illness, which formed part of a larger paper 'The masks of Nietzsche and eternal return of the repressed'. This was presented at the 6th Annual Conference of The Friedrich Nietzsche Society, September 1996, Manchester UK, as reported by Nussbaumer-Benz (1998). PMID:11045229
ERIC Educational Resources Information Center
Zielsprache Englisch, 1976
1976-01-01
The phonetic symbols in the "Advanced Learners Dictionary" (Oxford University Press, London) are discussed critically in articles by L. Alfes, H. Arndt, E. Bauch, G. Dahlmann-Resing, W. Friedrich, E. Germer, B. Haycraft, H. P. Kelz. Reference is made to an earlier article "Neue Zeichen", by H. G. Hoffmann. (Text is in German.) (IFS/WGA)
Writing with Light: Jacob Riis's Ambivalent Exposures
ERIC Educational Resources Information Center
Carter, Christopher
2008-01-01
The current interest in multimodal rhetoric was anticipated by Jacob Riis's social documentary texts and presentations during the late nineteenth and early twentieth centuries. In contrast with the socialist urban critiques presented by Friedrich Engels, Riis's work demonstrated profound ambivalence toward the city's poor. While calling for reform…
Marxisms as Utopias: Evolving Ideologies.
ERIC Educational Resources Information Center
Wallerstein, Immanuel
1986-01-01
Contends that there have been three stages or eras of social science: the philosophic, the scientific, and the as yet unnamed present era. Maintains that the three eras match, in chronological development, the successive periods of Marxian thought and the three different views of utopia offered by Thomas More, Friedrich Engels, and Karl Mannheim.…
Taking Up Space: Museum Exploration in the Twenty-First Century
ERIC Educational Resources Information Center
Sutton, Tiffany
2007-01-01
Museums have become a crucible for questions of the role that traditional art and art history should play in contemporary art. Friedrich Nietzsche argued in the nineteenth century that museums can be no more than mausoleums for effete (fine) art. Over the course of the twentieth century, however, curators dispelled such blanket pessimism by…
On the Need for Dionysian Education in Schools Today
ERIC Educational Resources Information Center
Steel, Sean
2014-01-01
Although much has been written about Friedrich Nietzsche's views on education over the years, and much has also been written about Dionysus, god of wine and ecstasy, very little attention has been given to the meaning of, and need for, Dionysian education. In this article, Sean Steel attempts to begin that project. Drawing Nietzsche's…
"Groundhog Day, Deja Vu," and the Myth of the Eternal Recurrence.
ERIC Educational Resources Information Center
Voeltz, Richard A.
1998-01-01
Reveals that through the use of the movie "Groundhog Day," students in humanities courses can grasp Friedrich Nietzsche's myth of eternal recurrence; the myth addresses the question of what if everything that occurred in one's life occurred again just as it happened before. Discusses the similarities between Nietzsche's myth and the movie. (CMK)
Teachers Unions at Risk of Losing "Agency Fees"
ERIC Educational Resources Information Center
Antonucci, Mike
2016-01-01
For 50 years, American education policy has often danced to the tune of labor realities. "Friedrichs v. California Teachers Association" is a case that awaits hearing by the U.S. Supreme Court that could dramatically change this picture. The case, if decided for the plaintiffs, could end the practice of "agency" fees--money…
Chickens across the Curriculum: An Experiment in Experiential Learning.
ERIC Educational Resources Information Center
Poulsen, Kristin; And Others
This paper describes: (1) the experiences of a class of 6- and 7-year-old students as they designed and built a small farm on the Laboratory School grounds at Berry College (Georgia); (2) the understanding that comes with the relevant and meaningful experience of building a farm and raising animals; (3) the infusion of Friedrich Froebel's…
Love and Ruin(s): Robert Frost on Moral Repair
ERIC Educational Resources Information Center
Frank, Jeff
2011-01-01
This essay begins where Alasdair MacIntyre's "After Virtue" begins: facing a moral world in ruin. MacIntyre argues that this predicament leaves us with a choice: we can follow the path of Friedrich Nietzsche, accepting this moral destruction and attempting to create lives in a rootless, uncertain world, or the path of Aristotle, working to reclaim…
The Politics of Encyclopaedias
ERIC Educational Resources Information Center
Fozooni, Babak
2012-01-01
The paper assesses the political credibility of three encyclopaedias (Encyclopaedia Britannica, Encyclopedia of Marxism and Wikipedia) in relation to three chosen topics (Friedrich Engels's biography; the political philosophy of fascism; and, the discipline of social psychology). I was interested in discerning how entries are represented and…
The "Encounter" as an "Event of Truth" in Education: An Anthropological-Pedagogical Approach
ERIC Educational Resources Information Center
Pantazis, Vasileios E.
2012-01-01
In this essay, Vasileios Pantazis examines how two philosophers having different orientations acknowledge and study the phenomenon of the "encounter" ("Begegnung") and its fundamental importance to human life and education. On the one hand, Otto Friedrich Bollnow drew on existential philosophy and philosophical anthropology in his analysis of the…
Meeting Standards in the Changing Landscape of Today's Kinder"garden"
ERIC Educational Resources Information Center
McLennan, Deanna Pecaski
2011-01-01
First conceptualized by Friedrich Froebel as a "children's garden," kindergarten classrooms in Canada today emphasize play and exploration as the primary methods of learning and development. This garden provides multiple opportunities for children to become lost in spontaneous play and creative interactions with peers. Kindergarten has slowly…
Discussions on Some Educational Issues III. Research Report 94.
ERIC Educational Resources Information Center
Kansanen, Pertti, Ed.
This publication consists of eight articles in which contributors discuss the following educational issues: (1) "Prospects for Schooling" (Friedrich W. Busch); (2) "Broadcasting, Education and Active Citizenship" (Brian Groombridge); (3) "On the Role of Mother-tongue Education in Multilingual Societies" (Wilfried Hartmann); (4) "Theory, Practice…
Standardized Tests and Froebel's Original Kindergarten Model
ERIC Educational Resources Information Center
Jeynes, William H.
2006-01-01
The author argues that American educators rely on standardized tests at too early an age when administered in kindergarten, particularly given the original intent of kindergarten as envisioned by its founder, Friedrich Froebel. The author examines the current use of standardized tests in kindergarten and the Froebel model, including his emphasis…
Did the American Herbartians Have a Research Base?
ERIC Educational Resources Information Center
Westfall, Barry H.
The origins of the Herbartian Movement began with the writings of Johan Friedrich Herbart (1776-1841), a German philosopher and educator. He believed that, through instruction, the mind and morals of the child could be molded. For this purpose, ideas are available from two sources: experience, which furnishes knowledge of nature, and social…
Mental Maps and Ethnocentrism: Geographic Characterizations in the Past.
ERIC Educational Resources Information Center
Elliott, Harold M.
1979-01-01
Reexamines geographic thought regarding ethnocentrism as expressed in the writings including Ellen Churchill Semple, Hendrick Willem Van Loon, Ellsworth Huntington, Roswell C. Smith, J. Olney, Henry Thomas Buckle, Georg Friedrich Hegel, Johann Gottfried Von Herder, Charles de Montesquieu, Ibn Khaldun, and Hippocrates. (DB)
ERIC Educational Resources Information Center
Council of Europe Forum, 1985
1985-01-01
Highlighting the issue of violence, this Forum issue contains 12 essays. Titles and authors are: "Passivity in the Face of Violence" (Henri Laborit); "Democratisation without Violence?" (Friedrich Hacker); "Ritualised Violence in Sport" (Christian Bromberger); "Violence in Prisons" (Luige Daga); "Racial Aggression" (Geoffrey Bindman); "Violence in…
Rediscovering Froebel: A Call to Re-Examine His Life and Gifts
ERIC Educational Resources Information Center
Manning, John P.
2005-01-01
This article examines the life of Friedrich Froebel, the founder of the kindergarten movement and his first 10 "gifts to children." The author suggests that Froebel's philosophy of German Romanticism caused the waning use of his methods. He continues to state that Froebel's development of instructional material and structured play-based curricula…
ERIC Educational Resources Information Center
Daley, Patrick J.; Soloski, John
Karl Marx and Friedrich Engels had little to say specifically about communication and language, but their works hint at the direction their critique of communication might have taken. Language and consciousness are conditioned by specific means of production and sociopolitical circumstances and are therefore ideological. The domain of ideology…
"Translated, It Is: …"--An Ethics of Transreading
ERIC Educational Resources Information Center
Zhang, Huiwen
2014-01-01
Inspired by Friedrich Nietzsche's idea of philology and William Gass's concept of transreading, Huiwen (Helen) Zhang employs "transreader" to suggest the integration of four roles in one: reader, translator, writer, and scholar. "Transreader" recognizes that close reading, literary translation, creative writing, and…
If We Knew What Spirituality Was, We Would Teach for It
ERIC Educational Resources Information Center
Yob, Iris M.
2011-01-01
Two extraordinary recent experiences that the author would call highly "spiritual" are explored against the background of ideas provided by writers such as Friedrich Schleiermacher, Rudolf Otto, Paul Tillich, and Abraham Maslow to unpack what spirituality is, with particular attention to the emotions and the insights involved in spirituality. The…
Froebel Is Dead; Long Live Froebel! The National Froebel Foundation and English Education
ERIC Educational Resources Information Center
Nawrotzki, Kristen D.
2006-01-01
The German pedagogue Friedrich Froebel lived from 1782 to 1852. The pedagogy that made Froebel famous was encompassed in his Kindergarten, a set of strictly defined methods and activities for the education of young children, which he developed and refined in the second quarter of the nineteenth century. Froebel's Kindergarten reached England in…
Between Knowledge and "Plagiarism," or, How the Chinese Language Was Studied in the West
ERIC Educational Resources Information Center
Tong, Q. S.
2008-01-01
This article looks at descriptions of the Chinese language in Western intellectual writings as indicative of a particular process of knowledge formation and reproduction. Beginning with the first systematic account produced by Matteo Ricci (1552-1610), it charts views offered by John Wilkins (1614-1672), James Beattie (1735-1803), Friedrich von…
European Influences on the Theory and Philosophy of Viktor Lowenfeld.
ERIC Educational Resources Information Center
Michael, John A.; Morris, Jerry W.
1985-01-01
Discusses how the work of art theorists, art educators, psychologists, and anthropologists who were predecessors or contemporaries of Viktor Lowenfeld influenced Lowenfeld's philosophy and theory of art education. Included are Friedrich Froebel, James Sully, Franz Cizek, Siegfried Levinstein, Max Verworn, Walter Krotzsch, George Luquet, and Karl…
Kafka: A Collection of Critical Essays. Twentieth Century Views Series.
ERIC Educational Resources Information Center
Gray, Ronald, Ed.
One of a series of works aimed at presenting contemporary critical opinion on major authors, this collection includes essays by Ronald Gray, Edwin Muir, Friedrich Beissner, R. O. C. Winkler, Johannes Pfeiffer, Caroline Gordon, Idris Parry, Edmund Wilson, Erich Heller, Austin Warren, Eliseo Vivas, Albert Camus, Martin Buber, and H. S. Reiss--all…
Montaigne, Nietzsche, and the Mnemotechnics of Student Agency
ERIC Educational Resources Information Center
Bingham, Charles
2007-01-01
This essay explores the educational implications of the thought of Michel de Montaigne and Friedrich Nietzsche on the subject of memory. It explores the sorts of cultural memory practices that Nietzsche has called "mnemotechnics", that is, the aspects of memory use that allow human beings to live life more fully. Nietzsche and Montaigne's work is…
Considering Hermeneutics and Education: Hermes, Teachers, and Intellectualism.
ERIC Educational Resources Information Center
Boyles, Deron Robert
Teacher roles in contemporary American schools should be more closely aligned to hermeneutics as the study of meaning (interpretation/understanding). A marriage between Platonic notions of interpretation and the quest for meaning with the interpretive theories of Friedrich Schleiermacher, Wilhelm von Humboldt, Wilhelm Dilthey, and Hans-Georg…
ERIC Educational Resources Information Center
Wolfram, Gary
2005-01-01
As Congress debates the reauthorization of the Higher Education Act (HEA), it should heed Friedrich Hayek's warning that democracy is "peculiarly liable, if not guided by accepted common principles, to produce over-all results that nobody wanted." One result of the federal government's student financial aid programs is higher tuition costs at the…
Burckhard F. Kommerell and Kommerell's Diverticulum
van Son, Jacques A.M.; Konstantinov, Igor E.
2002-01-01
Burckhard Friedrich Kommerell's scholarly description of the aortic diverticulum that bears his name was published in 1936. In the international literature, however, the name of Kommerell survives only as an eponym. We present biographical information about Kommerell, as supplied by family members, and comment on the surgical relevance of his 1936 report. (Tex Heart Inst J 2002;29:109–12) PMID:12075866
Quasioptimality of some spectral mixed methods
NASA Astrophysics Data System (ADS)
Gopalakrishnan, Jayadeep; Demkowicz, L. F. Leszek F.
2004-05-01
In this paper, we construct a sequence of projectors into certain polynomial spaces satisfying a commuting diagram property with norm bounds independent of the polynomial degree. Using the projectors, we obtain quasioptimality of some spectral mixed methods, including the Raviart-Thomas method and mixed formulations of Maxwell equations. We also prove some discrete Friedrichs type inequalities involving curl.
ERIC Educational Resources Information Center
Saeverot, Herner
2016-01-01
In the book "Forgotten Connections. On Culture and Upbringing," originally from 1983, the late German educator Klaus Mollenhauer interprets Johann Friedrich Herbart's educational concept of "Bildsamkeit", i.e., the ability and willingness to be educated. Furthermore, Mollenhauer conceives "Bildsamkeit" as growing out…
Von Steuben and the German Contribution to the American Revolution: A Selective Bibliography.
ERIC Educational Resources Information Center
Krewson, Margrit B.
This Library of Congress selected bibliography highlights the efforts of Baron Friedrich Wilhelm von Steuben, other German and German-American military leaders, and the Hessian auxiliary military forces in assisting the American colonies during the Revolutionary War. The booklet is divided into five parts. Part 1 provides historical information…
"Their Little Wooden Bricks": A History of the Material Culture of Kindergarten in the United States
ERIC Educational Resources Information Center
Prochner, Larry
2011-01-01
This article explores the material culture of kindergarten in the United States in relation to the production and consumption of materials and kindergarten theory and pedagogy. The focus is on Friedrich Froebel's building gifts as they were manufactured and sold by the Milton Bradley Company from 1869 to 1939. A review of trade catalogues over the…
Reuniting Art and Nature in the Life of the Child
ERIC Educational Resources Information Center
Strauch-Nelson, Wendy
2012-01-01
Sometimes looking at the history of education can be a bit frustrating. Examination of the past is necessary, however, if people are to move forward responsibly for the sake of the child. In this article, the author examines the common ancestry of the kindergarten, art, and nature study. As the founder of the kindergarten, Friedrich Froebel played…
NASA Astrophysics Data System (ADS)
Dick, Wolfgang R.; Duerbeck, H. W.; Hamel, Jürgen
The contributions deal with astronomical events of the past 1000 years. We elucidate the person of the single European observer of the supernova of 1006, and the views of Christoph Scheiner and Otto von Guericke on the structure and substance of the cosmos. A study of the development of the Copernican and the cosmological principles conclude this group of themes. Biographical investigations were carried out on the clockmaker Nikolaus Lilienfeld, the astronomers Johann Wurzelbau, Friedrich Wilhelm Toennies and Boris Karpov as well as the “panbabylonist” Alfred Jeremias. Astronomers can be active also in poetry and fiction. This is shown in the studies of Johann Leonard Rost and Friedrich Wilhelm Bessel. Finally, Johannes Hevelius' Observatory in Danzig/Gdansk, destroyed by a fire in 1679, is reconstructed by means of printed sources, old maps and photographs. The book concludes by short communications, obituaries and book reviews.
Friedel phase discontinuity and bound states in the continuum in quantum dot systems
NASA Astrophysics Data System (ADS)
Solís, B.; Ladrón de Guevara, M. L.; Orellana, P. A.
2008-06-01
In this Letter we study the Friedel phase of the electron transport in two different systems of quantum dots which exhibit bound states in the continuum (BIC). The Friedel phase jumps abruptly in the energies of the BICs, which is associated to the vanishing width of these states, as shown by Friedrich and Wintgen in [H. Friedrich, D. Wintgen, Phys. Rev. A 31 (1985) 3964]. This odd behavior of the Friedel phase has consequences in the charge through the Friedel sum rule. Namely, if the energy of the BIC drops under the Fermi energy the charge changes abruptly in a unity. We show that this behavior closely relates to discontinuities in the conductance predicted for interacting quantum dot systems.
The Magnetic Observatory Buildings at the Royal Observatory, Cape
NASA Astrophysics Data System (ADS)
Glass, I. S.
2015-10-01
During the 1830s there arose a strong international movement, promoted by Carl Friedrich Gauss and Alexander von Humboldt, to characterise the earth's magnetic field. By 1839 the Royal Society in London, driven by Edward Sabine, had organised a "Magnetic Crusade" - the establishment of a series of magnetic and meteorological observatories around the British Empire, including New Zealand, Australia, St Helena and the Cape. This article outlines the history of the latter installation, its buildings and what became of them.
Völker, A
1990-04-01
The 200th anniversary of the death of Christian Andreas Cothenius gave occasion to appreciate life and work of this personage of a physician. Cothenius maintained manifold connections to Halle, of which the golden doctorate and the heritage of the pharmaceutic enterprises of his teacher Friedrich Hoffmann were treated in this place. The picture of the local relations was supplemented by the history of the Cothenius medal which is today awarded by the Leopoldina of Halle. PMID:2198714
Some observations on a new numerical method for solving Navier-Stokes equations
NASA Technical Reports Server (NTRS)
Kumar, A.
1981-01-01
An explicit-implicit technique for solving Navier-Stokes equations is described which, is much less complex than other implicit methods. It is used to solve a complex, two-dimensional, steady-state, supersonic-flow problem. The computational efficiency of the method and the quality of the solution obtained from it at high Courant-Friedrich-Lewy (CFL) numbers are discussed. Modifications are discussed and certain observations are made about the method which may be helpful in using it successfully.
The design of an improved endwall film-cooling configuration
Friedrichs, S.; Hodson, H.P.; Dawes, W.N.
1999-10-01
The endwall film-cooling cooling configuration investigated by Friedrichs et al. (1196, 1997) had in principle sufficient cooling flow for the endwall, but in practice, the redistribution of this coolant by secondary flows left large endwall areas uncooled. This paper describes the attempt to improve upon this datum cooling configuration by redistributing the available coolant to provide a better coolant coverage on the endwall surface, while keeping the associated aerodynamic losses small. The design of the new, improved cooling configuration was based on the understanding of endwall film-cooling described by Friedrichs et al. (1996, 1997). Computational fluid dynamics were used to predict the basic flow and pressure field without coolant ejection. Using this as a basis, the above-described understanding was used to place cooling holes so that they would provide the necessary cooling coverage at minimal aerodynamic penalty. The simple analytical modeling developed by Friedrichs et al. (1997) was then used to check that the coolant consumption and the increase in aerodynamic loss lay within the limits of the design goal. The improved cooling configuration was tested experimentally in a large-scale, low-speed linear cascade. An analysis of the results shows that the redesign of the cooling configuration has been successful in achieving an improved coolant coverage with lower aerodynamic losses, while using the same amount of coolant as in the datum cooling configuration. The improved cooling configuration has reconfirmed conclusions from Friedrichs et al. (1996, 1997): First, coolant ejection downstream of the three-dimensional separation lines on the endwall does not change the secondary flow structures: second, placement of holes in regions of high static pressure helps reduce the aerodynamic penalties of platform coolant ejection: finally, taking account of secondary flow can improve the design of endwall film-cooling configurations.
Furious Frederich: Nietzsche's neurosyphilis diagnosis and new hypotheses.
André, Charles; Rios, André Rangel
2015-12-01
The causes of Friedrich Nietzsche's mental breakdown in early 1889 and of the subsequent slow decay to end-stage dementia along ten years will possibly remain open to debate. The diagnosis of syphilitic dementia paralytica, based only on medical anamnesis and physical examination, was considered indisputable by Otto Binswanger. On the other hand, taking into account recently described diseases, selectively collected evidence lend some support to alternative hypotheses: basal forebrain meningioma, CADASIL, MELAS and frontotemporal dementia. PMID:26465288
Study of astrophysics at the ``Babeş-Bolyai'' University
NASA Astrophysics Data System (ADS)
Ureche, Vasile; Roman, Rodica
2007-03-01
This paper presents the history of the study of astrophysics at the ``Babeş-Bolyai'' University, from 1945 until now. Some special epochs are analyzed and the contributions of professors of astronomy at the study of astrophysics is put in evidence. The continuity of this study and the collaboration of the ``Babeş-Bolyai'' University with the ``Friedrich Wilhelms'' University of Germany, in the field of astrophysics is emphasized.
NASA Astrophysics Data System (ADS)
Rasulov, T. Kh.
2010-04-01
We consider a model Schrödinger operator Hμ associated with a system of three particles on the threedimensional lattice ℤ 3 with a functional parameter of special form. We prove that if the corresponding Friedrichs model has a zero-energy resonance, then the operator Hμ has infinitely many negative eigenvalues accumulating at zero (the Efimov effect). We obtain the asymptotic expression for the number of eigenvalues of Hμ below z as z → -0.
NASA Astrophysics Data System (ADS)
Miyamoto, Manabu
2004-09-01
The long-time behavior of the survival probability for unstable multilevel systems that follows the power-decay law is studied based on the N -level Friedrichs model, and is shown to depend on the initial population in unstable states. A special initial state maximizing the asymptote of the survival probability at long times is found and examined by considering the spontaneous-emission process for the hydrogen atom interacting with the electromagnetic field.
06-1464 - Deltakeeper Chapter of Baykeeper et al v. Brasil and Sons Dairy, Inc. et al
Code of Federal Regulations, 2011 CFR
2007-06-27
... Stipulated Dismissal and Settlement; Order 1 Case. No. CV 06-01464 OWW (DLB) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Layne Friedrich (Bar No. 195431) layne@lawyersforcleanwater.com Drevet Hunt (Bar No. 240487) Lawyers For Clean Water, Inc. 1004A O’Reilly Avenue San Francisco, California 94129 Telephone:...
NASA Astrophysics Data System (ADS)
Obukhov, Yuri N.
1993-11-01
Following recent studies of Ford, we suggest - in the framework of general relativity - an inflationary cosmological model with self-interacting spinning matter. A generalization of the standard fluid model is discussed and estimates of the physical parameters of the evolution are given. I would like to thank Professor Friedrich W. Hehl for the careful reading of the manuscript and useful advice. This research was supported by the Alexander von Humboldt Foundation (Bonn).
Nonlinear stability of discrete shocks for systems of conservation laws
NASA Astrophysics Data System (ADS)
Liu, Jian-Guo; Xin, Zhouping
1993-09-01
In this paper we study the asymptotic nonlinear stability of discrete shocks for the Lax-Friedrichs scheme for approximating general m×m systems of nonlinear hyperbolic conservation laws. It is shown that weak single discrete shocks for such a scheme are nonlinearly stable in the L p-norm for all p ≧ 1, provided that the sums of the initial perturbations equal zero. These results should shed light on the convergence of the numerical solution constructed by the Lax-Friedrichs scheme for the single-shock solution of system of hyperbolic conservation laws. If the Riemann solution corresponding to the given far-field states is a superposition of m single shocks from each characteristic family, we show that the corresponding multiple discrete shocks are nonlinearly stable in L p (P ≧ 2). These results are proved by using both a weighted estimate and a characteristic energy method based on the internal structures of the discrete shocks and the essential monotonicity of the Lax-Friedrichs scheme.
Bihari, A; Mészáros, K; Reményi, A; Lichtenberger, G
2006-12-01
The aim of this study was to objectively evaluate the voices of patients suffering from unilateral vocal cord paralysis, before and after endoscopic augmentation and thyroplasty. In the past, we used injectable Teflon to treat this condition; later techniques included collagen injection and Isshiki thyroplasty. In the last 7 years, preferred treatment methods have included Bioplastique injection and lipoaugmentation of the vocal cords as well as medialization thyroplasty using a titanium implant according to Friedrich. Pre- and postoperative data was evaluated and compared to 25 patients. Appropriate glottic closure of the vocal cords was achieved in every case, in most cases after the first intervention. We used voice range profile measurements to evaluate the results. An objective evaluation was performed using the Friedrich dysphonia index. Significant improvements were found: the dysphonia index decreased in every case, from an average of 2.47, preoperatively, to an average of 1.18 postoperatively. In agreement with earlier studies, voice pitch range was the only parameter that not significantly improved. There was no statistical difference between the lipoaugmentation and thyroplasty according to Friedrich. We concluded that both endoscopic methods and thyroplasty can be used to achieve an optimal result. Cases must be evaluated individually so that the best technique, or combination of methods can be determined. PMID:16896756
[The history of medical physics and biophysics at the Humboldt University in Berlin].
Schneck, P
2001-01-01
The present Institute of Medical Physics and Biophysics (former Institute of Radiation Research) was established on September 1st in 1923 by Walter Friedrich (1883-1968). It was after the Institute in Frankfurt A.M. (founded by Friedrich Dessauer in 1921) - the second Institute of its kind in Germany. As a physicist who wrote his dissertation under Wilhelm Conrad Röntgen, he did research together with a Gynecologist in Friedburg on problems of radiation therapy and the prevention of radiation injuries. Thus Friedrich became one of the first German Biomedical Physicists and was appointed to a professorship at the university of Berlin and its faculty of medicine. The paper gives a survey of the history of the Institute of Radiation Research in the twenties, in the time of Nazi-rule, the period after the World War II and in the era of GDR until 1990 and up to the present time. The succession of directorship of the Institute and the main research subjects in medical physics and biophysics have been sketched. PMID:11710396
Low energy singly and multiply charged ion irradiation of astrophysical ices
NASA Astrophysics Data System (ADS)
Dawes, A.; Holtom, P. D.; Mukerji, R. J.; Davis, M. P.; Sivaraman, B.; McCullough, R. W.; Williams, I.; Mason, N. J.
Ion induced processes play an important role in the chemical modification of astrophysical ices, both on the surfaces of satellites in the outer solar system and in the depths of dark molecular clouds where few photons penetrate. To date many laboratory studies have been developed to study energetic singly charged ion interactions with astrophysical ice analogues (e.g. Mennella, et al 2004; Strazzulla, Baratta & Palumbo 2001; Gerakines, Moore, & Hudson 2000) and have been found to produce new chemical species and cause significant effects on ice morphology (Palumbo 2005). However, the effects of low energy and multiply charged ions have not yet been investigated. Such ions are prevalent in many astrophysical environments: as primary and secondary particles generated by cosmic ray bombardment and as constituents of planetary magnetospheres (e.g. Jupiter and Saturn). These ions comprise a rich variety of reactive species in a variety of charge states with typical kinetic energies of few keV. The effect of slow, multiply charged ions (MCIs) with the surfaces of astrophysical ices and their possible effect on chemical processing is unclear. However, studies of MCI impacts with insulator surfaces suggest that they may play an important role due to surplus potential energy imparted at the surface of the target (Winter & Aumayr 2001). We have developed a research program to study ion interactions with astrophysical ices using an Electron Cyclotron Resonance (ECR) ion source at Queens University Belfast. Such a source can produce different species of ions with variable energy and different charge states. Ices are prepared in situ by depositing gas onto a cold infrared transmitting window. Samples are analysed using FTIR spectroscopy during irradiation. We have conducted a series of experiments to investigate the effects of ion charge state (potential vs. kinetic energy effects), ion energy (nuclear vs. electronic stopping processes) and sample temperature. In this poster
Late Pleistocene oscillations of the Drau Glacier (southern Austria)
NASA Astrophysics Data System (ADS)
Karnitschar, Christina; Reitner, Jürgen; Draganits, Erich
2016-04-01
The Drau Glacier was the largest Pleistocene glacier in the southeastern part of the Alps and significantly shaped the landscape in this region. The study area is located at the termination of the Drau Glacier in the southern part of Austria (Carinthia). The investigation aims to decipher glacial dynamics during the Late Pleistocene glacial advance, stabilisation and final recession of this glacier based on geological/geomorphological mapping, interpretation of airborne laser scan (ALS) topographic data and lithostratigraphic investigations of glacial and periglacial sediments. Special emphasis is laid on the reconstruction of the maximum extent of the glaciation (LGM). Based on previous mapping by Bobek (1959) and Ucik (1996-1998) more details have been gained for the paleogeographic reconstruction based on glacial and non-glacial erosion and accumulation features. These include traces of pre-Upper Pleistocene glaciation, drumlins, terminal moraines and kettle holes. Paleogeographic reconstruction was done with correlation of different outcrops based on lithostratigraphy and ALS topography. Sequences of gravel related to glacial advance covered by till, followed by periglacial sediments allowed detailed reconstruction of the glacial sequence in this area and the complex succession of various extents of the Drau Glacier. References Bobek, Hans. 1959: Der Eisrückgang im östlichen Klagenfurter Becken. In: Mitteilungen der österreichischen geographischen Gesellschaft, Wien. Ucik, Friedrich Hans. 1996: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 141, S. 340, Wien. Ucik, Friedrich Hans. 1997: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 141, S. 325-326, Wien. Ucik, Friedrich Hans. 1998: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 142, S. 333-334, Wien.
Numerical methods for supersonic astrophysical jets
NASA Astrophysics Data System (ADS)
Ha, Youngsoo
2003-09-01
The Euler equations of gas dynamics are used for the simulation of general astrophysical fluid flows including high Mach number astrophysical jets with radiative cooling. To accurately compute supersonic jet solutions with sharp resolution of shock waves, three modern numerical methods for gas dynamics were used: (1)a second-order Godunov method in LeVeque's software package CLAWPACK, (2)the Nessyahu-Tadmor-Kurganov (NTK) central hyperbolic scheme, and (3)the WENO-LF (Weighted Essentially Non-Oscillatory Lax-Friedrichs) scheme. Then simulations of supersonic astrophysical jets were compared, first without and then with radiative cooling. CLAWPACK consists of routines for solving time-dependent nonlinear hyperbolic conservation laws based on higher order Godunov methods and approximate Riemann problem solutions; the NTK scheme solves conservation laws using a modified Lax-Friedrichs central difference method without appealing to Riemann problem solutions; and the WENO-LF finite difference scheme is based on the Essentially Non-Oscillatory (ENO) idea by using Lax- Friedrichs flux splitting. The ENO method constructs a solution using the smoothness of the interpolating polynomial on given stencils; on the other hand, the WENO scheme uses a convex combination of the interpolate functions on all candidate stencils. The third-order and fifth-order WENO-LF methods were used to simulate the high Mach number jets. Appropriate numerical methods for incorporating radiative cooling in these numerical methods are also discussed. Interactions of supersonic jets with their environments (jet-“blob” interactions) are shown after modifying the codes to handle high Mach numbers and radiative cooling.
Some Historical Points of Interest in Göttingen
NASA Astrophysics Data System (ADS)
Hentschel, Klaus
The Georgia Augusta University of Göttingen, founded in 1737, was a child of the Enlightenment, and the new sciences have always played a major role here.1 Among the teachers of physics, physical chemistry, astronomy, and related subjects we find Johann Christian Polykarp Erxleben, Georg Christoph Lichtenberg, Johann Tobias Mayer, Carl Friedrich Gauss, Johann B. Listing, Wilhelm Eduard Weber, Woldemar Voigt, Friedrich Kohlrausch, Eduard Riecke, Walther Nernst and Peter Debye — the last two subsequently moved on to Berlin. In the 1920s, physics students were jestingly referred to as “Frankierte, Bornierte und Polierte” (loosely translated as stamped, limited and polished), in allusion to their teachers, the theoretical physicist Max Born and the experimentalists James Franck and Robert Wichard Pohl, the first two being important figures in the history of quantum theory, the third, one of the founding fathers of experimental solid state physics.2 The National Socialist’s rise to power had a devastating effect on this world-renowned center for physics and mathematics. Most of its high-caliber scientists either were dismissed on the basis of the racist “Law for the Restoration of the Professional Civil Service” or themselves felt compelled to emigrate: About a dozen members of the physics faculty, including Born and Franck, and ten from the mathematics faculty left Göttingen.3 After the war, Richard Becker, who in 1936 had received a compulsory order to take the chair for theoretical physics vacant since Born’s emigration, and Friedrich Hund, who was also an enthusiastic historian of science, distinguished themselves as physics teachers there but the university as a whole never recovered its international standing of before 1933 (see Figs. 1 and 2).
NASA Astrophysics Data System (ADS)
Bui-Thanh, Tan
2015-08-01
By revisiting the basic Godunov approach for system of linear hyperbolic Partial Differential Equations (PDEs) we show that it is hybridizable. As such, it is a natural recipe for us to constructively and systematically establish a unified hybridized discontinuous Galerkin (HDG) framework for a large class of PDEs including those of Friedrichs' type. The unification is fourfold. First, it provides a single constructive procedure to devise HDG schemes for elliptic, parabolic, hyperbolic, and mixed-type PDEs. The key that we exploit is the fact that, for many PDEs, irrespective of their type, the first order form is a hyperbolic system. Second, it reveals the nature of the trace unknowns as the upwind states. Third, it provides a parameter-free HDG framework, and hence eliminating the "usual complaint" that HDG is a parameter-dependent method. Fourth, it allows us to rediscover most existing HDG methods and furthermore discover new ones. We apply the proposed unified framework to three different PDEs: the convection-diffusion-reaction equation, the Maxwell equation in frequency domain, and the Stokes equation. The purpose is to present a step-by-step construction of various HDG methods, including the most economic ones with least trace unknowns, by exploiting the particular structure of the underlying PDEs. The well-posedness of the resulting HDG schemes, i.e. the existence and uniqueness of the HDG solutions, is proved. The well-posedness result is also extended and proved for abstract Friedrichs' systems. We also discuss variants of the proposed unified framework and extend them to the popular Lax-Friedrichs flux and to nonlinear PDEs. Numerical results for transport equation, convection-diffusion equation, compressible Euler equation, and shallow water equation are presented to support the unification framework.
NASA Astrophysics Data System (ADS)
Gontier, H.; Schaffarczyk, A. P.; Kleinhans, D.; Friedrich, R.
2007-07-01
This project funded by the federal ministry of education and research from the research group 'Wind turbulence and its significance in the use of wind energy' handles a comparison between the load ranges for horizontal axis wind turbines resulting from different turbulence models, i.e. between the usual models as defined in the standards and a new model designed by Friedrich and Kleinhans. This should enable an evaluation of the relevance of this new model for wind modelling for wind turbines and if so, provide the community with new tools in wind simulation. Indeed, spectral models do not well reproduce extreme wind increments as met in gusts. Those models simulate using purely Gaussian statistics. However, measurements show that those increments do not follow normal statistics. The new model developed aims at correcting this problem. The turbulence models used are the Kaimal, von Karman and Mann models as defined in the IEC guidelines and the Friedrich-Kleinhans model, based on stochastic processes called Continuous Time Random Walks. The comparison is based on load ranges resulting from an RFC analysis of 100 time series obtained for 100 different seed numbers. Five wind speeds are investigated. The aeroelastic code used is FLEX5. The main conclusion that can be drawn from this study is that the non-Gaussian Friedrich-Kleinhans model produces loads that are significantly different from the loads obtained with the Kaimal model. That proves that the form of the tails of the increment distribution has a major influence on the loads of the wind turbine and should be considered when making fatigue calculations.
Bettin, H; Friedrich, C
2000-01-01
The biography of Carl Friedrich August Theodor Kastner (1797-after 1841), the brother of the famous chemist and teacher of Justus von Liebig (1803-1873) Karl Wilhelm Gottlob Kastner (1783-1857), is an interesting example of the difficult situation of outside lecturers at the universities in the first half of the 19th century; a big group of scientists, which are absolutely underrepresented in the source material and in the historiography too. This paper tries to show the facts and the backgrounds for the problems in the career of outside lecturers. PMID:11305171
WENO wavelet method for a hyperbolic model of two-phase flow in conservative form
NASA Astrophysics Data System (ADS)
Zeidan, Dia; Kozakevicius, Alice J.; Schmidt, Alex A.; Jakobsson, Stefan
2016-06-01
The current work presents a WENO wavelet adaptive method for solving multiphase flow problems. The grid adaptivity in each time step is obtained by the application of a thresholded interpolating wavelet transform, which allows the construction of a small yet effective sparse point representation of the solution. The spatial operator is solved by the Lax-Friedrich flux splitting approach in which the flux derivatives are approximated by the WENO scheme. Hyperbolic models of two-phase flow in conservative form are efficiently solved since shocks and rarefaction waves are precisely captured by the chosen methodology. Substantial computational gains are obtained through the grid reduction feature while maintaining the quality of the solutions.
The Dürrenmatt's ``Physicists'' as a Tool in Understanding the Ethics of Science
NASA Astrophysics Data System (ADS)
Kapor, Darko
2007-04-01
Part of the course of the History of Physics taught by the author is dedicated to the ethics of science, in particular to moral responsibility of the scientist towards society. In order to make the subject more interesting to the students, the first step is reading the play ``Physicists'' by Friedrich Dürrenmatt (1962). The students are then asked to relate some of the events connected to the nuclear studies before and during the World War II and armaments race with some situations in the play or the author's theses related to it.
A mixed system modeling two-directional pedestrian flows.
Goatin, Paola; Mimault, Matthias
2015-04-01
In this article, we present a simplified model to describe the dynamics of two groups of pedestrians moving in opposite directions in a corridor. The model consists of a 2 x 2 system of conservation laws of mixed hyperbolic-elliptic type. We study the basic properties of the system to understand why and how bounded oscillations in numerical simulations arise. We show that Lax-Friedrichs scheme ensures the invariance of the domain and we investigate the existence of measure-valued solutions as limit of a subsequence of approximate solutions. PMID:25811441
Finite-element method for a uniformly loaded cantilever beam with general cross section
Lin, S.C.
1987-05-01
The Michell (1901) theory for the analysis of beam-type structures is combined with that of Friedrich and Lin (1984) to obtain a finite element solution for a uniformly loaded cantilever beam with general cross section. A plane-strain problem established with internal body and boundary forces that were computed from the warping displacement is solved by means of the regular two-dimensional finite element program, on the same model used for warping displacement calculation. Numerical examples are given for cantilever beams with circular and thin-rectangular cross section. 6 references.
The discrete one-sided Lipschitz condition for convex scalar conservation laws
NASA Technical Reports Server (NTRS)
Brenier, Yann; Osher, Stanley
1986-01-01
Physical solutions to convex scalar conservation laws satisfy a one-sided Lipschitz condition (OSLC) that enforces both the entropy condition and their variation boundedness. Consistency with this condition is therefore desirable for a numerical scheme and was proved for both the Godunov and the Lax-Friedrichs scheme--also, in a weakened version, for the Roe scheme, all of them being only first order accurate. A new, fully second order scheme is introduced here, which is consistent with the OSLC. The modified equation is considered and shows interesting features. Another second order scheme is then considered and numerical results are discussed.
NASA Astrophysics Data System (ADS)
Leue, Hans-Joachim
More than 200 years ago, the first large reflectors on the European continent were built at Johann Hieronymus Schroeter's observatory in Lilienthal near Bremen. Johann Gottlieb Friedrich Schrader, professor of physics and chemistry at Kiel University, developed a white reflecting metal alloy during his 10-month stay with Schroeter, and used it for the production of numerous telescope mirrors. The period of telescope making at Lilienthal started with Schrader. This paper describes the cooperation of the two astronomers and reports about the results of an optical and chemical analysis of three Herschel telescope mirrors.
Mineral resource of the month: cadmium
Tolcin, Amy C.
2012-01-01
The element cadmium was discovered in 1817 by Friedrich Stromeyer, a professor of chemistry at the University of Göttingen in Germany. Stromeyer noticed that a yellowish glow would occur when heat was applied to certain samples of calamine, a zinc-carbonate. This was unusual as the reaction was expected to be colorless. After further testing, Stromeyer deduced that an unknown metallic impurity in the carbonate caused the color change. He called the new metal "cadmium" after "kadmeia," the Greek word for calamine.
Chladni Patterns on Drumheads: A ``Physics of Music'' Experiment
NASA Astrophysics Data System (ADS)
Worland, Randy
2011-01-01
In our "Physics of Music" class for non-science majors, we have developed a laboratory exercise in which students experiment with Chladni sand patterns on drumheads. Chladni patterns provide a kinesthetic, visual, and entertaining way to illustrate standing waves on flat surfaces and are very helpful when making the transition from one-dimensional systems, such as string and wind instruments, to the two-dimensional membranes and plates of the percussion family. Although the sand patterns attributed to Ernst Florens Friedrich Chladni (1756-1827) are often demonstrated for this purpose using metal plates,2-4 the use of drumheads offers several pedagogical and practical advantages in the lab.
Wise, M Norton; Wise, Elaine M
2002-12-01
English gardens powered by steam engines offer an intriguing view of how technological and scientific progress was naturalized in the landscape of 19th-century Prussia, and in Prussian culture, during the early years of industrial modernization. One such garden is Peacock Island, in the Havel River near Potsdam. A product of the reform era that preceded and followed the Napoleonic Wars, it expressed the goal of Friedrich Wilhelm III and his government to enter into the British system of factory production and world trade. Modern science, as represented especially by Alexander von Humboldt, played a prominent role. PMID:12535923
Nietzsche: An intellectual Nebuchadnezzar.
Baird, R M
1987-09-01
The essay introduces and defines the concept of "an intellectual Nebuchadnezzar"-one who, despite his hostility to religion, serves God's purposes by the depth of his ideas. In terms of this notion, some of Friedrich Nietzsche's views are explored. Specifically, Nietzsche's perspective on artistic creativity is analyzed and applied to the notion of creativity in human relationships. In addition to concluding that Nietzsche is himself an "intellectual Nebuchadnezzar," the broader point is made that truth and insight should be welcomed by the religious community even if the source of that truth is one ostensibly hostile to religion. PMID:24302037
The Tortured History of Gauss's Law
NASA Astrophysics Data System (ADS)
Spencer, Ross
2009-10-01
American physics textbooks contain the following equation, which is called Gauss's law: E .d S = qenclosed ɛ0 It is odd, however, that biographies of Karl Friedrich Gauss (1777-1855) contain no mention of this law. A brief history of this important result will be presented in which it will be shown that what we call Gauss's law today was originally guessed at by Joseph Priestly (1733-1804) after he read a letter from Benjamin Franklin (1706-1790), then was derived, forgotten, and re-derived several times in two different contexts by many of the luminaries of physics in the eighteenth and nineteenth centuries.
George, Daniel R
2013-09-01
In The Birth of Tragedy, Friedrich Nietzsche celebrated the dueling forces of reason and emotion as personified by the ancient Greek gods Apollo and Dionysus. A subtle Apollonian-Dionysian balance can be observed in TimeSlips, a group-based creative storytelling activity developed in the 1990s and increasingly used in dementia care settings worldwide. This article explains how the Apollonion-Dionysian aspects of TimeSlips are beneficial not only for persons with dementia, but also for their carers. Narrative data from medical students at Penn State College of Medicine who participated in TimeSlips at a local retirement community are shared. PMID:23722245
Introduction to the special issue: under pressure.
Howard, Yetta
2013-01-01
This article introduces this special issue on the theme "Under Pressure." It uses an analysis of experimental lesbian filmmaker Su Friedrich's Seeing Red (2005) to frame the issue's focus on the ways that the category "lesbian" is placed under pressure and/or the pressure "lesbian" places on twentieth- and twenty-first-century cultural production. After this overview, the introduction summarizes all seven articles in the order that they appear in the issue. These summaries also show the connections between the articles and suggest possibilities for future critical dialogues on the theme. PMID:23316837
A New Mixed Model Based on the Velocity Structure Function
NASA Astrophysics Data System (ADS)
Brun, Christophe; Friedrich, Rainer; Da Silva, Carlos B.; Métais, Olivier
We propose a new mixed model for Large Eddy-Simulation based on the 3D spatial velocity increment. This approach blends the non-linear properties of the Increment model (Brun & Friedrich (2001)) with the eddy viscosity characteristics of the Structure Function model (Métais & Lesieur (1992)). The behaviour of this subgrid scale model is studied both via a priori tests of a plane jet at ReH=3000 and Large Eddy-Simulation of a round jet at ReD=25000. This approach allows to describe both forward and backward energy transfer encountered in transitional shear flows.
NASA Astrophysics Data System (ADS)
Chen, Ming-Keh
1999-09-01
We examine the possibility of the resonances of an H- 1,3Po dipole series being formed below the n = 2 hydrogen threshold. Including the relativistic and QED corrections as first-order perturbations, the series will be terminated after the third resonance for 1Po symmetry and the fourth resonance for 3Po symmetry. The total angular momentum, J, is shown to be 0 for the fourth resonance of a 3Po series. This figure is in disagreement with that of Purr and Friedrich. The present resonant energies and widths were calculated by the saddle-point complex rotation method with B-spline functions.
NASA Astrophysics Data System (ADS)
Veit, Th.; Friedrich, J.; Offermann, E. A. J. M.
1993-12-01
The procedures used to model [J. Friedrich, Nucl. Instr. and Meth. A 293 (1990) 575] or to determine [N. Voegler et al., Nucl. Instr. and Meth. A 249 (1986) 337, H. Blok et al., ibid., vol. A 262 (1987) 291, and E.A.J.M. Offermann et al., ibid., vol. A 262 (1987) 298] the mapping properties of a magnetic spectrometer are based on a minimization of the variance of target coordinates. We show that backtracing with matrix elements, determined in this way, may contain systematic errors. As alternative, we propose to minimize the variance of the detector coordinates. This procedure avoids these systematic errors.
AGU members elected to Academy
NASA Astrophysics Data System (ADS)
Six AGU members are among the sixty new members and fifteen foreign associates elected on April 27 to the National Academy of Sciences in recognition of their distinguished and continuing achievements in original research.AGU members elected were AGU Past-President G. Brent Dalrymple of USGS, Menlo Park, Calif.; Donald J . DePaolo, University of California, Berkeley; Ho-Kwang (David) Mao, Carnegie Institution, Washington, D.C.; Mario J . Molina, Massachusetts Institute of Technology, Cambridge; and Alexandra Navrotsky, Princeton University, Princeton, N.J. Elected as foreign associates were Nikolai V. Sobolev, Russian Academy of Sciences, Novosibirsk, and Friedrich H. Busse, University of Bayreuth, Germany.
NASA Astrophysics Data System (ADS)
Albeverio, S.; Lakaev, S. N.; Muminov, Z. I.
2007-12-01
A model operator H associated to a system of three particles on the threedimensional lattice ℤ3 that interact via nonlocal pair potentials is studied. The following results are established. (i) The operator H has infinitely many eigenvalues lying below the bottom of the essential spectrum and accumulating at this point if both the Friedrichs model operators h_{μ _α } (0), α = 1, 2, have threshold resonances. (ii) The operator H has finitely many eigenvalues lying outside the essential spectrum if at least one of the operators h_{μ _α } (0), α = 1, 2, has a threshold eigenvalue.
Analysis of 2-spar cantilever wings with special reference to torsion and load transference
NASA Technical Reports Server (NTRS)
Kuhn, Paul
1936-01-01
This report deals with the analysis of 2-spar cantilever wings in torsion, taking cognizance of the fact that the spars are not independent, but are interconnected by ribs and other structural members. The principles of interaction are briefly explained, showing that the mutual relief action occurring depends on the "pure torsional stiffness" of the wing cross section. Various practical methods of analysis are outlined. The "Friedrichs-Von Karman equations" are shown to require the least amount of labor. Numerical examples by the several methods of analysis are given and the agreement between the calculation and experiment is shown.
[Weizsäcker's concept of time from the current viewpoint].
Kiefer, Claus
2014-01-01
Carl Friedrich von Weizsäcker's concept of time is deeply based on the asymmetry between past and future, which he considers as a fundamental aspect of Nature. I review these ideas and their philosophical back ground and confront them with a presentation of the concept of time in modern physics. I argue that the observed irreversibility of our world can be understood from fundamental laws which are invariant under time reversal. I conclude with an outlook on the expected theory of quantum gravity. PMID:24974601
[Poet-physicians in German literature].
Perels, C
1991-12-17
Starting with standards arising from the relationship between medicine and art in classical antiquity, biblical tradition and teutonic-pagan antiquity, this article roams through german literature from the Middle Ages up to the 20th century, from Hildegard of Bingen to Gottfried Benn and Alfred Döblin, guided by the question, how strongly medical knowledge and medical practise are reflected in the poetry of writing physicians. Individual dispositions and epoque-specific features are discussed. Special attention is given to Paul Fleming and Angelus Silesius, Albrecht von Haller and Friedrich Schiller, romanticism and Georg Büchner. PMID:1754781
Axes, planes and tubes, or the geometry of embryogenesis.
Brauckmann, Sabine
2011-12-01
The paper presents selected figures of chick embryogenesis as depicted in the classic studies of Caspar Friedrich Wolff (1734-1794), Christian Heinrich Pander (1794-1865) and Karl Ernst von Baer (1792-1786). My main objective here is (1) to demonstrate how the imagery of Wolff, Pander and Baer attempted to project an image of a 3-dimensional rotating body into static figures on paper by means of linear contours, and (2) to ponder on the efficacy and pervasiveness of dots, lines and arrows for depicting embryogenesis. PMID:22035710
A critique of Bernstein's beyond objectivism and relativism: science, hermeneutics, and praxis.
Matusitz, Jonathan; Kramer, Eric
2011-06-01
This analysis comments on Bernstein's lack of clear understanding of subjectivity, based on his book, Beyond Objectivism and Relativism: Science, Hermeneutics, and Praxis. Bernstein limits his interpretation of subjectivity to thinkers such as Gadamer and Habermas. The authors analyze the ideas of classic scholars such as Edmund Husserl and Friedrich Nietzsche. Husserl put forward his notion of transcendental subjectivity and phenomenological ramifications of the relationship between subjectivity and objectivity. Nietzsche referred to subjectivity as "perspectivism," the inescapable fact that any and all consciousnesses exist in space and time. Consciousness is fundamentally constituted of cultural, linguistic, and historical dimensions. PMID:21874130
NASA Astrophysics Data System (ADS)
Buchwald, Jed
2016-03-01
The pressures of publication, the desire to be first in innovation, and moral convictions have long been at work in the history of science and technology. Historians think and argue best through stories, so I've chosen three examples that exemplify one or more of these aspects. The first involves the discovery of electric waves by Heinrich Hertz in 1888; the second concerns the controlled production of electromagnetic radiation by Marconi and Fleming in the early 1900s; our final case involves a bitter controversy between the physicist Hermann von Helmholtz and the astronomer Friedrich Zöllner in the 1890s.
History of experimental psychology from an Estonian perspective.
Allik, Jüri
2007-11-01
A short review of the development of experimental psychology from an Estonian perspective is presented. The first rector after the reopening of the University of Dorpat (Tartu) in 1802, Georg Friedrich Parrot (1767-1852) was interested in optical phenomena which he attempted to explain by introducing the concept of unconscious inferences, anticipating a similar theory proposed by Herman von Helmholtz 20 years later. One of the next rectors, Alfred Wilhelm Volkmann (1800-1878) was regarded by Edwin Boring as one of the founding fathers of the experimental psychology. Georg Wilhelm Struve (1793-1864) played an essential part in solving the problem of personal equations. Arthur Joachim von Oettingen (1836-1920) developed a theory of music harmony, which stimulated his student Wilhelm Friedrich Ostwald (1853-1932) to study colour harmony. Emil Kraepelin (1856-1926), the founder of modern psychiatry, is by far the most important experimental psychologist who has worked in Estonia. His successor Wladimir von Tchisch (1855-1922), another student of Wilhelm Wundt, continued Kraepelin's work in experimental psychology. The lives of Wolfgang Köhler (1887-1967), who was born in Reval (Tallinn), and Oswald Külpe (1862-1915), who graduated from the University of Dorpat, extended the link between the history of experimental psychology and Estonia. Karl Gustav Girgensohn (1875-1925), the founder of the Dorpat School of the psychology of religion, stretched the use of experimental methods to the study of religious experience. PMID:16639614
Cameron, M.K.; Fomel, S.B.; Sethian, J.A.
2009-01-01
In the present work we derive and study a nonlinear elliptic PDE coming from the problem of estimation of sound speed inside the Earth. The physical setting of the PDE allows us to pose only a Cauchy problem, and hence is ill-posed. However we are still able to solve it numerically on a long enough time interval to be of practical use. We used two approaches. The first approach is a finite difference time-marching numerical scheme inspired by the Lax-Friedrichs method. The key features of this scheme is the Lax-Friedrichs averaging and the wide stencil in space. The second approach is a spectral Chebyshev method with truncated series. We show that our schemes work because of (1) the special input corresponding to a positive finite seismic velocity, (2) special initial conditions corresponding to the image rays, (3) the fact that our finite-difference scheme contains small error terms which damp the high harmonics; truncation of the Chebyshev series, and (4) the need to compute the solution only for a short interval of time. We test our numerical scheme on a collection of analytic examples and demonstrate a dramatic improvement in accuracy in the estimation of the sound speed inside the Earth in comparison with the conventional Dix inversion. Our test on the Marmousi example confirms the effectiveness of the proposed approach.
Building fast well-balanced two-stage numerical schemes for a model of two-phase flows
NASA Astrophysics Data System (ADS)
Thanh, Mai Duc
2014-06-01
We present a set of well-balanced two-stage schemes for an isentropic model of two-phase flows arisen from the modeling of deflagration-to-detonation transition in granular materials. The first stage is to absorb the source term in nonconservative form into equilibria. Then in the second stage, these equilibria will be composed into a numerical flux formed by using a convex combination of the numerical flux of a stable Lax-Friedrichs-type scheme and the one of a higher-order Richtmyer-type scheme. Numerical schemes constructed in such a way are expected to get the interesting property: they are fast and stable. Tests show that the method works out until the parameter takes on the value CFL, and so any value of the parameter between zero and this value is expected to work as well. All the schemes in this family are shown to capture stationary waves and preserves the positivity of the volume fractions. The special values of the parameter 0,1/2,1/(1+CFL), and CFL in this family define the Lax-Friedrichs-type, FAST1, FAST2, and FAST3 schemes, respectively. These schemes are shown to give a desirable accuracy. The errors and the CPU time of these schemes and the Roe-type scheme are calculated and compared. The constructed schemes are shown to be well-balanced and faster than the Roe-type scheme.
NASA Astrophysics Data System (ADS)
Aichelburg, P. C.
Contents: Einleitung(P. C. Aichelburg). 1. Über Zeit, Bewegung und Veränderung (Aristoteles). 2. Ewigkeit und Zeit (Plotin). 3. Was ist die Zeit? (Augustinus). 4. Von der Zeit (Immanuel Kant). 5. Newtons Ansichten über Zeit, Raum und Bewegung (Ernst Mach). 6. Über die mechanische Erklärung irreversibler Vorgänge (Ludwig Boltzmann). 7. Das Maß der Zeit (Henri Poincaré). 8. Dauer und Intuition (Henri Bergson). 9. Die Geschichte des Unendlichkeitsproblems (Bertrand Russell). 10. Raum und Zeit (Hermann Minkowski). 11. Der Unterschied von Zeit und Raum (Hans Reichenbach). 12. Newtonscher und Bergsonscher Zeitbegriff (Norbert Wiener). 13. Die Bildung des Zeitbegriffs beim Kinde (JeanPiaget).14. Eine Bemerkung über die Beziehungen zwischen Relativitätstheorie und der idealistischen Philosophie (Kurt Gödel). 15. Der zweite Hauptsatz und der Unterschied von Vergangenheit und Zukunft (Carl Friedrich v. Weizsäcker). 16. Zeit als physikalischer Begriff (Friedrich Hund). 17. Zeitmessung und Zeitbegriff in der Astronomie (Otto Heckmann). 18. Kann die Zeit rückwärts gehen? (Martin Gardner). 19. Zeit und Zeiten (Ilya Prigogine, Isabelle Stengers). 20. Zeit als dynamische Größe in der Relativitätstheorie (P. C. Aichelburg).
Digital learning programs - competition for the classical microscope?
Schmidt, Peter
2013-01-01
The development of digital media has been impressive in recent years which is also among the reason for their increasing use in academic teaching. This is especially true for teaching Anatomy and Histology in the first two years in medical and dental curricula. Modern digital technologies allow for efficient, affordable and easily accessible distribution of histological images in high quality. Microscopy depends almost exclusively on such images. Since 20 years numerous digital teaching systems have been developed for this purpose. Respective developments have changed the ways students acquire knowledge and prepare for exams. Teaching staff should adapt lectures, seminars and labs accordingly. As a first step, a collection of high resolution digital microscopic slides was made available for students at the Friedrich-Schiller-University in Jena. The aim of the present study was to evaluate the importance of conventional light microscopy and related technologies in current and future medical and dental education aswell. A survey was done among 172 medical and dental students at the Friedrich-Schiller-University Jena. 51% of students use now frequently new digital media for learning histology in contrast to 5% in the year 2000 [1]. Digital media including Internet, CD- based learning combined with social networks successfully compete with classical light microscopy. PMID:23467698
Karl Knorre - First Astronomer of the Nicolaev Observatory
NASA Astrophysics Data System (ADS)
Petrov, G.; Pinigin, G.
Karl Friedrich Knorre was born 28th March 1801 in family of the professor of astronomy of Dorpat university Ernst Knorre. During education in the Dorpat university he got acquantance with the future director of Pulkovo observatory Wilhelm Struve. According passion of K. Knorre for astronomy W. Struwe recommended him to the director position of planned naval observatory in Nikolaev. From the foundation of Nikolaev naval and later astronomical observatory in 1821 K. Knorre was a first director. He made star position observations with the meridian circle, worked as a teacher of astronomy for sea navigators, compiled the fifth page of star map of the Berlin Academy of sciences and headed by all hydrographic determinations on the sea of Asov and Black sea. After 50 years K. Knorre retired 1871 from the Directorship of the Nikolaev observatory and moved to Berlin. Nikolaev astronomical observatory arranges the international scientific conference devoted to the 180 anniversary of NAO and 200's birthday of Karl Friedrich Knorre in 2001.
The Knorre astronomers' dynasty
NASA Astrophysics Data System (ADS)
Pinigin, G.
2009-06-01
We attempt to throw light upon the poorly known astronomical dynasty of Knorre and describe its contribution to astronomy. The founder of the dynasty, Ernst Christoph Friedrich Knorre (1759-1810), was born in Germany in 1759, and since 1802 he was a Professor of Mathematics at the Tartu University, and observer at its temporary observatory. He determined the first coordinates of Tartu by stellar observations. Karl Friedrich Knorre (1801-1883) was the first director of the Naval Observatory in Nikolaev since the age of 20, provided the Black Sea navy with accurate time and charts, trained mariners in astronomical navigation, and certified navigation equipment. He compiled star maps and catalogues, and determined positions of comets and planets. He also participated in Bessel's project of the Academic Star Charts, and was responsible for Hora 4, published by the Berlin Academy of Sciences. This sheet permitted to discover two minor planets, Astraea and Flora. Viktor Knorre (1840-1919) was born in Nikolaev. In 1862 he left for Berlin to study astronomy. After defending his thesis for a doctor's degree, he went to Pulkovo as an astronomical calculator in 1867. Since 1873 Viktor worked as an observer of the Berlin Observatory Fraunhofer refractor. His main research focussed on minor planets, comets and binary stars. He discovered the minor planets Koronis, Oenone, Hypatia and Penthesilea. Viktor Knorre also worked on improving astronomical instrumentation, e.g. the Knorre / Heele equatorial telescope mounting.
Discontinuous Galerkin Method with Numerical Roe Flux for Spherical Shallow Water Equations
NASA Astrophysics Data System (ADS)
Yi, T.; Choi, S.; Kang, S.
2013-12-01
In developing the dynamic core of a numerical weather prediction model with discontinuous Galerkin method, a numerical flux at the boundaries of grid elements plays a vital role since it preserves the local conservation properties and has a significant impact on the accuracy and stability of numerical solutions. Due to these reasons, we developed the numerical Roe flux based on an approximate Riemann problem for spherical shallow water equations in Cartesian coordinates [1] to find out its stability and accuracy. In order to compare the performance with its counterpart flux, we used the Lax-Friedrichs flux, which has been used in many dynamic cores such as NUMA [1], CAM-DG [2] and MCore [3] because of its simplicity. The Lax-Friedrichs flux is implemented by a flux difference between left and right states plus the maximum characteristic wave speed across the boundaries of elements. It has been shown that the Lax-Friedrichs flux with the finite volume method is more dissipative and unstable than other numerical fluxes such as HLLC, AUSM+ and Roe. The Roe flux implemented in this study is based on the decomposition of flux difference over the element boundaries where the nonlinear equations are linearized. It is rarely used in dynamic cores due to its complexity and thus computational expensiveness. To compare the stability and accuracy of the Roe flux with the Lax-Friedrichs, two- and three-dimensional test cases are performed on a plane and cubed-sphere, respectively, with various numbers of element and polynomial order. For the two-dimensional case, the Gaussian bell is simulated on the plane with two different numbers of elements at the fixed polynomial orders. In three-dimensional cases on the cubed-sphere, we performed the test cases of a zonal flow over an isolated mountain and a Rossby-Haurwitz wave, of which initial conditions are the same as those of Williamson [4]. This study presented that the Roe flux with the discontinuous Galerkin method is less
Causes and consequences of hypoxia on the Western Black Sea Shelf
NASA Astrophysics Data System (ADS)
Friedrich, Jana; Gomoiu, Marian-Trajan; Naeher, Sebastian; Secrieru, Dan; Teaca, Adrian
2013-04-01
The Black Sea, containing the world's largest natural anoxic basin since ca 7500 years (Jones & Gagnon 1994), suffers from combined effects of anthropogenic eutrophication, overfishing and climate variability (Oguz & Gilbert 2007). We discuss causes for hypoxia in western shelf waters. Freshwater runoff by the large rivers Danube, Dniester and Dnieper results in strong thermohaline stratification that limits bottom water ventilation on the north-western shelf during warm seasons. This makes the western shelf generally prone to oxygen deficiency. During autumn and winter, the thermohaline stratification is eroded by frequent storms and the water column is re-oxygenated. The causal chain of anthropogenic eutrophication since the 1970s led to seasonal hypoxia on the western shelf for more than 20 years causing the catastrophic decline of key shelf habitats (Mee et al. 2005). More frequent and intense algal blooms, red tides (i.e. Noctiluca, Prorocentrum cordatum) and changes in species composition in phytoplankton resulted in deposition of surplus organic matter on the seafloor increasing the oxygen demand, with serious consequences for pelagic and benthic ecosystem structure and functioning. During hypoxia, release of reduced substances like ammonia and phosphate from the sediment to the water fuelled eutrophication internally (Friedrich et al. 2002). The combination of existing data with those gained during EU FP7 HYPOX on the Romanian shelf enables to assess the development of bottom water hypoxia and changes in benthic community and hence, the current state and trends in recovery of the Romanian Black Sea shelf ecosystem. Mud worms are the winners of eutrophication and hypoxia, whereas filter feeders like Mytilus galloprovincialis and Acanthocardia paucicostata are the losers. The western shelf benthic ecosystem showed a significant reduction in species diversity, a reduction of biofilter strength due to the loss of filter-feeder populations and flourishing of
A semi-Lagrangian approximation in the Navier-Stokes equations for the gas flow around a wedge
NASA Astrophysics Data System (ADS)
Shaydurov, V.; Liu, Tiegang; Shchepanovskaya, G.; Yakubovich, M.
2015-10-01
In the paper, a semi-Lagrangian approximation is presented for the numerical solution of the two-dimensional time-dependent Navier-Stokes equations for viscous heat-conducting gas. In each equation, a combination of three first-order derivatives describing the transfer of a corresponding substance (density, velocity components, or internal energy) along trajectories is interpreted as the "transfer derivative" in the transfer direction. The other terms of the equations are written in the Euler form. On the sought-for time level, the standard conforming finite element method is realized for them with the linear elements on triangles and the bilinear ones on rectangles. The stencil adaptation along trajectories enables us to avoid the Courant-Friedrichs-Lewy upper limit which describes the dependence of the time step on the mesh-size of the space triangulation. At the end of the paper, a numerical example illustrates the implementation of the described algorithms.
NASA Astrophysics Data System (ADS)
Dick, Wolfgang R.; Hamel, Jürgen
The contributions span a time interval of more than 450 years. There are biographical investigations on Georg Joachim Rheticus, C.W.A. von Wahl and K.F. Heym, investigation on a reprint of a chapter of the principal work of Nicolaus Copernicus, on Christoph Scheiner and the "camera obscura", and, with respect to the history of timekeeping, on the "big Nuremberg clock". 19th century topics are: a contribution on the honorary doctorate of Joseph Fraunhofer, and on the construction of a lunar globe by Wilhelmine Witte, while the report on Friedrich Wilhelm Bessel and the cholera pandemia in Königsberg in the year 1831 gives a view into everyday life of scientists. 20th century topics are: the contributions on Bruno Thüring in Vienna and his relations with national socialism, as well as on Arthur Beer, Albert Einstein and the Warburg library. The book concludes by short communications, obituaries and book reviews.
NASA Astrophysics Data System (ADS)
Lang, Michael; Fischer, Jakob; Werner, Marco; Sommer, Jens-Uwe
2014-03-01
The swelling equilibrium of Olympic gels is studied by Monte Carlo Simulations. We observe that gels consisting of flexible cyclic molecules of a higher degree of polymerization N show a smaller equilibrium swelling degree Q ~N - 0 . 28φ0- 0 . 72 for the same monomer volume fraction φ0 at network preparation. This observation is explained by a disinterpenetration process of overlapping non-concatenated polymers upon swelling. In the limit of a sufficiently large number of concatenations per cyclic molecule we expect that the equilibrium degree of swelling becomes proportional to φ0- 1 / 2 independent of N. Our results challenge current textbook models for the equilibrium degree of swelling of entangled polymer networks. Now at: Bio Systems Analysis Group, Jena Centre for Bioinformatics (JCB) and Department for Mathematics and Computer Sciences, Friedrich Schiller University of Jena, 07743 Jena, Germany.
NASA Astrophysics Data System (ADS)
Schrimpf, Andreas
2014-09-01
During the summer of 1837 Christian Ludwig Gerling, a former student of Carl Friedrich Gauß's, organized the world wide first determination of the deflection of the vertical in longitude. From a mobile observatory at the Frauenberg near Marburg (Hesse) he measured the astronomical longitude difference between C.F. Gauß's observatory at Göttingen and F.G.B. Nicolai's observatory at Mannheim within an error of 0.̋4. To achieve this precision he first used a series of light signals for synchronizing the observatory clocks and, second, he very carefully corrected for the varying reaction time of the observers. By comparing these astronomical results with the geodetic-determined longitude differences he had recently measured for the triangulation of Kurhessen, he was able to extract a combined value of the deflection of the vertical in longitude of Göttingen and Mannheim. His results closely agree with modern vertical deflection data.
NASA Astrophysics Data System (ADS)
Zahoransky, Richard; Allelein, Hans-Josef; Bollin, Elmar; Oehler, Helmut; Schelling, Udo
Stationäre Gasturbinen-Kraftwerke zur Stromerzeugung wurden zuerst von Holzwarth Anfang des 20. Jahrhunderts zur kommerziellen Reife entwickelt und bis zum 2. Weltkrieg hergestellt. Hierbei handelte es sich um Verpuffungs-Gasturbinen mit isochorer Wärmezufuhr [6.1]. 1939 präsentierte die Firma BBC auf der Zürcher Landesausstellung die erste stationäre Gasturbine mit isobarer Wärmezufuhr, nach deren Prinzip die heutigen Gasturbinen aufgebaut sind. Diese 4 MW Maschine ist noch heute in Neuchâtel betriebsbereit. Friedrich Stolze gilt als Erfinder dieser Gasturbinen-Bauweise. Seine erste, schon 1904 bei BBC gebaute Anlage erbrachte wegen zu geringer Maschinenwirkungsgrade und zu geringer Turbineneintrittstemperatur jedoch keine Nutzleistung [6.2].
NASA Technical Reports Server (NTRS)
Harten, A.; Tal-Ezer, H.
1981-01-01
An implicit finite difference method of fourth order accuracy in space and time is introduced for the numerical solution of one-dimensional systems of hyperbolic conservation laws. The basic form of the method is a two-level scheme which is unconditionally stable and nondissipative. The scheme uses only three mesh points at level t and three mesh points at level t + delta t. The dissipative version of the basic method given is conditionally stable under the CFL (Courant-Friedrichs-Lewy) condition. This version is particularly useful for the numerical solution of problems with strong but nonstiff dynamic features, where the CFL restriction is reasonable on accuracy grounds. Numerical results are provided to illustrate properties of the proposed method.
Non-oscillatory central differencing for hyperbolic conservation laws
NASA Technical Reports Server (NTRS)
Nessyahu, Haim; Tadmor, Eitan
1990-01-01
Many of the recently developed high resolution schemes for hyperbolic conservation laws are based on upwind differencing. The building block for these schemes is the averaging of an appropriate Godunov solver; its time consuming part involves the field-by-field decomposition which is required in order to identify the direction of the wind. Instead, the use of the more robust Lax-Friedrichs (LxF) solver is proposed. The main advantage is simplicity: no Riemann problems are solved and hence field-by-field decompositions are avoided. The main disadvantage is the excessive numerical viscosity typical to the LxF solver. This is compensated for by using high-resolution MUSCL-type interpolants. Numerical experiments show that the quality of results obtained by such convenient central differencing is comparable with those of the upwind schemes.
Portin, Petter
2014-04-01
The development of the DNA theory of inheritance culminated in the publication of the molecular structure of DNA 60 years ago. This paper describes this development, beginning with the discovery of DNA as a chemical substance by Friedrich Miescher in 1869, followed by its basic chemical analysis and demonstration of its participation in the structure of chromosomes. Subsequently it was discovered by Oswald Avery in 1944 that DNA was the genetic material, and then Erwin Chargaff showed that the proportions of the bases included in the structure of DNA followed a certain law. These findings, in association with the biophysical studies of Maurice Wilkins and Rosalind Franklin with Raymond Gosling, led James Watson and Francis Crick to the discovery of the double-helical structure of DNA in 1953. The paper ends with a short description of the development of the DNA theory of inheritance after the discovery of the double helix. PMID:24840850
NASA Astrophysics Data System (ADS)
Ramadan, Omar Salameh
2010-03-01
Accurate and unconditionally stable finite difference time domain (FDTD) algorithm is presented for modeling electromagnetic wave propagation in double-negative (DNG) meta-material domains. The proposed algorithm is based on incorporating the Bilinear transformation technique into the FDTD implementations of Maxwell’s equations. The stability of the proposed approach is studied by combining the von Neumann method with the Routh-Huwitz criterion and it has been observed that the proposed algorithm is free from the Courant-Friedrichs-Lewy (CFL) stability limit of the conventional FDTD scheme. Furthermore, the proposed algorithm is incorporated with the split-step FDTD scheme to model two-dimensional problems. Numerical examples carried out in one and two dimensional domains are included to show the validity of the proposed algorithm.
The complex mechanism of HM pectin self-assembly: A rheological investigation.
Giacomazza, D; Bulone, D; San Biagio, P L; Lapasin, R
2016-08-01
Several biopolymers are widely employed in food, pharmaceutical and biomedical sectors by virtue of their ability to generate supramolecular structures, typically physical hydrogels. In the case of high methoxyl pectins (HMP) the gel formation is promoted by the presence of cosolutes (sugars or polyols) and low pH. The present investigation regards the structuring kinetics of aqueous HMP solutions having different polymer concentration and equal sucrose content at 20°C. A sequence of consecutive frequency sweep was applied to each sample immediately after its preparation. The time evolution of the linear viscoelastic behavior is described by the sigmoidal profiles of both moduli at each applied frequency and more thoroughly defined through the change of the mechanical spectrum, i.e. the variation of the parameters of the generalized Maxwell model or the Friedrich-Braun model which are both suitable to provide a satisfactory data fitting. PMID:27112864
Non-oscillatory central differencing for hyperbolic conservation laws
NASA Technical Reports Server (NTRS)
Nessyahu, Haim; Tadmor, Eitan
1988-01-01
Many of the recently developed high resolution schemes for hyperbolic conservation laws are based on upwind differencing. The building block for these schemes is the averaging of an appropriate Godunov solver; its time consuming part involves the field-by-field decomposition which is required in order to identify the direction of the wind. Instead, the use of the more robust Lax-Friedrichs (LxF) solver is proposed. The main advantage is simplicity: no Riemann problems are solved and hence field-by-field decompositions are avoided. The main disadvantage is the excessive numerical viscosity typical to the LxF solver. This is compensated for by using high-resolution MUSCL-type interpolants. Numerical experiments show that the quality of results obtained by such convenient central differencing is comparable with those of the upwind schemes.
NASA Technical Reports Server (NTRS)
Stallings, R. L., Jr.
1984-01-01
Longitudinal aerodynamic characteristics of a Sparrow 3 wing control missile model were measured through a range of separation distances relative to a flat plate surface that represented the parent-body configuration. Measurements were obtained with and without two dimensional circular arc protuberances attached to the flat plate surface. The tests were conducted at a Mach number of 2.86 and a Reynolds number per meter of 6.56 million. The behavior of these longitudinal characteristics with varying separation distance in the flow field created by the flat plate and protuberance was generally as would be expected on the basis of flow field boundaries determined from the second order approximation of Friedrich. In general, varying roll angle from 0 deg to 45 deg caused no significant effect on the store separation characteristics.
Helmstädter, Axel
2011-01-01
Demeter Georgievitz-Weitzer (1873-1949), called "Surya", Sanskrit for "sun", was an important representative of medical occultism in the first half of the 20th century. He worked as a journal editor and published a 13-volume book series about occult medicine, mainly written by himself. His hypotheses were closely related to the "Lebensreform" movement around 1900. Regarding diagnostics, he relied on astrology, cheiromancy, and clairvoyance, while therapeutics were dominated by diet and spagyric remedies according to Cesare Mattei (1809-1896) and Carl-Friedrich Zimpel (1801-1879). In his later years, he developed his own healing system, initially comprising eight, later only two preparations. Surya remedies were commercially available until the end of the 20th century, PMID:22822609
A history of erotic philosophy.
Soble, Alan
2009-01-01
This essay historically explores philosophical views about the nature and significance of human sexuality, starting with the Ancient Greeks and ending with late 20th-century Western philosophy. Important figures from the history of philosophy (and theology) discussed include Sappho, Plato, Aristotle, St. Augustine, St. Jerome, the Pelagians, St. Thomas Aquinas, Michel de Montaigne, Rene Descartes, Thomas Hobbes, David Hume, Immanuel Kant, Søren Kierkegaard, Arthur Schopenhauer, Jeremy Bentham, John Stuart Mill, Karl Marx, Friedrich Engels, Sigmund Freud, Jean-Paul Sartre, Simone de Beauvoir, Wilhelm Reich, and Herbert Marcuse. Contemporary philosophers whose recent work is discussed include Michel Foucault, Thomas Nagel, Roger Scruton, Karol Wojtyla (Pope John Paul II), Catharine MacKinnon, Richard Posner, and John Finnis. To show the unity of the humanities, the writings of various literary figures are incorporated into this history, including Mark Twain, Arthur Miller, James Thurber, E. B. White, Iris Murdoch, and Philip Roth. PMID:19308838
[Heinrich Hoffmann's Der Struwwelpeter (1845/1859): a parody on the romantic cult of childhood].
Wesseling, Lies
2006-01-01
This article analyzes the cultural dynamics of the construction and deconstruction of childhood images, by means of a case study of Heinrich Hoffmann's classic picture book, Der Struwwelpeter (1845/1859). Childhood images are the joint product of sciences (especially anthropology, pedagogy and developmental psychology) and arts (especially painting, photography and (children's) literature). These images are historically variable, because childhood is the permanent target of idealization and demystification. This article interprets Der Struwwelpeter as a demystication of Romantic idealizations of childhood as propounded by Romantic Naturphilosophie and, more specifically, the pedagogy of Friedrich Fröbel (1772-1852). In my view, this picture book satirizes the developmentalism and the pastoryl idyll which informed the Romantic image of childhood, through its verbal and visual components. As I argue at length, this satire directly bears upon leading scientific and political controversies of Hoffmann's time. PMID:20681191
Plimpton, Steven J.; Sershen, Cheryl L.; May, Elebeoba E.
2015-01-01
This paper describes a method for incorporating a diffusion field modeling oxygen usage and dispersion in a multi-scale model of Mycobacterium tuberculosis (Mtb) infection mediated granuloma formation. We implemented this method over a floating-point field to model oxygen dynamics in host tissue during chronic phase response and Mtb persistence. The method avoids the requirement of satisfying the Courant-Friedrichs-Lewy (CFL) condition, which is necessary in implementing the explicit version of the finite-difference method, but imposes an impractical bound on the time step. Instead, diffusion is modeled by a matrix-based, steady state approximate solution to the diffusion equation. Moreover, presented in figure 1 is the evolution of the diffusion profiles of a containment granuloma over time.
Plimpton, Steven J.; Sershen, Cheryl L.; May, Elebeoba E.
2015-01-01
This paper describes a method for incorporating a diffusion field modeling oxygen usage and dispersion in a multi-scale model of Mycobacterium tuberculosis (Mtb) infection mediated granuloma formation. We implemented this method over a floating-point field to model oxygen dynamics in host tissue during chronic phase response and Mtb persistence. The method avoids the requirement of satisfying the Courant-Friedrichs-Lewy (CFL) condition, which is necessary in implementing the explicit version of the finite-difference method, but imposes an impractical bound on the time step. Instead, diffusion is modeled by a matrix-based, steady state approximate solution to the diffusion equation. Moreover, presented in figuremore » 1 is the evolution of the diffusion profiles of a containment granuloma over time.« less
Scalar field probes of power-law space-time singularities
NASA Astrophysics Data System (ADS)
Blau, Matthias; Frank, Denis; Weiss, Sebastian
2006-08-01
We analyse the effective potential of the scalar wave equation near generic space-time singularities of power-law type (Szekeres-Iyer metrics) and show that the effective potential exhibits a universal and scale invariant leading inverse square behaviour ~ x-2 in the ``tortoise coordinate'' x provided that the metrics satisfy the strict Dominant Energy Condition (DEC). This result parallels that obtained in [1] for probes consisting of families of massless particles (null geodesic deviation, a.k.a. the Penrose Limit). The detailed properties of the scalar wave operator depend sensitively on the numerical coefficient of the x-2-term, and as one application we show that timelike singularities satisfying the DEC are quantum mechanically singular in the sense of the Horowitz-Marolf (essential self-adjointness) criterion. We also comment on some related issues like the near-singularity behaviour of the scalar fields permitted by the Friedrichs extension.
Liquid-crystal science from 1888 to 1922: building a revolution.
Mitov, Michel
2014-05-19
The saga of liquid crystals started with their discovery in 1888 by the botanist Friedrich Reinitzer, who unexpectedly observed "two melting points" for crystals extracted from the root of a carrot. At the end of the nineteenth century, most scientists did not believe in the existence of "liquid crystals" as promoted by the crystallographer Otto Lehmann. The controversies were very vivid; to the point that the recognition of mesomorphic states of matter by the scientific community required more than two decades. In the end, liquid crystals have changed our vision of matter by shattering the three-state paradigm. Since the mid-1970s, liquid crystals have revolutionized the worldwide information-display industry and now play a host of key roles in various technologies. PMID:24482315
The Lenticular Process of the Incus
Graboyes, Evan M.; Hullar, Timothy E.; Chole, Richard A.
2011-01-01
17th century anatomists, including Franciscus Sylvius, identified a small bony structure between the distal end of the incus and the stapes that they believed was a separate and thus additional ossicle. The existence of the ossicle at the distal portion of the long process of the incus was controversial for the next two hundred years. In the 19th century, anatomists including Johann Friedrich Blumenbach, Henry Jones Shrapnell, Eduard Hagenbach, and Joseph Hyrtl provided numerous arguments to demonstrate why the so-called additional ossicle was actually attached to the incus by a thin strut, and thus not a separate bone. Since then, the ovoid end of the incus has been referred to as the “lenticular process” of the incus. The best nomenclature for the bony connection between the lenticular process and the rest of the incus remains uncertain, but the term “lenticular process” should not include its connecting pedicle. PMID:21986927
Solar Corona Simulation Model With Positivity-preserving Property
NASA Astrophysics Data System (ADS)
Feng, X. S.
2015-12-01
Positivity-preserving is one of crucial problems in solar corona simulation. In such numerical simulation of low plasma β region, keeping density and pressure is a first of all matter to obtain physical sound solution. In the present paper, we utilize the maximum-principle-preserving flux limiting technique to develop a class of second order positivity-preserving Godunov finite volume HLL methods for the solar wind plasma MHD equations. Based on the underlying first order building block of positivity preserving Lax-Friedrichs, our schemes, under the constrained transport (CT) and generalized Lagrange multiplier (GLM) framework, can achieve high order accuracy, a discrete divergence-free condition and positivity of the numerical solution simultaneously without extra CFL constraints. Numerical results in four Carrington rotation during the declining, rising, minimum and maximum solar activity phases are provided to demonstrate the performance of modeling small plasma beta with positivity-preserving property of the proposed method.
NASA Astrophysics Data System (ADS)
Frenkel, Victor Ya.
The following sections are included: * PROFESSOR FRIEDRICH HOUTERMANS: WORKS, LIFE, FATE * Introduction * Beginnings * Göttingen * Berlin * 1933 * London * Impressions of Kharkov * Kharkov: 1935-1937 * Arrests * Last Months in the USSR (From Charlotte Houtermans' Diary) * Descent into the Prisons: 1937-39 * From Desperation to Hope (Continuation of Charlotte Houtermans' Diary) * Fighting for Freedom * Descent into the Prisons: 1939-40 * The Bridge over the River Bug * On the Other Shore * Back in Berlin * The Plutonium Report * "They should Accelerate!" * Back in Kharkov * Kharkov Trace (What Happened at the Session of the Academy of Sciences) * Who are Beck and Godin? * War's End * The Age of the Earth * Friends on Houtermans * Chronology * Appendices (Compiled by the Editor) * Last Diary * Odessa 1930 * Chronological Report of my Life in Russian Prisons * Alexander Weissberg's Letter * After the War
[The biography of Maximilian Nitze (1848-1906) and his contribution to the urology].
Verger-Kuhnke, A B; Beccaría, M L
2007-01-01
Maximilian Carl Friedrich Nitze was born on the 18 of September of 1848 in Berlin the capital of Prussia. 1869 while still being a Student of the Heidelberg University the first nephrectomy of the world performed by Gustav Simon (1824-1876) woke his interest in urology. 1874 by the age of 26 he passed his state examination and obtained a doctor degree in medicine. On the 2 October of 1877 he presented the first cystoscope to the members of the Real Medical School in Dresden. Nitzes doubtless valuable contribution to urology was making real the endoscopical exploration of the genitourinary system and initializing the era of surgical treatments under direct vision. By the beginning of the XX century urology reached the status of an independent specialty by separating from surgery, dermatology/venerology, internal medicine and pathology. PMID:17902461
Variational theorems for superimposed motions in elasticity, with application to beams
NASA Technical Reports Server (NTRS)
Doekmeci, M. C.
1976-01-01
Variational theorems are presented for a theory of small motions superimposed on large static deformations and governing equations for prestressed beams on the basis of 3-D theory of elastodynamics. First, the principle of virtual work is modified through Friedrichs's transformation so as to describe the initial stress problem of elastodynamics. Next, the modified principle together with a chosen displacement field is used to derive a set of 1-D macroscopic governing equations of prestressed beams. The resulting equations describe all the types of superimposed motions in elastic beams, and they include all the effects of transverse shear and normal strains, and the rotatory inertia. The instability of the governing equations is discussed briefly.
Nietzsche, autobiography, history: mourning and Martin and John.
Champagne, J
1998-01-01
How might gay and lesbian literature be read not as a mimetic representation of homosexuality, but as an activity linked to problems of subjectivity and historiography? Reading Dale Peck's novel Martin and John alongside passages from Friedrich Nietzsche's "On the Uses and Disadvantages of History for Life" and Sigmund Freud's "Mourning and Melancholia," this essay argues for an understanding of Peck's text as an attempt to link two apparently different processes of import to contemporary gay male subjects in particular: the writing of what Nietzsche terms "critical history," and the mourning of those lost to HIV disease. It concludes by linking Martin and John to feminist critiques of identity and traditional historiography, as well as noting the connection between these two critiques. PMID:9505231
Wilkes, J
2000-06-01
Friedrich Nietzsche is supposed to have been one of the harshest critics of compassion. Many of his publications try to unmask its failings and to expose its true motives. From an ardent admirer of Schopenhauers's ethics of compassion, Nietzsche turned into a vigorous despiser of compassionate feelings. It is shown that this change was above all caused by overwhelming personal experiences of compassion due to illness and death in his family and, later on, with his first aid activities in military hospitals during the German-French war in 1870. Combined with that, Nietzsche suffered from feelings of passivity and helplessness, which gave him the impression of compassion being a negative and--in the end--loathed emotion. PMID:10909298
Carta, Stefano
2012-09-01
This paper deals with friendship and therapeutic alliance as a transformation of the libidinal love that structures the Oedipal complex. The author considers the relationship between Jung and Freud as a formidable test that may shed light on their personalities and on the relevance of the Oedipal complex for both of them and for their particular theories and practices. The author discusses the possibility that the Oedipal complex may be seen under a finalistic frame of reference and discusses which implicit goals it may express. Such a goal has not been reached by either Freud nor Jung, but might be the key to underline and recognize the fundamental importance of the 'therapeutic alliance' within the analytical situation, seen as a potential relationship between the selves of the patient and of the analyst springing from a transformation of libidinal love into 'friendship' as it was described by Friedrich Nietzsche. PMID:22954047
NASA Astrophysics Data System (ADS)
Kragh, Helge
2012-12-01
The idea that space is not Euclidean by necessity, and that there are other kinds of "curved" spaces, diffused slowly to the physical and astronomical sciences. Until Einstein's general theory of relativity, only a handful of astronomers contemplated a connection between non-Euclidean geometry and real space. One of them, the German astrophysicist Johann Carl Friedrich Zöllner (1834-1882), suggested in 1872 a remarkable cosmological model describing a finite universe in closed space. I examine Zöllner's little-known contribution to cosmology and also his even more unorthodox speculations of a four-dimensional space including both physical and spiritual phenomena. I provide an overview of Zöllner's scientific work, of his status in the German scientific community, and of the controversies caused by his polemical style of science. Zöllner's cosmology was effectively forgotten, but there is no reason why it should remain an unwritten chapter in the history of science.
Parallax: The Race to Measure the Cosmos
NASA Astrophysics Data System (ADS)
Hirshfeld, A. W.
2001-05-01
The new book "Parallax: The Race to Measure the Cosmos" chronicles the centuries-long struggle to secure the first distance to a star through detection of stellar parallax. Beginning with the naked-eye attempts of Tycho Brahe and proceeding through the telescopic studies of Robert Hooke, James Bradley, and William Herschel, all three of whom employed observational strategies suggested by Galileo, the effort to measure stellar parallax gained momentum in the early 19th century with dramatic improvements in telescope technology by German craftsmen such as Joseph Fraunhofer. Three near-contemporaneous announcements of stellar parallaxes were made in the late 1830s by Thomas Henderson (Alpha Centauri), Wilhelm Struve (Vega), and Friedrich Bessel (61 Cygni). By consensus of the astronomical community, Bessel was credited with the first successful measurement of a star's distance. With its biographical focus, "Parallax: The Race to Measure the Cosmos" highlights the human dimensions of scientific achievement.
Fetus-in-fetu: a pediatric rarity
Narayanasamy, Jeyanthi N.; Nallusamy, Mohan Arunasalam; Baharuddin, Nur Daliza
2014-01-01
Fetus-in-fetu (FIF) is a rare entity resulting from abnormal embryogenesis in diamniotic monochorionic twins, being first described by Johann Friedrich Meckel (1800s). This occurs when a vertebrate fetus is enclosed in a normally growing fetus. Clinical manifestations vary. Detection is most often in infancy, the oldest reported age being 47. We report the case of a 4-day-old girl who was referred postnatally following a prenatal fetal scan which had revealed the presence of a multi-loculated retroperitoneal mass lesion with calcifications within. A provisional radiological diagnosis of FIF was made. Elective laparotomy revealed a well encapsulated retroperitoneal mass containing among other structures a skull vault and rudimentary limb buds. Recovery was uneventful. Here we discuss the difference between FIF and teratomas, risks of non-operative therapy and the role of serology in surveillance and detection of malignant change. PMID:24876368
Darwin, Engels und die Rolle der Arbeit in der biologischen und kulturellen Evolution des Menschen
NASA Astrophysics Data System (ADS)
Reichholf, Josef H.
Im Jahre 1876, 5 Jahre nach Erscheinen von Darwins Buch über die Evolution des Menschen und die sexuelle Selektion (Darwin 1871), veröffentlichte Friedrich Engels den berühmt gewordenen Essay "Anteil der Arbeit an der Menschwerdung des Affen“ (Engels 1876). Die Kernfrage darin lautet in Kurzform: Warum hat der Mensch eigentlich ein Bedürfnis nach Arbeit? Engels Antwort wird nachfolgend näher betrachtet und vom gegenwärtigen Kenntnisstand aus beurteilt. Wie sich zeigen wird, beantworten seine Überlegungen die Frage nicht wirklich. Sie ist weiterhin offen. Es können lediglich einige zusätzliche Anhaltspunkte zur Diskussion gestellt werden. Angesichts des drängenden Problems millionenfacher Arbeitslosigkeit und der Forderungen nach einem "Grundrecht auf Arbeit“ kommt den Überlegungen zum möglichen Ursprung des Bedürfnisses nach Arbeit mehr als nur akademisches Interesse zu.
Akhtar, R; Izhar, N
1986-01-01
"Between one country and another, one province and another and even one locality and another there will always exist a certain inequality in the conditions of life, which it will be possible to reduce to a minimum but never entirely remove", Friedrich Engels, 1875, Quoted from D. M. Smith's Where the Grass is Greener; Geographical Perspectives on Inequality. London, 1979. And it is true that there are wide disparities in the availability of welfare facilities including health at international, national, regional and inter-regional levels. At the same time such disparities are increasing over time. In terms of spatial distribution, not only the developing world but even developed countries such as the U.S.A. and the United Kingdom, face problems resulting from wide imbalances in the provision of welfare facilities. In this paper, an attempt has been made to study inequalities in the distribution of health facilities in India and Zambia. PMID:3092360
The social origins of illness: a neglected history.
Waitzkin, H
1981-01-01
Although interest in the social origins of illness has grown recently, the sources of this concern in Marxist thought have received little attention. Friedrich Engels, Rudolf Virchow, and Salvador Allende made important early contributions to this field. Engels analyzed features of the workplace and environment that caused disability and early death for the British working class. Virchow's studies in "social medicine" and infectious diseases called for social change as a solution to medical problems. Allende traced poor health to class oppression, economic underdevelopment, and imperialism. These analysts provided divergent, though complementary, views of social etiology, multifactorial causation, the methodology of dialectic materialism, an activist role for medical scientists and practitioners, social epidemiology, health policy, and strategies of sociomedical change. The social origins of illness remain with us and reveal the scope of reconstruction needed for meaningful solutions. PMID:7016768
[Condensing osteitis of the middle third of the clavicle].
Baciu, C C; Muncaciu, S; Dumitrescu, D
1989-01-01
A total of 16 cases only have been reported in the world specialized literature. This is a new case, of a patient aged 20 years, a male working in the metallurgical industry. This is the first case reported in our country. Clinically the patient presented a painful global swelling of the median third of the clavicula on the left side. Biological constant were normal. Radiographic investigations revealed an increase in volume and a condensation of the median part of the clavicula, and scintigraphical studies revealed an intense incorporation of the radioisotope. Histopathologic studies showed lamellar and spongious bone tissue, with a normal trabecular structure, although considerably thickened. Data for the differential diagnosis are presented, and in the first place those concerning intra-sterno-clavicular hyperostosis, sterno-costo-clavicular arthrosis, chronic subacute osteitis, avascular necrosis of the clavicular epiphysis (Friedrich disease), and Tietze syndrome. The etiopathogenesis of this rare benign clinico-radiologic entity remains unknown. PMID:2534838
NASA Astrophysics Data System (ADS)
Brosche, Peter
We recall Zach's direct contributions to various sciences, such as his involvement in the search for the first minor planets, the measurement of the Earth at small and large scales - including the deviation of the plumb line - and the development of instruments. Apart from these highlights, he shouldered a fair share of the more tedious but basic parts of the labour involved: the observations for and construction of solar tables, star catalogues and nutation tables. He was a sought-after expert for the founding and equipment of observatories (Gotha, Marseille, Naples, Marlia), a teacher who introduced practical astronomy for young scientists (such as Carl Friedrich Gauss and Carl Burckhardt) and encouraged, advised and supervised many scientific travellers (Alexander v. Humboldt, Karsten Niebuhr, Eduard Rüuppell). Beyond that, he promoted communication amongst astronomers in a most outstanding and productive manner, by his specialized journals and by the first astronomical meeting in 1798.
A Posteriori Analysis for Hydrodynamic Simulations Using Adjoint Methodologies
Woodward, C S; Estep, D; Sandelin, J; Wang, H
2009-02-26
This report contains results of analysis done during an FY08 feasibility study investigating the use of adjoint methodologies for a posteriori error estimation for hydrodynamics simulations. We developed an approach to adjoint analysis for these systems through use of modified equations and viscosity solutions. Targeting first the 1D Burgers equation, we include a verification of the adjoint operator for the modified equation for the Lax-Friedrichs scheme, then derivations of an a posteriori error analysis for a finite difference scheme and a discontinuous Galerkin scheme applied to this problem. We include some numerical results showing the use of the error estimate. Lastly, we develop a computable a posteriori error estimate for the MAC scheme applied to stationary Navier-Stokes.
A three-sphere swimmer for flagellar synchronization
NASA Astrophysics Data System (ADS)
Polotzek, Katja; Friedrich, Benjamin M.
2013-04-01
In a recent letter (Friedrich et al 2012 Phys. Rev. Lett. 109 138102), a minimal model swimmer has been proposed that propels itself at low Reynolds numbers by the revolving motion of a pair of spheres. The motion of the two spheres can synchronize by virtue of a hydrodynamic coupling that depends on the motion of the swimmer, but is rather independent of direct hydrodynamic interactions. This novel synchronization mechanism could account for the synchronization of a pair of flagella, e.g. in the green algae Chlamydomonas. In this paper, we discuss in detail how swimming and synchronization depend on the geometry of the model swimmer and compute the swimmer design for optimal synchronization. Our analysis highlights the role of broken symmetries in swimming and synchronization.
Chung, Sharon A.; Seo, Philip
2010-01-01
Synopsis In 1923, Friedrich Wohlwill described two patients with a “microscopic form of periarteritis nodosa”, which was distinct from classical polyarteritis nodosa. This disease, now known as microscopic polyangiitis (MPA), is a primary systemic vasculitis characterized by inflammation of the small-caliber blood vessels and the presence of circulating antineutrophil cytoplasmic antibodies (ANCA). Typically, microscopic polyangiitis presents with glomerulonephritis and pulmonary capillaritis, although involvement of the skin, nerves, and gastrointestinal tract is not uncommon. Treatment of MPA generally requires use of a cytotoxic agent (such as cyclophosphamide) in addition to high-dose glucocorticoids. Recent research has focused on identifying alternate treatment strategies that minimize or eliminate exposure to cytotoxic agents. This article will review the history, pathogenesis, clinical manifestations, and treatment of MPA. PMID:20688249
Conserved quantities in a black hole collision
NASA Astrophysics Data System (ADS)
Dain, S.; Valiente-Kroon, J. A.
2002-02-01
The Newman-Penrose constants of the spacetime corresponding to the development of the Brill-Lindquist initial data are calculated by making use of a particular representation of spatial infinity due to H Friedrich. The Brill-Lindquist initial data set represents the head-on collision of two non-rotating black holes. In this case one non-zero constant is obtained. Its value is given in terms of the product of the individual masses of the black holes and the square of a distance parameter separating the two black holes. This constant retains its value all along null infinity, and therefore it provides information about the late time evolution of the collision process. In particular, it is argued that the magnitude of the constants provides information about the amount of residual radiation contained in the spacetime after the collision of the black holes.
Bound-state eigenenergy outside and inside the continuum for unstable multilevel systems
NASA Astrophysics Data System (ADS)
Miyamoto, Manabu
2005-12-01
The eigenvalue problem for the dressed bound state of unstable multilevel systems is examined both outside and inside the continuum, based on the N -level Friedrichs model, which describes the couplings between the discrete levels and the continuous spectrum. It is shown that a bound-state eigenenergy always exists below each of the discrete levels that lie outside the continuum. Furthermore, by strengthening the couplings gradually, the eigenenergy corresponding to each of the discrete levels inside the continuum finally emerges. On the other hand, the absence of the eigenenergy inside the continuum is proved in weak but finite coupling regimes, provided that each of the form factors that determine the transition between some definite level and the continuum does not vanish at that energy level. An application to the spontaneous emission process for the hydrogen atom interacting with the electromagnetic field is demonstrated.
Simulations of the chromosphere with regard to the solar atmospheric heating problem
NASA Astrophysics Data System (ADS)
Piantschitsch, Isabell
The limited observation capacities concerning the chromosphere force us to develop sophisticated simulation models describing effects like magnetic reconnection, which is one of the processes held causative for chromospheric and coronal heating. Since the inclusion of neutral hydrogen particles in the models highly influences the rates of magnetic reconnection, our aim is to develop a new numerical code which will be based on a two-fluid magnetohydrodynamics (MHD) model of the chromosphere. Developed from the Total Variation Diminishing Lax-Friedrichs scheme, the numerical code shall perform a 2.5D MHD-simulation including the effects of ion-neutral collisions, ionisation/recombination, thermal/resistive diffusivity as well as collisional/resistive heating. In this contribution we will show in detail our approach and give some first test results.
Lagrangian statistics in forced two-dimensional turbulence
NASA Astrophysics Data System (ADS)
Kamps, Oliver; Friedrich, Rudolf
2007-11-01
In recent years the Lagrangian description of turbulent flows has attracted much interest from the experimental point of view and as well is in the focus of numerical and analytical investigations. We present detailed numerical investigations of Lagrangian tracer particles in the inverse energy cascade of two-dimensional turbulence. In the first part we focus on the shape and scaling properties of the probability distribution functions for the velocity increments and compare them to the Eulerian case and the increment statistics in three dimensions. Motivated by our observations we address the important question of translating increment statistics from one frame of reference to the other [1]. To reveal the underlying physical mechanism we determine numerically the involved transition probabilities. In this way we shed light on the source of Lagrangian intermittency.[1ex] [1] R. Friedrich, R. Grauer, H. Hohmann, O. Kamps, A Corrsin type approximation for Lagrangian fluid Turbulence , arXiv:0705.3132
Perturbative Solutions of the Extended Constraint Equations in General Relativity
NASA Astrophysics Data System (ADS)
Butscher, Adrian
2007-05-01
The extended constraint equations arise as a special case of the conformal constraint equations that are satisfied by an initial data hypersurface {mathcal{Z}} in an asymptotically simple space-time satisfying the vacuum conformal Einstein equations developed by H. Friedrich. The extended constraint equations consist of a quasi-linear system of partial differential equations for the induced metric, the second fundamental form and two other tensorial quantities defined on {mathcal{Z}} , and are equivalent to the usual constraint equations that {mathcal{Z}} satisfies as a space-like hypersurface in a space-time satisfying Einstein’s vacuum equation. This article develops a method for finding perturbative, asymptotically flat solutions of the extended constraint equations in a neighbourhood of the flat solution on Euclidean space. This method is fundamentally different from the ‘classical’ method of Lichnerowicz and York that is used to solve the usual constraint equations.
Students explore history of the Göttingen Institute of Geophysics
NASA Astrophysics Data System (ADS)
Ritter, Joachim R. R.
The Institute of Geophysics at the University of Gottingen, Germany has a long tradition that began long before its official founding in January 1898. Its history goes back to at least 1756, to the work on geophysical problems by Tobias Meyer, Carl-Friedrich GauS, and Wilhelm Weber. At the beginning of the 20th century, the first director of the institute, Emil Wiechert, established a seismological working group that was a worldwide leader in this type of research for the next 10 to 12 years. In those golden years of seismology at Gottingen, famous students and co-workers of Wiechert such as G. H. Angenheister, L. Geiger, B. Gutenberg, L. Mintrop, and K. Zoeppritz made fundamental discoveries.
Influence of realistic atom wall potentials in quantum reflection traps
NASA Astrophysics Data System (ADS)
Madroñero, Javier; Friedrich, Harald
2007-02-01
We study the influence of atom-surface interactions close to the surface on the confinement properties in a recently proposed model [A. Jurisch and H. Friedrich, Phys. Lett. A 349, 230 (2006)] for quantum reflection traps and test the reliability of the sharp-step approximation used there. Accurate numerical calculations show a dependence of the surviving particle fraction on characteristic potential lengths determined by the behavior of the interaction in the limits r→0 and r→∞ of the atom-surface distance r . For interactions dominated by the retarded potential proportional to 1/r4 we find that the simplified sharp-step potential reproduces the behavior of the trapped atoms well, both qualitatively and quantitatively.
Revisiting Titan's exosphere and atmospheric evolution after Huygens
NASA Astrophysics Data System (ADS)
Penz, T.; Langmayr, D.; Lammer, H.; Kulikov, Y. N.; Biernat, H. K.; Erkaev, N. V.
An overview of Titan s complex exospheric environment after Huygens is presented Temperature profiles inferred during the descent of the Huygens probe indicate that atomic hydrogen can reach blow-off conditions under certain circumstances We apply a time-dependent numerical algorithm which solves the system of hydrodynamic equations numerically The mass and momentum conservation equations are rewritten in their characteristic form and are integrated by applying Godunov s method Stability of the numerical scheme is achieved by determining an adequate time step subject to the Courant-Friedrichs-Lewy condition at each time interval A stationary solution is obtained as a result of time relaxation of nonsteady solutions starting from the initial steady-state profiles with small perturbations We compare the atomic hydrogen density distribution and escape rates for the Jeans and hydrodynamic conditions Furthermore we discuss the evolution of Titan s atmosphere based on the in-situ measured enrichment of 15 N isotopes
On the Spectrum of an Hamiltonian in Fock Space. Discrete Spectrum Asymptotics
NASA Astrophysics Data System (ADS)
Albeverio, Sergio; Lakaev, Saidakhmat N.; Rasulov, Tulkin H.
2007-04-01
A model operator H associated with the energy operator of a system describing three particles in interaction, without conservation of the number of particles, is considered. The location of the essential spectrum of H is described. The existence of infinitely many eigenvalues (resp. the finiteness of eigenvalues) below the bottom τess( H) of the essential spectrum of H is proved for the case where the associated Friedrichs model has a threshold energy resonance (resp. a threshold eigenvalue). For the number N( z) of eigenvalues of H lying below z < τess( H) the following asymptotics is found limlimits_{z to tau_ess(H)-0}N(z)/|log |z-tau_ess(H)||={U}_0 (0<{U}_0
10. Exploring the Conformal Constraint Equations
NASA Astrophysics Data System (ADS)
Butscher, Adrian
One method of studying the asymptotic structure of spacetime is to apply Penrose's conformal rescaling technique. In this setting, the rescaled Einstein equations for the metric and the conformal factor in the unphysical spacetime degenerate where the conformal factor vanishes, namely at the boundary representing null infinity. This problem can be avoided by means of a technique of H. Friedrich, which replaces the Einstein equations in the unphysical spacetime by an equivalent system of equations which is regular at the boundary. The initial value problem for these equations produces a system of constraint equations known as the conformal constraint equations. This work describes some of the properties of the conformal constraint equations and develops a perturbative method of generating solutions near Euclidean space under certain simplifying assumptions.
Epigenesis in Kant: Recent reconsiderations.
Zammito, John H
2016-08-01
Epigenesis has become a far more exciting issue in Kant studies recently, especially with the publication of Jennifer Mensch's Kant' Organicism. In my commentary, I propose to clarify my own position on epigenesis relative to that of Mensch and others by once again considering the discourse of epigenesis in the wider eighteenth century. Historically, I maintain that Kant was never fully an epigenesist because he feared its materialist implications. This makes it highly unlikely that he drew heavily, as other interpreters like Dupont and Huneman have suggested, on Caspar Friedrich Wolff for his ultimate theory of "generic preformation." In order to situate more precisely what Kant made of epigenesis, I distinguish his metaphysical use, as elaborated by Mensch, from his view of it as a theory for life science. In that light, I raise questions about the scope and authority of philosophy vis a vis natural science. PMID:27474189
[Original procreation or generational change? The investigation of cysticercus and tapeworms].
Geus, A
2007-01-01
The doctrine of the abiogenesis postulated the origin of human and animal intestinal worms from "not complete digested ingesta". Indeed Peter Simon Pallas (1741-1811) defined already 1760 in his dissertation that endoparasitic worms reproduce themselves by eggs. But he characterised the nature of cysticercus as "pathologically degenerated tail bladder". In 1856 Rudolf Leuckart (1822-1898) paraphrased the alternation of generation with "marvellous metamorphoses and peculiar form of development". The Dane Johannes Japetus Smith Steenstrup (1813-1897) recognised finally the principle of the alternation of generation and Gottlob Friedrich Heinrich Küchenmeister (1821-1890), a physician at the Saxon city Zittau realised the special correlation between the alternate and end host of tapeworms. Both, Leuckart and Küchenmeister proved their insights by animal and human experimentations. PMID:17243446
[The case of Sefeloge: a contribution to the history of forensic psychiatry].
Haack, K; Herpertz, S C; Kumbier, E
2007-05-01
In 1850 the mentally disordered Sergeant Maximilian Joseph Sefeloge (1821-1859) tried to assassinate the Prussian King Friedrich Wilhelm IV (1795-1861). Besides clarification of the political background to the assassination, the question of the delinquent's criminal responsibility has been posed from the very beginning. For the first time Sefeloge's case is examined from a medicohistorical perspective. Due to the importance of the circumstances, a forensic scientist and three well-known psychiatrists made this forensic examination. These medical professionals seemed particularly competent because of their common experience with psychiatric patients. This unique case from nineteenth century Germany is exemplary in that the psychiatrist was generally accepted as an expert witness to evaluate crimes in the context of unclear mental conditions. From there the development of forensic psychiatry could proceed without hindrance. PMID:17574489
NASA Astrophysics Data System (ADS)
Coutant, Antonin; Michel, Florent; Parentani, Renaud
2016-06-01
Black hole dynamical instabilities have been mostly studied in specific models. We here study the general properties of the complex-frequency modes responsible for such instabilities, guided by the example of a charged scalar field in an electrostatic potential. We show that these modes are square integrable, have a vanishing conserved norm, and appear in mode doublets or quartets. We also study how they appear in the spectrum and how their complex frequencies subsequently evolve when varying some external parameter. When working on an infinite domain, they appear from the reservoir of quasi-normal modes obeying outgoing boundary conditions. This is illustrated by generalizing, in a non-positive definite Krein space, a solvable model (Friedrichs model) which originally describes the appearance of a resonance when coupling an isolated system to a mode continuum. In a finite spatial domain instead, they arise from the fusion of two real frequency modes with opposite norms, through a process that closely resembles avoided crossing.
NASA Technical Reports Server (NTRS)
Maccormack, R. W.; Baldwin, B. S.
1975-01-01
A numerical method for solving the compressible form of the unsteady Navier-Stokes equations is described. This method was originally presented in 1970 and has since been modified during the development of computer programs at Ames for implementing models that account for the effects of turbulence in shock-induced separated flows. Although this paper does not describe the turbulence models themselves, a complete description of the basic numerical method is given with emphasis on the choice of a computational mesh for high Reynolds number flows, finite-difference approximations for mixed partial derivatives, extension of the Courant-Friedrichs-Lewy stability condition for viscous flows, mesh boundary conditions, and numerical smoothing for strong shock-wave calculations.
Assessing the child psychopathology beast: a reply to Achenbach and Dumenci's (2001) commentary.
Lengua, L J; Sadowski, C A
2001-08-01
This article is a response to T. M. Achenbach and L. Dumenci's (2001) commentary concerning L. J. Lengua, C. A. Sadowski, W. N. Friedrich, and J. Fisher's (2001) article proposing an alternative scoring approach for the Child Behavior Checklist. The authors note that T. M. Achenbach and L. Dumenci do not comment on the stated goals of the alternative scoring approach and focus on a limited set of the results to make their argument. Although the original and proposed scoring approaches operate similarly, important differences suggest that the proposed scoring approach is promising for use in specific instances, including identifying distinct etiologies, developmental course, and co-occurrence of specific syndromes. The importance of combining rational and empirical approaches in articulating conceptual definitions and developing measures of child psychopathology is discussed. PMID:11550736
PHURBAS: AN ADAPTIVE, LAGRANGIAN, MESHLESS, MAGNETOHYDRODYNAMICS CODE. II. IMPLEMENTATION AND TESTS
McNally, Colin P.; Mac Low, Mordecai-Mark; Maron, Jason L. E-mail: jmaron@amnh.org
2012-05-01
We present an algorithm for simulating the equations of ideal magnetohydrodynamics and other systems of differential equations on an unstructured set of points represented by sample particles. The particles move with the fluid, so the time step is not limited by the Eulerian Courant-Friedrichs-Lewy condition. Full spatial adaptivity is required to ensure the particles fill the computational volume and gives the algorithm substantial flexibility and power. A target resolution is specified for each point in space, with particles being added and deleted as needed to meet this target. We have parallelized the code by adapting the framework provided by GADGET-2. A set of standard test problems, including 10{sup -6} amplitude linear magnetohydrodynamics waves, magnetized shock tubes, and Kelvin-Helmholtz instabilities is presented. Finally, we demonstrate good agreement with analytic predictions of linear growth rates for magnetorotational instability in a cylindrical geometry. This paper documents the Phurbas algorithm as implemented in Phurbas version 1.1.
A minimum entropy principle in the gas dynamics equations
NASA Technical Reports Server (NTRS)
Tadmor, E.
1986-01-01
Let u(x bar,t) be a weak solution of the Euler equations, governing the inviscid polytropic gas dynamics; in addition, u(x bar, t) is assumed to respect the usual entropy conditions connected with the conservative Euler equations. We show that such entropy solutions of the gas dynamics equations satisfy a minimum entropy principle, namely, that the spatial minimum of their specific entropy, (Ess inf s(u(x,t)))/x, is an increasing function of time. This principle equally applies to discrete approximations of the Euler equations such as the Godunov-type and Lax-Friedrichs schemes. Our derivation of this minimum principle makes use of the fact that there is a family of generalized entrophy functions connected with the conservative Euler equations.
Hilbert's axiomatic method and Carnap's general axiomatics.
Stöltzner, Michael
2015-10-01
This paper compares the axiomatic method of David Hilbert and his school with Rudolf Carnap's general axiomatics that was developed in the late 1920s, and that influenced his understanding of logic of science throughout the 1930s, when his logical pluralism developed. The distinct perspectives become visible most clearly in how Richard Baldus, along the lines of Hilbert, and Carnap and Friedrich Bachmann analyzed the axiom system of Hilbert's Foundations of Geometry—the paradigmatic example for the axiomatization of science. Whereas Hilbert's axiomatic method started from a local analysis of individual axiom systems in which the foundations of mathematics as a whole entered only when establishing the system's consistency, Carnap and his Vienna Circle colleague Hans Hahn instead advocated a global analysis of axiom systems in general. A primary goal was to evade, or formalize ex post, mathematicians' 'material' talk about axiom systems for such talk was held to be error-prone and susceptible to metaphysics. PMID:26386526
The tragic and the metaphysical in philosophy and psychoanalysis.
Stolorow, Robert D; Atwood, George E
2013-06-01
This article elaborates a claim, first introduced by Wilhelm Dilthey, that metaphysics represents an illusory flight from the tragedy of human finitude. Metaphysics, of which psychoanalytic metapsychologies are a form, transforms the unbearable fragility and transience of all things human into an enduring, permanent, changeless reality, an illusory world of eternal truths. Three "clinical cases" illustrate this thesis in the work and lives of a philosopher and two psychoanalytic theorists: Friedrich Nietzsche and his metaphysical doctrine of the eternal return of the same, Sigmund Freud and his dual instinct theory, and Heinz Kohut and his theoretical language of the self. It is contended that the best safeguard against the pitfalls of metaphysical illusion lies in a shared commitment to reflection on the constitutive contexts of all our theoretical ideas. PMID:23638662
Historical and literary roots of Münchhausen syndromes: as intriguing as the syndromes themselves.
Olry, Régis; Haines, Duane E
2013-01-01
Hieronymus Carl Friedrich Freiherr von Münchhausen (1720-1797) was a famous eighteenth-century teller of extravagant stories. In 1785, Rudolph Erich Raspe anonymously published the first book-form edition of Münchhausen's Tales, and a German translation was made available by Gottfried August Bürger the following year. Since that time, these adventures remained a best seller, and the name of the Baron was twice referred to in psychiatric terminology: "Münchhausen syndrome" coined by Richard Asher in 1951 and "Münchhausen syndrome by proxy" coined by Roy Meadow in 1977. This chapter examines the legitimacy of these terms in the light of historical and literary records and analyzes the synonyms or clinical types as found in medical publications. PMID:24290479
3D shape reconstruction of medical images using a perspective shape-from-shading method
NASA Astrophysics Data System (ADS)
Yang, Lei; Han, Jiu-qiang
2008-06-01
A 3D shape reconstruction approach for medical images using a shape-from-shading (SFS) method was proposed in this paper. A new reflectance map equation of medical images was analyzed with the assumption that the Lambertian reflectance surface was irradiated by a point light source located at the light center and the image was formed under perspective projection. The corresponding static Hamilton-Jacobi (H-J) equation of the reflectance map equation was established. So the shape-from-shading problem turned into solving the viscosity solution of the static H-J equation. Then with the conception of a viscosity vanishing approximation, the Lax-Friedrichs fast sweeping numerical method was used to compute the viscosity solution of the H-J equation and a new iterative SFS algorithm was gained. Finally, experiments on both synthetic images and real medical images were performed to illustrate the efficiency of the proposed SFS method.
Hufeland's interest in plant movements.
Aschoff, J
1991-01-01
Christoph Wilhelm Hufeland (1762-1836) was one of the eminent physicians at the time of Goethe. When only 21 years old, he followed his father as a medical practitioner in Weimar. In 1793 he became Professor of Medicine at the University of Jena, from where he moved, in 1801, to Berlin as the physician in ordinary to king Friedrich Wilhelm III, council of state, and Professor at the leading hospital, the Charité. Hufeland pioneered in what today would be called public hygiene. Many of his lectures and publications were addressed to the educated laymen. In his most read book, the 'Makrobiotik', he emphasizes the importance of the 24-h periodicity as a basic unit of biological chronometry. In view of this, Hufeland has become a kind of 'patron saint' to modern chronobiologists. PMID:1760962
Relationship between directions of wave and energy propagation for cold plasma waves
NASA Technical Reports Server (NTRS)
Musielak, Zdzislaw E.
1986-01-01
The dispersion relation for plasma waves is considered in the 'cold' plasma approximation. General formulas for the dependence of the phase and group velocities on the direction of wave propagation with respect to the local magnetic field are obtained for a cold magnetized plasma. The principal cold plasma resonances and cut-off frequencies are defined for an arbitrary angle and are used to establish basic regimes of frequency where the cold plasma waves can propagate or can be evanescent. The relationship between direction of wave and energy propagation, for cold plasma waves in hydrogen atmosphere, is presented in the form of angle diagrams (angle between group velocity and magnetic field versus angle between phase velocity and magnetic field) and polar diagrams (also referred to as 'Friedrich's diagrams') for different directions of wave propagation. Morphological features of the diagrams as well as some critical angles of propagation are discussed.
The role of tone sensation and musical stimuli in early experimental psychology.
Klempe, Sven Hroar
2011-01-01
In this article, the role of music in early experimental psychology is examined. Initially, the research of Wilhelm Wundt is considered, as tone sensation and musical elements appear as dominant factors in much of his work. It is hypothesized that this approach was motivated by an understanding of psychology that dates back to Christian Wolff 's focus on sensation in his empirical psychology of 1732. Wolff, however, had built his systematization of psychology on Gottfried Wilhelm von Leibniz, who combined perception with mathematics,and referred to music as the area in which sensation is united with numerical exactitude. Immanuel Kant refused to accept empirical psychology as a science, whereas Johann Friedrich Herbart reintroduced the scientific basis of empirical psychology by, among other things, referring to music. PMID:21462196
An implicit velocity decoupling procedure for the incompressible Navier-Stokes equations
NASA Astrophysics Data System (ADS)
Kim, Kyoungyoun; Baek, Seung-Jin; Sung, Hyung Jin
2002-01-01
An efficient numerical method to solve the unsteady incompressible Navier-Stokes equations is developed. A fully implicit time advancement is employed to avoid the Courant-Friedrichs-Lewy restriction, where the Crank-Nicolson discretization is used for both the diffusion and convection terms. Based on a block LU decomposition, velocity-pressure decoupling is achieved in conjunction with the approximate factorization. The main emphasis is placed on the additional decoupling of the intermediate velocity components with only nth time step velocity. The temporal second-order accuracy is preserved with the approximate factorization without any modification of boundary conditions. Since the decoupled momentum equations are solved without iteration, the computational time is reduced significantly. The present decoupling method is validated by solving several test cases, in particular, the turbulent minimal channel flow unit. Copyright
Keller, Vera; Penman, Leigh T I
2015-03-01
Many historians have traced the accumulation of scientific archives via communication networks. Engines for communication in early modernity have included trade, the extrapolitical Republic of Letters, religious enthusiasm, and the centralization of large emerging information states. The communication between Samuel Hartlib, John Dury, Duke Friedrich III of Gottorf-Holstein, and his key agent in England, Frederick Clodius, points to a less obvious but no less important impetus--the international negotiations of smaller states. Smaller states shaped communication networks in an international (albeit politically and religiously slanted) direction. Their networks of negotiation contributed to the internationalization of emerging science through a political and religious concept of shared interest. While interest has been central to social studies of science, interest itself has not often been historicized within the history of science. This case study demonstrates the co-production of science and society by tracing how period concepts of interest made science international. PMID:26027306
"Cosmomorphistic geometry" in the unconscious geometry of Johannes Kepler
NASA Astrophysics Data System (ADS)
Adam, Adolf
Some mathematical aspects of the Music theory by Johannes Kepler are discussed, paying a special attention to the book "De harmonice mundi". Other scientists interested in Music theory are mentioned throughout the paper: The Pythagorean school, Klaudios Ptolemaios, Leonard Euler, Gottfried Wilhelm Leibniz, Christian von Goldbach, Hermann Ludwig Ferdinand von Helmholz, Karl Friedrich Gauss. The relation with the ancient chinese schools of cosmography has been discussed: From the the Pythagorean to the ancient Chinese schools of cosmography we find arithmo-geometrical applications of numbers which are emblematic, hold meaning or represent the essence of things, the author writes. It was Johannes Kepler who taught us this "transconstructive method" of forming classical and ancient begginings of structuralistic thinking into a system from which deductions can readily be made.
PREFACE: 15th International Conference on the Physics of Highly Charged Ions
NASA Astrophysics Data System (ADS)
Zou, Yaming; Hutton, Roger
2011-07-01
, under the Chairmanship of Professors Thomas Stoehlker and Joachim Ullrich. We wish them all the best with their plans and look forward to meeting you all again in 2012. Committees, Exhibitors and Sponsors HCI2010 International Advisory Committee F Aumayr (Austria) T Azuma (Japan) P Beiersdorfer (USA) J Burgdoerfer (Austria) A Cassimi (France) H Cederquist (Sweden) J Costello (Ireland) F Currell (UK) R Hoekstra (Holland) X Ma (China) F Martín (Spain) A Mueller (German) N Nakamura (Japan) M Pajek (Poland) R Rivarola (Argentina) Z Rudzikas (Lithuania) V Shabaev (Russia) R Schuch (Sweden) T Stoehlker (Germany) J Tanis (USA) L Tribedi (India) K Tokési (Hungary) J Ullrich (Germany) D Vernhet (France) Y Zou (China) T Zouros (Greece) HCI2010 Local Organizing Committee Co-chairs: Yaming Zou and Roger Hutton (Fudan university) Secretaries: Baoren Wei and Yunqing Fu (Fudan University) Treasurers: Xiuqing Xu and Daoli Xu (Shanghai Nuclear Society) Members Chongyang Chen (Shanghai) Jianmin Yuan (Changsha) Jun Yan (Beijing) Chenzhong Dong (Lanzhou) Xiaohong Cai (Lanzhou) Xinwen Ma (Lanzhou) Xuru Duan (Sichuan) Baohan Zhang (Sichuan) Exhibitors Andor Technology andor.com Shanghai Kelin Technology Development Co. Ltd chnkelin.com Varian Inc. varianinc.com Sponsors Natural Science Foundation of China International Union of Pure and Applied Physics (IUPAP) Fudan University
Tree ring and ice core time scales around the Santorini eruption
NASA Astrophysics Data System (ADS)
Löfroth, Elin; Muscheler, Raimund; Aldahan, Ala; Possnert, Göran; Berggren, Ann-Marie
2010-05-01
When studying cosmogenic radionuclides in ice core and tree ring archives around the Santorini eruption a ~20 year discrepancy was found between the records (Muscheler 2009). In this study a new 10Be dataset from the NGRIP ice core is presented. It has a resolution of 7 years and spans the period 3752-3244 BP (1803-1295 BC). The NGRIP 10Be record and the previously published 10Be GRIP record were compared to the IntCal datasets to further investigate the discrepancy between the ice core and tree ring chronologies. By modelling the 14C production rate based on atmospheric 14C records a comparison could be made to the 10Be flux which is assumed to represent the 10Be production rate. This showed a time shift of ~23 years between the records. The sensitivity of the results to changes in important model parameters was evaluated. Uncertainties in the carbon cycle model cannot explain a substantial part of the timing differences. Potential influences of climate and atmospheric processes on the 10Be deposition were studied using δ18O from the respective cores and GISP2 ice core ion data. The comparison to δ18O revealed a small but significant correlation between 10Be flux and δ18O when the 14C-derived production signal was removed from the 10Be curves. The ion data, as proxies for atmospheric circulation changes, did not show any correlations to the 10Be record or the 10Be/14C difference. When including possible data uncertainties there is still a minimum discrepancy of ~10 years between the 10Be ice core and the 14C tree ring record. Due to lack of alternative explanations it is concluded that the ice core and/or the tree ring chronologies contains unaccounted errors in this range. This also reconciles the radiocarbon 1627-1600 BC (Friedrich et al., 2006) and ice core 1642±5 BC (Vinther et al., 2006) datings of the Santorini eruption. Friedrich, W.L., Kromer, B., Friedrich, M., Heinemeier, J., Pfeiffer, T., & Talamo, S., 2006: Santorini eruption radiocarbon dated to
From X-rays to the h-hypothesis: Sommerfeld and the early quantum theory 1909-1913
NASA Astrophysics Data System (ADS)
Eckert, Michael
2015-09-01
Sommerfeld was deeply interested in the nature of X-rays. In 1900 he concluded from diffraction experiments on slits that, if X-rays are electromagnetic radiation, their "impulse width" should be of the order of magnitude of the size of molecules. In 1905 Sommerfeld regarded it "a shame that after ten years after Röntgen*s discovery one still does not know what is going on with X-rays". When he became Röntgen*s colleague a year later, he perceived this shame even more as a challenge. By that time it was discovered that X-rays come in two varieties. One sort of X-rays was independent of the anti-cathode material and could be explained by Sommerfeld in 1909 as "Bremsstrahlung", i.e. as an electromagnetic radiation caused by the deceleration of electrons at their impact in the anti-cathode. The other part had the character of a fluorescent radiation. The "Bremsstrahlung" was polarized and displayed an angular distribution of intensity with a characteristic shape dependent on the energy of the electrons at the impact in the anti-cathode; the other part was unpolarized and characteristic for the material of the anti-cathode. Sommerfeld*s "Bremsstrahlen"-theory could not be elaborated without further assumptions about the impact of electrons in the anti-cathode. Sommerfeld closed his theory by a quantum hypothesis: He linked the time required to stop an electron, t, and the energy released in this process, E, to Planck*s quantum of action, h, via tE = h. This so-called h-hypothesis became the subject of Sommerfeld*s presentation at the first Solvay Conference. Although met with criticism, the quantum effort at Munich raised curiosity. Sommerfeld attempted to verify this hypothesis theoretically and experimentally in his institute with Walther Friedrich, his experimental assistant. Friedrich, a doctoral student from Röntgen*s institute, was persuaded however by Max Laue, then Sommerfeld*s Privatdozent, to perform another experiment which led to the discovery of X
Parameterisation of clastic sediments including benthic structures
NASA Astrophysics Data System (ADS)
Bobertz, B.; Harff, J.; Bohling, B.
2009-02-01
The sediment transport processes in the south-western Baltic Sea are predicted by means of a numerical model in the project DYNAS. There are two sediment parameters that influence the results of modelling remarkably: critical shear stress velocity and bottom roughness. This paper presents the way how to parameterise these factors and extrapolate them into the investigation area. The critical shear stress velocity is parameterised basing on grain size data, combining approximations after Hjulström [Hjulström, F., 1935: Studies in the morphological activity of rivers as illustrated by the river Fyris. Geological Institution of University of Uppsala: Bulletin (25): 221-528.], Shields [Shields, A., 1936: Anwendung der Ähnlichkeits-Mechanik und der Turbulenzforschung auf die Geschiebebewegung. Mitteilungen der Preussischen Versuchsanstalt für Wasserbau und Schiffahrt (26): 26 pp.] and Bohling [Bohling, B., 2003: Untersuchungen zur Mobilität natürlicher und anthropogener Sedimente in der Mecklenburger Bucht. unpublished doctoral thesis, Mathematisch-Naturwissenschaftliche Fakultät, Ernst-Moritz-Arndt-Universität Greifswald/Germany, 156 pp.]. The roughness length, in the case of absence of macro zoo-benthos and their structures, is parameterised basing on grain size too employing Soulsby [Soulsby, R.L., 1997: Dynamics of Marine Sands: a Manual for Practical Applications. London, Thomas Telford Publications. 249 pp.], Nielsen [Nielsen, P., 1983: Analytical determination of nearshore wave height variation due to refraction shoaling and friction. Coastal Engineering 7, 233-251.] and Yalin [Yalin, M.S., 1977: Mechanics of Sediment Transport. Pergamon Press, New York. 298 pp.]. No equivalent simple parameterisations for biologically caused bed roughness exist. Here, findings of Friedrichs [Friedrichs, M., 2004: Flow-induced effects of macro zoo-benthic structures on the near-bed sediment transport. Dissertation, Universität Rostock, 80 S.] and estimations by the DYNAS
IRI, an International Standard for the Ionosphere
NASA Astrophysics Data System (ADS)
Bilitza, D.; Reinisch, B.; Triskova, L.; Friedrich, M.
2003-04-01
The International Reference Ionosphere (IRI) is a data-based model of the ionosphere that has been steadily improved and updated by a joint working group of the Committee on Space Research and the International Union of Radio Science. We will report about the most recent IRI workshops and the improvements and additions planned for the next version of the model. In particular new models will be included for the D-region electron density (Friedrich et al., 2002), and for the ion densities (Triskova et al., 2003) the latter based on Atmosphere Explorer C, D, E and Intercosmos 24 data. A correction term will be introduced in the topside electron density model to alleviate problems at high solar activities and high altitudes (Bilitza, 2002). A special IRI task groups is working on an occurrence probability model for spread-F (Abdu et al., 2003) for inclusion in IRI. A quantitative description of ionospheric variability (standard deviation from monthly mean) is the goal of a special IRI task force activity at the International Center for Theoretical Physics (Radicella 2002). We will also report about activities to update IRI with actual measurements and thus obtain a more accurate description of the actual ionosphere. A proposal to make the IRI model the ISO standard for the ionosphere is now pending before the International Standardization Organization (ISO). The IRI homepage is at http://nssdc.gsfc.nasa.gov/space/model/ionos/iri.html and a web-interface for computing and plotting IRI parameters can be found at http://nssdc.gsfc.nasa.gov/space/model/models/iri.html . Abdu, M. A., J. R de Souza, I. S. Batista, and J. H. A. Sobral, Equatorial Spread F statistics and their empirical modeling for the IRI: A regional model for the Brazilian longitude sector, Adv. Space Res., in press, 2003. Triskova, L., V. Truhlik and J. Smilauer, An empirical model of ion composition in the outer ionosphere, Adv. Space Res., in press, 2003 Bilitza, D., A Correction for the IRI Topside
NASA Astrophysics Data System (ADS)
Laß, Kristian; Bange, Hermann W.; Friedrichs, Gernot
2013-04-01
periodicity of nanolayer intensity and its temporal shift with respect to other influential factors. References [1] K. Laß, G. Friedrichs, J. Geophys. Res. 116 (2011) C08042/1-15 [2] K. Laß, J. Kleber, G. Friedrichs, Limnol. Oceanogr.: Methods 8 (2010) 216-228
What may happen to a man who thinks a great deal but reads very little
NASA Astrophysics Data System (ADS)
Frenkel, Viktor; Yavelov, Boris
In his biography of Einstein, first published in 1952, Carl Seelig says: "It is not well known that, at that time, Einstein took a run at aircraft design. ... He undertook a new airfoil design intended for serial production", but two test pilots found "As an aircraft designer, the great theoretician Einstein failed". Friedrich Herneck, however, calls the story told by Seelig into question: "It is hardly probable that in 1916 [?] Einstein made an unsuccessful attempt to improve the design of military [?] airplanes, as one of his biographers asserts" (Herneck 1966). Einstein scholars generally agree that Seelig's book is a reliable source: No one has so far been able to find any deliberate distortions of facts or signs of unscrupulousness in his work. On the other hand, Herneck is also respected throughout the world as a conscientious historian and as the author of widely-read biographies of prominent physicists. Who, then, is right? Did this episode really happen or was it just one of the numerous anecdotes connected with the famous name? In support of his doubts, Herneck notes that, first there is no evidence that Einstein participated in aircraft design; and second, this course of action would run counter to his consistently pacifist stance. We shall discuss both points.
Böttger stoneware from North America and Europe; are they authentic
NASA Astrophysics Data System (ADS)
Swann, Charles P.; Nelson, Christina H.
2000-03-01
In the early 18th century, Johann Friedrich Böttger, an alchemist recently arrived in Dresden, was assigned to ceramic experimentation under the orders of Augustus the Strong, Elector of Saxony and King of Poland. The Elector and his advisors hoped to discover the secret of making hard paste porcelain like the wares imported into Europe from China and Japan. In 1706-1707, Böttger produced his first ceramic body, a red stoneware similar to the wares produced in Yixing, China. The first objects were made following the forms of chinese prototypes or European metalwork of the period. Recently, the authenticity of a number of `Böttger' objects in various museums and private collections in North America and Europe has been questioned. To aide in resolving these questions several non-destructive analytical techniques have been employed, the most important being PIXE. This report is on an initial study of 25 objects with 16 elements from Al to Zr and Pb being analysed. The results strongly suggest three different groupings, one of objects from the Meissen factory during the 20th century, one from the work of Böttger himself early in the 18th century and one from an as yet unknown time period and site. The first two groups were previously identified by one of the authors (C.N.).
NASA Astrophysics Data System (ADS)
Lemarié, F.; Debreu, L.; Madec, G.; Demange, J.; Molines, J. M.; Honnorat, M.
2015-08-01
Except for vertical diffusion (and possibly the external mode and bottom drag), oceanic models usually rely on explicit time-stepping algorithms subject to Courant-Friedrichs-Lewy (CFL) stability criteria. Implicit methods could be unconditionally stable, but an algebraic system must be solved at each time step and other considerations such as accuracy and efficiency are less straightforward to achieve. Depending on the target application, the process limiting the maximum allowed time-step is generally different. In this paper, we introduce offline diagnostics to predict stability limits associated with internal gravity waves, advection, diffusion, and rotation. This suite of diagnostics is applied to a set of global, regional and coastal numerical simulations with several horizontal/vertical resolutions and different numerical models. We show that, for resolutions finer that 1/2°, models with an Eulerian vertical coordinate are generally constrained by vertical advection in a few hot spots and that numerics must be extremely robust to changes in Courant number. Based on those results, we review the stability and accuracy of existing numerical kernels in vogue in primitive equations oceanic models with a focus on advective processes and the dynamics of internal waves. We emphasize the additional value of studying the numerical kernel of oceanic models in the light of coupled space-time approaches instead of studying the time schemes independently from spatial discretizations. From this study, we suggest some guidelines for the development of temporal schemes in future generation multi-purpose oceanic models.
A computational approach to negative priming
NASA Astrophysics Data System (ADS)
Schrobsdorff, H.; Ihrke, M.; Kabisch, B.; Behrendt, J.; Hasselhorn, M.; Herrmann, J. Michael
2007-09-01
Priming is characterized by a sensitivity of reaction times to the sequence of stimuli in psychophysical experiments. The reduction of the reaction time observed in positive priming is well-known and experimentally understood (Scarborough et al., J. Exp. Psycholol: Hum. Percept. Perform., 3, pp. 1-17, 1977). Negative priming—the opposite effect—is experimentally less tangible (Fox, Psychonom. Bull. Rev., 2, pp. 145-173, 1995). The dependence on subtle parameter changes (such as response-stimulus interval) usually varies. The sensitivity of the negative priming effect bears great potential for applications in research in fields such as memory, selective attention, and ageing effects. We develop and analyse a computational realization, CISAM, of a recent psychological model for action decision making, the ISAM (Kabisch, PhD thesis, Friedrich-Schiller-Universitat, 2003), which is sensitive to priming conditions. With the dynamical systems approach of the CISAM, we show that a single adaptive threshold mechanism is sufficient to explain both positive and negative priming effects. This is achieved by comparing results obtained by the computational modelling with experimental data from our laboratory. The implementation provides a rich base from which testable predictions can be derived, e.g. with respect to hitherto untested stimulus combinations (e.g. single-object trials).
NASA Astrophysics Data System (ADS)
Mazzia, Annamaria; Putti, Mario
2005-09-01
Two-dimensional Godunov mixed methods have been shown to be effective for the numerical solution of density-dependent flow and transport problems in groundwater even when concentration gradients are high and the process is dominated by density effects. This class of discretization approaches solves the flow equation by means of the mixed finite element method, thus guaranteeing mass conserving velocity fields, and discretizes the transport equation by mixed finite element and finite volumes techniques combined together via appropriate time splitting. In this paper, we extend this approach to three dimensions employing tetrahedral meshes and introduce a spatially variable time stepping procedure that improves computational efficiency while preserving accuracy by adapting the time step size according to the local Courant-Friedrichs-Lewy (CFL) constraint. Careful attention is devoted to the choice of a truly three-dimensional limiter for the advection equation in the time-splitting technique, so that to preserve second order accuracy in space (in the sense that linear functions are exactly interpolated). The three-dimensional Elder problem and the saltpool problem, recently introduced as a new benchmark for testing three-dimensional density models, provide assessments with respect to accuracy and reliability of this numerical approach.
NASA Astrophysics Data System (ADS)
Betzinger, Markus; Friedrich, Christoph; Blügel, Stefan
2013-08-01
In a previous publication [Betzinger, Friedrich, Görling, and Blügel, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.85.245124 85, 245124 (2012)] we presented a technique to compute accurate all-electron response functions, e.g., the density response function, within the full-potential linearized augmented-plane-wave (FLAPW) method. Response contributions that are not captured (completely) within the finite Hilbert space spanned by the LAPW basis are taken into account by an incomplete-basis-set correction (IBC). The latter is based on a formal response of the basis functions themselves, which is derived by exploiting their dependence on the effective potential. Its construction requires the solution of radial differential equations, having the form of Sternheimer equations, by numerical integration. The approach includes a formally exact treatment of the response contribution from the core states. While we restricted the formalism to spherical perturbations in the previous work, we here generalize the formalism to nonspherical perturbations. The improvements are demonstrated with exact-exchange optimized-effective-potential (EXX-OEP) calculations of antiferromagnetic NiO. It is shown that with the generalized IBC a basis-set convergence is realized that is as fast as in density-functional theory calculations using standard local or semilocal functionals. The EXX-OEP band gap, magnetic moment, and spectral function of NiO are in substantially better agreement with experiment than results obtained from calculations with local and semilocal functionals.
Asymptotic properties of the development of conformally flat data near spatial infinity
NASA Astrophysics Data System (ADS)
Valiente Kroon, Juan Antonio
2007-06-01
The analysis of the relation between Bondi-type systems (NP-gauge) and a gauge used in the analysis of the structure of spatial infinity (F-gauge) which was carried out by Friedrich and Kánnár (2000 J. Math Phys. 41 2195) is retaken and applied to the development of a suitable class of conformally flat initial data sets with non-vanishing second fundamental form. The calculations presented depend on a certain assumption about the existence and regularity of the solutions to the conformal Einstein field equations close to null and spatial infinity. As a result of the calculations the Newman-Penrose constants of both future and past null infinity are calculated in terms of initial data and are shown to be equal. It is also shown that the asymptotic shear goes to zero as one approaches spatial infinity along the generators of null infinity so that it is possible to select, in a canonical fashion, the Poincaré group out of the BMS group. An expansion—again in terms of initial data quantities—of the Bondi mass close to spatial infinity is calculated. This expansion shows that if the existence and regularity assumptions hold, the Bondi mass approaches the ADM mass. A discussion of possible conditions on the initial data which would render a peeling development is presented.
NASA Astrophysics Data System (ADS)
Wu, Kailiang; Tang, Huazhong
2015-10-01
The paper develops high-order accurate physical-constraints-preserving finite difference WENO schemes for special relativistic hydrodynamical (RHD) equations, built on the local Lax-Friedrichs splitting, the WENO reconstruction, the physical-constraints-preserving flux limiter, and the high-order strong stability preserving time discretization. They are extensions of the positivity-preserving finite difference WENO schemes for the non-relativistic Euler equations [20]. However, developing physical-constraints-preserving methods for the RHD system becomes much more difficult than the non-relativistic case because of the strongly coupling between the RHD equations, no explicit formulas of the primitive variables and the flux vectors with respect to the conservative vector, and one more physical constraint for the fluid velocity in addition to the positivity of the rest-mass density and the pressure. The key is to prove the convexity and other properties of the admissible state set and discover a concave function with respect to the conservative vector instead of the pressure which is an important ingredient to enforce the positivity-preserving property for the non-relativistic case. Several one- and two-dimensional numerical examples are used to demonstrate accuracy, robustness, and effectiveness of the proposed physical-constraints-preserving schemes in solving RHD problems with large Lorentz factor, or strong discontinuities, or low rest-mass density or pressure etc.
Hands of beauty, hands of horror: fear and Egyptian art at the Fin de Siècle.
Briefel, Aviva
2008-01-01
This essay examines the gothicization of Egyptian manual productions in late-Victorian mummy narratives. These narratives often isolate the mummy's hand as a signifier of craftsmanship, a troubling object for a culture that was mourning the figurative loss of its artisans' hands to mechanized production. Focusing on Bram Stoker's 1903 novel, The Jewel of Seven Stars, I contend that the horror of the mummy's hand emanates from its ambiguous position as an artifact that is itself a means of production. It displaces Friedrich Engels's conception of the Western hand as a self-creating appendage into the atavistic domain of a long-lost Egyptian tradition, and in doing so, it forces the English observer to recognize the irrecoverable nature of aesthetic craftsmanship. Brought into violent contact with the creative potential of the mummy's hand, the characters in Stoker's novel try to disassociate the mummy from manual production but only succeed in confirming their own status as products of a mechanized age. PMID:19069003
The Cauchy-Lagrangian method for numerical analysis of Euler flow
NASA Astrophysics Data System (ADS)
Podvigina, O.; Zheligovsky, V.; Frisch, U.
2016-02-01
A novel semi-Lagrangian method is introduced to solve numerically the Euler equation for ideal incompressible flow in arbitrary space dimension. It exploits the time-analyticity of fluid particle trajectories and requires, in principle, only limited spatial smoothness of the initial data. Efficient generation of high-order time-Taylor coefficients is made possible by a recurrence relation that follows from the Cauchy invariants formulation of the Euler equation (Zheligovsky and Frisch, 2014 [44]). Truncated time-Taylor series of very high order allow the use of time steps vastly exceeding the Courant-Friedrichs-Lewy limit, without compromising the accuracy of the solution. Tests performed on the two-dimensional Euler equation indicate that the Cauchy-Lagrangian method is more - and occasionally much more - efficient and less prone to instability than Eulerian Runge-Kutta methods, and less prone to rapid growth of rounding errors than the high-order Eulerian time-Taylor algorithm. We also develop tools of analysis adapted to the Cauchy-Lagrangian method, such as the monitoring of the radius of convergence of the time-Taylor series. Certain other fluid equations can be handled similarly.
A world from brave to new: Talcott Parsons and the war effort at Harvard University.
Gerhardt, U
1999-01-01
This article argues that for Parsons and some of his colleagues at Harvard, the Second World War and the post-war period provided a context in which their work contributed to the transformation from totalitarianism to democracy in Central Europe (especially Germany) and Japan. The various agendas of Parsons' work are shown, supplemented by that of three of his colleagues with whom he collaborated (Gordon W. Allport, Carl J. Friedrich, Clyde Kluckhohn). The immediate effect of this work, for Parsons, however, meant frustration rather than fame, and his eventual reputation, I maintain, came unexpectedly with the third of his three attempts in the immediate post-war period to sum up what he believed were crucial insights that the Second World War had yielded concerning the ways in which sociology could contribute to the analytical understanding of democracy. The significance of this work is that it was both political and scientific. Because of the world situation of the 1940s, when the Holocaust in Germany was the nadir of civilization, Parsons believed that social science could contribute to the cause of making the world safe for future democracy. In the 1940s, this future depended on brave citizens, or such might have been Parsons' worldview. Targets envisaged for the 1950s, then, were community and citizenship in the newly democratic societies such as (West) Germany, the land that defeated Nazism. PMID:10398174
Fritz Reiche and German Refugee Scientists
NASA Astrophysics Data System (ADS)
Bederson, Benjamin
2003-04-01
Fritz Reiche (1883-1969) was a distinguished theoretical physicist, a student and colleague of Wilhelm Roentgen, Max Planck, Fritz Haber, Rudolf Ladenburg, James Franck, Max Born, Max von Laue and other early luminaries. He was coauthor of the famous Thomas-Reiche-Kuhn sum rule, and author of the seminal book The Quantum Theory, first published in 1920. He was one of the last Jewish physicists to leave Germany during the Nazi period, in 1941. In his book "Heisenberg's War" Thomas Powers relates that Reiche bore news of German work on nuclear fission, in a message from Friedrich Houtermans to Wigner and others in Princeton, where Reiche lived in Einstein's home during the summer of 1941. Reiche's son Hans later claimed that this incident played a significant role in convincing Einstein to write that letter to President Roosevelt. In this talk I will relate the difficulties Reiche experienced, first in leaving Germany and then in reestablishing his physics career in the US. He finally obtained an adjunct position at NYU where he served until his retirement. The role played by the renowned Emergency Committee in Aid of Displaced Foreign Scholars will be discussed. The particular role played by Ladenburg, who was instrumental in obtaining a small grant for Reiche permitting him to obtain a US visa, in helping many physicists leave Nazi Germany and occupied countries, will also be described.
Moradi, Hamed; Cally, Paul S.
2014-02-20
The rapid exponential increase in the Alfvén wave speed with height above the solar surface presents a serious challenge to physical modeling of the effects of magnetic fields on solar oscillations, as it introduces a significant Courant-Friedrichs-Lewy time-step constraint for explicit numerical codes. A common approach adopted in computational helioseismology, where long simulations in excess of 10 hr (hundreds of wave periods) are often required, is to cap the Alfvén wave speed by artificially modifying the momentum equation when the ratio between the Lorentz and hydrodynamic forces becomes too large. However, recent studies have demonstrated that the Alfvén wave speed plays a critical role in the MHD mode conversion process, particularly in determining the reflection height of the upwardly propagating helioseismic fast wave. Using numerical simulations of helioseismic wave propagation in constant inclined (relative to the vertical) magnetic fields we demonstrate that the imposition of such artificial limiters significantly affects time-distance travel times unless the Alfvén wave-speed cap is chosen comfortably in excess of the horizontal phase speeds under investigation.
An Act of Scientific Creativity: Meitner, Frisch, and Nuclear Fission
NASA Astrophysics Data System (ADS)
Stuewer, Roger H.
2002-04-01
The dominant event that lay in the background to Werner Heisenberg's fateful meeting with Niels Bohr in occupied Copenhagen in September 1941 was the discovery and interpretation of nuclear fission three years earlier. Michael Frayn has explored that meeting in his play "Copenhagen" in an act of extraordinary literary creativity. In this talk I will explore Lise Meitner's and Otto Robert Frisch's interpretation of nuclear fission as an act of extraordinary scientific creativity. My aim is to understand historically how it was possible for Meitner and Frisch, and only Meitner and Frisch, to arrive at their interpretation as they talked and walked in the snow in the small Swedish village of Kungälv over the Christmas holidays in December 1938. This will require us to examine the history of the liquid-drop model of the nucleus over the preceding decade, from George Gamow's conception of that model in 1928, through Heisenberg and Carl Friedrich von Weizsäcker's extension of it between 1933 and 1936, and finally through Bohr's use of it in his theory of the compound nucleus between 1936 and 1938. We will see how Meitner and Frisch combined their different knowledge of these developments creatively to arrive at their momentous interpretation of nuclear fission.
G. F. Parrot and the theory of unconscious inferences.
Allik, Jüri; Konstabel, Kenn
2005-01-01
In 1839, Georg Friedrich Parrot (1767-1852) published a short note about a peculiar visual phenomenon--the diminishing of the size of external objects situated at a relatively small distance from the window of a fast-moving train. For the explanation of this illusion, Parrot proposed a concept of unconscious inferences, a very rapid syllogistic conclusion from two premises, which anticipated the revival of Alhazen's theory of unconscious inferences by Hermann von Helmholtz, Wilhelm Wundt, and John Stuart Mill. He also advanced the notion that the speed of mental processes is not infinitely high and that it can be measured by means of systematic experimentation. Although Parrot was only partly correct in the description of the movement-induced changes of the perceived size, his general intention to understand basic mechanisms of the human mind was in harmony with the founding ideas of experimental psychology: it is possible to study the phenomena of the mind in the same general way that the physical world is studied, either in terms of mechanical or mathematical laws. PMID:16196051
RBIS - An Environmental Information System
NASA Astrophysics Data System (ADS)
Zander, F.; Kralisch, S.
2012-04-01
The River Basin Information System (RBIS) developed at the Department of Geoinformatics at the Friedrich Schiller University of Jena provides a modular structured and web-based platform for environmental data management and data sharing (http://www.rbis.uni-jena.de). The system is used in several multidisciplinary research projects and provides user-friendly functions for the management, analysis, visualization and presentation of different types of data. These types of data include time series data (e.g. hydrological, climatologically …), geodata, documents and more domain specific modules for example related to soil, vegetation, scenarios, simulation models or indicators. One main focus lies on the maintenance on meta-data to make sure information about data provenance and responsible parties are preserved. Furthermore the fine grained user and permission management of RBIS take care about the access and manipulation rights of all stored data. For an easy data exchange of time series data and other data types RBIS provides several interfaces. One example is a prototypical implementation using OGC standards (Sensor Observation Service (SOS) and WaterML2.0). Since RBIS is used for data in research regions located in different countries (e.g. Brazil, Vietnam, Angola, Chile, Germany) a Multilanguage support was added to address not only research project partners but also local stakeholder and public. We will present the structure, modules, main functions, permission management and interfaces for data exchange of RBIS together with selected examples of RBIS instances.
FIRST REPORTS OF CLINICAL PHARMACOKINETICS IN NIGERIA
Michael, O.S.
2015-01-01
The German Friedrich Hartmut Dost (1910-1985) introduced the word Pharmacokinetics. Clinical pharmacokinetics is the direct application of knowledge regarding a drug's pharmacokinetics to a therapeutic situation in an individual or a population. It is the basis of therapeutic drug monitoring with the ultimate goal of keeping drugs safe. This branch of pharmacology has become the most relevant to the sub-specialty of clinical pharmacology. First reports of Clinical Pharmacokinetics in Nigeria can be credited to two gifted Nigerians, Prof Ayodele O. Iyun and Prof Lateef A. Salako, both of whom were affiliated to the great institutions- University of Ibadan (UI) and the Teaching Hospital, University College Hospital (UCH). Prof A.O Iyun was Nigeria's first home-trained Clinical Pharmacologist, while Prof L.A. Salako played a most significant role in the creation of the Department of Clinical Pharmacology, UCH. This edition of the Chronicles highlights a few of the first reports of this exciting branch of pharmacology in Nigeria. This historical review is based on publications listed on the United States National Library of Medicine database (PUBMED). PMID:26807087
NASA Astrophysics Data System (ADS)
Stern, David P.
2002-11-01
The history of geomagnetism began around the year 1000 with the discovery in China of the magnetic compass. Methodical studies of the Earth's field started in 1600 with William Gilbert's De Magnete [Gilbert, 1600] and continued with the work of (among others) Edmond Halley, Charles Augustin de Coulomb, Carl Friedrich Gauss, and Edward Sabine. The discovery of electromagnetism by Hans Christian Oersted and André-Marie Ampére led Michael Faraday to the notion of fluid dynamos, and the observation of sunspot magnetism by George Ellery Hale led Sir Joseph Larmor in 1919 to the idea that such dynamos could sustain themselves naturally in convecting conducting fluids. From that came modern dynamo theory, of both the solar and terrestrial magnetic fields. Paleomagnetic studies revealed that the Earth's dipole had undergone reversals in the distant past, and these became the critical evidence in establishing plate tectonics. Finally, the recent availability of scientific spacecraft has demonstrated the intricacy of the Earth's distant magnetic field, as well as the existence of magnetic fields associated with other planets and with satellites in our solar system.
Austria's Scientific Contribution to the Observation of the Venus Transit of 1874
NASA Astrophysics Data System (ADS)
Kopper, M.
2004-12-01
Already since the mid-19th century, it was a task of the Imperial-Royal Austro-Hungarian Navy not only to take part in military actions, to train sea cadets, to strengthen diplomatic relations, and to protect the coasts, the sea trade, and Austrian citizens in far countries, but also to carry out coast surveys and soundings, as well as scientific observations during their missions. On a trip around the earth, Tobias von Österreicher, commander of the corvette "Erzherzog Friedrich", was instructed to observe the Venus transit of December 8, 1874 in Yokohama. This order was only one out of many that he had to fulfill: to train the Navy cadets, to explore the possibility of the installation of a colony on the island of Borneo, to meet diplomats and consulate representatives, to carry out soundings and coast surveys to improve sea-charts, and to make meteorological observations. The "qualification list" indicates that all these tasks were fulfilled according to expectations. However, an incident on Borneo in 1875 took the life of two of his sailors. In its aftermath he did not react according to rules, he was reproached by the Navy Section of the Imperial War Ministry, and his career as a ship commander came to an end. Besides the Austrian expedition to observe the Venus transit of 1874 in Yokohama, a second one was carried out by the astronomers Eduard Weiss and Theodor Oppolzer in Jassy (Romania), which was supported by the Vienna Academy of Sciences.
Mudry, Albert; von Deuster, Christian; Peinhardt, Juliane
2016-05-01
Anton Friedrich Baron von Tröltsch (1829-1890) was a very famous German otologist in Würzburg in the second part of the 19th century. The aim of this study is to present some unpublished documents related to his biography: a 4-page autobiographical unsigned text probably written for his habilitation in 1861, a 4-page autobiographical letter sent by von Tröltsch to the editors of the Brockhaus-Conversations-Lexikon in 1872, a unique album of portraits of the main otologists of the second part of the 19th century, collected for his 1886 Privat Docent jubilee anniversary, and a portrait of unknown origin. They are discussed with other unusual portraits. These new documents demonstrate at least two major points. One, von Tröltsch was aware of his qualities and the importance of his work in otology but he was not boastful. Two, he was really loved and respected by its colleagues, nearly 150 of them came just for a one-day ovation in Würzburg for his 25th Privat Docent Jubilee and his retirement from his otological practice. Von Tröltsch was and remains an example for all otologists. PMID:26589899
Life and work of E.F.F. Chladni
NASA Astrophysics Data System (ADS)
Ullmann, D.
2007-06-01
Ernst Florens Friedrich Chladni, the son of the rector of the University of Wittenberg, studied law and philosophy at the Universities of Wittenberg and Leipzig, wrote a dissertation in each of these disciplines and became an experimentalist concerned with sound and vibrations. Chladni's name is associated with the Chladni figures, and this is the first real effort to experimentally investigate the nature of sound. In the lecture the publications of Chladni are presented and, cursorily, his new instruments, designed and built by the physicist. Chladni began to tour half Europe in his own coach with sufficient space for his musical instruments. He gave lectures on the physics of plate and rod vibrations and included demonstrations of the figures and his musical instruments. Chladni's work has had a profound influence on the experimental advances in acoustics, room acoustics, in the verification of theories of superposition of waves, in elasticity, vibrational modes, sound velocities in various media, and much more. The lecture presents a portrait of the scientist Chladni, the times, and his contributions to experimental acoustics which influenced research for many decades.
Potential of The Object Modeling System For Development and Application of Decision Support Systems
NASA Astrophysics Data System (ADS)
Krause, P.; David, O.
For future-proof development and implementation of Decision Support Systems flex- ible software tools assisting the developers as well as the users are needed. With the Object Mod-eling System (OMS), which was developed in a joint approach by the USGS (Denver, Col.), the USDA (Ft. Collins, Col.) and the Friedrich-Schiller- University (Jena, Germany) such a tool has become available. By its object oriented and modular design the OMS provides a system independent framework for model as well as DSS development and application. Addi-tionally different views for devel- opers, modellers or operational users can be defined provid-ing each group with only that functionality they need for their daily work. Besides the core components for sys- tems development and application a GIS interface for spatial queries and analyses is currently under development. The hydrological model PRMS and the Root Zone Wa- ter Quality Model RZWQM have al-ready been integrated into the OMS and can be used for prognostic simulations of quantitative and qualitative modelling of the water balance. The integration of other models and the ge-neric development of new com- ponents and process modules will be carried out continuously. In the presentation the OMS will be introduced and its potential for future-proof development and application of DSS will be demonstrated.
NASA Astrophysics Data System (ADS)
Moiseyev, Nimrod; Gupta, Ashish Kumar
2012-08-01
The harmonic generation spectra (HGS) of two different ensembles of the same heteronuclear (polar) diatomic molecule are studied. In one ensemble the molecules are aligned (i.e. CO ↔ OC) whereas in the second ensemble the molecules are randomly distributed in different directions (and therefore not all molecules have the same orientation, e.g. CO or OC along one of the axes in the laboratory frame). Using the non-Hermitian formalism of quantum mechanics we prove that the HGS of the two ensembles consist of odd-order harmonics only, provided the photo-induced dynamics is controlled by a single resonance (metastable) state. As we show here by using the Friedrich and Herschbach approach [J. Phys. Chem. A 103, 10280 (1999); J. Chem. Phys. 111, 6157 (1999)], it is possible to distinguish between the ensemble of 'perfectly' aligned molecules and an ensemble of molecules with a random directional distribution, provided the dc-field is turned on adiabatically slow and all aligned molecules are in the same quantum state. As an illustrative numerical example the HGS of aligned and ensemble of random directional distributed CO molecules with and without dc field were computed by carrying out ab initio electronic structure calculations.
Modeling Urban Flood Dynamics Using High-Resolution Topography and Bathymetry
NASA Astrophysics Data System (ADS)
Dwelle, M. C.; Kim, J.; Ivanov, V. Y.
2015-12-01
Flooding is the leading cause of death from natural disasters and poses public health and economic risks to developed and developing cities. In order to better assess these risks, models of flooding need to rely on modern, up-to-date information about urban environments. Approaches based on traditional grids are computationally expensive because of the restriction of the Courant-Friedrichs-Levy condition. This condition introduces a resolution dependency into hydrodynamic models, affecting a number of states such as velocity and water depth, and therefore may impact management and design decisions, becoming a serious weakness in real-time situations.This research links watershed processes to the urban environment by applying an upscaling method that relies on fine-scale information on elevation, roughness, land cover, and soil moisture. The benefit of this approach is that it reduces resolution dependency, allowing for the calculation of hydrodynamic variables at subgrid scales. This approach negates the need for grid refinement in complex geometries and surface conditions of the urban interface, improving the computational efficiency for simulating and predicting flooding events.
NASA Astrophysics Data System (ADS)
Mulder, W. A.; Zhebel, E.; Minisini, S.
2014-02-01
We analyse the time-stepping stability for the 3-D acoustic wave equation, discretized on tetrahedral meshes. Two types of methods are considered: mass-lumped continuous finite elements and the symmetric interior-penalty discontinuous Galerkin method. Combining the spatial discretization with the leap-frog time-stepping scheme, which is second-order accurate and conditionally stable, leads to a fully explicit scheme. We provide estimates of its stability limit for simple cases, namely, the reference element with Neumann boundary conditions, its distorted version of arbitrary shape, the unit cube that can be partitioned into six tetrahedra with periodic boundary conditions and its distortions. The Courant-Friedrichs-Lewy stability limit contains an element diameter for which we considered different options. The one based on the sum of the eigenvalues of the spatial operator for the first-degree mass-lumped element gives the best results. It resembles the diameter of the inscribed sphere but is slightly easier to compute. The stability estimates show that the mass-lumped continuous and the discontinuous Galerkin finite elements of degree 2 have comparable stability conditions, whereas the mass-lumped elements of degree one and three allow for larger time steps.
The metaphor of epigenesis: Kant, Blumenbach and Herder.
Helbig, Daniela; Nassar, Dalia
2016-08-01
Over the last few decades, the meaning of the scientific theory of epigenesis and its significance for Kant's critical philosophy have become increasingly central questions. Most recently, scholars have argued that epigenesis is a key factor in the development of Kant's understanding of reason as self-grounding and self-generating. Building on this work, our claim is that Kant appealed to not just any epigenetic theory, but specifically Johann Friedrich Blumenbach's account of generation, and that this appeal must be understood not only in terms of self-organization, but also in terms of the demarcation of a specific domain of inquiry: for Blumenbach, the study of life; for Kant, the study of reason. We argue that Kant adopted this specific epigenetic model as a result of his dispute with Herder regarding the independence of reason from nature. Blumenbach's conception of epigenesis and his separation of a domain of the living from the non-living lent Kant the tools to demarcate metaphysics, and to guard reason against Herder's attempts to naturalize it. PMID:27474190
Mercado-Salas, Nancy F.; Suárez-Morales, Eduardo
2014-01-01
Abstract The freshwater copepod genus Eucyclops contains many supposedly cosmopolitan species whose taxonomic status is still under discussion; some of them represent species complexes. The problem is not exclusive to these widespread species; there are several American Eucyclops needing a taxonomic re-evaluation. Based on the examination of Friedrich Kiefer’s collection in Karlsruhe, Germany, the type specimens of four American species of Eucyclops (E. delachauxi (Kiefer, 1926), E. prionophorus Kiefer, 1931, E. bondi Kiefer, 1934, E. leptacanthus Kiefer, 1956) were re-examined and redescribed using upgraded descriptive standards. Kiefer’s translated descriptions and unpublished original drawings of these species are also presented. Characters like the ornamentation of the antennal basis, ornamentation of intercoxal sclerites of the swimming legs 1–4, length of basipodal seta of leg 1, ornamentation of caudal rami, the presence of aesthetascs and modified setae on the antennules in male, and the structure of the male sixth leg are compared herein to aid a more accurate separation of these American species. A revision of the American records of these species confirms that some are likely to refer to undescribed species. Overall, the diversity of the American Eucyclops appears to be underestimated and certainly deserves further study. PMID:24843261
On Accuracy of Adaptive Grid Methods for Captured Shocks
NASA Technical Reports Server (NTRS)
Yamaleev, Nail K.; Carpenter, Mark H.
2002-01-01
The accuracy of two grid adaptation strategies, grid redistribution and local grid refinement, is examined by solving the 2-D Euler equations for the supersonic steady flow around a cylinder. Second- and fourth-order linear finite difference shock-capturing schemes, based on the Lax-Friedrichs flux splitting, are used to discretize the governing equations. The grid refinement study shows that for the second-order scheme, neither grid adaptation strategy improves the numerical solution accuracy compared to that calculated on a uniform grid with the same number of grid points. For the fourth-order scheme, the dominant first-order error component is reduced by the grid adaptation, while the design-order error component drastically increases because of the grid nonuniformity. As a result, both grid adaptation techniques improve the numerical solution accuracy only on the coarsest mesh or on very fine grids that are seldom found in practical applications because of the computational cost involved. Similar error behavior has been obtained for the pressure integral across the shock. A simple analysis shows that both grid adaptation strategies are not without penalties in the numerical solution accuracy. Based on these results, a new grid adaptation criterion for captured shocks is proposed.
From fire in the belly to a boiling heart: fuel for participatory research.
Hijane, Karima; Heyman, Carly; Bell, Maureen; Busby, Mary Beth
2008-01-01
It has been said that governmental bureaucracies lack the animating life force that is normally provided by the human conscience. Research efforts that include patients and their representatives in the planning and regulatory process can add back this animating life force, a force Friedrich Wilhelm Nietzsche describes "... that your self be in your deed as the mother is in her child-let that be your word concerning virtue." This paper comprises our invited introductory remarks as patient activists at this symposium, entitled "The Menstrual Cycle and Adolescent Health" and held in Potomac, Maryland in mid October 2007. Attendees included patients, patient advocates, and experts from a variety of fields and disciplines. While our stories have their share of pain, that pain developed into a passion to help others in similar circumstances. A consortium of passionate community activists interested in the menstrual cycle could play the role as a "governmental conscience" around this issue. Developing a community consortium initiated via partnerships between patient advocates and investigators could direct more attention and funding toward menstrual cycle research. PMID:18574202
Effect of gaseous void on bipolar charge transport in layered polymer film
NASA Astrophysics Data System (ADS)
Lean, Meng H.; Chu, Wei-Ping L.
2014-02-01
This paper describes a hybrid algorithm to study the effect of a gaseous void on bipolar charge transport in layered polymer film. This hybrid algorithm uses a source distribution technique based on an axisymmetric boundary integral equation method to solve the Poisson equation and a fourth order Runge-Kutta (RK4) method with an upwind scheme for time integration. Iterative stability is assured by satisfying the Courant-Friedrichs-Levy stability criterion. Dynamic charge mapping is achieved by allowing conducting and insulating boundaries and material interfaces to be represented by equivalent free and bound charge distributions that collectively satisfy all local and far-field conditions. This hybrid technique caters to bipolar charge injection, field-dependent mobility transport, recombination, and trapping/de-trapping in the bulk and at material and physical interfaces. The resulting charge map is the taxonomy of the different charge types and their abundance, and presents a dynamic view of the temporal and spatial distributions. The paper is motivated by images of breakdown experiments that point to the role of gaseous void in delamination growth. For the test configuration, the high field at the edge of the gaseous void act as a sink first for positive and then negative charge. The net effect is to increase delamination stress at the edge leading to further growth of the defect and increasing the potential for partial discharge within the void.
Simulation of bipolar charge transport in nanocomposite polymer films
NASA Astrophysics Data System (ADS)
Lean, Meng H.; Chu, Wei-Ping L.
2015-03-01
This paper describes 3D particle-in-cell simulation of bipolar charge injection and transport through nanocomposite film comprised of ferroelectric ceramic nanofillers in an amorphous polymer matrix. The classical electrical double layer (EDL) model for a monopolar core is extended (eEDL) to represent the nanofiller by replacing it with a dipolar core. Charge injection at the electrodes assumes metal-polymer Schottky emission at low to moderate fields and Fowler-Nordheim tunneling at high fields. Injected particles migrate via field-dependent Poole-Frenkel mobility and recombine with Monte Carlo selection. The simulation algorithm uses a boundary integral equation method for solution of the Poisson equation coupled with a second-order predictor-corrector scheme for robust time integration of the equations of motion. The stability criterion of the explicit algorithm conforms to the Courant-Friedrichs-Levy limit assuring robust and rapid convergence. The model is capable of simulating a wide dynamic range spanning leakage current to pre-breakdown. Simulation results for BaTiO3 nanofiller in amorphous polymer matrix indicate that charge transport behavior depend on nanoparticle polarization with anti-parallel orientation showing the highest leakage conduction and therefore lowest level of charge trapping in the interaction zone. Charge recombination is also highest, at the cost of reduced leakage conduction charge. The eEDL model predicts the meandering pathways of charge particle trajectories.
Early American Strabismus Surgery: 1840-1845.
Currie, Benjamin D; Feibel, Robert M
2015-01-01
The discovery of effective surgical therapy for strabismus was one of the outstanding triumphs of the first half of 19th-century ophthalmology, just prior to the invention of the ophthalmoscope in 1850. Although priority for the development of strabismus surgery belongs to Johann Friedrich Dieffenbach of Germany, who first reported his surgical results in 1839, 4 cases of tenotomy of the medial rectus muscle had been performed in the United States by William Gibson in 1818 but never published. By 1840, the reports of surgery in Europe had rapidly spread to America where surgeons immediately began using these procedures. The first American surgeon to perform eye muscle surgery and publish his results was John Dix of Boston, and other surgeons were soon reporting their cases as well. We discuss 8 American pioneers in this field during the time (1840-1845) of the first burst of enthusiasm for this surgery. Although these surgeons were active in performing a large number of cases and carefully reporting their experiences and results, they did not make any major advances in the field. PMID:26669424
Interface-capturing lattice Boltzmann equation model for two-phase flows
NASA Astrophysics Data System (ADS)
Lou, Qin; Guo, Zhaoli
2015-01-01
In this work, an interface-capturing lattice Boltzmann equation (LBE) model is proposed for two-phase flows. In the model, a Lax-Wendroff propagation scheme and a properly chosen equilibrium distribution function are employed. The Lax-Wendroff scheme is used to provide an adjustable Courant-Friedrichs-Lewy (CFL) number, and the equilibrium distribution is presented to remove the dependence of the relaxation time on the CFL number. As a result, the interface can be captured accurately by decreasing the CFL number. A theoretical expression is derived for the chemical potential gradient by solving the LBE directly for a two-phase system with a flat interface. The result shows that the gradient of the chemical potential is proportional to the square of the CFL number, which explains why the proposed model is able to capture the interface naturally with a small CFL number, and why large interface error exists in the standard LBE model. Numerical tests, including a one-dimensional flat interface problem, a two-dimensional circular droplet problem, and a three-dimensional spherical droplet problem, demonstrate that the proposed LBE model performs well and can capture a sharp interface with a suitable CFL number.
Direct calculations of waves in fluid flows using high-order compact difference scheme
NASA Technical Reports Server (NTRS)
Yu, Sheng-Tao; Hultgren, Lennart S.; Liu, Nan-Suey
1994-01-01
The solution of the unsteady Euler equations by a sixth-order compact difference scheme combined with a fourth-order Runge-Kutta method is investigated. Closed-form expression for the amplification factors and their corresponding dispersion correlations are obtained by Fourier analysis of the fully discretized, two-dimensional Euler equations. The numerical dissipation, dispersion, and anisotropic effects are assessed. It is found that the Courant-Friedrichs-Lewy (CFL) limit for stable calculations is about 0.8. For a CFL number equal to 0.6, the smallest wavelength which is resolved without numerical damping is about six - eight grid nodes. For phase speeds corresponding to acoustic waves, the corresponding time period is resolved by about 200 - 300 time steps. Three numerical examples of waves in compressible flow are included: (1) sound propagation in a duct with linear shear, (2) linear wave growth in a compressible free shear layer, and (3) vortex pairing in a compressible free shear layer perturbed at two frequencies.
A marching in space and time (MAST) solver of the shallow water equations. Part II: The 2D model
NASA Astrophysics Data System (ADS)
Aricò, C.; Nasello, C.; Tucciarelli, T.
2007-05-01
A novel methodology for the solution of the 2D shallow water equations is proposed. The algorithm is based on a fractional step decomposition of the original system in (1) a convective prediction, (2) a convective correction, and (3) a diffusive correction step. The convective components are solved using a Marching in Space and Time (MAST) procedure, that solves a sequence of small ODEs systems, one for each computational cell, ordered according to the cell value of a scalar approximated potential. The scalar potential is sought after computing first the minimum of a functional via the solution of a large linear system and then refining locally the optimum search. Model results are compared with the experimental data of two laboratory tests and with the results of other simulations carried out for the same tests by different authors. A comparison with the analytical solution of the oblique jump test has been also considered. Numerical results of the proposed scheme are in good agreement with measured data, as well as with analytical and higher order approximation methods results. The growth of the CPU time versus the cell number is investigated successively refining the elements of an initially coarse mesh. The CPU specific time, per element and per time step, is found out to be almost constant and no evidence of Courant-Friedrichs-Levi (CFL) number limitation has been detected in all the numerical experiments.
Modeling Relativistic Jets Using the Athena Hydrodynamics Code
NASA Astrophysics Data System (ADS)
Pauls, David; Pollack, Maxwell; Wiita, Paul
2014-11-01
We used the Athena hydrodynamics code (Beckwith & Stone 2011) to model early-stage two-dimensional relativistic jets as approximations to the growth of radio-loud active galactic nuclei. We analyzed variability of the radio emission by calculating fluxes from a vertical strip of zones behind a standing shock, as discussed in the accompanying poster. We found the advance speed of the jet bow shock for various input jet velocities and jet-to-ambient density ratios. Faster jets and higher jet densities produce faster shock advances. We investigated the effects of parameters such as the Courant-Friedrichs-Lewy number, the input jet velocity, and the density ratio on the stability of the simulated jet, finding that numerical instabilities grow rapidly when the CFL number is above 0.1. We found that greater jet input velocities and higher density ratios lengthen the time the jet remains stable. We also examined the effects of the boundary conditions, the CFL number, the input jet velocity, the grid resolution, and the density ratio on the premature termination of Athena code. We found that a grid of 1200 by 1000 zones allows the code to run with minimal errors, while still maintaining an adequate resolution. This work is supported by the Mentored Undergraduate Summer Experience program at TCNJ.
THE NEOLIBERAL TURN IN AMERICAN HEALTH CARE.
Gaffney, Adam
2015-01-01
Leaving millions both uninsured and underinsured, the Affordable Care Act does not create a system of universal health care in the United States. To understand its shortcomings, we have to understand it as part of a historic shift in the political economy of American health care. This "neoliberal turn" began as a reaction against the welfare state as it expanded during the New Deal and post-World War II period. What began as a movement associated with philosophers like Friedrich Hayek ultimately had a powerful impact via the attraction of powerful corporate sponsors and political supporters, and it was to historically transform American health care thought and organization. In health policy circles, for example, it can be seen in a rising emphasis on "moral hazard," overuse, and cost sharing above a concern with universalism and equity. It was likewise manifested by the corporatization of the health maintenance organization and the rise of the "consumer-driven" health care movement. By the time of the health care reform debate, the influence of corporate "stakeholders" was to prove predominant. These developments, however, must be construed as connected parts of a much larger political transformation, reflected in rising inequality and privatization, occurring both domestically and internationally. PMID:26460446
NASA Astrophysics Data System (ADS)
von Berlepsch, R.; Strassmeier, K. G.
2009-06-01
We present facsimiles of some of the scientifically and historically most relevant papers published in Astronomische Nachrichten/Astronomical Notes (AN) between 1821 and 1938. Almost all of these papers were written and printed in German and it is sometimes not completely straightforward to find these original works and then to cite the historically correct version, e.g. in case of a series of articles or editorial letters. It was common during the early years that many contributions were made in form of letters to the editor. We present a summary for these original works with an English translation of their titles. Among the highlights are the originals of the discovery of stellar parallaxes by Friedrich Wilhelm Bessel, the discovery of the solar cycle by Heinrich Schwabe, the discovery of the planet Neptune by Johann Gottfried Galle, the first ever measured stellar radial velocity by Hermann Vogel, the discovery of radio emission from the Sun by Wilsing and Scheiner, the first ever conducted photoelectric photometry of stars by Paul Guthnick and up to the pioneering work by Karl Schwarzschild, Ejnar Hertzsprung, Erwin Finlay Freundlich and others. As a particular gimmick we present the still world record holding shortest paper ever published; by Johannes Hartmann in AN 226, 63 (1926) on Nova Pictoris. Our focus is on contributions in the early years and published until 1938 near the verge of the second world war.
Direct Replacement of Arbitrary Grid-Overlapping by Non-Structured Grid
NASA Technical Reports Server (NTRS)
Kao, Kai-Hsiung; Liou, Meng-Sing
1994-01-01
A new approach that uses nonstructured mesh to replace the arbitrarily overlapped structured regions of embedded grids is presented. The present methodology uses the Chimera composite overlapping mesh system so that the physical domain of the flowfield is subdivided into regions which can accommodate easily-generated grid for complex configuration. In addition, a Delaunay triangulation technique generates nonstructured triangular mesh which wraps over the interconnecting region of embedded grids. It is designed that the present approach, termed DRAGON grid, has three important advantages: eliminating some difficulties of the Chimera scheme, such as the orphan points and/or bad quality of interpolation stencils; making grid communication in a fully conservative way; and implementation into three dimensions is straightforward. A computer code based on a time accurate, finite volume, high resolution scheme for solving the compressible Navier-Stokes equations has been further developed to include both the Chimera overset grid and the nonstructured mesh schemes. For steady state problems, the local time stepping accelerates convergence based on a Courant - Friedrichs - Leury (CFL) number near the local stability limit. Numerical tests on representative steady and unsteady supersonic inviscid flows with strong shock waves are demonstrated.
The Rot-Div System in Exterior Domains
NASA Astrophysics Data System (ADS)
Mucha, Piotr B.; Pokorný, Milan
2014-08-01
The goal of this paper is to reconsider the classical elliptic system rot v = f, div v = g in simply connected domains with bounded connected boundaries (bounded and exterior sets). The main result shows solvability of the problem in the maximal regularity regime in the L p -framework taking into account the optimal/minimal requirements on the smoothness of the boundary. A generalization for the Besov spaces is studied, too, for {{f} in dot B^s_{p,q}(Ω)} for {-1+frac 1p < s < frac 1p} . As a limit case we prove the result for {{f} in dot B^0_{3,1}(Ω)} , provided the boundary is merely in {B^{2-1/3}_{3,1}} . The dimension three is distinguished due to the physical interpretation of the system. In other words we revised and extended the classical results of Friedrichs (Commun Pure Appl Math 8;551-590, 1955) and Solonnikov (Zap Nauch Sem LOMI 21:112-158, 1971).
Schiltz, L; Maugendre, M; Brytek-Matera, A
2010-01-01
Questing one's personal identity and developing a coherent representation of oneself, the other and the world are major tasks in adolescence. Research showed that a satisfactory resolution of the crisis of adolescence can be favoured by psychological counselling based on artistic mediations. The objective of this study consisted in exploring the effect of music on the pictorial expression of a non clinical sample of female adolescents (N=157) aged from 17 to 28 years. We analysed free drawings realised by the test group with the help of a rating scale constructed in a phenomenological and structural perspective (Schiltz, 2006). The adolescents painted under musical induction. We proposed three different styles of music, i.e. baroque music (Georg Friedrich Händel and Johann Sebastian Bach), classical music (Wolfgang Amadeus Mozart and Ludwig van Beethoven) and polish ethnical music (Kapela ze Wsi Warszawa-Warsaw Village Band). By using non parametric inferential and multi dimensional statistics, we could show that structural characteristics of music styles lead to differences in formal and content variables on the rating scales for the pictures. The results of our exploratory study open some tracks for future research. It would be pertinent to enlarge the population to other categories of age and to investigate the influence of gender. PMID:20653187
The Kaiser's cancer revisited: was Virchow totally wrong?
Cardesa, Antonio; Zidar, Nina; Alos, Llucia; Nadal, Alfons; Gale, Nina; Klöppel, Günter
2011-06-01
On 15 June 1888, the German Emperor, Kaiser Friedrich III, died of laryngeal cancer. Three biopsies of his laryngeal lesion had been taken by the British laryngologist, Morel Mackenzie, in 1887 and diagnosed by Rudolf Virchow as "pachydermia verrucosa laryngis", confirming Mackenzie's assessment that the Kaiser's disease was benign. A fourth specimen coughed up by the patient was considered by Virchow to be nondiagnostic. A further specimen expectorated by the patient 3 months before his death was diagnosed as carcinoma by Wilhelm Waldeyer. The autopsy revealed squamous carcinoma in the larynx with a cervical lymph node metastasis. The discrepancies between the initial diagnoses and the final outcome of the Kaiser's disease gave rise to a never-ending medical controversy. Our investigations on this historical case were limited to the official German documents and publications and their English translations and to subsequent literature sources of the time, after having received confirmation that the histological slides and Virchow's original reports had been lost. Based on current surgical pathology knowledge, we propose that the tumour that challenged the diagnostic skills of the founder of pathology was hybrid verrucous carcinoma (HVC), an extremely rare, metastasizing variant of verrucous carcinoma (VC) composed of pure VC mixed with clusters of conventional squamous cell carcinoma. As we see it now, Virchow was therefore not totally wrong. Our retrospective evaluation suggests that Virchow's detailed description of the Kaiser's cancer preceded the paper that contributed to the full understanding of HVC of the larynx by 110 years. PMID:21494762
Mörgeli, C
1992-05-26
The death by violence of the scientist and statesman Johannes Hegetschweiler (1789-1839), M.D., constituted a double tragedy: just previously, at the instigation of his friends, he had withdrawn an already submitted petition to be relieved of all his public functions. And from the outset he declared himself an opponent to the appointment of the theologian Friedrich David Strauss to the Zurich Professorship for Dogmatics, an appointment leading to political unrest ('Züriputsch'). On September 6, 1839, Hegetschweiler dashed, as a member of the Cantonal Government, between the militia of the Government and the advancing insurrectionists with instructions to effect a cease-fire. While doing so, he was wounded in the head by a deliberately aimed discharge of a shot, succumbing after three days of suffering. The general turbulence occasioned by the Züriputsch, the unprecedented animosity among the political misdemeanors and felonies rendered any legal prosecution impossible. It is here proven that one of the insurrectionists from the Zurich Oberland is the only person who can be considered as the murderer of Hegetschweiler. PMID:1604083
Schloegel, Judy Johns; Schmidgen, Henning
2002-12-01
This essay aims to shed new light on the relations between physiology and psychology in the late nineteenth and early twentieth centuries by focusing on the use of unicellular organisms as research objects during that period. Within the frameworks of evolutionism and monism advocated by Ernst Haeckel, protozoa were perceived as objects situated at the borders between organism and cell and individual and society. Scholars such as Max Verworn, Alfred Binet, and Herbert Spencer Jennings were provoked by these organisms to undertake experimental investigations situated between general physiology and psychology that differed from the physiological psychology advocated by Wilhelm Wundt. Some of these investigations sought to locate psychological properties in the molecular structure of protoplasm; others stressed the existence of organic and psychological individuality in protozoa. In the following decades, leading philosophers such as Friedrich Nietzsche, Charles Sanders Peirce, and Henri Bergson, as well as psychological researchers like Sigmund Freud, integrated the results of these investigations into their reflections on such problems as the nature of the will, the structure of the ego, and the holistic nature of the reactions of organisms to their environment. PMID:12664793
FIRST REPORTS OF CLINICAL PHARMACOKINETICS IN NIGERIA.
Michael, O S
2015-06-01
The German Friedrich Hartmut Dost (1910-1985) introduced the word Pharmacokinetics. Clinical pharmacokinetics is the direct application of knowledge regarding a drug's pharmacokinetics to a therapeutic situation in an individual or a population. It is the basis of therapeutic drug monitoring with the ultimate goal of keeping drugs safe. This branch of pharmacology has become the most relevant to the sub-specialty of clinical pharmacology. First reports of Clinical Pharmacokinetics in Nigeria can be credited to two gifted Nigerians, Prof Ayodele O. Iyun and Prof Lateef A. Salako, both of whom were affiliated to the great institutions- University of Ibadan (UI) and the Teaching Hospital, University College Hospital (UCH). Prof A.O Iyun was Nigeria's first home-trained Clinical Pharmacologist, while Prof L.A. Salako played a most significant role in the creation of the Department of Clinical Pharmacology, UCH. This edition of the Chronicles highlights a few of the first reports of this exciting branch of pharmacology in Nigeria. This historical review is based on publications listed on the United States National Library of Medicine database (PUBMED). PMID:26807087
Burger, Pascal H.; Scholz, Michael
2014-01-01
Theories on learning styles and types have been integral to discussions on the basics of teaching for nearly 40 years. The learning style typology of Kolb divides learners into four groups (Diverger, Assimilator, Converger and Accomodator), which differ both in terms of their learning behaviour as well as personality and preferences. We studied the sense of coherence and burnout symptoms in medical students of the preclinical semesters (1st to 4th semester) at the Friedrich-Alexander University of Erlangen within the context of the observed learning styles. A total of 530 students were interviewed in winter semester 2012/13 using standardized psychometric questionnaires. Our students showed a significant correlation between the respective learning styles and expression of a sense of coherence, as well as cognitive and emotional burnout symptoms. The learning styles of the students differed significantly within these same parameters. We also demonstrated that learning styles and types not only influence study performance, but that there are also relationships to sense of coherence and psychological ailments. A more forward-looking integration of the theory of learning types in the medical education curriculum could positively influence both the performance and psychological well-being of the students. PMID:25489342
[Relationship between Copenhagen and Göttingen regarding earth magnetism].
Reich, Karin
2013-01-01
Hans Christian Oersted is mostly known as the discoverer of electromagnetism and for being one of the physicists who were deeply influenced and fascinated by the romantic natural philosophy. In this article another side of Oersted is presented. What is underestimated until now is Oersted's contribution to the research of geomagnetism. Oersted stood in close contact with Carl Friedrich Gauss and Wilhelm Weber, whom he visited in 1834 in Göttingen. Oersted's aim was to learn the new developments in geomagnetism. Afterwards he was crucial in the building of a new magnetic observatory in Copenhagen as well as a second one with better equipment. Oersted formed a huge team for magnetic observations and the gathered data were sent to Gauss and Weber who published them. The correspondence between Oersted, Gauss and Weber was mostly dedicated to the transmission of these data, details about instruments and the best way of building a magnetic observatory. Unfortunately, Gauss and Weber had to stop their very successful collaboration in 1843, because Weber belonged to the Göttingen Seven and later on Oersted stopped his observations, because he had lost his partners in this research project. PMID:24195332
Quantum enhancement of vibrational predissociation near the dissociation threshold
Cote, R.; Dashevskaya, E.I.; Nikitin, E.E.; Troe, J.
2004-01-01
We discuss quantum enhancement of the quasiclassical vibrational predissociation (VP) rate of an atom (A)-diatom (BC) van der Waals (vdW) complex A-BC from a state lying close to the dissociation threshold. The enhancement is due to the accumulation of a noticeable fraction of the state population near the outer turning point of the A-BC bond. For potentials behaving as power-laws at large separations, the enhancement manifests itself in the variation of the energy dependence of the VP frequency factor from the classical frequency to its quantum counterpart. We show that it is related to the complex scattering length associated with the vibrational relaxation of BC in collisions with A. We also discuss the corrected quasiclassical quantization condition for energy levels of a diatom lying very close to the dissociation threshold. Our results generalize those of J. Trost, C. Eltshka, and H. Friedrich [J. Phys. B 31, 361 (1998)] and C. Boisseau et al. [Eur. Phys. J. D 12, 199 (2000)] for the calculation of complex energy levels of an anharmonic oscillator that dissociates from highly excited states under the action of a weak high-frequency perturbation.
NASA Technical Reports Server (NTRS)
Schmid, L. A.
1977-01-01
The first and second variations are calculated for the irreducible form of Hamilton's Principle that involves the minimum number of dependent variables necessary to describe the kinetmatics and thermodynamics of inviscid, compressible, baroclinic flow in a specified gravitational field. The form of the second variation shows that, in the neighborhood of a stationary point that corresponds to physically stable flow, the action integral is a complex saddle surface in parameter space. There exists a form of Hamilton's Principle for which a direct solution of a flow problem is possible. This second form is related to the first by a Friedrichs transformation of the thermodynamic variables. This introduces an extra dependent variable, but the first and second variations are shown to have direct physical significance, namely they are equal to the free energy of fluctuations about the equilibrium flow that satisfies the equations of motion. If this equilibrium flow is physically stable, and if a very weak second order integral constraint on the correlation between the fluctuations of otherwise independent variables is satisfied, then the second variation of the action integral for this free energy form of Hamilton's Principle is positive-definite, so the action integral is a minimum, and can serve as the basis for a direct trail and error solution. The second order integral constraint states that the unavailable energy must be maximum at equilibrium, i.e. the fluctuations must be so correlated as to produce a second order decrease in the total unavailable energy.
["Fabulous things". Drug narratives about coca and cocaine in the 19th century].
Wahrig, Bettina
2009-12-01
This contribution focuses on the history of Coca leaves and Cocaine in the second half of 19th century Europe. Even though, to date, no direct link has been established between the activities of the Milano physician Paolo Mantegazza, and the Göttingen chemist Friedrich Wöhler, it is not a mere coincidence that both published their findings in the same year, namely, 1859. Mantegazza authored the first treatise claiming that Coca had psychoactive qualities and touted its broad therapeutic faculties; he claimed that it should be introduced into European pharmacotherapy. In Wöhler's laboratory, cocaine was isolated from leaves by his pupil Alfred Niemann; later, Wilhelm Lossen refined and corrected Niemann's results. Narratives about medicinal drugs often streamline history into a story that starts with multiple meanings and impure matters and ends with well-defined substances, directed at clear-cut diseases and symptoms. In the case of Coca, however, the pure substance triggered no such process well into the 1880s, whereas the leaves continued to circulate as an exotic, pluripotent drug whose effects where miraculous and yet difficult to establish. PMID:20481059
Pharmacodynamic principles of homeopathy.
Widakowich, J
2000-05-01
Homeopathy was already known to Hippocrates and further studied by Hahnemann. However, since the discovery of the medical effects of digitalis by William Withering around 1785, and the first synthesis of an organic molecule, urea, by Friedrich Wöhler in 1828, and through the further rapid evolution of modern pharmacological chemistry and molecular biology, it has gradually been abandoned as a serious therapeutic alternative to allopathy by most practitioners of scientifically founded medicine. Because a credible scientific explanation for its mode of action has been lacking, homeopathy is regarded by many medical researchers and scientists as, at best, placebo therapy, in spite of the fact that for centuries hosts of patients have testified to its effects. It is suggested that the gulf between homeopathy and allopathy can be reconciled if one takes into consideration modern knowledge of physiology, biochemistry and the physical properties of the water used in the potentiation process. A description of the mechanisms occurring during potentiation, both inside and outside a live mammalian organism, is presented. PMID:10859675
Simmer, H H
1981-07-01
Eugen Franz Freiherr von Gorup-Besanez, born 1817 in Graz, was appointed on 28. 11. 1846 to the post of lecturer in the faculty of medicine of the University of Erlangen. He had previously studied medicine in Vienna, Padua and Munich, followed by physiological and clinical-chemical studies under Louis Andreas Buchner in Munich, and further studies in organic and analytical chemistry under Friedrich Wöhler in Göttingen. In 1849 in Erlangen he became reader in organic and analytical chemistry, then, in 1855, moved to the faculty of philosophy as professor of chemistry. Von Gorup-Besanez was one of the early representatives of clinical chemistry in Germany. He tried to help clinicians by the analysis of urine, blood and tissues. In his lectures and through his books he was an outstanding teacher. His greatest contribution was the discovery of the amino acid valine. The lack of a laboratory in the medical faculty and his dissatisfaction with what could be achieved in clinical chemistry at that time may chiefly explain his move from the medical to the philosophical faculty. The life of von Gorup-Besanez illustrates the difficulties faced by clinical chemistry and its exponents in the middle of the 19th century. PMID:7035607
Takahashi, Hiroyuki R.; Ohsuga, Ken
2013-08-01
We develop a numerical scheme for solving fully special relativistic, resistive radiation magnetohydrodynamics. Our code guarantees conservation of total mass, momentum, and energy. The radiation energy density and the radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation field, in contrast to the Eddington approximation, as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly the Harten-Lax-van Leer scheme; the HLLC and HLLD schemes are also solved for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in an optically thick regime or a large magnetic Reynolds number regime. Although we need to invert 4 Multiplication-Sign 4 matrices (for the gas-radiation interaction) and 3 Multiplication-Sign 3 matrices (for the magnetic energy dissipation) at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek-type magnetic reconnection, revealing the reduction of the reconnection rate via radiation drag.
Alexandr Oparin and the origin of life on Earth.
Pennazio, Sergio
2009-01-01
In the long essay here examined, the Soviet biochemist A. Oparin elaborated and proposed in a coherent and exhaustive way the three main historical phases characterising the origin of life on Earth from an entirely inorganic environment: i) formation of simple organic molecules; ii) appearance of macromolecules interacting with an aqueous substrate so as to form primitively organised microstructures; iii) constitution of metabolically active protocells working as thermodynamically open system. On the whole, Oparin described a biochemical adventure marked by chemico-physics and natural selection, this latter working on microstructure. Oparin worked according to the canons of dialectic materialism applied to Nature by Friedrich Engels and did not give anything to divine and fantastic. He treated all questions biochemically and neglected Morgan's genetics: mitosis, chromosomes and genes were for Oparin conceptual, and then questionable, elements that he set up against the firm bases of biochemico-physics. In such context, proteins and enzymes were the dominant substances of life owing to their manifold activities. Oparin's book was translated into about fifty languages and was a decisive factor for the successive development of detailed experimental research. Even though dated, this book still shows interesting topics on which the specialists are working at the best of the current technology. PMID:19718625
Relativistic Flows Using Spatial And Temporal Adaptive Structured Mesh Refinement. I. Hydrodynamics
Wang, Peng; Abel, Tom; Zhang, Weiqun; /KIPAC, Menlo Park
2007-04-02
Astrophysical relativistic flow problems require high resolution three-dimensional numerical simulations. In this paper, we describe a new parallel three-dimensional code for simulations of special relativistic hydrodynamics (SRHD) using both spatially and temporally structured adaptive mesh refinement (AMR). We used method of lines to discrete SRHD equations spatially and used a total variation diminishing (TVD) Runge-Kutta scheme for time integration. For spatial reconstruction, we have implemented piecewise linear method (PLM), piecewise parabolic method (PPM), third order convex essentially non-oscillatory (CENO) and third and fifth order weighted essentially non-oscillatory (WENO) schemes. Flux is computed using either direct flux reconstruction or approximate Riemann solvers including HLL, modified Marquina flux, local Lax-Friedrichs flux formulas and HLLC. The AMR part of the code is built on top of the cosmological Eulerian AMR code enzo, which uses the Berger-Colella AMR algorithm and is parallel with dynamical load balancing using the widely available Message Passing Interface library. We discuss the coupling of the AMR framework with the relativistic solvers and show its performance on eleven test problems.
Geodetic documents in the Gotha library
NASA Astrophysics Data System (ADS)
Hopf, Cornelia; Schwarz, Oliver
Until 1800, there existed only rough maps in the dukedoms Gotha-Altenburg and Weimar based on a net of geographical positions measured by simple instruments. After Franz Xaver von Zach had made his first astronomical observations to determine geographical coordinates he realised that these old maps had an accuracy of at best some minutes of arc. The king of Prussia, Friedrich Wilhelm III (1797-1840), asked Zach in October 1802 to accept the direction of the measurement of the territories around Erfurt and the Eichsfeld. In this situation it was obvious for Zach to consider a survey of Thuringia and a great measurement of degree similar to the French model. His ideas were promoted by the duke of Sachsen-Gotha-Altenburg, Ernst II (1772-1804). Zach planned to perform his survey in four degrees of latitude and six degrees of longitude with respect to the Seeberg observatory. The measurements had to cross over the borderlines of several countries. The documents in the Forschungs- and Landesbibliothek prove that the diplomatic preparations for the survey got on until the end of 1803. Zach obtained passports and grants to pass and to survey some territories (Hessen-Kassel, Hannover, Coburg-Saalfeld, Braunschweig, Sachsen). Their governments had exchanged diplomatic notes on this topic. The death of Ernst II in 1804, the consequences of the war (battle of Jena and Auerstedt in 1806) and Zach's resignation as director of the Seeberg observatory led to the end of the survey.
Differential longitudes in Thuringia
NASA Astrophysics Data System (ADS)
Schwarz, Oliver; Conrad, Wolfgang
Zach and the Prussian officer Friedrich Carl Ferdinand von Müffling (1775-1851) started a survey in 1803. The first campaign had the target to obtain a net of exactly known geographical places. The latitudes of these places were fixed with solar observations and by the registration of upper and lower culminations of stars. The differences in longitudes between these places and the Seeberg observatory (as exactly known reference point of the survey) were determined with a ``transport'' of local time by powder lightnings. These signals were sent from the mountains Inselsberg, Schneekopf, Hörselberg and Brocken (Harz) especially. We have checked the longitudes measured with the help of powder lightnings. For that purpose we took only such geographical places (in the System 40, Bessel Ellipsoid) into account that agree with Zach's descriptions. The mountain tops in Thuringia are relatively flat. Already for that reason errors of the order of some arcseconds could appear in the comparison between Zach's values and its coordinates in the System 40 (at 51 latitude 1 arc second = 20 m). The differences between Zach's and the modern longitudes are given. The longitude of the Geba mountain is rather inexact. The other values have errors of the order of 2 seconds of time for the more distant stations (Dietrichsberg, Wartburg, Ettersberg) and of the order of 1 second of time for stations near the observatory at Seeberg. Zach himself supposed the error of time to be of the order of one second.
Nietzche's echo--a dialogue with Thomas Altizer.
Moss, David M
2010-03-01
Prophets provoke psychological unrest, especially when exposing accepted beliefs as profound deceptions. The biblical prophets exemplify such confrontation as do certain atheists ardently opposed to the images of God created by those seers. The German philosopher Friedrich Nietzsche dramatically illustrates this type of counterforce to the Judeo-Christian tradition. His prophet Zarathustra is intended to be a model for the modern mind, one free of superstitions inflicted by antiquated religious dogma. Nietzsche's credo "God is dead" served as a declaration for the nineteenth century. In the twentieth century, it became a theological diagnosis. As a "movement," or "tenor," the death of God or radical theology was spearheaded by Thomas Altizer, a well-published young professor center-staged during the turbulent 1960s. His work foreshadows a new strain of atheism currently represented by biologist Richard Dawkins (2006, The God delusion. New York: Houghton Mifflin), philosopher Daniel Dennett (2006, Breaking the spell. New York: Penquin), neuroscientist Sam Harris (2004, The end of faith. New York: W.W. Norton; 2008, Letter to a Christian nation. New York: Vintage), journalist Christopher Hitchens (2007, God is not great. New York: Twelve), and mathematician John Allen Paulos (Paulos 2008, Irreligion. New York: Hill & Wang). This twenty-first century crusade against belief in God is best understood as a psychodynamic ignited by Altizer's Christian atheism. The present dialogue reflects that dynamic while the prologue and epilogue reveal evidence of Providence amidst claims of God's demise in contemporary history. PMID:19399624
The Yang-Mills Heat Semigroup on Three-Manifolds with Boundary
NASA Astrophysics Data System (ADS)
Charalambous, Nelia; Gross, Leonard
2013-02-01
Long time existence and uniqueness of solutions to the Yang-Mills heat equation is proven over a compact 3-manifold with smooth boundary. The initial data is taken to be a Lie algebra valued connection form in the Sobolev space H 1. Three kinds of boundary conditions are explored, Dirichlet type, Neumann type and Marini boundary conditions. The last is a nonlinear boundary condition, specified by setting the normal component of the curvature to zero on the boundary. The Yang-Mills heat equation is a weakly parabolic nonlinear equation. We use gauge symmetry breaking to convert it to a parabolic equation and then gauge transform the solution of the parabolic equation back to a solution of the original equation. Apriori estimates are developed by first establishing a gauge invariant version of the Gaffney-Friedrichs inequality. A gauge invariant regularization procedure for solutions is also established. Uniqueness holds upon imposition of boundary conditions on only two of the three components of the connection form because of weak parabolicity. This work is motivated by possible applications to quantum field theory.
Suffering, justice, and the politics of becoming.
Connolly, W E
1996-09-01
To suffer is to undergo, to bear, to endure. Suffering exists on the underside of agency; it is as important to ethics as agency. The experience of suffering is never entirely captured by the ethical, political, medical and spiritual categories in which it is represented. Perhaps an engagement with suffering can open up hidden connections between these domains. After examining John Caputo and Friedrich Nietzsche comparatively on the relation between suffering and ethics, this essay explores the relation of the "politics of becoming" to suffering. The politics of becoming is a paradoxical process by which a new cultural identity is drawn into being and yet is irreducible to the energies and motives that spurred its initiators to action. To exemplify and think the politics of becoming is to call into question the sufficiency of existing paradigms of morality. A critical examination of the Rawlsian model of justice brings out, for example, the insufficiency of justice to the politics of becoming. It suggests the need, first, to pursue an "ethics of engagement" between several parties drawing upon a variety of sources of ethical inspiration and, second, to cultivate "critical responsiveness" to new social movements that struggle to place new identities onto the cultural register. If the latter movements sometimes modify general understandings of suffering, identity, justice and medical practice they also indicate the role cultural thinkers can play in re-examining periodically established codes of interaction between these domains. PMID:8899281
NASA Astrophysics Data System (ADS)
Takahashi, Hiroyuki R.; Ohsuga, Ken
2013-08-01
We develop a numerical scheme for solving fully special relativistic, resistive radiation magnetohydrodynamics. Our code guarantees conservation of total mass, momentum, and energy. The radiation energy density and the radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation field, in contrast to the Eddington approximation, as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly the Harten-Lax-van Leer scheme; the HLLC and HLLD schemes are also solved for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in an optically thick regime or a large magnetic Reynolds number regime. Although we need to invert 4 × 4 matrices (for the gas-radiation interaction) and 3 × 3 matrices (for the magnetic energy dissipation) at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek-type magnetic reconnection, revealing the reduction of the reconnection rate via radiation drag.
The Semi-implicit Time-stepping Algorithm in MH4D
NASA Astrophysics Data System (ADS)
Vadlamani, Srinath; Shumlak, Uri; Marklin, George; Meier, Eric; Lionello, Roberto
2006-10-01
The Plasma Science and Innovation Center (PSI Center) at the University of Washington is developing MHD codes to accurately model Emerging Concept (EC) devices. Examination of the semi-implicit time stepping algorithm implemented in the tetrahedral mesh MHD simulation code, MH4D, is presented. The time steps for standard explicit methods, which are constrained by the Courant-Friedrichs-Lewy (CFL) condition, are typically small for simulations of EC experiments due to the large Alfven speed. The CFL constraint is more severe with a tetrahedral mesh because of the irregular cell geometry. The semi-implicit algorithm [1] removes the fast waves constraint, thus allowing for larger time steps. We will present the implementation method of this algorithm, and numerical results for test problems in simple geometry. Also, we will present the effectiveness in simulations of complex geometry, similar to the ZaP [2] experiment at the University of Washington. References: [1]Douglas S. Harned and D. D. Schnack, Semi-implicit method for long time scale magnetohy drodynamic computations in three dimensions, JCP, Volume 65, Issue 1, July 1986, Pages 57-70. [2]U. Shumlak, B. A. Nelson, R. P. Golingo, S. L. Jackson, E. A. Crawford, and D. J. Den Hartog, Sheared flow stabilization experiments in the ZaP flow Zpinch, Phys. Plasmas 10, 1683 (2003).
[A matter of methods: the historicity of Koch's postulates 1840-2000].
Gradmann, Christoph
2008-01-01
This paper analyses the historical origins and the popularity of 'Koch's Postulates'. In 1884 Friedrich Löffler wrote down the well-known three steps of isolation, cultivation and inoculation as conditions for establishing the existence of a pathogen. These postulates are frequently invoked in textbooks of medical history. Yet they seem to have had little relevance in medical research. Their assumed inventor, Robert Koch, produced numerous variations in his own methodology. However, underlying his work was a sort of trivial ontology of diseases which rendered an experimental reconstruction of human pathologies in animal models practical and meaningful. There were many ways to pursue this end. Koch usually limited his discussion to practical questions related to the course that investigations had to take, while matters of principle were only treated implicitly in his writings. Löffler's achievement was to popularise Koch's views in his postulates. Given that, it is not surprising that the countless references to Koch's postulates which one finds in the 20th century usually refer to the spirit rather than the literal meaning of the postulates. For example, proponents of virology or molecular medicine devise variations of Koch's postulates that serve to relate their own work to Koch's bacteriology. The latter is perceived as the origin of modern experimental medicine. The nature of such references is less historical than anecdotal: referring to a historical object that did not exist as such, these references produce ex traditione credentials for experimental medicine. PMID:18839931
Two-fluid 2.5D code for simulations of small scale magnetic fields in the lower solar atmosphere
NASA Astrophysics Data System (ADS)
Piantschitsch, Isabell; Amerstorfer, Ute; Thalmann, Julia Katharina; Hanslmeier, Arnold; Lemmerer, Birgit
2015-08-01
Our aim is to investigate magnetic reconnection as a result of the time evolution of magnetic flux tubes in the solar chromosphere. A new numerical two-fluid code was developed, which will perform a 2.5D simulation of the dynamics from the upper convection zone up to the transition region. The code is based on the Total Variation Diminishing Lax-Friedrichs method and includes the effects of ion-neutral collisions, ionisation/recombination, thermal/resistive diffusivity as well as collisional/resistive heating. What is innovative about our newly developed code is the inclusion of a two-fluid model in combination with the use of analytically constructed vertically open magnetic flux tubes, which are used as initial conditions for our simulation. First magnetohydrodynamic (MHD) tests have already shown good agreement with known results of numerical MHD test problems like e.g. the Orszag-Tang vortex test, the Current Sheet test or the Spherical Blast Wave test. Furthermore, the single-fluid approach will also be applied to the initial conditions, in order to compare the different rates of magnetic reconnection in both codes, the two-fluid code and the single-fluid one.
Worldwide Geomagnetic Data Collection and Management
NASA Astrophysics Data System (ADS)
Mandea, Mioara; Papitashvili, Vladimir
2009-11-01
Geomagnetic data provided by different platforms piece together a global picture of Earth's magnetic field and its interaction with geospace. Furthermore, a great diversity of the geomagnetic field changes, from secular (over decades to centuries) to short time variations (down to minutes and seconds), can be detected only through continued observations. An international effort to watch and record geomagnetic changes first began in the 1830s with a network of scientific observers organized by Karl Friedrich Gauss in Germany, and this effort has continued since then. One of the most remarkable achievements in understanding the geomagnetic field morphology and time behavior was made possible by the International Geophysical Year (IGY), an exploration and research effort that lasted for 18 months, starting on 1 July 1957. The IGY encompassed 11 geoscience disciplines, including geomagnetism. The IGY has represented a giant step forward in the quality and quantity of worldwide geomagnetic measurements, as well as in the widespread interest in magnetic measurements. A half century of probing the geomagnetic field spatial and temporal variations has produced a number of outstanding results, and the interested reader can find recent reviews on various geomagnetic field topics (from measurements to modeling) in Encyclopedia of Geomagnetism and Paleomagnetism [Gubbins and Herrero-Bervera, 2007] or Treatise on Geophysics: Geomagnetism [Kono, 2007].
Complete genome sequence of Syntrophobotulus glycolicus type strain (FlGlyRT)
Han, Cliff; Mwirichia, Romano; Chertkov, Olga; Held, Brittany; Lapidus, Alla L.; Nolan, Matt; Lucas, Susan; Hammon, Nancy; Deshpande, Shweta; Cheng, Jan-Fang; Tapia, Roxanne; Goodwin, Lynne A.; Pitluck, Sam; Huntemann, Marcel; Liolios, Konstantinos; Ivanova, N; Pagani, Ioanna; Mavromatis, K; Ovchinnikova, Galina; Pati, Amrita; Chen, Amy; Palaniappan, Krishna; Land, Miriam L; Hauser, Loren John; Brambilla, Evelyne-Marie; Rohde, Manfred; Spring, Stefan; Sikorski, Johannes; Goker, Markus; Woyke, Tanja; Bristow, James; Eisen, Jonathan; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter; Detter, J. Chris
2011-01-01
Syntrophobotulus glycolicus Friedrich et al. 1996 is currently the only member of the genus Syntrophobotulus within the family Peptococcaceae. The species is of interest because of its isolated phylogenetic location in the genome-sequenced fraction of tree of life. When grown in pure culture with glyoxylate as carbon source the organism utilizes glyoxylate through fermentative oxidation, whereas, when grown in syntrophic co-culture with homoacetogenic or methanogenic bacteria, it is able to oxidize glycolate to carbon dioxide and hydrogen. No other organic or inorganic carbon source is utilized by S. glycolicus. The subdivision of the family Peptococcaceae into genera does not reflect the natural relationships, particularly re- garding the genera most closely related to Syntrophobotulus. Both Desulfotomaculum and Pelotomaculum are paraphyletic assemblages, and the taxonomic classification is in signifi- cant conflict with the 16S rRNA data. S. glycolicus is already the ninth member of the family Peptococcaceae with a completely sequenced and publicly available genome. The 3,406,739 bp long genome with its 3,370 protein-coding and 69 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.
[Medical history as an academic subject at the Bamberg University].
Locher, W
2000-01-01
A full program of medicine was taught at the Catholic University of Bamberg (founded 1648 as the Academia Ottonia) from 1773 through 1803. Within this period of time, the History of Medicine was taught from 1790 through 1795 by Johann Baptist Dominicus Fin(c)k. This paper elucidates how in this instance protestant universities served as models for catholic universities. Interestingly, it was not the medical faculty itself which developed an interest in teaching medical history. Rather, it was Adalbert Friedrich Marcus (1753-1816), physician-in-waiting of the Prince-Bishop Franz Ludwig von Erthal and medical officer in the principality of Bamberg since June 22, 1790, who was charged by the Prince-Bishop with developing guidelines for medical education. The start of the History of Medicine lectures brought with it a heated dispute about an appropriate textbook. The discussion is evidence of a transition from historiography understood as an account of learned doctors of the past to a study of history in a modern sense. PMID:11068514
NASA Astrophysics Data System (ADS)
Lanzafame, G.
2013-03-01
Current explicit integration techniques in fluid dynamics are deeply limited by the Courant-Friedrichs-Lewy condition of the time step progression, based on the adopted spatial resolution coupled with the maximum value between the kinetic velocity or the signal transmission speed in the computational domain. Eulerian implicit integration techniques, even though more time consuming, can allow us to perform stable computational fluid dynamics paying the price of a relatively larger inaccuracy in the calculations, without suffering such a strict temporal limitation. In this paper, we present a simple and effective scheme to perform free Lagrangian Smooth Particle Hydrodynamics (SPH) implicit integrations in the semi-Lagrangian approach without any Jacobian matrix inversion operations for viscous Navier-Stokes flows. Applications to SPH accretion disc simulation around a massive black hole (MBH) in a binary stellar system are shown, together with the comparison to the same results obtained according to the traditional explicit integration techniques. Some 1D and 2D critical tests are also discussed to check the validity of the technique.
Demetrowitsch, Tobias J; Petersen, Beate; Keppler, Julia K; Koch, Andreas; Schreiber, Stefan; Laudes, Matthias; Schwarz, Karin
2015-01-01
After his study of food science at the Rheinische Friedrich-Wilhelms University of Bonn, Tobias J Demetrowitsch obtained his doctoral degree in the research field of metabolomics at the Christian-Albrechts-University of Kiel. The present paper is part of his doctoral thesis and describes an extended strategy to evaluate and verify complex or large-scale experiments and data sets. Large-scale studies result in high sample numbers, requiring the analysis of samples in different batches. So far, the verification of such LC-MS-based metabolomics studies is difficult. Common approaches have not provided a reliable validation procedure to date. This article shows a novel verification process for a large-scale human urine study (analyzed by a LC/QToF-MS system) using a two-step validation procedure. The first step comprises a targeted approach that aims to examine and exclude statistical outliers. The second step consists of a principle component analysis, with the aim of a tight cluster of all quality controls and a second for all volunteer samples. The applied study design provides a reliable two-step validation procedure for large-scale studies and additionally contains an inhouse verification procedure. PMID:25558939
Computational techniques for high-speed flows with viscous and chemical effects
NASA Technical Reports Server (NTRS)
Li, C. P.
1993-01-01
Algorithms for solving the Euler and the Navier-Stokes equations in conjunction with chemical kinetic equations are presented. The convective flux is estimated from a quasi one dimensional interpolation procedure. Shock, contact, and expansion waves and thermochemical nonequilibrium phenomena are captured by the Lax-Friedrichs technique. Relaxation techniques were developed to enhance their effectiveness in dealing with spatial and temporal stiffness associated with the physical problems. Both explicit and implicit smoothers were implemented into the standard multigrid time stepping method. Unsteady and steady scalar problems are discussed. A perfect gas and equilibrium air shock tube problem is investigated. Numerical schemes and techniques are compared for the problems of shock and boundary layer interaction and three dimensional viscous, nonequilibrium flow encompassing an aerobrake. The results are comparable in accuracy against other high order non-oscillatory techniques. The multigrid methods are assessed using a Mach 8 flow over a complete planar body, a sphere, and a blunt delta wing at 20 deg incidence. Applying an implicit multigrid method on a nested grid of 128 by 64 nodes the reduction factor is 0.25. The central processing unit reduction factor is 2.2 after both the single and multigrid Runge-Kutta solutions converged to machine zero on a grid of 37 by 41 by 73 nodes.
High-temperature single-crystal neutron diffraction study of natural chondrodite
NASA Astrophysics Data System (ADS)
Kunz, Martin; Lager, George A.; Bürgi, Hans-Beat; Fernandez-Diaz, Maria Teresa
2006-03-01
The H-atom environment in a Tilly Foster chondrodite was analyzed using single-crystal neutron-diffraction data collected at 500, 700 and 900 K and previously published low temperature data collected at 10, 100 and 300 K on the same crystal (Mg4.64Fe0.28Mn0.014Ti0.023(Si1.01O4)2F1.16(OH)0.84; Friedrich et al. in Am Mineral 86:981-989, 2001). The full mean square displacement matrix Σ of the O-H pair was determined from the temperature dependence of the anisotropic displacement parameters, enabling a proper correction of the O-H bond for thermal vibration without assumptions about the correlation of O and H movements. The results show that the perpendicular O-H motions in chondrodite are intermediate between the riding and the independent motion models. The corrected O-H bond lengths do not change with temperature whereas the corrected H···F distances show an increase of ~0.02 Å with temperature, as do the Mg-O distances. This result shows that spectroscopic observations on the strength of the covalent O-H bond cannot be interpreted unambiguously in terms of a corresponding behaviour of the associated H···O/F hydrogen bond.
Quantum Threshold Effects On The Determination Of RKR Potentials
NASA Astrophysics Data System (ADS)
Boisseau, C.; Cote, R.
2000-06-01
In 1970, R.J. LeRoy and R.B. Berstein and independantly W.C. Stwalley (LeR) R.J. LeRoy and R.B. Bernstein, J. Chem. Phys. 52, 3869 (1970). W.C. Stwalley, Chem. Phys. Lett. 6, 241 (1970). used semiclassical JWKB calculations to represent vibrational levels converging toward the dissociation limit by an analytic formula. This formula is well adapted for low lying states of potentials varying asymptotically as -C_n/r^n (n>2), but it is not accurate for the last few levels near the dissociation limit. For these last levels, one needs to include a correction term in the standard JWKB quantization condition (Trost) J. Trost, C. Eltschka and H. Friedrich, J. Phys. B 31, 361 (1998). C. Boisseau, E. Audouard and J. Vigué, Europhys. Lett. 41, 349 (1998). C. Boisseau, E. Audouard, J. Vigué and V.V. Flambaum submitted to Euro. Phys. J. D.. We present an extension of LeRoy, Bernstein and Stwalley formulas, and show how the RKR method can be modified to include the corrected JWKB quantization condition formula. We also illustrate how this modification can be used to extrapolate C_n.
Solution of Time-dependent Hydrodynamic Equations and application in Early Earth's Atmosphere
NASA Astrophysics Data System (ADS)
Tian, F.; Toon, O. B.; Pavlov, A. A.; Sterck, H. D.
2003-12-01
Hydrodynamic escape has important applications in the formation and evolution of planetary atmospheres. Watson et. al. (1981) treated the time-independent hydrodynamic equations by assuming single layer heating and this approach has been followed by researches in this field since then. Solutions to the time-independent hydrodynamic equations are difficult to find due to the existence of a singularity point. In our work, the Lax-Friedrichs scheme is used to solve the 1D time-dependent hydrodynamic equations without the single layer heating approximation. Our results show that variables such as energy input rate at the top of the atmosphere, density and temperature at the homopause have a non-linear impact on the escape flux. In our preliminary calculations, for the same hydrogen mixing ratio near homopause in Earth's atmosphere, hydrodynamic escape flux driven by intense solar EUV heating is much smaller than the diffusion limited escape flux. This escape rate suggests that the huge amount of H2 outgassing from interior of the Earth to compensate the previously assumed large scale escape may not be necessary to support substantial CH4 mixing ratios in the early Earth's atmosphere. FT is supported by the CU Astrobiology Institute.
On the Right Hamiltonian for Singular Perturbations:. General Theory
NASA Astrophysics Data System (ADS)
Neidhardt, Hagen; Zagrebnov, Valentin
Let the pair of self-adjoint operators {A≥0,W≤0} be such that: (a) there is a dense domain { D} subseteqdom (A)∩ dom(W) such that ˙ {H}=(A+W)|{ D} is semibounded from below (stability domain), (b) the symmetric operator ˙ {H} is not essentially self-adjoint (singularity of the perturbation), (c) the Friedrichs extension hat {A} of ˙ {A}=A|{ D} is maximal with respect to W, i.e., dom(√ {-W})∩ ker (˙ {A}*-{η }I)=\\{0\\}. η < 0. Let \\{Wn\\}∞ n=1 be a regularizing sequence of bounded operators which tends in the strong resolvent sense to W. The abstract problem of the right Hamiltonian is: (i) to give conditions such that the limit H of self-adjoint regularized Hamiltonians ˜ {H}n=˜ {A}+W_n exists and is unique for any self-adjoint extension ˜ {A} of ˙ {A}, (ii) to describe the limit H. We show that under the conditions (a)-(c) there is a regularizing sequence \\{Wn\\}∞ n=1 such that ˜ {H}n=˜ {A}+W_n tends in the strong resolvent sense to unique (right Hamiltonian) hat {H}=hat {A}.+W, otherwise the limit is not unique.
Fred's Contributions to Stellar Evolution
NASA Astrophysics Data System (ADS)
Mestel, L.
2003-07-01
Fred began work on stellar structure after Hans Bethe and Carl-Friedrich von Weizsäcker had independently established that the thermonuclear fusion of hydrogen into helium is the primary source of the energy radiated by the Sun and other main sequence stars. A joint paper with Ray Lyttleton included this temperature-sensitive process explicitly in the energy equation, effectively vindicating the essentials of the theory of homogeneous gaseous stars presented in Sir Arthur Eddington's celebrated monograph `The Internal Constitution of the Stars'. Agreement with the solar luminosity can be obtained with two alternative values for the hydrogen content. In a subsequent paper, Fred argued convincingly in favour of the case with a very high rather than a moderate fraction of hydrogen. An epoch-making joint paper with Martin Schwarzschild followed the evolution of a low mass star through nuclear processing, from the main sequence into the giant domain in the Hertzsprung-Russell diagram. The slowly growing, burnt-out core becomes degenerate and nearly isothermal, while the photospheric boundary condition forces the expanding envelope to become largely convective. At the top of the giant branch, the degenerate core becomes hot enough for the fusion of helium into carbon; the consequent secular instability, noted first in studies of white dwarfs, brings the star down to the `horizontal branch', the location of the short-period globular cluster Cepheids. Two subsequent papers with Brian Haselgrove studied in further detail the structure of both main sequence and giant stars.
Implicit Predictor-Corrector finite difference scheme for the ideal MHD simulations
NASA Astrophysics Data System (ADS)
Tsai, T.; Yu, H.; Lai, S.
2012-12-01
A innovative simulation code for ideal magnetohydrodynamics (MHD) is developed. We present a multiple-dimensional MHD code based on high-order implicit predictor-corrector finite difference scheme (high-order IPCFD scheme). High-order IPCFD scheme adopts high-order predictor-corrector scheme for the time integration and high-order central difference method as the spatial derivative solver. We use Elimination-of-the-Runoff-Errors (ERE) technology to avoid the numerical oscillations and numerical instability in the simulation results. In one-dimensional MHD problem, our simulation results show good agreement with the Brio & Wu MHD shock tube problem. The divergent B constraint remains fully satisfied, that is the divergent B equals to zero throughout the simulation. When solving the two-dimensional (2D) linear wave in MHD plasma, we clearly obtain the group-velocity Friedrichs diagrams of the MHD waves. Here we demonstrate 2D simulation results of rotor problem, Orszag-Tang vortex system, vortex type K-H instability, and kink type K-H instability by using our IPCFD MHD code and discuss the advantage of our simulation code.
Time Delay for Dispersive Systems in Quantum Scattering Theory
NASA Astrophysics Data System (ADS)
Tiedra de Aldecoa, Rafael
We consider time delay and symmetrized time delay (defined in terms of sojourn times) for quantum scattering pairs {H0 = h(P), H}, where h(P) is a dispersive operator of hypoelliptic-type. For instance, h(P) can be one of the usual elliptic operators such as the Schrödinger operator h(P) = P2 or the square-root Klein-Gordon operator h(P) = √ {1 + P2}. We show under general conditions that the symmetrized time delay exists for all smooth even localization functions. It is equal to the Eisenbud-Wigner time delay plus a contribution due to the non-radial component of the localization function. If the scattering operator S commutes with some function of the velocity operator ∇h(P), then the time delay also exists and is equal to the symmetrized time delay. As an illustration of our results, we consider the case of a one-dimensional Friedrichs Hamiltonian perturbed by a finite rank potential. Our study puts into evidence an integral formula relating the operator of differentiation with respect to the kinetic energy h(P) to the time evolution of localization operators.
The Hamiltonian (p2 + m2)1/2 - α/r near the critical value αc = 2/pi
NASA Astrophysics Data System (ADS)
Le Yaouanc, A.; Oliver, L.; Raynal, J.-C.
1997-08-01
We elucidate the behavior of the operator (p2+m2)1/2-α/r near the critical value α=αc where it ceases to be bounded below, by obtaining a family H(z) of operators which is self-adjoint holomorphic in a domain including all real z>-√αc-αc', and such that H(√αc-α )(α⩽αc) is just the operator (p2+m2)1/2-α/r or its Friedrich extension, while H(-√αc-α )(αc'<α<αc) is another self-adjoint extension. The operators H(z) (z real) are shown to be positive, and to have only discrete spectrum below m. The eigenvalues are then analytic functions of √αc-α near α=αc (and become the eigenvalues of a non-self-adjoint operator when α>αc). We show that these eigenvalues cannot vanish, but that the lowest eigenvalue of H(-√αc-α ) goes to zero when α→αc'. The L>0 eigenvalues are analytic in α at α=αc.
NASA Astrophysics Data System (ADS)
Wu, S. T.; Zheng, Huinan; Wang, S.; Thompson, B. J.; Plunkett, S. P.; Zhao, X. P.; Dryer, M.
2001-11-01
We investigate the global large amplitude waves propagating across the solar disk as observed by the SOHO/Extreme Ultraviolet Imaging Telescope (EIT). These waves appear to be similar to those observed in Hα in the chromosphere and which are known as ``Moreton waves,'' associated with large solar flares [Moreton, 1960, 1964]. Uchida [1968] interpreted these Moreton waves as the propagation of a hydromagnetics disturbance in the corona with its wavefront intersecting the chromosphere to produce the Moreton wave as observed in movie sequences of Hα images. To search for an understanding of the physical characteristics of these newly observed EIT waves, we constructed a three-dimensional, time-dependent, numerical magnetohydrodynamic (MHD) model. Measured global magnetic fields, obtained from the Wilcox Solar Observatory (WSO) at Stanford University, are used as the initial magnetic field to investigate hydromagnetics wave propagation in a three-dimensional spherical geometry. Using magnetohydrodynamic wave theory together with simulation, we are able to identify these observed EIT waves as fast mode MHD waves dominated by the acoustic mode, called magnetosonic waves. The results to be presented include the following: (1) comparison of observed and simulated morphology projected on the disk and the distance-time curves on the solar disk; (2) three-dimensional evolution of the disturbed magnetic field lines at various viewing angles; (3) evolution of the plasma density profile at a specific location as a function of latitude; and (4) computed Friedrich's diagrams to identify the MHD wave characteristics.
Ab initio many-body calculations of light nuclei neutron and proton scattering
NASA Astrophysics Data System (ADS)
Quaglioni, Sofia
2008-10-01
One of the greatest challenges of nuclear physics today is the development of a quantitative microscopic theory of low-energy reactions on light nuclei. At the same time, technical progress on the theoretical front is urgent to match the major experimental advances in the study of exotic nuclei at the radioactive beam facilities. We build a new ab initio many-body approachootnotetextS. Quaglioni and P. Navratil, arXiv:0804.1560. capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group methodootnotetextY. C. Tang et al., Phys. Rep. 47, 167 (1978); K. Langanke and H. Friedrich, Advances in Nuclear Physics, chapter 4., Plenum, New York, 1987. with the ab initio no-core shell model.ootnotetextP. Navratil, J. P. Vary, and B. R. Barrett, Phys. Rev. Lett. 84, 5728 (2000); Phys. Rev. C 62, 054311 (2000).. In this way, we complement a microscopic-cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, while preserving Pauli principle and translational symmetry. I will present results for neutron and proton scattering on light nuclei, including n- and p-^4He phase shifts, and low-lying states of one-neutron halo p-shell nuclei, obtained using realistic nucleon-nucleon potentials. In particular, I will address the parity inversion of the ^11Be ground state.
On the number of eigenvalues of a model operator in fermionic Fock space
NASA Astrophysics Data System (ADS)
Muminov, Zahriddin; Ismail, Fudziah; Eshkuvatov, Zainidin
2013-04-01
We consider a model describing a truncated operator H (truncated with respect to the number of particles) acting in the direct sum of zero-, one-, and two-particle subspaces of a fermionic Fock space Script Fa(L2(Bbb T3)) over L2(Bbb T3). We admit a general form for the "kinetic" part of the hamiltonian H, which contains a parameter γ to distinguish the two identical particles from the third one. In this note: (i) We find a critical value γ* for the parameter γ that allows or forbids the Efimov effect (infinite number of bound states if the associated generalized Friedrichs model has a threshold resonance) and we prove that only for γ < γ* the Efimov effect is absent, while this effect exists for any γ > γ*. (ii) In the case γ > γ* we also establish the following asymptotics for the number N(z) of eigenvalues z below Emin, the lower limit of the essential spectrum of H:
Planetary transit observations at the University Observatory Jena: TrES-2
NASA Astrophysics Data System (ADS)
Raetz, St.; Mugrauer, M.; Schmidt, T. O. B.; Roell, T.; Eisenbeiss, T.; Hohle, M. M.; Koeltzsch, A.; Vaňko, M.; Ginski, Ch.; Marka, C.; Moualla, M.; Tetzlaff, N.; Seifahrt, A.; Broeg, Ch.; Koppenhoefer, J.; Raetz, M.; Neuhäuser, R.
2009-05-01
We report on observations of several transit events of the transiting planet TrES-2 obtained with the Cassegrain-Teleskop-Kamera at the University Observatory Jena. Between March 2007 and November 2008 ten different transits and almost a complete orbital period were observed. Overall, in 40 nights of observation 4291 exposures (in total 71.52 h of observation) of the TrES-2 parent star were taken. With the transit timings for TrES-2 from the 34 events published by the TrES-network, the Transit Light Curve project and the Exoplanet Transit Database plus our own ten transits, we find that the orbital period is P=(2.470614± 0.000001) d, a slight change by ˜ 0.6 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we found a second dip after the transit which could either be due to a blended variable star or occultation of a second star or even an additional object in the system. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons. Based on observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University Jena and the 80cm telescope of the Wendelstein Observatory of the Ludwig-Maximilians-University Munich.
Ab initio many-body calculations of nucleon scattering on ^16O
NASA Astrophysics Data System (ADS)
Navratil, Petr; Quaglioni, Sofia; Roth, Robert
2008-10-01
We develop a new ab initio many-body approachootnotetextS. Quaglioni and P. Navratil, arXiv:0804.1560. capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group methodootnotetextY. C. Tang et al., Phys. Rep. 47, 167 (1978); K. Langanke and H. Friedrich, Advances in Nuclear Physics, Plenum, New York, 1987. with the ab initio no-core shell model (NCSM).ootnotetextP. Navratil, J. P. Vary, and B. R. Barrett, Phys. Rev. Lett. 84, 5728 (2000); Phys. Rev. C 62, 054311 (2000). In this way, we complement a microscopic-cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, while preserving Pauli principle and translational symmetry. We will present results for low-energy nucleon scattering on ^16O and for A=17 bound states obtained using realistic nucleon-nucleon potentials. The ^16O wave functions are calculated within the importance-truncated NCSMootnotetextR. Roth and P. Navratil, Phys. Rev. Lett. 99, 092501 (2007). that allows the use of model spaces up to 18φ and ultimately enables to reach convergence of phase-shifts and other observables. Prepared by LLNL under Contract DE-AC52-07NA27344. Support from the U.S. DOE/SC/NP (Work Proposal No. SCW0498), and from the U. S. Department of Energy Grant DE-FC02-07ER41457 is acknowledged.
David Dennison, the specific heat of hydrogen, and the discovery of nuclear spin
NASA Astrophysics Data System (ADS)
Gearhart, Clayton
2008-04-01
The specific heat of hydrogen gas at low temperatures, first measured by Arnold Eucken in 1912, decreases sharply as the two rotational degrees of freedom freeze out. The ``old quantum theory'' could never explain this behavior satisfactorily, despite persistent efforts. Then in 1926, Heisenberg showed that in the new quantum mechanics, identical particles must have either symmetric or antisymmetric wave functions, and were the key to the spectrum of helium. Friedrich Hund first applied this concept to the rotational specific heat of hydrogen, with limited success. An experimental breakthrough came in 1926, when for the first time, spectral lines involving the ground state of molecular hydrogen were found in the far ultraviolet. Further measurements by the Japanese spectroscopist Takeo Hori led to a moment of inertia for molecular hydrogen more than double earlier estimates. Using this result, the American physicist David Dennison devised the modern theory in 1927, and in the process, found persuasive evidence for proton spin. Most of these actors were at Bohr's institute in Copenhagen in 1926--27; their interaction plays a central role in this story.
Vision loss and hearing loss in painting and musical composition.
Marmor, Michael F
2014-07-01
This article considers the impact of vision and hearing loss on great painters and musical composers. The visual work of Mary Cassatt, Georgia O'Keeffe, Edgar Degas, and Claude Monet all showed alterations as their vision failed. In contrast, Gabriel Fauré, Bedřich Smetana, and Ludwig von Beethoven wrote many of their best compositions while totally deaf, and Georg Friedrich Handel and Frederick Delius struggled to compose late in life when they lost their vision (although their hearing remained excellent). There are 2 major distinctions between the role of vision and hearing for these artistic disciplines. First, there is a surrogate means of "hearing" music, through the musical score, which allows composers to write and edit music while totally deaf. The greatest problem with deafness for a skilled composer is interference from internal noise (tinnitus). There is no surrogate for vision to allow a painter to work when the subject is a blur or the colors on the canvas cannot be distinguished. Second, although the appreciation of art is visual and that of music is auditory, the transcription of both art and musical composition is visual. Thus, visual loss does pose a problem for a composer accustomed to working with good sight, because it disrupts habitual methods of writing and editing music. PMID:24565744
The Kelvin–Helmholtz instability at Venus: What is the unstable boundary?
Möstl, Ute V.; Erkaev, Nikolay V.; Zellinger, Michael; Lammer, Helmut; Gröller, Hannes; Biernat, Helfried K.; Korovinskiy, Daniil
2011-01-01
The Kelvin–Helmholtz instability gained scientific attention after observations at Venus by the spacecraft Pioneer Venus Orbiter gave rise to speculations that the instability contributes to the loss of planetary ions through the formation of plasma clouds. Since then, a handful of studies were devoted to the Kelvin–Helmholtz instability at the ionopause and its implications for Venus. The aim of this study is to investigate the stability of the two instability-relevant boundary layers around Venus: the induced magnetopause and the ionopause. We solve the 2D magnetohydrodynamic equations with the total variation diminishing Lax–Friedrichs algorithm and perform simulation runs with different initial conditions representing the situation at the boundary layers around Venus. Our results show that the Kelvin–Helmholtz instability does not seem to be able to reach its nonlinear vortex phase at the ionopause due to the very effective stabilizing effect of a large density jump across this boundary layer. This seems also to be true for the induced magnetopause for low solar activity. During high solar activity, however, there could occur conditions at the induced magnetopause which are in favour of the nonlinear evolution of the instability. For this situation, we estimated roughly a growth rate for planetary oxygen ions of about 7.6 × 1025 s−1, which should be regarded as an upper limit for loss due to the Kelvin–Helmholtz instability. PMID:22347723
Representation of quantum mechanical resonances in the Lax-Phillips Hilbert space
Strauss, Y.; Horwitz, L. P.; Eisenberg, E.
2000-01-01
We discuss the quantum Lax-Phillips theory of scattering and unstable systems. In this framework, the decay of an unstable system is described by a semigroup. The spectrum of the generator of the semigroup corresponds to the singularities of the Lax-Phillips S-matrix. In the case of discrete (complex) spectrum of the generator of the semigroup, associated with resonances, the decay law is exactly exponential. The states corresponding to these resonances (eigenfunctions of the generator of the semigroup) lie in the Lax-Phillips Hilbert space, and therefore all physical properties of the resonant states can be computed. We show that the Lax-Phillips S-matrix is unitarily related to the S-matrix of standard scattering theory by a unitary transformation parametrized by the spectral variable σ of the Lax-Phillips theory. Analytic continuation in σ has some of the properties of a method developed some time ago for application to dilation analytic potentials. We work out an illustrative example using a Lee-Friedrichs model for the underlying dynamical system.
Teaching Anatomy in the XXI Century: New Aspects and Pitfalls
Papa, Veronica; Vaccarezza, Mauro
2013-01-01
Anatomy has historically been a cornerstone in medical education regardless of nation, racial background, or medical school system. By learning gross anatomy, medical students get a first “impression” about the structure of the human body which is the basis for understanding pathologic and clinical problems. Although the importance of teaching anatomy to both undergraduate and postgraduate students remains undisputed, there is currently a relevant debate concerning methods of anatomy teaching. In the past century, dissection and lectures were its sole pedagogy worldwide. Recently, the time allocated for anatomy teaching was dramatically reduced to such an extent that some suggest that it has fallen below an adequate standard. Traditional anatomy education based on topographical structural anatomy taught in lectures and gross dissection classes has been replaced by a multiple range of study modules, including problem-based learning, plastic models or computer-assisted learning, and curricula integration. “Does the anatomical theatre still have a place in medical education?” And “what is the problem with anatomic specimens?” We endeavor to answer both of these questions and to contribute to the debate on the current situation in undergraduate and graduate anatomy education. Doctors without anatomy are like moles.They work in the dark and the work of their hands are mounds. Friedrich TiedemannThe foundation of the study of the art of operating must be laid in the dissecting room. Robert Liston PMID:24367240
NASA Astrophysics Data System (ADS)
Einkemmer, Lukas
2016-05-01
The recently developed semi-Lagrangian discontinuous Galerkin approach is used to discretize hyperbolic partial differential equations (usually first order equations). Since these methods are conservative, local in space, and able to limit numerical diffusion, they are considered a promising alternative to more traditional semi-Lagrangian schemes (which are usually based on polynomial or spline interpolation). In this paper, we consider a parallel implementation of a semi-Lagrangian discontinuous Galerkin method for distributed memory systems (so-called clusters). Both strong and weak scaling studies are performed on the Vienna Scientific Cluster 2 (VSC-2). In the case of weak scaling we observe a parallel efficiency above 0.8 for both two and four dimensional problems and up to 8192 cores. Strong scaling results show good scalability to at least 512 cores (we consider problems that can be run on a single processor in reasonable time). In addition, we study the scaling of a two dimensional Vlasov-Poisson solver that is implemented using the framework provided. All of the simulations are conducted in the context of worst case communication overhead; i.e., in a setting where the CFL (Courant-Friedrichs-Lewy) number increases linearly with the problem size. The framework introduced in this paper facilitates a dimension independent implementation of scientific codes (based on C++ templates) using both an MPI and a hybrid approach to parallelization. We describe the essential ingredients of our implementation.
Frercks, Jan
2008-01-01
Atypical career of a chemist in Germany around 1800 consisted of being trained as an apothecary, followed by an occupation as a professor at a university or another institution of higher education. These conditions deeply influenced the concept and the practice of chemistry as a science. Johann Friedrich August Göttling is an intriguing example for merging education and daily duties of teaching with the self-image of a scientific chemist. He linked chemical teaching, work, and research by using different hybrid media, such as the Almanach oder Taschenbuch für Scheidekünstler und Apotheker, a stove specifically designed for the narrow student's room, portable laboratories, a pharmaceutical boarding school and textbooks. This allowed him to practice three different forms of chemistry as a science. A "socio-epistemological diagram" of German chemistry around 1800 shows that these forms neatly corresponded to the then predominant three-level epistemology. In particular, the concept of a chemical fact served to link pharmaceutical practice with teaching practice, while granting only the chemistry done by professors the status of a science. PMID:19244834
History of the Emergence and Recognition of Syringomyelia in the 19th Century.
Walusinski, Olivier
2012-01-01
Charles-Prosper Ollivier d'Angers coined the term "syringomyelia" in 1827 to describe the presence of a cavity in the spinal cord, which he considered pathological in all cases. In 1882 in Germany, Otto von Kahler and Friedrich Schultze defined the clinical syndrome, which associated Duchenne-Aran muscular dystrophy of a limb with sensory dissociation. They explained the syndrome by the presence of an abnormal cavity, distinct from that found in the spinal cord of healthy adults. Although Guillaume Duchenne de Boulogne and Jean-Martin Charcot had observed cases in France, both failed to identify syringomyelia, whereas a family physician in Brittany, Augustin Morvan, described the clinical symptomatology using the term "analgesic whitlow" in 1883. Based on several dozen observations that they collated in their remarkable theses,Anna Bumler in Zurich in 1887 and Isidore Bruhl in Paris in 1890 established the complete clinical picture of syringomyelia, covering anatomic functional and pathological aspects. Whereas Charcot isolated pathologies by correlating clinical signs with anatomo-pathological lesions, the isolation of syringomyelia initially involved an anatomo-pathological concept before the semiology was defined. In addition, this work would later enhance physiological understanding of sensory spinal pathways. PMID:26591071
Folding into being: early embryology and the epistemology of rhythm.
Wellmann, Janina
2015-03-01
Historians have often described embryology and concepts of development in the period around 1800 in terms of "temporalization" or "dynamization". This paper, in contrast, argues that a central epistemological category in the period was "rhythm", which played a major role in the establishment of the emerging discipline of biology. I show that Caspar Friedrich Wolff's epigenetic theory of development was based on a rhythmical notion, namely the hypothesis that organic development occurs as a series of ordered rhythmical repetitions and variations. Presenting Christian Heinrich Pander's and Karl Ernst von Baer's theory of germ layers, I argue that Pander and Baer regarded folding as an organizing principle of ontogenesis, and that the principle's explanatory power stems from their understanding of folding as a rhythmical figuration. In a brief discussion of the notion of rhythm in contemporary music theory, I identify an underlying physiological epistemology in the new musical concept of rhythm around 1800. The paper closes with a more general discussion of the relationship between the rhythmic episteme, conceptions of life, and aesthetic theory at the end of the eighteenth century. PMID:26013433
Haller, T; Dietl, P; Pfaller, K; Frick, M; Mair, N; Paulmichl, M; Hess, M W; Furst, J; Maly, K
2001-10-15
In alveolar type II cells, the release of surfactant is considerably delayed after the formation of exocytotic fusion pores, suggesting that content dispersal may be limited by fusion pore diameter and subject to regulation at a postfusion level. To address this issue, we used confocal FRAP and N-(3-triethylammoniumpropyl)-4-(4-[dibutylamino]styryl) pyridinium dibromide (FM 1-43), a dye yielding intense localized fluorescence of surfactant when entering the vesicle lumen through the fusion pore (Haller, T., J. Ortmayr, F. Friedrich, H. Volkl, and P. Dietl. 1998. Proc. Natl. Acad. Sci. USA. 95:1579-1584). Thus, we have been able to monitor the dynamics of individual fusion pores up to hours in intact cells, and to calculate pore diameters using a diffusion model derived from Fick's law. After formation, fusion pores were arrested in a state impeding the release of vesicle contents, and expanded at irregular times thereafter. The expansion rate of initial pores and the probability of late expansions were increased by elevation of the cytoplasmic Ca2+ concentration. Consistently, content release correlated with the occurrence of Ca2+ oscillations in ATP-treated cells, and expanded fusion pores were detectable by EM. This study supports a new concept in exocytosis, implicating fusion pores in the regulation of content release for extended periods after initial formation. PMID:11604423
Differential distribution of calpain small subunit 1 and 2 in rat brain.
Friedrich, Peter; Papp, Henrietta; Halasy, Katalin; Farkas, Attila; Farkas, Bence; Tompa, Peter; Kása, Peter
2004-04-01
Calpains, the Ca(2+)-dependent thiol proteases, are abundant in the nervous tissue. The ubiquitous enzyme forms in mammals are heterodimers consisting of a specific, micro or m, large (catalytic) subunit and, apparently, a common small (regulatory) subunit (CSS1). Recently, however, we described a second form of small subunit (CSS2), which is of restricted occurrence [Schád, E., Farkas, A., Jékely, G., Tompa, P. & Friedrich, P. (2002) Biochem. J., 362, 383-388]. Here we analysed the distribution of immunoreactivity in various parts of rat brain against two anti-CSS1 and two anti-CSS2 antibodies by correlated light and electron microscopy. Remarkably, the antibodies showed differential distribution in various parts of rat cortex: anti-CSS1 reacted mainly with perikarya and dendrites, whereas anti-CSS2 was more prominent in axons. In serial sections CSS2 and synaptophysin gave very similar patterns, i.e. these epitopes seem to colocalize. Electron microscopy confirmed that CSS1 was mainly localized postsynaptically in dendrites and somata, whereas CSS2 was found presynaptically. The hypothesis is advanced that these distinct distributions of calpain subunits may be related to the transport of these enzymes in nerve cells. PMID:15078555
Politics, Morality, Innovation, and Misrepresentation in Physical Science and Technology
NASA Astrophysics Data System (ADS)
Buchwald, Jed Z.
2016-08-01
The pressures of politics, the desire to be first in innovation, moral convictions, and the potential dangers of error are all factors that have long been at work in the history of science and technology. Every so often, the need to reach a result may require leaving out a few steps here and there. Historians think and argue best through stories, so what follows are several tales, each of which exemplifies one or more of these aspects, though some reach back nearly two hundred years. The first concerns the depletion of the ozone layer; the second involves the discovery of electric waves by Heinrich Hertz in 1888; the third concerns the controlled production of electromagnetic radiation by Guglielmo Marconi and John Ambrose Fleming in the early 1900s; the fourth portrays the circumstances surrounding Joseph von Fraunhofer's discovery and use of the spectral lines in the 1810s; our final case involves a bitter controversy between the physicist Hermann von Helmholtz and the astronomer Friedrich Zöllner in the 1890s.
Quantum Chemistry in Great Britain: Developing a Mathematical Framework for Quantum Chemistry
NASA Astrophysics Data System (ADS)
Simões, Ana; Gavroglu, Kostas
By 1935 quantum chemistry was already delineated as a distinct sub-discipline due to the contributions of Fritz London, Walter Heitler, Friedrich Hund, Erich Hückel, Robert Mulliken, Linus Pauling, John van Vleck and John Slater. These people are credited with showing that the application of quantum mechanics to the solution of chemical problems was, indeed, possible, especially so after the introduction of a number of new concepts and the adoption of certain approximation methods. And though a number of chemists had started talking of the formation of theoretical or, even, mathematical chemistry, a fully developed mathematical framework of quantum chemistry was still wanting. The work of three persons in particular-of John E. Lennard-Jones, Douglas R. Hartree, and Charles Alfred Coulson-has been absolutely crucial in the development of such a framework. In this paper we shall discuss the work of these three researchers who started their careers in the Cambridge tradition of mathematical physics and who at some point of their careers all became professors of applied mathematics. We shall argue that their work consisted of decisive contributions to the development of such a mathematical framework for quantum chemistry.
Study of the rheological behaviour of human blood using a controlled stress rheometer.
Alves, Maria M; Rocha, Cristina; Gonçalves, Maria P
2013-01-01
The aim of this work was to investigate the rheological behaviour of human blood, in a controlled stress rheometer, using different cone-plate and parallel plate geometries. Steady-shear (flow curves and kinetics) and oscillatory (strain, frequency and time sweeps) tests were performed at 37°C. The results demonstrated that rheological data are significantly influenced by the measuring geometry and the rheological parameters obtained from rheological models must be analysed with great caution. The Cross model provided a better fit of the flow curves and the Power Law model gave a better concordance between the rheological parameters obtained with the different measuring systems. The oscillatory measurements demonstrated a linear viscoelastic behaviour below a critical frequency and the Friedrich-Braun model described well the frequency sweeps experimental data in that region. The correlation between steady-shear and oscillatory properties (Cox-Merz rule) suggests that the two methods can be complementary and may give important information on red blood cells aggregation and deformability. Results from oscillatory time sweeps confirm a blood aggregation process in two steps. PMID:23579279
Duality and cohomology in M-theory with boundary
NASA Astrophysics Data System (ADS)
Sati, Hisham
2012-05-01
We consider geometric and analytical aspects of M-theory on a manifold with boundary Y11. The partition function of the C-field requires summing over harmonic forms. When Y11 is closed, Hodge theory gives a unique harmonic form in each de Rham cohomology class, while in the presence of a boundary the Hodge-Morrey-Friedrichs decomposition should be used. This leads us to study the boundary conditions for the C-field. The dynamics and the presence of the dual to the C-field gives rise to a mixing of boundary conditions with one being Dirichlet and the other being Neumann. We describe the mixing between the corresponding absolute and relative cohomology classes via Poincaré duality angles, which we also illustrate for the M5-brane as a tubular neighborhood. Several global aspects are then considered. We provide a systematic study of the extension of the E8 bundle and characterize obstructions. Considering Y11 as a fiber bundle, we describe how the phase looks like on the base, hence providing dimensional reduction in the boundary case via the adiabatic limit of the eta invariant. The general use of the index theorem leads to a new effect given by a gravitational Chern-Simons term CS11 on Y11 whose restriction to the boundary would be a generalized WZW model. This suggests that holographic models of M-theory can be viewed as a sector within this index-theoretic approach.
[Stahl, Leibniz, Hoffmann and breathing].
Carvallo, Sarah
2006-01-01
At the beginning of the XVIII th century, Wilhelm Gottfried Leibniz and Friedrich Hoffmann criticize Georg Ernst Stahl's medical theory. They differenciate between unsound and true reasonings. Namely, they validate Stahl's definition of breath but extracting it from its animist basis and placing it in an epistemology obeying to the principle of sufficient reason and to the mechanical model. The stahlian discovery consists in understanding breath as a calorific ventilation against the ancient conception; the iatromechanists recognize its accuracy, but they try then to transpose it to a mechanical model of ventilation. Using it in a different epistemological context implies that they analyze the idea of discovery "true" in its contents, but "wrong" in its hypothesis. It impels to examine the epistemology of medical knowledge, as science and therapeutics, and in its links with the other scientific theories. Thus, if Leibniz as philosopher and Hoffmann as doctor consider Stahl's animism so important, it is because its discoveries question the fundamental principles of medicine. PMID:17153053
The 'chemistry of space': the sources of Hermann Grassmann's scientific achievements.
Petsche, Hans-Joachim
2014-10-01
Albert Lewis's article (Annals of Science, 1977) analysing the influence of Friedrich Schleiermacher on Hermann Grassmann, stimulated many different studies on the founder of n-dimensional outer algebra. Following a brief outline of the various, sometimes diverging, analyses of Grassmann's creative thinking, new research is presented which confirms Lewis's original contribution and widens it considerably. It will be shown that: i. Grassmann, although a self-taught mathematician, was at the centre of a hitherto understated intellectual trend, which was defining for Germany. Initiated by Pestalozzi's concept of elementary mathematical education and culminating in the modern mathematics of the late 19th Century, it was reflected in the contributions of Grassmann, Riemann, Jacobi and Eisenstein. ii. Hermann Grassmann, his father Justus, and his brother Robert were all demonstrably influenced by Schleiermacher's dialectic; however the two brothers responded to it in very different ways. iii. Whilst the more philosophical parts of Hermann's 1844 Extension Theory are characterised by the influence of Schleiermacher and also by the mathematical knowledge of his father, the entire development of this work is the unfolding of a single idea based on the father's interpretation of combinatorial multiplication as a 'chemical conjunction', which was developed largely dialectically by Hermann. PMID:25508514
The 'chemistry of space': the sources of Hermann Grassmann's scientific achievements.
Petsche, Hans-Joachim
2014-10-01
Albert Lewis's article (Annals of Science, 1977) analysing the influence of Friedrich Schleiermacher on Hermann Grassmann, stimulated many different studies on the founder of n-dimensional outer algebra. Following a brief outline of the various, sometimes diverging, analyses of Grassmann's creative thinking, new research is presented which confirms Lewis's original contribution and widens it considerably. It will be shown that: i. Grassmann, although a self-taught mathematician, was at the centre of a hitherto understated intellectual trend, which was defining for Germany. Initiated by Pestalozzi's concept of elementary mathematical education and culminating in the modern mathematics of the late 19th Century, it was reflected in the contributions of Grassmann, Riemann, Jacobi and Eisenstein. ii. Hermann Grassmann, his father Justus, and his brother Robert were all demonstrably influenced by Schleiermacher's dialectic; however the two brothers responded to it in very different ways. iii. Whilst the more philosophical parts of Hermann's 1844 Extension Theory are characterised by the influence of Schleiermacher and also by the mathematical knowledge of his father, the entire development of this work is the unfolding of a single idea based on the father's interpretation of combinatorial multiplication as a 'chemical conjunction', which was developed largely dialectically by Hermann. PMID:25470887
PHURBAS: AN ADAPTIVE, LAGRANGIAN, MESHLESS, MAGNETOHYDRODYNAMICS CODE. I. ALGORITHM
Maron, Jason L.; McNally, Colin P.; Mac Low, Mordecai-Mark E-mail: cmcnally@amnh.org
2012-05-01
We present an algorithm for simulating the equations of ideal magnetohydrodynamics and other systems of differential equations on an unstructured set of points represented by sample particles. Local, third-order, least-squares, polynomial interpolations (Moving Least Squares interpolations) are calculated from the field values of neighboring particles to obtain field values and spatial derivatives at the particle position. Field values and particle positions are advanced in time with a second-order predictor-corrector scheme. The particles move with the fluid, so the time step is not limited by the Eulerian Courant-Friedrichs-Lewy condition. Full spatial adaptivity is implemented to ensure the particles fill the computational volume, which gives the algorithm substantial flexibility and power. A target resolution is specified for each point in space, with particles being added and deleted as needed to meet this target. Particle addition and deletion is based on a local void and clump detection algorithm. Dynamic artificial viscosity fields provide stability to the integration. The resulting algorithm provides a robust solution for modeling flows that require Lagrangian or adaptive discretizations to resolve. This paper derives and documents the Phurbas algorithm as implemented in Phurbas version 1.1. A following paper presents the implementation and test problem results.
Schumann's wheel tachistoscope: its reconstruction and its operation.
Stock, Armin
2014-05-01
In the fall and winter of 1910, Max Wertheimer (1880-1943) performed his famous experiments on perceived motion, published in 1912. Besides slider experiments he mainly used a wheel tachistoscope developed by Friedrich Schumann (1863-1940) at the end of the 19th century. The Adolf-Wuerth-Center for the History of Psychology has several wheel tachistoscopes in its collection of instruments. Their provenance can be traced back to the Institute of Psychology of the University of Frankfurt and the University of Zurich. It is very plausible that Wertheimer, who performed his experiments at the Frankfurt Institute, used one of them. But the wheel tachistoscope alone is not sufficient to reconstruct Wertheimer's original experiments. As always, the devil is in the details. Wertheimer's descriptions of the necessary accessories, a prism, a viewing device, and an electric motor to move the wheel, are rather sparse. This article describes the results of a search for traces in the literature, in archives, and in literary depositories to shed some light on Wertheimer's experimental equipment. As a result, it was possible to reconstruct the entire apparatus and to obtain the same optical impressions with the reconstructed devices as Wertheimer's observers reported. In addition, one of his results was replicated with new participants exactly 100 years after its first publication. PMID:24818744
Valentinuzzi, Max; Beneke, Klaus; Gonzalez, German
2012-01-01
The thought reproduced in the above epigraph is taken from an article by Thurau et al. [1], who attribute it to Arthur Schopenhauer (17881860), an outstanding philosopher and author of the far-reaching piece Die Welt als Wille und Vorstellung (The World as Will and Representation). In German, it would perhaps read as etwas denken, das niemand vorher gedacht hat, während etwas sehen, was jeder sieht. We could not assert whether Schopenhauer really said that, but it should not be at all surprising if it were, because it sounds simple, perhaps even naïve, and very deep, indeed. It fits perfectly to Carl Friedrich Wilhelm Ludwigs personality (18161895), whom we will look at as physiologist in this second note. Yes, second note-because in the first one [2], we looked at him as bioengineer. A third and last Retrospectroscope column completing this series will deal with his wonderful and always humble and generous activities as teacher. PMID:23014707
NASA Astrophysics Data System (ADS)
Fromang, S.; Hennebelle, P.; Teyssier, R.
2006-10-01
Aims. In this paper, we present a new method to perform numerical simulations of astrophysical MHD flows using the Adaptive Mesh Refinement framework and Constrained Transport. Methods: . The algorithm is based on a previous work in which the MUSCL-Hancock scheme was used to evolve the induction equation. In this paper, we detail the extension of this scheme to the full MHD equations and discuss its properties. Results: . Through a series of test problems, we illustrate the performances of this new code using two different MHD Riemann solvers (Lax-Friedrich and Roe) and the need of the Adaptive Mesh Refinement capabilities in some cases. Finally, we show its versatility by applying it to two completely different astrophysical situations well studied in the past years: the growth of the magnetorotational instability in the shearing box and the collapse of magnetized cloud cores. Conclusions: . We have implemented a new Godunov scheme to solve the ideal MHD equations in the AMR code RAMSES. We have shown that it results in a powerful tool that can be applied to a great variety of astrophysical problems, ranging from galaxies formation in the early universe to high resolution studies of molecular cloud collapse in our galaxy.
The success story of crystallography.
Schwarzenbach, Dieter
2012-01-01
Diffractionists usually place the birth of crystallography in 1912 with the first X-ray diffraction experiment of Friedrich, Knipping and Laue. This discovery propelled the mathematical branch of mineralogy to global importance and enabled crystal structure determination. Knowledge of the geometrical structure of matter at atomic resolution had revolutionary consequences for all branches of the natural sciences: physics, chemistry, biology, earth sciences and material science. It is scarcely possible for a single person in a single article to trace and appropriately value all of these developments. This article presents the limited, subjective view of its author and a limited selection of references. The bulk of the article covers the history of X-ray structure determination from the NaCl structure to aperiodic structures and macromolecular structures. The theoretical foundations were available by 1920. The subsequent success of crystallography was then due to the development of diffraction equipment, the theory of the solution of the phase problem, symmetry theory and computers. The many structures becoming known called for the development of crystal chemistry and of data banks. Diffuse scattering from disordered structures without and with partial long-range order allows determination of short-range order. Neutron and electron scattering and diffraction are also mentioned. PMID:22186283
The Wolffian roots of Kant's teleology.
van den Berg, Hein
2013-12-01
Kant's teleology as presented in the Critique of Judgment is commonly interpreted in relation to the late eighteenth-century biological research of Johann Friedrich Blumenbach. In the present paper, I show that this interpretative perspective is incomplete. Understanding Kant's views on teleology and biology requires a consideration of the teleological and biological views of Christian Wolff and his rationalist successors. By reconstructing the Wolffian roots of Kant's teleology, I identify several little known sources of Kant's views on biology. I argue that one of Kant's main contributions to eighteenth-century debates on biology consisted in demarcating biology from metaphysics. Kant rejected Wolffian views on the hierarchy of sciences, according to which propositions specifying the functions of organisms are derived from theological truths. In addition, Kant argued that organic self-organization necessitates a teleological description in order to show that self-organization does not support materialism. By demarcating biology and metaphysics, Kant made a small yet important contribution to establishing biology as a science. PMID:23932232
Computational Modeling of Multi-Phase/Multi-Species Flows with Applications to Liquid Rocket Engines
NASA Technical Reports Server (NTRS)
Navaz, Homayun K.
1996-01-01
Accurate prediction of all physical phenomena in a combustion chamber is essential for better understanding of the system performance. Atomization, evaporation, combustion, chemical kinetics, and turbulence are those processes of great importance that need to be well understood. Processes involving the liquid phase in a combustion chamber will be further complicated under supercritical conditions. More advanced and accurate numerical techniques are required to extend our understanding of the above phenomena. A computer program for multi-species/multi-phase flow was developed for NASA/MSFC in 1992. This code, called Liquid Thrust Chamber Performance (LTCP) program takes an Eulerian- Eulerian approach and is based on the Total Variation Diminishing (TVD) technique with Lax-Friedrichs upwind method. Under the NASA/ASEE SFFP the LTCP code was used to predict the performance characteristics of several engines that were of particular interest to NASA. This code was also successful in a combustion detonation study. Converting the program to the PC platform was accomplished which extends usability and makes it available to a wider range of users. The Eulerian formulation of the liquid phase provides a suitable model that can be extended to include combustion modeling under supercritical conditions. The results have been compared against the ones of other codes and available measured data. The algorithm proved to be robust and efficient for problems with stiff source terms.
Validation and Simulation of ARES I Scale Model Acoustic Test -1- Pathfinder Development
NASA Technical Reports Server (NTRS)
Putnam, G. C.
2011-01-01
The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. To take advantage of this data, a digital representation of the ASMAT test setup has been constructed and test firings of the motor have been simulated using the Loci/CHEM computational fluid dynamics software. Within this first of a series of papers, results from ASMAT simulations with the rocket in a held down configuration and without water suppression have then been compared to acoustic data collected from similar live-fire tests to assess the accuracy of the simulations. Detailed evaluations of the mesh features, mesh length scales relative to acoustic signals, Courant-Friedrichs-Lewy numbers, and spatial residual sources have been performed to support this assessment. Results of acoustic comparisons have shown good correlation with the amplitude and temporal shape of pressure features and reasonable spectral accuracy up to approximately 1000 Hz. Major plume and acoustic features have been well captured including the plume shock structure, the igniter pulse transient, and the ignition overpressure. Finally, acoustic propagation patterns illustrated a previously unconsidered issue of tower placement inline with the high intensity overpressure propagation path.
Alter, Stephen G
2008-03-01
This paper examines Charles Darwin's idea that language-use and humanity's unique cognitive abilities reinforced each other's evolutionary emergence-an idea Darwin sketched in his early notebooks, set forth in his Descent of man (1871), and qualified in Descent's second (1874) edition. Darwin understood this coevolution process in essentially Lockean terms, based on John Locke's hints about the way language shapes thinking itself. Ironically, the linguist Friedrich Max Müller attacked Darwin's human descent theory by invoking a similar thesis, the German romantic notion of an identity between language and thought. Although Darwin avoided outright contradiction, when he came to defend himself against Müller's attacks, he undercut some of his own argumentation in favor of the coevolution idea. That is, he found it difficult to counter Müller's argument while also making a case for coevolution. Darwin's efforts in this area were further complicated by British and American writers who held a naturalistic view of speech origins yet still taught that language had been invented by fully evolved homo sapiens, thus denying coevolution. PMID:18331953
Discovery and development of x-ray diffraction
NASA Astrophysics Data System (ADS)
Jeong, Yeuncheol; Yin, Ming; Datta, Timir
2013-03-01
In 1912 Max Laue at University of Munich reasoned x-rays to be short wavelength electromagnetic waves and figured interference would occur when scattered off crystals. Arnold Sommerfeld, W. Wien, Ewald and others, raised objections to Laue's idea, but soon Walter Friedrich succeeded in recording x-ray interference patterns off copper sulfate crystals. But the Laue-Ewald's 3-dimensional formula predicted excess spots. Fewer spots were observed. William Lawrence Bragg then 22 year old studying at Cambridge University heard the Munich results from father William Henry Brag, physics professor at Univ of Leeds. Lawrence figured the spots are 2-d interference of x-ray wavelets reflecting off successive atomic planes and derived a simple eponymous equation, the Bragg equation d*sin(theta) = n*lamda. 1913 onward the Braggs dominated the crystallography. Max Laue was awarded the physics Nobel in 1914 and the Braggs shared the same in 1915. Starting with Rontgen's first ever prize in 1901, the importance of x-ray techniques is evident from the four out of a total 16 physics Nobels between 1901-1917. We will outline the historical back ground and importance of x-ray diffraction giving rise to techniques that even in 2013, remain work horses in laboratories all over the globe.
Nilsson, I M
1994-01-01
Haemophilia is a bleeding disorder which has always attracted wide interest both among physicians and the laity--uncontrollable haemorrhage, blood that fails to coagulate and heredity with only males affected. The disease is probably best known to the public through its appearance in European royal families and in the Russian Imperial family. The oldest known description of haemophilia is to be found in the Talmud, the collection of ancient Judaic books from the early centuries of our era. The first clinical account of haemophilia was published by the American, Otto, in 1803. He described the disease as an inheritable bleeding disorder occurring only in males, and transmitted by female carriers who are not themselves affected. The disease manifests itself in early childhood, joint bleedings being its most characteristic feature. Otto called the male patients "bleeders". The term, haemophilia, originated with a German, Friedrich Hopff (1828), who coined the name "haemorrhaphilia" which was later abbreviated to haemophilia. ... As to future prospects, it is hoped that it will soon be possible to cure the disease by means of gene therapy, and to this end promising experimental work is already in progress. PMID:11640407
Friederich Nietzsche and the seduction of Occam's razor.
Danesh-Meyer, Helen V; Young, Julian
2010-08-01
Friedrich Nietzsche developed dementia at the age of 44 years. It is generally assumed that the cause of his dementia was neurosyphilis or general pareisis of the insane (GPI). Others have proposed frontal-based meningioma as the underlying cause. We have reviewed Nietzsche's medical history and evaluated the evidence from the medical examinations he underwent by various physicians. We have viewed the possible diagnosis of GPI or meningioma in light of present neuro-ophthalmic understanding and found that Nietzsche did not have the neurological or neuro-ophthalmic symptoms consistent with a diagnosis of GPI. The anisocoria which was assumed to be Argyll Robertson pupil was present since he was six years of age. He did not have tongue tremor, lacked progressive motor features and lived at least 12 years following the onset of his neurological signs. Furthermore, the headaches that have been attributed to a frontal-based tumour were present since childhood and the pupil abnormality that has been interpreted as an "afferent pupillary defect" had the characteristics of an abnormality of the efferent pupillary innervation. None of the medical records or photographs suggest there was any ocular misalignment. We concluded that neither diagnosis of GPI nor frontal-based meningioma is convincing. It is likely that Nietzsche suffered from migraines, his blindness in his right eye was a consequence of high progressive myopia associated with retinal degeneration, his anisocoria explained by unilateral tonic pupil, and his dementia by an underlying psychiatric disease. PMID:20542432
[Famous cases for amputation].
Klimpel, Volker
2004-01-01
After a short historical survey 14 cases of celebrated personalities one woman and 13 men, with the grave handicap of amputation are represented. The causes of the lost limbs, once of the nose, were battle injuries (guns) or accidents. In many cases the protheseology followed the amputation, dependent on the technological level of the day. Often medical providing was bad and terrible. The introduction of anaesthesia changed the amputation technique. During different periods from renaissance to the first half of the twentieth century remarkable fates happened. Heroes as the emperor Friedrich III., the knight Goetz von Berlichingen, well known by the spectacle of Goethe, the scientist Tycho Brahe, the merchant and skipper Peter Stuyvesant, the military men Duke Christian II. of Braunschweig-Lueneburg-Wolfenbuettel, William Bayly, Admiral Lord Nelson and Earl Claus Stauffenberg, the actress Sarah Bernhard, the squadron leader of RAF Douglas R. S. Bader and other gave an excellent example for fulfilled life despite handicap. With their artificial legs, arms or hands they rode, fought, shoot, made sports etc. PMID:15633275
High Performance Parallel Methods for Space Weather Simulations
NASA Technical Reports Server (NTRS)
Hunter, Paul (Technical Monitor); Gombosi, Tamas I.
2003-01-01
This is the final report of our NASA AISRP grant entitled 'High Performance Parallel Methods for Space Weather Simulations'. The main thrust of the proposal was to achieve significant progress towards new high-performance methods which would greatly accelerate global MHD simulations and eventually make it possible to develop first-principles based space weather simulations which run much faster than real time. We are pleased to report that with the help of this award we made major progress in this direction and developed the first parallel implicit global MHD code with adaptive mesh refinement. The main limitation of all earlier global space physics MHD codes was the explicit time stepping algorithm. Explicit time steps are limited by the Courant-Friedrichs-Lewy (CFL) condition, which essentially ensures that no information travels more than a cell size during a time step. This condition represents a non-linear penalty for highly resolved calculations, since finer grid resolution (and consequently smaller computational cells) not only results in more computational cells, but also in smaller time steps.
Sizyuk, V.; Hassanein, A.; Morozov, V.; Sizyuk, T.; Mathematics and Computer Science
2007-01-16
The HEIGHTS integrated model has been developed as an instrument for simulation and optimization of laser-produced plasma (LPP) sources relevant to extreme ultraviolet (EUV) lithography. The model combines three general parts: hydrodynamics, radiation transport, and heat conduction. The first part employs a total variation diminishing scheme in the Lax-Friedrich formulation (TVD-LF); the second part, a Monte Carlo model; and the third part, implicit schemes with sparse matrix technology. All model parts consider physical processes in three-dimensional geometry. The influence of a generated magnetic field on laser plasma behavior was estimated, and it was found that this effect could be neglected for laser intensities relevant to EUV (up to {approx}10{sup 12} W/cm{sup 2}). All applied schemes were tested on analytical problems separately. Benchmark modeling of the full EUV source problem with a planar tin target showed good correspondence with experimental and theoretical data. Preliminary results are presented for tin droplet- and planar-target LPP devices. The influence of three-dimensional effects on EUV properties of source is discussed.
Die Deutsche Statistische Gesellschaft in der Weimarer Republik und während der Nazidiktatur
NASA Astrophysics Data System (ADS)
Wilke, Jürgen
Nach anfänglichen Schwierigkeiten durch den 1. Weltkrieg erlangte die Deutsche Statistische Gesellschaft (DStatG) unter dem renommierten Statistiker und Vorsitzenden der DStatG, Friedrich Zahn, durch eine Vielzahl von Aktivitäten hohes Ansehen. Es gab Bestrebungen, Statistiker aus allen Arbeitsfeldern der Statistik in die DStatG zu integrieren, wobei die "Mathematische Statistik" nur zögerlich akzeptiert wurde (Konjunkturforschung, Zeitreihenanalyse). Nach der Machtübernahme 1933 durch Adolf Hitler geriet die DStatG in das Fahrwasser nationalsozialistischer Ideologie und Politik (Führerprinzip, Gleichschaltung des Vereinswesens). Damit war eine personelle Umstrukturierung in der DStatG verbunden. Politisch Missliebige und rassisch Verfolgte mussten die DStatG verlassen (Bernstein, Freudenberg, Gumbel u.a.). Unter den Statistikern gab es alle Abstufungen im Verhalten zum Regime von Ablehnung und zwangsweiser Anpassung über bereitwilliges Mitläufertum bis zu bewusster Täterschaft. Besonders die Bevölkerungsstatistik wurde durch die NS- Rassenpolitik auf lange Sicht diskreditiert. Im Rahmen von Wirtschaftsplanung und Aufrüstung wurden neue zukunftsträchtige statistische Modelle (Grünig, Bramstedt, Leisse) entwickelt.
Schlumbohm, J
2001-01-01
Drawing on the admission records, the medical casebooks and the publications of its director, this article explores how the University of Göttingen's maternity hospital achieved its three official goals: teaching medical students, training female midwives, and providing shelter for needy parturient women. Since educating medical men was the most important aim of the hospital, the paper particularly focuses on how the demands of instruction shaped day-to-day obstetrical practices, especially under the directorship of Professor Friedrich Benjamin Osiander (1792-1822). He was a keen advocate of the forceps, whereas the first director, Professor Johann Georg Roederer (1751-63), had taken a moderate, that is a much less interventionist, approach to obstetrics. Osiander avowedly was determined to subordinate the parturient women to the demands of the clinic and to treat them as 'living manikins'. In spite of that, there is evidence that the pregnant and parturient women, most of whom were unmarried and from the lower classes, made use of the lying-in hospital for their own purposes, and that sometimes they refused to play the role assigned to them. The link between the maternity hospital and the rise of the man-midwife and of 'scientific' obstetrics appears to have been particularly strong in the case of Göttingen and other German university hospitals, compared with lying-in hospitals in other countries where the link was more indirect. PMID:14524351
General Relativity During the Great War
NASA Astrophysics Data System (ADS)
Trimble, Virginia L.
2016-01-01
Einstein's (and Hilbert's) equations saw light of day in the darkness of Berlin 1915, as is well known. Moving from this highlight to less conspicuous topics, we find Karl Schwarzschild's solution of those equations (1916) followed shortly by his death. On the observational and American front, Slipher's assemblage of galaxy radial velocities, begun in 1912 with M31, continued apace. Shapley was busily moving us out of the galactic center. Also at Mt. Wilson, Charles St. John looked for gravitational redshift in the solar spectrum in 1917 without firmly detecting it. Adams demonstrated the very low luminosities of Sirius B and 40 Eri B in 1914 (but his attempt at a redshift for the former came only in 1923). Perhaps least well known is that a handful of additional critical theoretical papers date from the war years and describe the Lense-Thirring effect, the Reissner-Nordstrom solution, and a charged solution with a cosmological constant (due to the even more obscure Friedrich Kottler). Some of these came out of neutral Holland, but Kottler served both at Ypres and on the Galician front. Interesting mixes of military service and relativistic contributions are also associated with the names of Friedmann, Le Lemaître, Weyl (of the tensor), Minkowski, Hubble, Flamm, Droste, and Kretschmann. Astronomers in neutral Denmark, Holland and (until 1917) the USA facilitated transmittal of astronomical observations and other news across the battle lines so that Schwarzschild received an obituary in Nature and Moseley one in Naturwissenschaften.
Theoretical study of the incompressible Navier-Stokes equations by the least-squares method
NASA Technical Reports Server (NTRS)
Jiang, Bo-Nan; Loh, Ching Y.; Povinelli, Louis A.
1994-01-01
Usually the theoretical analysis of the Navier-Stokes equations is conducted via the Galerkin method which leads to difficult saddle-point problems. This paper demonstrates that the least-squares method is a useful alternative tool for the theoretical study of partial differential equations since it leads to minimization problems which can often be treated by an elementary technique. The principal part of the Navier-Stokes equations in the first-order velocity-pressure-vorticity formulation consists of two div-curl systems, so the three-dimensional div-curl system is thoroughly studied at first. By introducing a dummy variable and by using the least-squares method, this paper shows that the div-curl system is properly determined and elliptic, and has a unique solution. The same technique then is employed to prove that the Stokes equations are properly determined and elliptic, and that four boundary conditions on a fixed boundary are required for three-dimensional problems. This paper also shows that under four combinations of non-standard boundary conditions the solution of the Stokes equations is unique. This paper emphasizes the application of the least-squares method and the div-curl method to derive a high-order version of differential equations and additional boundary conditions. In this paper, an elementary method (integration by parts) is used to prove Friedrichs' inequalities related to the div and curl operators which play an essential role in the analysis.
Transonic Shocks for the Full Compressible Euler System in a General Two-Dimensional De Laval Nozzle
NASA Astrophysics Data System (ADS)
Li, Jun; Xin, Zhouping; Yin, Huicheng
2013-02-01
In this paper, we study the transonic shock problem for the full compressible Euler system in a general two-dimensional de Laval nozzle as proposed in Courant and Friedrichs (Supersonic flow and shock waves, Interscience, New York, 1948): given the appropriately large exit pressure p e( x), if the upstream flow is still supersonic behind the throat of the nozzle, then at a certain place in the diverging part of the nozzle, a shock front intervenes and the gas is compressed and slowed down to subsonic speed so that the position and the strength of the shock front are automatically adjusted such that the end pressure at the exit becomes p e( x). We solve this problem completely for a general class of de Laval nozzles whose divergent parts are small and arbitrary perturbations of divergent angular domains for the full steady compressible Euler system. The problem can be reduced to solve a nonlinear free boundary value problem for a mixed hyperbolic-elliptic system. One of the key ingredients in the analysis is to solve a nonlinear free boundary value problem in a weighted Hölder space with low regularities for a second order quasilinear elliptic equation with a free parameter (the position of the shock curve at one wall of the nozzle) and non-local terms involving the trace on the shock of the first order derivatives of the unknown function.
Phase transitions in nonequilibrium traffic theory
Zhang, H.M.
2000-02-01
This paper uses the center difference scheme of Lax-Friedrichs to numerically solve a newly developed continuum traffic flow theory and the kinematic theory of Lighthill and Whitham, and Richards, and it studies the flow-concentration phase transitions in flow containing both shock and rarefaction waves. A homogeneous road with finite length was modeled by both theories. Numerical simulations show that both theories yield nearly identical results for two representative Riemann problems--one has a shock solution and the other a rarefaction wave solution. Their phase transition curves, however, are different: those derived from the new theory have two branches--one for acceleration flow and one for deceleration flow, whereas those derived from the LWR theory comprise a single curve--the equilibrium curve. The phase transition curves in the shock case agree well with certain experimental observations but disagree with others. This disagreement may be resolved by studying transitions among nonequilibrium states, which awaits further development of a more accurate finite difference approximation of the nonequilibrium theory.
A semi-implicit gas-kinetic scheme for smooth flows
NASA Astrophysics Data System (ADS)
Wang, Peng; Guo, Zhaoli
2016-08-01
In this paper, a semi-implicit gas-kinetic scheme (SIGKS) is derived for smooth flows based on the Bhatnagar-Gross-Krook (BGK) equation. As a finite-volume scheme, the evolution of the average flow variables in a control volume is under the Eulerian framework, whereas the construction of the numerical flux across the cell interface comes from the Lagrangian perspective. The adoption of the Lagrangian aspect makes the collision and the transport mechanisms intrinsically coupled together in the flux evaluation. As a result, the time step size is independent of the particle collision time and solely determined by the Courant-Friedrichs-Lewy (CFL) condition. An analysis of the reconstructed distribution function at the cell interface shows that the SIGKS can be viewed as a modified Lax-Wendroff type scheme with an additional term. Furthermore, the addition term coming from the implicitness in the reconstruction is expected to be able to enhance the numerical stability of the scheme. A number of numerical tests of smooth flows with low and moderate Mach numbers are performed to benchmark the SIGKS. The results show that the method has second-order spatial accuracy, and can give accurate numerical solutions in comparison with benchmark results. It is also demonstrated that the numerical stability of the proposed scheme is better than the original GKS for smooth flows.
[Weizsäcker's cosmogony, Farm Hall and the origin of modern turbulence theory].
Eckert, Michael
2014-01-01
The modem statistical theory of turbulence was originated by Andrey Nikolaevich Kolmogorov (1903-1987), Lars Onsager (1903-1976), Ludwig Prandtl (1875-1953), Werner Heisenberg (1901-1976) und Carl Friedrich von Weizsäcker (1912-2007). With the exception of Kolmogorovs theory which was published in 1941 but became widely known only after the war, these contributions emerged largely independently from another in a "remarkable series of coincidences" (Batchelor 1946). Heisenberg and Weizäscker developed their theories during their detention at Farm Hall. Their work was motivated by von Weizsäcker's interest in astrophysics. Weizsäcker aimed at an understanding of the role of turbulence for the motion of interstellar matter for his theory about the origin of the planetary system which he had published in 1943. Weizsäcker's work on cosmogony and turbulence illustrates an early interaction between the disciplines of astronomy and fluid mechanics that became characteristic for astrophysics in the second half of the twentieth century. PMID:24974597
NASA Astrophysics Data System (ADS)
Sterken, C.; Dick, W. R.; Hamel, J.
2002-12-01
The 14th volume of the Acta Historica Astronomiae is the Proceedings of a Colloquium International Relationships in Astronomy (in German) organised by the History of Astronomy Section of the Astronomische Gesellschaft held on September 18 in Lilienthal, Germany. The book contains 13 articles on astronomical topics covering the 19th and 20th centuries. The first paper is by Guenther Oestmann and deals with contemporary assessments of Johann Hieronymus Schroeter's (1745-1816) astronomical works and with later judgements of the scientific importance and significance of his observations as seen by astronomers and historians. This report is complemented by a second article on Schroeter's 25-ft reflector in Lilienthal near Bremen. To this end, author Felix Luehning has constructed a scale model of the telescope, and shows how the building of a model brings a deeper understanding of function and handling of this instrument. This brings us to a third paper on telescope building in Lilienthal: Hans-Joachim Leue describes the cooperation of Johann Hieronymus Schroeter and Johann Gottlieb Schrader in developing a white reflecting metal alloy for use as telescope mirror. The fourth article, by Klaus Schillinger, describes on the basis of archival documents the aquisition history of the Herschel telescopes, including telescope quality check, repair and building. Memorial sites referring to Wilhelm Olbers, Johann Hieronymus Schroeter, Friedrich Wilhelm Bessel and Carl Friedrich Gauss are described by Arno Langkavel in two walks outlined in the very last paper of this book. Peter Brosche, in the fifth paper, discusses the rediscovery of Ceres in December1801, a discovery that was the result of the combined efforts of a theoretician (Gauss) and an observer (Zach). Juergen Hamel's paper is based on previously unused archival sources and discusses the outstanding role played by H. C. Schumacher (1780-1850, editor of the Astronomische Nachrichten) in the communication between
Investigations into Rare Earth Oxide Use and Behaviour
NASA Astrophysics Data System (ADS)
Pryce, Owen
2010-05-01
Quinton, 2008), and alternative REO extraction methods was compared using tagged and untagged soils. Extractions were also performed upon REO powders and a certified reference soil to identify which of the commonly used REOs are unsuitable for tracing studies. This paper will also report on investigations into the transport behaviour of REO tracers at different slope gradients, including comparisons between the transport of sediment bound phosphorus and REOs. References: Kimoto, A., Nearing, M., Shipitalo, M., Polyakov, V., 2006. Multi-year tracking of sediment sources in a small agricultural watershed using rare earth elements. Earth Surface Processes and Landforms, 31, pp.1763-1774. Li, M., Li, Z., Ding, W., Liu, P., Yao, W., 2006. Using rare earth element tracers and neutron activation analysis to study rill erosion processes. Applied Radiation and Isotopes, 64, pp.402-408. Polyakov, V., Nearing, M., Shipitalo, M., 2004. Tracking sediment redistribution in a small watershed: Implications for agro-landscape evolution. Earth Surface Processes and Landforms, 29, pp.1275-1291. Stevens, C., Quinton, J., 2008. Investigating source areas of eroded sediments transported in concentrated overland flow using rare earth element tracers. Catena, 74, pp.31-36. Zhang, X., Friedrich, J., Nearing, M., Norton, L., 2001. Potential use of Rare Earth Oxides as Tracers for Soil Erosion and Aggregation Studies. Soil Science Society of America Journal, 65, pp.1508-1515. Zhang, X., Nearing, M., Polyakov, V., Friedrich, J., 2003. Using Rare-Earth Oxide Tracers for Studying Soil Erosion Dynaimcs. Soil Science Society of America Journal, 67, pp.279-288.
Modelling past landslide-induced tsunami in Lake Geneva to evaluate the present threat
NASA Astrophysics Data System (ADS)
Franz, Martin; Jaboyedoff, Michel; Podladchikov, Yury
2014-05-01
In the south-eastern part of Lake Geneva, in the community of Meillerie, France, is located a forested depression, which indicates that a landslide occurred at this place in a distant past. It is a partially submerged slide composed of Trias to Jurassic carbonates. As its volume is greater than 10 mio m3, we assume that a potential brusque failure would have generated an impulse wave able to spread across the lake and reach the location of contemporary cities. Since this type of events is still likely to occur nowadays, this study aims to characterise the tsunami triggered by the past landslide event in order to know the potential wave height in populated places around the lake for events of similar magnitude. The volume of the displaced mass is estimated using the inverse Sloping Local Base Level (SLBL) by subtracting the pre-failure topography (built with the SLBL) to the actual one. In order to model landslide-triggered tsunami, it is necessary to be able to simulate the generation, the propagation of the wave in the lake and on the shores. This task is performed using a two-dimensional numerical model based on the shallow water equations. The Lax-Friedrichs scheme is used for the numerical stabilisation. The preliminary results indicate that the wave propagated across the lake up to distant places. As the shores are today extensively urbanised, in a similar case, they would be subject to catastrophic consequences. Thus, sensitivity tests are conducted for variation of the size and the velocities of the landslide in the model in order to give a distribution of the associated risks.
History of the Munich-Maisach-Fürstenfeldbruck Geomagnetic Observatory
NASA Astrophysics Data System (ADS)
Soffel, H. C.
2015-07-01
The Munich-Maisach-Fürstenfeldbruck Geomagnetic Observatory is one of the observatories with the longest recordings of the geomagnetic field. It started with hourly measurements on 1 August 1840. The founder of the observatory in Munich was Johann von Lamont (1805-1879), the Director of the Royal Bavarian Astronomical Observatory. He had been stimulated to build his own observatory by the initiative of the Göttingen Magnetic Union founded in 1834 by Alexander von Humboldt (1769-1859) and Carl Friedrich Gauss (1777-1855). Before 1840 fewer than five observatories existed; the most prominent ones were those in London and Paris. At the beginning Lamont used equipment delivered by Gauss in Göttingen, but soon started to build instruments of his own design. Among them was a nonmagnetic theodolite which allowed precise geomagnetic measurements to be made also in the field. During the 1850s Lamont carried out geomagnetic surveys and produced geomagnetic maps for Germany and many other European countries. At the end of the nineteenth century accurate geomagnetic measurements in Munich became more and more disturbed by the magnetic stray fields from electric tramways and industry. During this period the quality of the data suffered and the measurements had to be interrupted several times. After a provisional solution in Maisach, a village 25 km west of Munich, a final solution could be found in the vicinity of the nearby city of Fürstenfeldbruck. Here the measurements started again on 1 January 1939. Since the 1980s the observatory has been part of INTERMAGNET, an organization providing almost real-time geomagnetic data of the highest quality.
NASA Astrophysics Data System (ADS)
Betzinger, Markus; Friedrich, Christoph; Görling, Andreas; Blügel, Stefan
2012-06-01
The optimized-effective-potential method is a special technique to construct local Kohn-Sham potentials from general orbital-dependent energy functionals. In a recent publication [M. Betzinger, C. Friedrich, S. Blügel, A. Görling, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.83.045105 83, 045105 (2011)] we showed that uneconomically large basis sets were required to obtain a smooth local potential without spurious oscillations within the full-potential linearized augmented-plane-wave method. This could be attributed to the slow convergence behavior of the density response function. In this paper, we derive an incomplete-basis-set correction for the response, which consists of two terms: (1) a correction that is formally similar to the Pulay correction in atomic-force calculations and (2) a numerically more important basis response term originating from the potential dependence of the basis functions. The basis response term is constructed from the solutions of radial Sternheimer equations in the muffin-tin spheres. With these corrections the local potential converges at much smaller basis sets, at much fewer states, and its construction becomes numerically very stable. We analyze the improvements for rock-salt ScN and report results for BN, AlN, and GaN, as well as the perovskites CaTiO3, SrTiO3, and BaTiO3. The incomplete-basis-set correction can be applied to other electronic-structure methods with potential-dependent basis sets and opens the perspective to investigate a broad spectrum of problems in theoretical solid-state physics that involve response functions.
NASA Astrophysics Data System (ADS)
Klette, Reinhard
2000-10-01
The history of cell complexes is closely related to the birth and development of topology in general. Johann Benedict Listing (1802 - 1882) introduced the term 'topology' into mathematics in a paper published in 1847, and he also defined cell complexes for the first time in a paper published in 1862. Carl Friedrich Gauss (1777 - 1855) is often cited as the one who initiated these ideas, but he did not publish either on topology or on cell complexes. The pioneering work of Leonhard Euler (1707 - 1783) on graphs is also often cited as the birth of topology, and Euler's work was cited by Listing in 1862 as a stimulus for his research on cell complexes. There are different branches in topology which have little in common: point set topology, algebraic topology, differential topology etc. Confusion may arise if just 'topology' is specified, without clarifying the used concept. Topological subjects in mathematics are often related to continuous models, and therefore quite irrelevant to computer based solutions in image analysis. Compared to this, only a minority of topology publications in mathematics addresses discrete spaces which are appropriate for computer-based image analysis. In these cases, often the notion of a cell complex plays a crucial role. This paper briefly reports on a few of these publications. This paper is not intended to cover the very lively progress in cell complex studies within the context of image analysis during the last two decades. Basically it stops its historic review at the time when this subject in image analysis research gained speed in 1980 - 1990. As a general point of view, the paper indicates that image analysis contributes to a fusion of topological concepts, the geometric and the abstract cell structure approach and point set topology, which may lead towards new problems for the study of topologies defined on geometric or abstract cell complexes.
Analyzing numerics of bulk microphysics schemes in community models: warm rain processes
NASA Astrophysics Data System (ADS)
Sednev, I.; Menon, S.
2012-08-01
Implementation of bulk cloud microphysics (BLK) parameterizations in atmospheric models of different scales has gained momentum in the last two decades. Utilization of these parameterizations in cloud-resolving models when timesteps used for the host model integration are a few seconds or less is justified from the point of view of cloud physics. However, mechanistic extrapolation of the applicability of BLK schemes to the regional or global scales and the utilization of timesteps of hundreds up to thousands of seconds affect both physics and numerics. We focus on the mathematical aspects of BLK schemes, such as stability and positive-definiteness. We provide a strict mathematical definition for the problem of warm rain formation. We also derive a general analytical condition (SM-criterion) that remains valid regardless of parameterizations for warm rain processes in an explicit Eulerian time integration framework used to advanced finite-difference equations, which govern warm rain formation processes in microphysics packages in the Community Atmosphere Model and the Weather Research and Forecasting model. The SM-criterion allows for the existence of a unique positive-definite stable mass-conserving numerical solution, imposes an additional constraint on the timestep permitted due to the microphysics (like the Courant-Friedrichs-Lewy condition for the advection equation), and prohibits use of any additional assumptions not included in the strict mathematical definition of the problem under consideration. By analyzing the numerics of warm rain processes in source codes of BLK schemes implemented in community models we provide general guidelines regarding the appropriate choice of time steps in these models.
A unified discontinuous Galerkin framework for time integration.
Zhao, Shan; Wei, G W
2014-05-15
We introduce a new discontinuous Galerkin approach for time integration. On the basis of the method of weighted residual, numerical quadratures are employed in the finite element time discretization to account for general nonlinear ordinary differential equations. Many different conditions, including explicit, implicit, and symplectic conditions, are enforced for the test functions in the variational analysis to obtain desirable features of the resulting time-stepping scheme. The proposed discontinuous Galerkin approach provides a unified framework to derive various time-stepping schemes, such as low-order one-step methods, Runge-Kutta methods, and multistep methods. On the basis of the proposed framework, several explicit Runge-Kutta methods of different orders are constructed. The derivation of symplectic Runge-Kutta methods has also been realized. The proposed framework allows the optimization of new schemes in terms of several characteristics, such as accuracy, sparseness, and stability. The accuracy optimization is performed on the basis of an analytical form of the error estimation function for a linear test initial value problem. Schemes with higher formal order of accuracy are found to provide more accurate solutions. We have also explored the optimization potential of sparseness, which is related to the general compressive sensing in signal/imaging processing. Two critical dimensions of the stability region, that is, maximal intervals along the imaginary and negative real axes, are employed as the criteria for stability optimization. This gives the largest Courant-Friedrichs-Lewy time steps in solving hyperbolic and parabolic partial differential equations, respectively. Numerical experiments are conducted to validate the optimized time-stepping schemes. PMID:25382889
Ocean surface waves in an ice-free Arctic Ocean
NASA Astrophysics Data System (ADS)
Li, Jian-Guo
2016-08-01
The retreat of the Arctic ice edge implies that global ocean surface wave models have to be extended at high latitudes or even to cover the North Pole in the future. The obstacles for conventional latitude-longitude grid wave models to cover the whole Arctic are the polar problems associated with their Eulerian advection schemes, including the Courant-Friedrichs-Lewy (CFL) restriction on diminishing grid length towards the Pole, the singularity at the Pole and the invalid scalar assumption for vector components defined relative to the local east direction. A spherical multiple-cell (SMC) grid is designed to solve these problems. It relaxes the CFL restriction by merging the longitudinal cells towards the Poles. A round polar cell is used to remove the singularity of the differential equation at the Pole. A fixed reference direction is introduced to define vector components within a limited Arctic part in mitigation of the scalar assumption errors at high latitudes. The SMC grid has been implemented in the WAVEWATCH III model and validated with altimeter and buoy observations, except for the Arctic part, which could not be fully tested due to a lack of observations as the polar region is still covered by sea ice. Here, an idealised ice-free Arctic case is used to test the Arctic part and it is compared with a reference case with real ice coverage. The comparison indicates that swell wave energy will increase near the ice-free Arctic coastlines due to increased fetch. An expanded Arctic part is used for comparisons of the Arctic part with available satellite measurements. It also provides a direct model comparison between the two reference systems in their overlapping zone.
Abraham Pais Prize Talk: The Joy of History
NASA Astrophysics Data System (ADS)
Stuewer, Roger H.
2013-04-01
Physicists and historians of physics share a common goal, the quest for understanding, but their objects are different: Physicists attempt to understand Nature, while historians attempt to understand the past, finding both the challenge and joy of history in exploring the contingencies of historical events, their dependence on scientific, biographical, sociopolitical, cultural, and other factors, and shaping them into a coherent narrative. My first example will focus on the history of the photon concept, in particular on the work of Arthur Holly Compton between 1916 and 1922 that led to his discovery of the Compton effect, whose understanding ultimately rested on a close examination of his laboratory notebooks. I will then turn to two episodes in the history of nuclear physics. The first deals with a controversy between 1922 and 1927 between Ernest Rutherford and James Chadwick at the Cavendish Laboratory in Cambridge and Hans Pettersson and Gerhard Kirsch at the Institute for Radium Research in Vienna that involved their fundamentally different experimental observations and theoretical interpretations of the artificial disintegration of nuclei whose resolution could only be understood after uncovering crucial correspondence between the protagonists. The second episode traces George Gamow's creation and development of the liquid-drop model of the nucleus in 1928 and 1929 and its subsequent development in two stages, first by Werner Heisenberg and Carl Friedrich von Weizsäcker from 1933 to 1936, and second by Niels Bohr and Fritz Kalckar in 1936 and 1937, both of which merged in the minds of Lise Meitner and Otto Robert Frisch at the end of 1938 to yield the correct interpretation of nuclear fission, an act of creation whose understanding rested on a detailed analysis of the published literature.
Government intervention in child rearing: governing infancy.
Davis, Robert A
2010-01-01
In this essay, Robert Davis argues that much of the moral anxiety currently surrounding children in Europe and North America emerges at ages and stages curiously familiar from traditional Western constructions of childhood. The symbolism of infancy has proven enduringly effective over the last two centuries in associating the earliest years of children's lives with a peculiar prestige and aura. Infancy is then vouchsafed within this symbolism as a state in which all of society's hopes and ideals for the young might somehow be enthusiastically invested, regardless of the complications that can be anticipated in the later, more ambivalent years of childhood and adolescence. According to Davis, the understanding of the concept of infancy associated with the rise of popular education can trace its pedigree to a genuine shift in sensibility that occurred in the middle of the eighteenth century. After exploring the essentially Romantic positions of Johann Heinrich Pestalozzi and Friedrich Fröbel and their relevance to the pattern of reform of early childhood education in the United Kingdom and the United States, Davis also assesses the influence of figures such as Stanley Hall and John Dewey in determining the rationale for modern early childhood education. A central contention of Davis's essay is that the assumptions evident in the theory and practice of Pestalozzi and his followers crystallize a series of tensions in the understanding of infancy and infant education that have haunted early childhood education from the origins of popular schooling in the late eighteenth century down to the policy dilemmas of the present day. PMID:20662168
Ocean surface waves in an ice-free Arctic Ocean
NASA Astrophysics Data System (ADS)
Li, Jian-Guo
2016-06-01
The retreat of the Arctic ice edge implies that global ocean surface wave models have to be extended at high latitudes or even to cover the North Pole in the future. The obstacles for conventional latitude-longitude grid wave models to cover the whole Arctic are the polar problems associated with their Eulerian advection schemes, including the Courant-Friedrichs-Lewy (CFL) restriction on diminishing grid length towards the Pole, the singularity at the Pole and the invalid scalar assumption for vector components defined relative to the local east direction. A spherical multiple-cell (SMC) grid is designed to solve these problems. It relaxes the CFL restriction by merging the longitudinal cells towards the Poles. A round polar cell is used to remove the singularity of the differential equation at the Pole. A fixed reference direction is introduced to define vector components within a limited Arctic part in mitigation of the scalar assumption errors at high latitudes. The SMC grid has been implemented in the WAVEWATCH III model and validated with altimeter and buoy observations, except for the Arctic part, which could not be fully tested due to a lack of observations as the polar region is still covered by sea ice. Here, an idealised ice-free Arctic case is used to test the Arctic part and it is compared with a reference case with real ice coverage. The comparison indicates that swell wave energy will increase near the ice-free Arctic coastlines due to increased fetch. An expanded Arctic part is used for comparisons of the Arctic part with available satellite measurements. It also provides a direct model comparison between the two reference systems in their overlapping zone.
A fully implicit dynamo model for long-term evolution of the geomagnetic field
NASA Astrophysics Data System (ADS)
Zhan, X.; Chen, R.; Cai, X. C.; Zhang, K.
2014-12-01
In this work, we present a Newton-Krylov-Schwarz (NKS) based parallel implicit solver for the governing equations of Earth's dynamo. NKS is a general purpose parallel solver for nonlinear systems and has been widely applied to solve different kinds of nonlinear problems. All previously published dynamo models treat nonlinear terms of dynamo governing equations in an explicit or semi-explicit manner, consequently, the numerical schemes are constrained by the Courant-Friedrichs-Lewy (CFL) condition. To ensure numerical stability, time step sizes should be rather small, especially for high-resolution dynamo simulations, which makes it impractical to use high-resolution dynamo models to study long term evolution of the geomagnetic field, such as reversals and superchrons. To avoid the time step size constraint imposed by CFL numbers associated with fine spacial mesh sizes, we try a fully implicit method and focus on efficiently solving the large nonlinear system at each time step on large scale parallel computers. Our algorithm begins with a discretization of the governing equations on an unstructured tetrahedron mesh with a stable finite element method in space and a fully implicit backward difference scheme in time. At each time step, an inexact Newton method is employed to solve the discretized large sparse nonlinear system while in the Newton steps, a domain decomposition preconditioned Krylov method is used to solve the Jacobian system which is constructed analytically in order to obtain the desired performance. Our numerical model is tested against known standard dynamo solutions at a moderate Ekman number. Additionally, numerical experiments show that our model has super-linear scalability with over eight thousand processors for dynamo problems with tens of millions of unknowns.
Hildebrand, Reinhard
2005-11-01
The Leipzig anatomist and physiologist Ernst Heinrich Weber had introduced physiological thinking in anatomy and exact methods of mathematical physics to the study of the functioning of the body making him the founder of a physically orientated physiology. But he would not have been that excellent physiologist without being a nonetheless distinguished anatomist since he solved his physiological problems usually following function in close relation to structure. Together with his brother Wilhelm Eduard Weber (1804-1891), who later was to become a famous physicist, in their theory of waves he laid the basis for an exact analysis of the movements of fluids in elastic tubes und was the first to apply the basic laws of hydrodynamics to the circulation of the blood. In collaboration with his youngest brother Eduard Friedrich Wilhelm Weber (1806-1871), who worked as a prosector at his institute and together with Wilhelm Weber had studied the mechanics of the walking apparatus, he demonstrated the inhibiting effect of the vagus nerve on the action of the heart. Ernst Heinrich Weber's approach to consider an organ as a whole not neglecting the study of its function set him apart from most of his contemporaries and has characterized the work of the Leipzig anatomists and physiologists since his time. Among those was Wilhelm His from Basle who succeeded him in the chair of anatomy in 1872. On the basis of a systematic analysis of human embryos by means of serial sections and plastic reconstruction His completely reformed the field of embryology and was the first to present a comprehensive treatise on human embryology. The making of modern human embryology was, above all, his achievement. He did not confine himself to mere description but wanted to gain deeper insight into the causal events by developmental-mechanical conceptions. With his detection of the neuroblasts and that they give rise to an axon and later to dendrites His provided the developmental foundations for the
[Carl Gillmeister: the first Doctor of veterinary medicine in Mecklenburg--and in Germany (1834)].
Kuhlmann, W; Schäffer, J
2004-02-01
German schools and faculties of veterinary medicine did not receive the sovereign right to award the degree "Doctor medicinae veterinarae" until the early twentieth century. Until then, in the nineteenth century there were two possibilities for veterinarians to earn a doctoral degree, usually referred to as the title of "Doctor": 1. On the basis of an exceptionally excellent dissertation and after very stringent examination a candidate could be awarded the degree "Dr. med." by the faculty of a medical school, or, if the candidate had studied at a philosophical faculty, the degree "Dr. phil." 2. A doctoral degree specifically in veterinary medicine could be earned only at a medical faculty. The Medical Faculty of the University of Giessen awarded the degree "Doctor in arte veterinaria" for the first time in 1832. In this study we prove that Giessen was not the first German university to award a doctorate in veterinary medicine, a priority which has never been questioned in the literature. As early as 1829, veterinarians could earn the degree "Doctor artis veterinariae" at the Medical Faculty of the University of Rostock, where three such awards are documented between 1829 and 1831. The designation "medicina" was also intially avoided in Rostock. Therefore, of particular significance is the discovery of a fourth such document from the Rostock University Archives, the doctoral diploma of Carl Jacob Friedrich Gillmeister, who at the age of 22 was awarded the degree "Doctor medicinae veterinariae" in Rostock after a successful defense. This is the earliest, but also the last archival record of the German doctoral degree in veterinary medicine in the modern sense, because after Gillmeister no veterinarian could earn a doctoral degree in Rostock further more. Gillmeisters vita sheds light on the times and the difficulties of the veterinary profession in the poor agricultural area of Mecklenburg. PMID:15032266
Optical properties of Si and Ge nanocrystals: Parameter-free calculations
NASA Astrophysics Data System (ADS)
Ramos, L. E.; Weissker, H.-Ch.; Furthmüller, J.; Bechstedt, F.
2005-12-01
The cover picture of the current issue refers to the Edi-tor's Choice article of Ramos et al. [1]. The paper gives an overview of the electronic and optical properties of silicon and germanium nanocrystals determined by state-of-the-art ab initio methods. Nanocrystals have promising applications in opto-electronic devices, since they can be used to confine electrons and holes and facilitate radiative recombination. Since meas-urements for single nanoparticles are difficult to make, ab initio theoretical investigations become important to understand the mechanisms of luminescence.The cover picture shows nanocrystals of four sizes with tetrahedral coordination whose dangling bonds at the surface are passivated with hydrogen. As often observed in experiments, the nanocrystals are not perfectly spherical, but contain facets. Apart from the size of the nanocrystals, which determines the quantum confinement, the way their dangling bonds are passivated is relevant for their electronic and optical properties. For instance, the passivation with hydroxyls reduces the quantum confine-ment. On the other hand, the oxidation of the silicon nanocrys-tals increases the quantum confinement and reduces the effect of single surface terminations on the gap. Due to the oscillator strengths of the lowest-energy optical transitions, Ge nanocrys-tals are in principle more suitable for opto-electronic applica-tions than Si nanocrystals.The first author, Luis E. Ramos, is a postdoc at the Institute of Solid-State Physics and Optics (IFTO), Friedrich-Schiller University Jena, Germany. He investigates electronic and optical properties of semiconductor nanocrystallites and is a member of the European Network of Excellence NANO-QUANTA and of the European Theoretical Spectroscopy Facility (ETSF).
Evaluating the performance of the particle finite element method in parallel architectures
NASA Astrophysics Data System (ADS)
Gimenez, Juan M.; Nigro, Norberto M.; Idelsohn, Sergio R.
2014-05-01
This paper presents a high performance implementation for the particle-mesh based method called particle finite element method two (PFEM-2). It consists of a material derivative based formulation of the equations with a hybrid spatial discretization which uses an Eulerian mesh and Lagrangian particles. The main aim of PFEM-2 is to solve transport equations as fast as possible keeping some level of accuracy. The method was found to be competitive with classical Eulerian alternatives for these targets, even in their range of optimal application. To evaluate the goodness of the method with large simulations, it is imperative to use of parallel environments. Parallel strategies for Finite Element Method have been widely studied and many libraries can be used to solve Eulerian stages of PFEM-2. However, Lagrangian stages, such as streamline integration, must be developed considering the parallel strategy selected. The main drawback of PFEM-2 is the large amount of memory needed, which limits its application to large problems with only one computer. Therefore, a distributed-memory implementation is urgently needed. Unlike a shared-memory approach, using domain decomposition the memory is automatically isolated, thus avoiding race conditions; however new issues appear due to data distribution over the processes. Thus, a domain decomposition strategy for both particle and mesh is adopted, which minimizes the communication between processes. Finally, performance analysis running over multicore and multinode architectures are presented. The Courant-Friedrichs-Lewy number used influences the efficiency of the parallelization and, in some cases, a weighted partitioning can be used to improve the speed-up. However the total cputime for cases presented is lower than that obtained when using classical Eulerian strategies.
A marching in space and time (MAST) solver of the shallow water equations. Part I: The 1D model
NASA Astrophysics Data System (ADS)
Aricò, C.; Tucciarelli, T.
2007-05-01
A new approach is presented for the numerical solution of the complete 1D Saint-Venant equations. At each time step, the governing system of partial differential equations (PDEs) is split, using a fractional time step methodology, into a convective prediction system and a diffusive correction system. Convective prediction system is further split into a convective prediction and a convective correction system, according to a specified approximated potential. If a scalar exact potential of the flow field exists, correction vanishes and the solution of the convective correction system is the same solution of the prediction system. Both convective prediction and correction systems are shown to have at each x - t point a single characteristic line, and a corresponding eigenvalue equal to the local velocity. A marching in space and time (MAST) technique is used for the solution of the two systems. MAST solves a system of two ordinary differential equations (ODEs) in each computational cell, using for the time discretization a self-adjusting fraction of the original time step. The computational cells are ordered and solved according to the decreasing value of the potential in the convective prediction step and to the increasing value of the same potential in the convective correction step. The diffusive correction system is solved using an implicit scheme, that leads to the solution of a large linear system, with the same order of the cell number, but sparse, symmetric and well conditioned. The numerical model shows unconditional stability with regard of the Courant-Friedrichs-Levi (CFL) number, requires no special treatment of the source terms and a computational effort almost proportional to the cell number. Several tests have been carried out and results of the proposed scheme are in good agreement with analytical solutions, as well as with experimental data.
First occurrence of Culicoides obsoletus-transmitted Bluetongue virus epidemic in Central Europe.
Mehlhorn, Heinz; Walldorf, Volker; Klimpel, Sven; Jahn, Birgit; Jaeger, Friedhelm; Eschweiler, Josef; Hoffmann, Bernd; Beer, Martin
2007-06-01
In August 2006, Bluetongue virus disease (BTD) was detected for the first time in the Netherlands, Belgium, Germany and Northern France. Serological tests as well as reverse transcriptase polymerase chain reaction (RT-PCR) proved the occurrence of Bluetongue virus (BTV) in diseased sheep and cattle, and the virus was identified as serotype 8. Therefore, the search for possible vectors was immediately initiated in the outbreak region in Germany. Traps with automatically regulated ultraviolet light lamps were placed at two different farms with sero-positive cattle, and insect monitoring was done from August 2006 until January 2007. The caught arthropods were weekly determined, and it could be observed that midges of the dipteran family Ceratopogonidae occurred in large numbers, sometimes representing up to 40% of all individuals. The microscopical analysis of the wing morphology showed that the species (complex) Culicoides obsoletus was most abundant covering about 97% of the analysed midges. On the second place ranged C. pulicaris, while C. nubeculosus and C. festivipennis were found only as single individuals. Fed and unfed females were separated, sent to the National Reference Laboratory for Bluetongue disease (Friedrich-Loeffler-Institut, Isle of Riems, Germany) and investigated with a BTV-8-specific real-time RT-PCR. It could be demonstrated that at both farms both fed and unfed C. obsoletus were tested positive for BTV-8 genomes, while none of the other species scored positive. This finding strongly supports that the BTD-epidemic, which reached in the meantime wide regions of North Rhine-Westphalia in Germany and of the neighbouring countries with several hundreds of affected farms, is initiated by virus transmission during the blood meal of midges of the C. obsoletus complex. Since they were captured still at the 21st of December close to cattle with clinical signs, it must be feared that BTV-8 is now established in Central Europe, where it had been absent
NASA Technical Reports Server (NTRS)
Yee, H. C.
1995-01-01
Two classes of explicit compact high-resolution shock-capturing methods for the multidimensional compressible Euler equations for fluid dynamics are constructed. Some of these schemes can be fourth-order accurate away from discontinuities. For the semi-discrete case their shock-capturing properties are of the total variation diminishing (TVD), total variation bounded (TVB), total variation diminishing in the mean (TVDM), essentially nonoscillatory (ENO), or positive type of scheme for 1-D scalar hyperbolic conservation laws and are positive schemes in more than one dimension. These fourth-order schemes require the same grid stencil as their second-order non-compact cousins. One class does not require the standard matrix inversion or a special numerical boundary condition treatment associated with typical compact schemes. Due to the construction, these schemes can be viewed as approximations to genuinely multidimensional schemes in the sense that they might produce less distortion in spherical type shocks and are more accurate in vortex type flows than schemes based purely on one-dimensional extensions. However, one class has a more desirable high-resolution shock-capturing property and a smaller operation count in 3-D than the other class. The extension of these schemes to coupled nonlinear systems can be accomplished using the Roe approximate Riemann solver, the generalized Steger and Warming flux-vector splitting or the van Leer type flux-vector splitting. Modification to existing high-resolution second- or third-order non-compact shock-capturing computer codes is minimal. High-resolution shock-capturing properties can also be achieved via a variant of the second-order Lax-Friedrichs numerical flux without the use of Riemann solvers for coupled nonlinear systems with comparable operations count to their classical shock-capturing counterparts. The simplest extension to viscous flows can be achieved by using the standard fourth-order compact or non-compact formula
Tepper, J; Schäfer, R; Hoffmann, A
1995-12-01
Analysis of indication-related drug prescription patterns is of particular interest with regard to rising costs of the health service being also reflected in higher expenditures for drugs at the University Hospital of the Friedrich-Schiller-University Jena. This is especially important at ICU's, since treatments in patients with acute or chronic multiorgan failure are very expensive. Over a period of 4 months in 1994 the indication-related drug consumption of 2 surgical ICU's of the University of Jena has been recorded and analyzed using a notebook-PC. The total costs of these drugs and blood products, which caused 80% of total costs in the last year, came up to 1,144,773 DM for 465 patients. Nearly two thirds of the recorded expenditures were caused in patients with severe trauma or with acute bleeding. The 10 leading substances (antithrombin III, human albumin 20%, prothrombine complex, etc.) represent 67% of total costs including blood products, antibiotics/antimycotics and IgM enriched intravenous immunoglobulines. Therefore, the indications of these drugs in particular have been further investigated. During and after the study the results have been discussed with the treating medical staff leading to new therapy recommendations. Until the end of 1994 a remarkable cost saving could already be achieved for some drugs by more critical and purposeful use providing same high standard of medical treatment. Blood products have to be included into analyses of indication-related drug administration on the meaning of high costs, difficulties of accurate indication, and possibly undesired side-effects. However, medical and ethical aspects, e.g. minimizing of side-effects, have to take priority over pharmacoeconomical considerations especially in intensive care medicine. PMID:8963483
Baumann, Nils; Arnold, Thuro; Haferburg, Götz
2014-01-01
Uranium concentrations in cultivated (sunflower, sunchoke, potato) and native plants, plant compartment specimens, and mushrooms, grown on a test site within a uranium-contaminated area in Eastern Thuringia, were analyzed and compared. This test site belongs to the Friedrich-Schiller University Jena and is situated on the ground of a former but now removed uranium mine waste leaching heap. For determination of the U concentrations in the biomaterials, the saps of the samples were squeezed out by using an ultracentrifuge, after that, the uranium concentrations in the saps and the remaining residue were measured, using ICP-MS. The study further showed that uranium concentrations observed in plant compartment and mushroom fruiting bodies sap samples were always higher than their associated solid residue sample. Also, it was found that the detected uranium concentration in the root samples were always higher than were observed in their associated above ground biomass, e.g., in shoots, leaves, blossoms etc. The highest uranium concentration was measured with almost 40 ppb U in a fruiting body of a mushroom and in roots of butterbur. However, the detected uranium concentrations in plants and mushrooms collected in this study were always lower than in the associated surface and soil water of the test site, indicating that under the encountered natural conditions, none of the studied plant and mushroom species turned out to be a hyperaccumulator for uranium, which could have extracted uranium in sufficient amounts out of the uranium-contaminated soil. In addition, it was found that the detected uranium concentrations in the sap samples, despite being above the sensitivity limit, proved to be too low-in combination with the presence of fluorescence quenching substances, e.g., iron and manganese ions, and/or organic quenchers-to extract a useful fluorescence signal, which could have helped to identify the uranium speciation in plants. PMID:23812734
NASA Astrophysics Data System (ADS)
Stökl, A.
2008-11-01
Context: In spite of all the advances in multi-dimensional hydrodynamics, investigations of stellar evolution and stellar pulsations still depend on one-dimensional computations. This paper devises an alternative to the mixing-length theory or turbulence models usually adopted in modelling convective transport in such studies. Aims: The present work attempts to develop a time-dependent description of convection, which reflects the essential physics of convection and that is only moderately dependent on numerical parameters and far less time consuming than existing multi-dimensional hydrodynamics computations. Methods: Assuming that the most extensive convective patterns generate the majority of convective transport, the convective velocity field is described using two parallel, radial columns to represent up- and downstream flows. Horizontal exchange, in the form of fluid flow and radiation, over their connecting interface couples the two columns and allows a simple circulating motion. The main parameters of this convective description have straightforward geometrical meanings, namely the diameter of the columns (corresponding to the size of the convective cells) and the ratio of the cross-section between up- and downdrafts. For this geometrical setup, the time-dependent solution of the equations of radiation hydrodynamics is computed from an implicit scheme that has the advantage of being unaffected by the Courant-Friedrichs-Lewy time-step limit. This implementation is part of the TAPIR-Code (short for The adaptive, implicit RHD-Code). Results: To demonstrate the approach, results for convection zones in Cepheids are presented. The convective energy transport and convective velocities agree with expectations for Cepheids and the scheme reproduces both the kinetic energy flux and convective overshoot. A study of the parameter influence shows that the type of solution derived for these stars is in fact fairly robust with respect to the constitutive numerical
Zambrano, L.; Vazquez-Dominguez, E.; Garcia-Bedoya, D.; Loftus, W.F.; Trexler, J.C.
2006-01-01
We evaluated the relationship between limnetic characteristics and fish community structure (based on species richness, abundance and individual size) in contrasting but interconnected inland aquatic habitats of freshwater karstic wetlands in the Yucatan peninsula, Mexico. In the western hemisphere, freshwater karstic wetlands are found in south-eastern Mexico, northern Belize, western Cuba, Andros Island, Bahamas and the Everglades of southern Florida. Only in the Everglades have fish communities been well described. Karstic wetlands are typically oligotrophic because calcium carbonate binds phosphorus, making it relatively unavailable for plants. Fourteen permanent and seasonally flooded water bodies were sampled in both wet and dry seasons in Sian Ka'an Biosphere Reserve, in the Mexican state of Quintana Roo. Water systems were divided by morphology in four groups: cenotes with vegetation (CWV), cenotes without vegetation (CNV), wetlands (WTL), and temporal cenotes (TPC). Discriminant analysis based on physical characteristics such as turbidity, temperature, depth and oxygen confirmed that these habitats differed in characteristics known to influence fish communities. A sample-based rarefaction test showed that species richness was significantly different between water systems groups, showing that WTL and CWV had higher richness values than CNV and TPC. The most abundant fish families, Poeciliidae, Cichlidae and Characidae, differed significantly in average size among habitats and seasons. Seasonal and inter-annual variation, reflecting temporal variation in rainfall, strongly influenced the environmental differences between shallow and deep habitats, which could be linked to fish size and life cycles. Five new records of species were found for the reserve, and one new record for Quintana Roo state. ?? 2006 by Verlag Dr. Friedrich Pfeil.
Global transonic conic shock wave for the symmetrically perturbed supersonic flow past a cone
NASA Astrophysics Data System (ADS)
Xu, Gang; Yin, Huicheng
In this paper, we are concerned with the global existence and stability of a steady transonic conic shock wave for the symmetrically perturbed supersonic flow past an infinitely long conic body. The flow is assumed to be polytropic, isentropic and described by a steady potential equation. Theoretically, as indicated in [R. Courant, K.O. Friedrichs, Supersonic Flow and Shock Waves, Interscience Publishers, Inc., New York, 1948], it follows from the Rankine-Hugoniot conditions and the entropy condition that there will appear a weak shock or a strong shock attached at the vertex of the sharp cone in terms of the different pressure states at infinity behind the shock surface, which correspond to the supersonic shock and the transonic shock respectively. In the references [Shuxing Chen, Zhouping Xin, Huicheng Yin, Global shock wave for the supersonic flow past a perturbed cone, Comm. Math. Phys. 228 (2002) 47-84; Dacheng Cui, Huicheng Yin, Global conic shock wave for the steady supersonic flow past a cone: Polytropic case, preprint, 2006; Dacheng Cui, Huicheng Yin, Global conic shock wave for the steady supersonic flow past a cone: Isothermal case, Pacific J. Math. 233 (2) (2007) 257-289] and [Zhouping Xin, Huicheng Yin, Global multidimensional shock wave for the steady supersonic flow past a three-dimensional curved cone, Anal. Appl. 4 (2) (2006) 101-132], the authors have established the global existence and stability of a supersonic shock for the perturbed hypersonic incoming flow past a sharp cone when the pressure at infinity is appropriately smaller than that of the incoming flow. At present, for the supersonic symmetric incoming flow, we will study the global transonic shock problem when the pressure at infinity is appropriately large.
Mechanistic aspects of the solid-state transformation of ammonium cyanate to urea at high pressure.
Méreau, Raphael; Desmedt, Arnaud; Harris, Kenneth D M
2007-04-19
The chemical transformation of ammonium cyanate into urea has been of interest to many generations of scientists since its discovery by Friedrich Wöhler in 1828. Although widely studied both experimentally and theoretically, several mechanistic aspects of this reaction remain to be understood. In this paper, we apply computational methods to investigate the behavior of ammonium cyanate in the solid state under high pressure, employing a theoretical approach based on the self-consistent-charges density-functional tight-binding method (SCC-DFTB). The ammonium cyanate crystal structure was relaxed under external pressure ranging from 0 to 700 GPa, leading to the identification of five structural phases. Significantly, the phase at highest pressure (above 535 GPa) corresponds to the formation of urea molecules. At ca. 25 GPa, there is a phase transition of ammonium cyanate (from tetragonal P4/nmm to monoclinic P21/m) involving a rearrangement of the ammonium cyanate molecules. This transformation is critical for the subsequent transformation to urea. The crystalline phase of urea obtained above 535 GPa also has P21/m symmetry (Z = 2). This polymorph of urea has never been reported previously. Comparisons to the known (tetragonal) polymorph of urea found experimentally at ambient pressure suggests that the new polymorph is more stable above ca. 8 GPa. Our computational studies show that the transformation of ammonium cyanate into urea is strongly exothermic (enthalpy change -170 kJ mol-1 per formula unit between 530 and 535 GPa). The proposed mechanism for this transformation involves the transfer of two hydrogen atoms of the ammonium cation toward nitrogen atoms of neighboring cyanate anions, and the remaining NH2 group creates a C-NH2 bond with the cyanate unit. PMID:17388562
A Detector Radioactive Particles Can't Evade
Hazi, A U
2007-02-12
As part of its national security mission, Lawrence Livermore develops technologies to help government agencies prevent terrorists from smuggling nuclear materials into the country. One ongoing effort is to design radiation detectors that can distinguish threat sources from legitimate sources, such as medical isotopes, and naturally occurring radiation. (See S&TR, September 2004, pp. 4-11; May 2006, pp. 4-10.) Detectors intended for use by nonspecialists must be easy to operate and require minimal maintenance. To be most effective, they also must detect both gamma and neutron energies. That may sound like a lot to ask of one instrument, but the Ultrahigh-Resolution Gamma and Neutron Spectrometer (UltraSpec) delivers all of these features. UltraSpec is so sensitive that even the minute thermal energy deposited by a single gamma ray or neutron can be detected with high precision. With this capability, the detector can identify differences in composition that help reveal a material's origin, processing history, and likely intended use. In addition to its application as a counterterrorism technology, UltraSpec can be used to protect nuclear material stored at nuclear power plants, to evaluate weapon stockpiles, and to verify material composition. UltraSpec was developed by a team of scientists and engineers from Livermore's Physics and Advanced Technologies and Engineering directorates working with VeriCold Technologies of Ismaning, Germany. The detector's design builds on a technology base established in three Laboratory Directed Research and Development projects. The UltraSpec team, which is led by Laboratory physicist Stephan Friedrich, received a 2006 R&D 100 Award for the detector's innovative design.
Capacitive Soil Moisture Sensor for Plant Watering
NASA Astrophysics Data System (ADS)
Maier, Thomas; Kamm, Lukas
2016-04-01
How can you realize a water saving and demand-driven plant watering device? To achieve this you need a sensor, which precisely detects the soil moisture. Designing such a sensor is the topic of this poster. We approached this subject with comparing several physical properties of water, e.g. the conductivity, permittivity, heat capacity and the soil water potential, which are suitable to detect the soil moisture via an electronic device. For our project we have developed a sensor device, which measures the soil moisture and provides the measured values for a plant watering system via a wireless bluetooth 4.0 network. Different sensor setups have been analyzed and the final sensor is the result of many iterative steps of improvement. In the end we tested the precision of our sensor and compared the results with theoretical values. The sensor is currently being used in the Botanical Garden of the Friedrich-Alexander-University in a long-term test. This will show how good the usability in the real field is. On the basis of these findings a marketable sensor will soon be available. Furthermore a more specific type of this sensor has been designed for the EU:CROPIS Space Project, where tomato plants will grow at different gravitational forces. Due to a very small (15mm x 85mm x 1.5mm) and light (5 gramm) realisation, our sensor has been selected for the space program. Now the scientists can monitor the water content of the substrate of the tomato plants in outer space and water the plants on demand.
The slowly pulsating B-star 18 Pegasi: A testbed for upper main sequence stellar evolution
NASA Astrophysics Data System (ADS)
Irrgang, A.; Desphande, A.; Moehler, S.; Mugrauer, M.; Janousch, D.
2016-06-01
The predicted width of the upper main sequence in stellar evolution models depends on the empirical calibration of the convective overshooting parameter. Despite decades of discussions, its precise value is still unknown and further observational constraints are required to gauge it. Based on a photometric and preliminary asteroseismic analysis, we show that the mid B-type giant 18 Peg is one of the most evolved members of the rare class of slowly pulsating B-stars and, thus, bears tremendous potential to derive a tight lower limit for the width of the upper main sequence. In addition, 18 Peg turns out to be part of a single-lined spectroscopic binary system with an eccentric orbit that is greater than 6 years. Further spectroscopic and photometric monitoring and a sophisticated asteroseismic investigation are required to exploit the full potential of this star as a benchmark object for stellar evolution theory. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 265.C-5038(A), 069.C-0263(A), and 073.D-0024(A). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), proposals H2005-2.2-016 and H2015-3.5-008. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, proposal W15BN015. Based on observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University.
["Fiction and Truth": Goethe's anatomical research at the University of Jena].
Schäfer, H H; Sivukhina, E; Dölz, W; Oehring, H
2012-12-01
Johann Wolfgang von Goethe was one of the most renowned German poets of the late Age of Enlightenment. However, his engagement went far beyond literature especially relating to politics and natural science. Goethe, primarily trained as a lawyer, developed his own theory of colors and even challenged the concepts of Isaac Newton. His discovery of the human intermaxilary bone questioned all the dogmas of the religious-minded world of the 18th century. Together with the anatomy professor Justus Christian Loder, Goethe performed comparative anatomy and proved the conceptual uniformity of humans and animals on 27 March 1784. Even though, Félix Vicq d'Azyr described the intermaxilary bone simultaneously in Catholic France, Goethe's findings were politically accepted due to the liberal Protestantism of the Duchy of Weimar. Nevertheless, leading anatomists of the century (Johann Friedrich Blumenbach, Petrus Camper and Samuel Thomas v. Soemmerring) mainly rejected Goethe's postulates which led to a delayed publication in 1820; almost 36 years after writing his original manuscript. Today, Goethe's discovery is known to be a fundamental basis for the development of Charles Darwin's theory of phylogenetic evolution. Nowadays, the Department of Anatomy contains the Museum Anatomicum Jenense which was founded by the Duke of Weimar, Carl August and Goethe and entails Goethe's premaxillary bones as its main attraction. The University values the cultural heritage of Goethe's contribution to Medicine and provides access to the collection to the public and generations of medical students. Still today Goethe's legacy is noticeable in the halls of the Alma Mater Jenensis. PMID:23233304
Oral Histories in Meteoritics and Planetary Science—XIX: Klaus Keil
NASA Astrophysics Data System (ADS)
Sears, Derek W. G.
2012-12-01
Abstract- Klaus Keil (Fig. 1) grew up in Jena and became interested in meteorites as a student of Fritz Heide. His research for his Dr. rer. nat. became known to Hans Suess who--with some difficulty--arranged for him to move to La Jolla, via Mainz, 6 months before the borders of East Germany were closed. In La Jolla, Klaus became familiar with the electron microprobe, which has remained a central tool in his research and, with Kurt Fredriksson, he confirmed the existence of Urey and Craig's chemical H and L chondrite groups, and added a third group, the LL chondrites. Klaus then moved to NASA Ames where he established a microprobe laboratory, published his definitive paper on enstatite chondrites, and led in the development of the Si(Li) detector and the EDS method of analysis. After 5 years at Ames, Klaus became director of the Institute of Meteoritics at the University of New Mexico where he built up one of the leading meteorite research groups while working on a wide variety of projects, including chondrite groups, chondrules, differentiated meteorites, lunar samples, and Hawai'ian basalts. The basalt studies led to a love of Hawai'i and a move to the University of Hawai'i in 1990, where he has continued a wide variety of meteorite projects, notably the role of volcanism on asteroids. Klaus Keil has received honorary doctorates from Friedrich-Schiller University, Jena, and the University of New Mexico, Albuquerque. He was President of the Meteoritical Society in 1969-1970 and was awarded the Leonard Medal in 1988.
Transonic Shock Problem for the Euler System in a Nozzle
NASA Astrophysics Data System (ADS)
Xin, Zhouping; Yan, Wei; Yin, Huicheng
2009-10-01
In this paper, we study the well-posedness problem on transonic shocks for steady ideal compressible flows through a two-dimensional slowly varying nozzle with an appropriately given pressure at the exit of the nozzle. This is motivated by the following transonic phenomena in a de Laval nozzle. Given an appropriately large receiver pressure P r , if the upstream flow remains supersonic behind the throat of the nozzle, then at a certain place in the diverging part of the nozzle, a shock front intervenes and the flow is compressed and slowed down to subsonic speed, and the position and the strength of the shock front are automatically adjusted so that the end pressure at exit becomes P r , as clearly stated by Courant and Friedrichs [Supersonic flow and shock waves, Interscience Publishers, New York, 1948 (see section 143 and 147)]. The transonic shock front is a free boundary dividing two regions of C 2,α flow in the nozzle. The full Euler system is hyperbolic upstream where the flow is supersonic, and coupled hyperbolic-elliptic in the downstream region Ω+ of the nozzle where the flow is subsonic. Based on Bernoulli’s law, we can reformulate the problem by decomposing the 3 × 3 Euler system into a weakly coupled second order elliptic equation for the density ρ with mixed boundary conditions, a 2 × 2 first order system on u 2 with a value given at a point, and an algebraic equation on ( ρ, u 1, u 2) along a streamline. In terms of this reformulation, we can show the uniqueness of such a transonic shock solution if it exists and the shock front goes through a fixed point. Furthermore, we prove that there is no such transonic shock solution for a class of nozzles with some large pressure given at the exit.
Implicit and semi-implicit schemes: Algorithms
NASA Astrophysics Data System (ADS)
Keppens, R.; Tóth, G.; Botchev, M. A.; van der Ploeg, A.
1999-06-01
This study formulates general guidelines to extend an explicit code with a great variety of implicit and semi-implicit time integration schemes. The discussion is based on their specific implementation in the Versatile Advection Code, which is a general purpose software package for solving systems of non-linear hyperbolic (and/or parabolic) partial differential equations, using standard high resolution shock capturing schemes. For all combinations of explicit high resolution schemes with implicit and semi-implicit treatments, it is shown how second-order spatial and temporal accuracy for the smooth part of the solutions can be maintained. Strategies to obtain steady state and time accurate solutions implicitly are discussed. The implicit and semi-implicit schemes require the solution of large linear systems containing the Jacobian matrix. The Jacobian matrix itself is calculated numerically to ensure the generality of this implementation. Three options are discussed in terms of applicability, storage requirements and computational efficiency. One option is the easily implemented matrix-free approach, but the Jacobian matrix can also be calculated by using a general grid masking algorithm, or by an efficient implementation for a specific Lax-Friedrich-type total variation diminishing (TVD) spatial discretization. The choice of the linear solver depends on the dimensionality of the problem. In one dimension, a direct block tridiagonal solver can be applied, while in more than one spatial dimension, a conjugate gradient (CG)-type iterative solver is used. For advection-dominated problems, preconditioning is needed to accelerate the convergence of the iterative schemes. The modified block incomplete LU-preconditioner is implemented, which performs very well. Examples from two-dimensional hydrodynamic and magnetohydrodynamic computations are given. They model transonic stellar outflow and recover the complex magnetohydrodynamic bow shock flow in the switch-on regime
Horizontal pendulum development and the legacy of Ernst von Rebeur-Paschwitz
NASA Astrophysics Data System (ADS)
Fréchet, Julien; Rivera, Luis
2012-04-01
Horizontal pendulum development was paramount in the birth of modern instrumental seismology and solid-earth tide study. This paper presents a revised history starting in the first part of the nineteenth century and culminating with Rebeur-Paschwitz's masterpiece in its latter part. The first stage began with the invention of the horizontal pendulum by Lorenz Hengler in 1832. He was followed by several, mostly independent, inventors during the three decades from the 1850s to the 1870s, in particular Friedrich Zöllner in 1869-1872 who popularized this instrument. With the exception of an instrument designed by Alexander Gerard in 1851, all these preliminary pendulums were suspended with two wires. Slightly different forms of horizontal pendulums were invented in Japan by James Ewing and Thomas Gray in the early 1880s, based on bracket or conical suspensions. The merit of demonstrating the outstanding potential of high-sensitivity horizontal pendulums completely relies on the work of Ernst von Rebeur-Paschwitz between 1886 and 1895. He successively developed three models of pendulums, in collaboration with three different manufacturers: the Fecker pendulum in 1886, the Repsold pendulum in 1888, from which six copies were produced, and finally, the Stückrath two-component model in 1894, built in three copies. Based on the scrutiny of a large number of previously unexploited archives, the detailed chronology of Rebeur-Paschwitz's achievements is presented. Archive, and in situ explorations allowed us to discover five out of the six original copies of the first Rebeur-Paschwitz's Repsold pendulum previously unknown or thought to be lost.
NASA Astrophysics Data System (ADS)
Rácz, István
2000-01-01
A rigidity theorem that applies to smooth electrovacuum spacetimes which represent either (A) an asymptotically flat stationary black hole or (B) a cosmological spacetime with a compact Cauchy horizon ruled by closed null geodesics was given in a recent paper by Friedrich et al (1999 Commun. Math. Phys. 204 691-707). Here we enlarge the framework of the corresponding investigations by allowing the presence of other types of matter fields. In the first part the matter fields are involved merely implicitly via the assumption that the dominant energy condition is satisfied. In the second part Einstein-Klein-Gordon (EKG), Einstein-[non-Abelian]-Higgs (E[nA]H), Einstein-[Maxwell]-Yang-Mills-dilaton (E[M]YMd) and Einstein-Yang-Mills-Higgs (EYMH) systems are studied. The black hole event horizon or, respectively, the compact Cauchy horizon of the considered spacetimes is assumed to be a smooth non-degenerate null hypersurface. It is proved that there exists a Killing vector field in a one-sided neighbourhood of the horizon in EKG, E[nA]H, E[M]YMd and EYMH spacetimes. This Killing vector field is normal to the horizon, moreover, the associated matter fields are also shown to be invariant with respect to it. The presented results provide generalizations of the rigidity theorems of Hawking (for case A) and of Moncrief and Isenberg (for case B) and, in turn, they strengthen the validity of both the black hole rigidity scenario and the strong cosmic censor conjecture of classical general relativity.
A unified radiative magnetohydrodynamics code for lightning-like discharge simulations
Chen, Qiang Chen, Bin Xiong, Run; Cai, Zhaoyang; Chen, P. F.
2014-03-15
A two-dimensional Eulerian finite difference code is developed for solving the non-ideal magnetohydrodynamic (MHD) equations including the effects of self-consistent magnetic field, thermal conduction, resistivity, gravity, and radiation transfer, which when combined with specified pulse current models and plasma equations of state, can be used as a unified lightning return stroke solver. The differential equations are written in the covariant form in the cylindrical geometry and kept in the conservative form which enables some high-accuracy shock capturing schemes to be equipped in the lightning channel configuration naturally. In this code, the 5-order weighted essentially non-oscillatory scheme combined with Lax-Friedrichs flux splitting method is introduced for computing the convection terms of the MHD equations. The 3-order total variation diminishing Runge-Kutta integral operator is also equipped to keep the time-space accuracy of consistency. The numerical algorithms for non-ideal terms, e.g., artificial viscosity, resistivity, and thermal conduction, are introduced in the code via operator splitting method. This code assumes the radiation is in local thermodynamic equilibrium with plasma components and the flux limited diffusion algorithm with grey opacities is implemented for computing the radiation transfer. The transport coefficients and equation of state in this code are obtained from detailed particle population distribution calculation, which makes the numerical model is self-consistent. This code is systematically validated via the Sedov blast solutions and then used for lightning return stroke simulations with the peak current being 20 kA, 30 kA, and 40 kA, respectively. The results show that this numerical model consistent with observations and previous numerical results. The population distribution evolution and energy conservation problems are also discussed.
Two-dimensional numerical investigation of a normal shock wave boundary layer interaction
NASA Astrophysics Data System (ADS)
Turlin, Miranda P.
Shock wave boundary layer interactions (SWBLIs) occur when a shock wave meets a boundary layer. This study aims to isolate the interaction through numerical investigation of a normal SWBLI and build knowledge of the computational fluid dynamics software, Wind-US 3.0. The test geometry, based on the experimental work of Bruce et al [16], contains a two-dimensional duct split into upper and lower channels by a shock holding plate. The boundary conditions were based on experimental conditions, and include: an inlet Mach number of 1.6; inlet total pressure and temperature of 62.5 psi and 522 degrees R, respectively; and viscous walls on all physical surfaces. Downstream boundary conditions are varied in attempts to produce a correct shock structure throughout the domain. This study uses two-dimensional structured grids containing approximately 832,000 elements. Wind-US solves the Reynolds-Averaged Navier-Stokes equations using Roe's second-order upwind-biased flux-difference splitting algorithm with a total variation diminishing (TVD) limiting parameter. The turbulence model selected for this study was the Menter SST k-o model. Attempts to produce the correct shock structure have included varying the downstream boundary conditions, changing the number of cycles and associated Courant-Friedrichs-Lewy, TVD, and grid sequencing parameters. This study used several tutorial files available through the NPARC Alliance to establish the analysis settings needed to produce a shock wave in the lower channel. This enables progress to be made on the next step of this project which is to simulate and analyze the interaction of a normal SWBLI in two dimensions. Results illustrate the correct combination of boundary conditions necessary to generate a shock in the expected location. In addition, an appropriate zonal configuration has been determined to eliminate the horizontal zone interfaces which can cause non-physical behavior in those locations.
NASA Astrophysics Data System (ADS)
Tseng, Chien-Hsun
2015-02-01
The technique of multidimensional wave digital filtering (MDWDF) that builds on traveling wave formulation of lumped electrical elements, is successfully implemented on the study of dynamic responses of symmetrically laminated composite plate based on the first order shear deformation theory. The philosophy applied for the first time in this laminate mechanics relies on integration of certain principles involving modeling and simulation, circuit theory, and MD digital signal processing to provide a great variety of outstanding features. Especially benefited by the conservation of passivity gives rise to a nonlinear programming problem (NLP) for the issue of numerical stability of a MD discrete system. Adopting the augmented Lagrangian genetic algorithm, an effective optimization technique for rapidly achieving solution spaces of NLP models, numerical stability of the MDWDF network is well received at all time by the satisfaction of the Courant-Friedrichs-Levy stability criterion with the least restriction. In particular, optimum of the NLP has led to the optimality of the network in terms of effectively and accurately predicting the desired fundamental frequency, and thus to give an insight into the robustness of the network by looking at the distribution of system energies. To further explore the application of the optimum network, more numerical examples are engaged in efforts to achieve a qualitative understanding of the behavior of the laminar system. These are carried out by investigating various effects based on different stacking sequences, stiffness and span-to-thickness ratios, mode shapes and boundary conditions. Results are scrupulously validated by cross referencing with early published works, which show that the present method is in excellent agreement with other numerical and analytical methods.
Space-time formulation of quantum transitions
NASA Astrophysics Data System (ADS)
Petrosky, T.; Ordonez, G.; Prigogine, I.
2001-12-01
In a previous paper we have studied dressed excited states in the Friedrichs model, which describes a two-level atom interacting with radiation. In our approach, excited states are distributions (or generalized functions) in the Liouville space. These states decay in a strictly exponential way. In contrast, the states one may construct in the Hilbert space of wave functions always present deviations from exponential decay. We have considered the momentum representation, which is applicable to global quantities (trace, energy transfer). Here we study the space-time description of local quantities associated with dressed unstable states, such as, the intensity of the photon field. In this situation the excited states become factorized in Gamow states. To go from local quantities to global quantities, we have to proceed to an integration over space, which is far from trivial. There are various elements that appear in the space-time evolution of the system: the unstable cloud that surrounds the bare atom, the emitted real photons and the ``Zeno photons,'' which are associated with deviations from exponential decay. We consider a Hilbert space approximation to our dressed excited state. This approximation leads already to decay close to exponential in the field surrounding the atom, and to a line shape different from the Lorentzian line shape. Our results are compared with numerical simulations. We show that the time evolution of an unstable state satisfies a Boltzmann-like H theorem. This is applied to emission and absorption as well as scattering. The existence of a microscopic H theorem is not astonishing. The excited states are ``nonequilibrium'' states and their time evolution leads to the emission of photons, which distributes the energy of the unstable state among the field modes.
NASA Astrophysics Data System (ADS)
Ishibashi, Akihiro; Wald, Robert M.
2003-08-01
It was previously shown by one of us that in any static, non-globally-hyperbolic, spacetime, it is always possible to define a sensible dynamics for a Klein Gordon scalar field. The prescription proposed for doing so involved viewing the spatial derivative part, A, of the wave operator as an operator on a certain L2 Hilbert space Script H and then defining a positive, self-adjoint operator on Script H by taking the Friedrichs extension (or other positive extension) of A. However, this analysis left open the possibility that there could be other inequivalent prescriptions of a completely different nature that might also yield satisfactory definitions of the dynamics of a scalar field. We show here that this is not the case. Specifically, we show that if the dynamics agrees locally with the dynamics defined by the wave equation, if it admits a suitable conserved energy and if it satisfies certain other specified conditions, then it must correspond to the dynamics defined by choosing some positive, self-adjoint extension of A on Script H. Thus, subject to our requirements, the previously given prescription is the only possible way of defining the dynamics of a scalar field in a static, non-globally-hyperbolic, spacetime. In a subsequent paper, this result will be applied to the analysis of scalar, electromagnetic and gravitational perturbations of anti-de Sitter spacetime. By doing so, we will determine all possible choices of boundary conditions at infinity in anti-de Sitter spacetime that give rise to sensible dynamics.
Development of nonlinear weighted compact schemes with increasingly higher order accuracy
NASA Astrophysics Data System (ADS)
Zhang, Shuhai; Jiang, Shufen; Shu, Chi-Wang
2008-07-01
In this paper, we design a class of high order accurate nonlinear weighted compact schemes that are higher order extensions of the nonlinear weighted compact schemes proposed by Deng and Zhang [X. Deng, H. Zhang, Developing high-order weighted compact nonlinear schemes, J. Comput. Phys. 165 (2000) 22-44] and the weighted essentially non-oscillatory schemes of Jiang and Shu [G.-S. Jiang, C.-W. Shu, Efficient implementation of weighted ENO schemes, J. Comput. Phys. 126 (1996) 202-228] and Balsara and Shu [D.S. Balsara, C.-W. Shu, Monotonicity preserving weighted essentially non-oscillatory schemes with increasingly high order of accuracy, J. Comput. Phys. 160 (2000) 405-452]. These nonlinear weighted compact schemes are proposed based on the cell-centered compact scheme of Lele [S.K. Lele, Compact finite difference schemes with spectral-like resolution, J. Comput. Phys. 103 (1992) 16-42]. Instead of performing the nonlinear interpolation on the conservative variables as in Deng and Zhang (2000), we propose to directly interpolate the flux on its stencil. Using the Lax-Friedrichs flux splitting and characteristic-wise projection, the resulted interpolation formulae are similar to those of the regular WENO schemes. Hence, the detailed analysis and even many pieces of the code can be directly copied from those of the regular WENO schemes. Through systematic test and comparison with the regular WENO schemes, we observe that the nonlinear weighted compact schemes have the same ability to capture strong discontinuities, while the resolution of short waves is improved and numerical dissipation is reduced.
NASA Astrophysics Data System (ADS)
Beuermann, Klaus; Borheck, Georg Heinrich
Die Göttinger Sternwarte, Wirkungsstätte des berühmten Gelehrten Carl Friedrich Gauß, ist ein bedeutendes Baudenkmal. Im Jahre 2005 wird sie gemeinsam von der Georg-August-Universität und der Akademie der Wissenschaften zu Göttingen renoviert, um dann als repräsentatives Gebäude der Universität und Arbeitsstätte der Akademie zu dienen. Die Nutzung der historischen Räume für Ausstellungen macht diesen imposanten Bau erstmals der Öffentlichkeit zugänglich. Die Sternwarte war bei ihrer Errichtung vor 200 Jahren ein nach seinerzeit neuesten wissenschaftlichen Erkenntnissen konzipierter Bau, der die Universität Göttingen in eine der vordersten Stellen Europa rückte. Auch aufgrund ihrer Architektur ist sie ein großer Wurf des Göttinger Universitätsbaumeisters Georg Heinrich Borheck. Durch die Kriegswirren der Napoleonischen Zeit zerschlug sich Borhecks Versuch einer Publikation seiner Beschreibung des Baus der Göttinger Sternwarte 1805. Doch seine Schrift ist auch heute noch aktuell und wird mit diesem Band erstmals einer breiten Öffentlichkeit zugängig gemacht. Er zeigt die Grundsätze, nach denen damals öffentliche Bauten konzipiert wurden, erläutert die Bedeutung des Baus aus kunst- und wissenschaftshistorischer Sicht und informiert über die Pläne zur Restaurierung der Sternwarte in einem separaten Beitrag und im Geleitwort des Präsidenten der Georg-August Universität Prof. Dr. Dr. h. c. Kurt von Figura.
Subdynamics and nonintegrable systems
NASA Astrophysics Data System (ADS)
Petrosky, T. Y.; Hasegawa, H.
1989-10-01
Work on the application of Poincaré's theorem to large classical or quantum systems with a continuous spectrum is continued. In situations where it is applicable, Poincaré's theorem prevents the construction of a complete set of eigenprojectors which would be hermitian as well as analytic in the coupling constant. In contrast, the theory of subdynamics as developed by the Brussels group permits the construction of a unique set of projectors limitП(ν)( for t > 0) , giving up the requirement of hermiticity which is replaced by “star-hermiticity”. The theory of subdynamics is presented in a new self-contained way, starting from the commutation relation limitП(ν) L H=L HlimitП(ν), where L H is the Liouvillian. This presentation is far more direct, and avoids some of the lengthy discussions associated with previous presentations (based mainly on the resolvent of the Liouvillian). Subdynamics appears to be of interest from many points of view. It generalizes the concept of spectral representation while permitting to retain all the degrees of freedom present in the unperturbed Hamiltonian. In contrast, degrees of freedom are lost when going to the spectral representation (e.g. in the Friedrichs model). Subdynamics permits us to solve the initial value problem associated with the Liouville equation retaining the “non-Markovian” contributions which appear in the standard presentation. Finally, it introduces a classification of large dynamical systems, classical or quantum, into integrable and nonintegrable ones. It is therefore of direct interest for a number of basic problems which belong to the class of nonintegrable dynamical systems, such as the interaction of matter with light. The applications of this technique to these problems will be worked out in subsequent papers.
Multirate Runge-Kutta schemes for advection equations
NASA Astrophysics Data System (ADS)
Schlegel, Martin; Knoth, Oswald; Arnold, Martin; Wolke, Ralf
2009-04-01
Explicit time integration methods can be employed to simulate a broad spectrum of physical phenomena. The wide range of scales encountered lead to the problem that the fastest cell of the simulation dictates the global time step. Multirate time integration methods can be employed to alter the time step locally so that slower components take longer and fewer time steps, resulting in a moderate to substantial reduction of the computational cost, depending on the scenario to simulate [S. Osher, R. Sanders, Numerical approximations to nonlinear conservation laws with locally varying time and space grids, Math. Comput. 41 (1983) 321-336; H. Tang, G. Warnecke, A class of high resolution schemes for hyperbolic conservation laws and convection-diffusion equations with varying time and pace grids, SIAM J. Sci. Comput. 26 (4) (2005) 1415-1431; E. Constantinescu, A. Sandu, Multirate timestepping methods for hyperbolic conservation laws, SIAM J. Sci. Comput. 33 (3) (2007) 239-278]. In air pollution modeling the advection part is usually integrated explicitly in time, where the time step is constrained by a locally varying Courant-Friedrichs-Lewy (CFL) number. Multirate schemes are a useful tool to decouple different physical regions so that this constraint becomes a local instead of a global restriction. Therefore it is of major interest to apply multirate schemes to the advection equation. We introduce a generic recursive multirate Runge-Kutta scheme that can be easily adapted to an arbitrary number of refinement levels. It preserves the linear invariants of the system and is of third order accuracy when applied to certain explicit Runge-Kutta methods as base method.
Styles, Suzy J.; Plunkett, Kim; Duta, Mihaela D.
2015-01-01
Recent behavioural studies with toddlers have demonstrated that simply viewing a picture in silence triggers a cascade of linguistic processing which activates a representation of the picture’s name (Mani and Plunkett, 2010, 2011). Electrophysiological studies have also shown that viewing a picture modulates the auditory evoked potentials (AEPs) triggered by later speech, from early in the second year of life (Duta et al., 2012; Friedrich and Friederici, 2005; Mani et al., 2011) further supporting the notion that picture viewing gives rise to a representation of the picture’s name against which later speech can be matched. However, little is known about how and when the implicit name arises during picture viewing, or about the electrophysiological activity which supports this linguistic process. We report differences in the visual evoked potentials (VEPs) of fourteen-month-old infants who saw photographs of animals and objects, some of which were name-known (lexicalized), while waiting for an auditory label to be presented. During silent picture viewing, lateralized neural activity was selectively triggered by lexicalized items, as compared to nameless items. Lexicalized items generated a short-lasting negative-going deflection over frontal, left centro-temporal, and left occipital regions shortly after the picture appeared (126–225 ms). A positive deflection was also observed over the right hemisphere (particularly centro-temporal regions) in a later, longer-lasting window (421–720 ms). The lateralization of these differences in the VEP suggests the possible involvement of linguistic processes during picture viewing, and may reflect activity involved in the implicit activation of the picture’s name. PMID:26232744
A Class of High-Resolution Explicit and Implicit Shock-Capturing Methods
NASA Technical Reports Server (NTRS)
Yee, H. C.
1994-01-01
The development of shock-capturing finite difference methods for hyperbolic conservation laws has been a rapidly growing area for the last decade. Many of the fundamental concepts, state-of-the-art developments and applications to fluid dynamics problems can only be found in meeting proceedings, scientific journals and internal reports. This paper attempts to give a unified and generalized formulation of a class of high-resolution, explicit and implicit shock capturing methods, and to illustrate their versatility in various steady and unsteady complex shock waves, perfect gases, equilibrium real gases and nonequilibrium flow computations. These numerical methods are formulated for the purpose of ease and efficient implementation into a practical computer code. The various constructions of high-resolution shock-capturing methods fall nicely into the present framework and a computer code can be implemented with the various methods as separate modules. Included is a systematic overview of the basic design principle of the various related numerical methods. Special emphasis will be on the construction of the basic nonlinear, spatially second and third-order schemes for nonlinear scalar hyperbolic conservation laws and the methods of extending these nonlinear scalar schemes to nonlinear systems via the approximate Riemann solvers and flux-vector splitting approaches. Generalization of these methods to efficiently include real gases and large systems of nonequilibrium flows will be discussed. Some perbolic conservation laws to problems containing stiff source terms and terms and shock waves are also included. The performance of some of these schemes is illustrated by numerical examples for one-, two- and three-dimensional gas-dynamics problems. The use of the Lax-Friedrichs numerical flux to obtain high-resolution shock-capturing schemes is generalized. This method can be extended to nonlinear systems of equations without the use of Riemann solvers or flux
Feng Xueshang; Yang Liping; Xiang Changqing; Zhou Yufen; Zhong Dingkun; Wu, S. T.
2010-11-01
The objective of this paper is to explore the application of a six-component overset grid to solar wind simulation with a three-dimensional (3D) Solar-InterPlanetary Conservation Element/Solution Element MHD model. The essential focus of our numerical model is devoted to dealing with: (1) the singularity and mesh convergence near the poles via the use of the six-component grid system, (2) the {nabla} {center_dot} B constraint error via an easy-to-use cleaning procedure by a fast multigrid Poisson solver, (3) the Courant-Friedrichs-Levy number disparity via the Courant-number insensitive method, (4) the time integration by multiple time stepping, and (5) the time-dependent boundary condition at the subsonic region by limiting the mass flux escaping through the solar surface. In order to produce fast and slow plasma streams of the solar wind, we include the volumetric heating source terms and momentum addition by involving the topological effect of the magnetic field expansion factor f{sub S} and the minimum angular distance {theta}{sub b} (at the photosphere) between an open field foot point and its nearest coronal hole boundary. These considerations can help us easily code the existing program, conveniently carry out the parallel implementation, efficiently shorten the computation time, greatly enhance the accuracy of the numerical solution, and reasonably produce the structured solar wind. The numerical study for the 3D steady-state background solar wind during Carrington rotation 1911 from the Sun to Earth is chosen to show the above-mentioned merits. Our numerical results have demonstrated overall good agreements in the solar corona with the Large Angle and Spectrometric Coronagraph on board the Solar and Heliospheric Observatory satellite and at 1 AU with WIND observations.
NASA Astrophysics Data System (ADS)
Palmer, Christopher D.; Lewis, Miles E.; Geraghty, Ciaran M.; Barbosa, Fernando; Parsons, Patrick J.
2006-08-01
A biomonitoring method for the determination of Pb, Cd, and Hg at background levels in whole blood by inductively coupled plasma-mass spectrometry is described. While this method was optimized for assessing Pb, Cd and Hg at environmental levels, it also proved suitable for assessing concentrations associated with occupational exposure. The method requires as little as 200 μl of blood that is diluted 1 + 49 for direct analysis in the inductively coupled plasma-mass spectrometer. Method performance is compared to well-established AAS methods. Initial method validation was accomplished using National Institute of Standards and Technology (NIST) Standard Reference Material 966, Toxic Metals in Bovine Blood. Method detection limits (3s) are 0.05 μg dl - 1 for Pb, 0.09 μg l - 1 for Cd; and 0.17 μg l - 1 for Hg. Repeatability ranged from 1.4% to 2.8% for Pb; 3% to 10% for Cd; and 2.6% to 8.8% for Hg. In contrast, AAS method detection limits were 1 μg dl - 1 , 0.54 μg l - 1 , and 0.6 μg l - 1 , for Pb, Cd, and Hg, respectively. Further performance assessments were conducted over a 2-year period via participation in four international External Quality Assessment Schemes (EQAS) operated specifically for toxic metals in blood. This includes schemes operated by (a) the New York State Department of Health's Wadsworth Center, Albany, NY, USA (b) L'Institut National de Santé Publique du Québec, Centre de Toxicologie du Québec, Canada, (c) Friedrich-Alexander University, Erlangen, Germany, and (d) the University of Surrey, Guildford, UK Trace Elements scheme. The EQAS data reflect analytical performance for blind samples analyzed independently by both inductively coupled plasma-mass spectrometry and AAS methods.
Klotz, Sebastian
2008-09-01
The study of acoustics, harmonics and of music has been providing scientific models since Greek Antiquity. Since the early modern ages, two separate cultures began to emerge out of the study of music: a technical acoustics and an aesthetically and philosophically inspired musical criticism. In the writings of Johann Friedrich Herbart (1811) a scientific approach to musical aesthetics and to music perception is taking shape that reinstalls the listening process as a highly complex and logical phenomenon. By opening music for a scientific psychological investigation, Herbart pioneered the physiologically and acoustically grounded seminal work by Hermann von Helmholtz On the sensations of tone (1863) which the author considered a prerequisite for musical aesthetics and music theory. Helmholtz in turn inspired the philosopher and psychologist Carl Stumpf to further investigate musical perception (beginning in 1883). To Stumpf, it provided a paradigm for experimental psychology as mental functions and phenomena could be studied in detail. These functions and phenomena are the actual objects of scientific study in Stumpf's inductive and descriptive psychology. Combining insights from statistics, ethnology, anthropology, psychoacoustics and the cultural history of mankind, Stumpf and his team developed a new blend of science which absorbs styles of reasoning, analytical procedures and academic convictions from natural history, the natural sciences and the humanities but at the same time identifies shortcomings of these approaches that fail to grasp the complexities of psychic functions. Despite their reliance on the quasi-objective phonograph and despite their commitment to objectivity, precision and measurement, mental phenomena relating to tonal perception and to music provided too complex a challenge to be easily articulated and shared by the scientific community after 1900. The essay illustrates these tensions against the background of a history of objectivity. PMID
Using time filtering to control the long-time instability in seismic wave simulation
NASA Astrophysics Data System (ADS)
Gao, L.; Brossier, R.; Virieux, J.
2016-03-01
Long-time instabilities have been observed in various scenarios of numerical simulation for seismic wave propagation. They appear as slowly magnifying spurious oscillations in the seismograms at the late stage of the simulation. Their magnifying speed is typically much slower than the magnifying speed observed when the Courant-Friedrichs-Lewy condition is violated. The simulations can therefore continue to proceed for a relatively long period without floating-point overflow. The impact of the long-time instabilities on the simulation accuracy at the early stage can be negligible in some cases. In existing literatures, spatial-filtering techniques that, in principle, average the solution within certain spatial range at the same time level are typically utilized to control the long-time instability. In this paper, we present an alternative time-filtering approach that, in principle, averages the solution at different time levels of the same spatial location to control the long-time instability. Comparing with the spatial filtering, the advantages of this time-filtering approach lie in its flexibility, particularly when boundaries or interfaces are involved, its simplicity and low additional arithmetic operations, at the expense of extra memory cost. When application of the time filtering is localized to regions where long-time instabilities are emitted from, for example, a boundary or an interface layer, the additional cost is negligible when compared with the cost of wave simulation. For linear wave equations, this time-filtering approach can be understood as the introduction of artificial diffusion. Its application has impact on the accuracy of the solution and the restriction of the time step size. We present an indicator-based approach to adjust the filtering parameters both spatially and temporally, in order to provide the best trade-off between accuracy and stability. The indicator is calculated heuristically by monitoring the spurious oscillation as the
[Struensee--physician and missjudged social reformer].
Nordlander, N B
1996-01-01
Johann Friedrich Struensee was born in 1737 in the German town of Halle where he graduated as doctor of Medicine at the age of 19. In 1757 he was appointed to be town physician in the big Danish town Altona, close to Hamburg. There he had a large medical practice among the poor, but he also succeeded in curing some important persons, which influenced his further career. During his eleven years in Altona he made many friends among the liberal circles and evolved an extensive writing of medical and social publications, where he called for reforms of housing, of hygiene, of fresh air and a sounder living. He organised a delivery clinic for single mothers and took care of the orphans. His opinions met with furious opposition from older doctors, whom he attacked for their greed and ignorance. In 1768 he was appointed to be the danish king Christian VII's physician during the kings visit to England. King Christian was mentally disturbed with fits of violence and confusion, but Struensee succeeded in gaining his confidence and after return to Denmark he was soon to be the absolute ruler of the country during three years. He started an intensive reform period with total freedom of the press, abolished peasant slavery and the death penalty, got rid of nepotism in the civil service, where only real competence should decide. He put an end to the great waste of money for luxury and superfluous staff in the court and in military units in order to improve the heavily indebted Danish economy. His reforms affronted many important persons and he never succeeded in gaining the confidence of the ordinary people, whose benefit he struggled for. By a sudden revolt Struensee's adversaries arrested him and forced the week and frightened king to sign the doctor's death sentence which was carried out April 28 1772 in spite of his noble document of defence. PMID:11624970
Bauer, A; Kelterer, D; Stadeler, M; Schneider, W; Kleesz, P; Wollina, U; Elsner, P
2001-02-01
Occupational skin diseases (OSD) are among the most frequent occupational diseases (OD). Compared to other occupations, bakers, confectioners and employees in the catering trades are at a high risk of developing OSD. In January 1999, the interdisciplinary Skin Disease Prevention Program in the Baking, Hotel and Catering Industries (SDPP) conducted by the Department of Dermatology and Allergology at the Friedrich Schiller University, Jena, in cooperation with the Research Center for Applied System Safety and Industrial Medicine, Erfurt, and the technical experts at the Social Insurance for the Food Industry and Related Professions (Berufsgenossenschaft für Nahrungsmittel und Gaststätten--(BGN)), Erfurt, was initiated. Following detailed analysis of the occupational exposure of the employees and their personal occupational disease history, the patients' diagnosis and therapy was re-evaluated and supplemented if necessary. Individual skin care and protection regimes were demonstrated and practically trained. Skin care and protection products were supplied. Skin-care and protection seminars were offered to volunteering participants. From January to December 1999, 29 affected employees were examined in the OSD clinic. 22 employees (76%) suffered from irritant contact dermatitis. The follow-up data of 11 employees are available. In 8 employees (73%), the skin disease improved or disappeared. Moreover, in 1 employee (9%), the skin condition was stabilized even though he continued working. In only 2 employees (18%) did the skin condition worsen. These preliminary results showed that most of the OSD were due to lack of or unsuitable skin care and protection. The program will be extended to cover a larger number of food industry employees with OSD. PMID:11205409
Witzmann, Florian; Schwarz-Wings, Daniela; Hampe, Oliver; Fritsch, Guido; Asbach, Patrick
2014-01-01
Pathologies in the skeleton of phytosaurs, extinct archosauriform reptiles restricted to the Late Triassic, have only been rarely described. The only known postcranial pathologies of a phytosaur are two pairs of fused vertebrae of "Angistorhinopsis ruetimeyeri" from Halberstadt, Germany, as initially described by the paleontologist Friedrich von Huene. These pathologic vertebrae are redescribed in more detail in this study in the light of modern paleopathologic methods. Four different pathologic observations can be made in the vertebral column of this individual: 1) fusion of two thoracic vertebral bodies by new bone formation within the synovial membrane and articular capsule of the intervertebral joint; 2) fusion and conspicuous antero-posterior shortening of last presacral and first sacral vertebral bodies; 3) destruction and erosion of the anterior articular surface of the last presacral vertebra; and 4) a smooth depression on the ventral surface of the fused last presacral and first sacral vertebral bodies. Observations 1-3 can most plausibly and parsimoniously be attributed to one disease: spondyloarthropathy, an aseptic inflammatory process in which affected vertebrae show typical types of reactive new bone formation and erosion of subchondral bone. The kind of vertebral shortening present in the fused lumbosacral vertebrae suggests that the phytosaur acquired this disease in its early life. Observation 4, the smooth ventral depression in the fused lumbosacral vertebrae, is most probably not connected to the spondyloarthropathy, and can be regarded as a separate abnormality. It remains of uncertain origin, but may be the result of pressure, perhaps caused by a benign mass such as an aneurysm or cyst of unknown type. Reports of spondyloarthropathy in Paleozoic and Mesozoic reptiles are still exceptional, and our report of spondyloarthropathy in fossil material from Halberstadt is the first unequivocal occurrence of this disease in a Triassic tetrapod and in a
Witzmann, Florian; Schwarz-Wings, Daniela; Hampe, Oliver; Fritsch, Guido; Asbach, Patrick
2014-01-01
Pathologies in the skeleton of phytosaurs, extinct archosauriform reptiles restricted to the Late Triassic, have only been rarely described. The only known postcranial pathologies of a phytosaur are two pairs of fused vertebrae of “Angistorhinopsis ruetimeyeri” from Halberstadt, Germany, as initially described by the paleontologist Friedrich von Huene. These pathologic vertebrae are redescribed in more detail in this study in the light of modern paleopathologic methods. Four different pathologic observations can be made in the vertebral column of this individual: 1) fusion of two thoracic vertebral bodies by new bone formation within the synovial membrane and articular capsule of the intervertebral joint; 2) fusion and conspicuous antero-posterior shortening of last presacral and first sacral vertebral bodies; 3) destruction and erosion of the anterior articular surface of the last presacral vertebra; and 4) a smooth depression on the ventral surface of the fused last presacral and first sacral vertebral bodies. Observations 1–3 can most plausibly and parsimoniously be attributed to one disease: spondyloarthropathy, an aseptic inflammatory process in which affected vertebrae show typical types of reactive new bone formation and erosion of subchondral bone. The kind of vertebral shortening present in the fused lumbosacral vertebrae suggests that the phytosaur acquired this disease in its early life. Observation 4, the smooth ventral depression in the fused lumbosacral vertebrae, is most probably not connected to the spondyloarthropathy, and can be regarded as a separate abnormality. It remains of uncertain origin, but may be the result of pressure, perhaps caused by a benign mass such as an aneurysm or cyst of unknown type. Reports of spondyloarthropathy in Paleozoic and Mesozoic reptiles are still exceptional, and our report of spondyloarthropathy in fossil material from Halberstadt is the first unequivocal occurrence of this disease in a Triassic tetrapod
Comparison of different nonlinear solvers for 2D time-implicit stellar hydrodynamics
NASA Astrophysics Data System (ADS)
Viallet, M.; Baraffe, I.; Walder, R.
2013-07-01
Time-implicit schemes are attractive since they allow numerical time steps that are much larger than those permitted by the Courant-Friedrich-Lewy criterion characterizing time-explicit methods. This advantage comes, however, at a cost: the solution of a system of nonlinear equations is required at each time step. In this work, the nonlinear system results from the discretization of the hydrodynamical equations with the Crank-Nicholson scheme. We compare the cost of different methods, based on Newton-Raphson iterations, to solve this nonlinear system, and benchmark their performances against time-explicit schemes. Since our general scientific objective is to model stellar interiors, we use as test cases two realistic models for the convective envelope of a red giant and a young Sun. Focusing on 2D simulations, we show that the best performances are obtained with the quasi-Newton method proposed by Broyden. Another important concern is the accuracy of implicit calculations. Based on the study of an idealized problem, namely the advection of a single vortex by a uniform flow, we show that there are two aspects: i) the nonlinear solver has to be accurate enough to resolve the truncation error of the numerical discretization; and ii) the time step has be small enough to resolve the advection of eddies. We show that with these two conditions fulfilled, our implicit methods exhibit similar accuracy to time-explicit schemes, which have lower values for the time step and higher computational costs. Finally, we discuss in the conclusion the applicability of these methods to fully implicit 3D calculations.
Tavil, Betül; Korkmaz, Ayşe; Bayhan, Turan; Aytaç, Selin; Unal, Sule; Kuskonmaz, Baris; Yigit, Sule; Cetin, Mualla; Yurdakök, Murat; Gumruk, Fatma
2016-03-01
In this study, we aimed to evaluate the incidence, risk factors, causes and clinical management of intracranial haemorrhage (ICH) diagnosed during foetal life or in the first month of life in term neonates with a discussion of the role of haematological risk factors. This study included term neonates (gestational age 37-42 weeks) with ICH diagnosed, treated and followed up in the Neonatal Intensive Care Unit of Hacettepe University, Ankara, Turkey, between January 1994 and January 2014. Medical follow-up was obtained retrospectively from hospital files and prospectively from telephonic interviews and/or clinical visits. During the study period, 16 term neonates were identified as having ICH in our hospital. In six (37.5%) neonates, ICH was diagnosed during foetal life by obstetric ultrasonography, and in 10 (62.5%) neonates, it has been diagnosed after birth. Haemorrhage types included intraventricular haemorrhage (IVH) in eight (50.0%), intraparenchymal haemorrhage in six (37.5%), subarachnoid haemorrhage in one (6.2%) and subdural haemorrhage in one (6.2%) neonate. IVH was the most common (n = 5/6, 83.3%) haemorrhage type among neonates diagnosed during foetal life. Overall, haemorrhage severity was determined as mild in three (18.7%) neonates, moderate in three (18.75%) neonates and severe in 10 (62.5%) neonates. During follow-up, one infant was diagnosed as afibrinogenemia, one diagnosed as infantile spasm, one cystic fibrosis, one orofaciodigital syndrome and the other diagnosed as Friedrich ataxia. Detailed haematological investigation and search for other underlying diseases are very important to identify the reason of ICH in term neonates. Furthermore, early diagnosis, close monitoring and prompt surgical interventions are significant factors to reduce disabilities. PMID:26829281
[Developments in neurophysiology in the 19th century].
Hess, C W
1994-04-19
The rise of neurophysiology in the 19th century was kindled by Luigi Aloysius Galvani's revolutionary claim for animal electricity at the end of the preceding century. He was first challenged by Allessandro Giuseppe Antonio Anastasio Volta who showed that the muscle twitch in Galvani's experiment was the result of electric stimulation rather than of an enabled biological current. The controversy between Galvani and Volta became a predominant and stimulating issue among the scientists of the early century and found its ultimate elucidation only 40 years later by the pioneering work of Carlo Matteucci of Pisa and Emil Heinrich Du Bois-Reymond of Berlin, who both deserve the reknown as founders of modern neurophysiology. As the first influential promoter and mastermind of the experimental physiology, François Magendie of Paris primarily investigated the nervous system and inaugurated the lesion experiments to clarify specific functions of neural structures. Johannes Müller founded the German school of physiology with its eminent neurophysiological offspring: Du Bois-Reymond, Hermann Ludwig Ferdinand von Helmholtz, and Eduard Friedrich Wilhelm Pflüger. It was Helmholtz's merit to have for the first time precisely assessed the motor conduction velocity by measuring the time interval between two different stimulation sites of the sciatic nerve of the frog. In their brilliant work published in 1870 Gustav Theodor Fritsch and Eduard Hitzig demonstrated that appropriately located focal electrical stimulation of the exposed cortex of dogs induces movement of the contralateral limbs and unequivocally disproved the then prevailing dogma of holistic capacity of the hemispheres, which denied localised functions within the cortex.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8191189
High-Order Space-Time Methods for Conservation Laws
NASA Technical Reports Server (NTRS)
Huynh, H. T.
2013-01-01
Current high-order methods such as discontinuous Galerkin and/or flux reconstruction can provide effective discretization for the spatial derivatives. Together with a time discretization, such methods result in either too small a time step size in the case of an explicit scheme or a very large system in the case of an implicit one. To tackle these problems, two new high-order space-time schemes for conservation laws are introduced: the first is explicit and the second, implicit. The explicit method here, also called the moment scheme, achieves a Courant-Friedrichs-Lewy (CFL) condition of 1 for the case of one-spatial dimension regardless of the degree of the polynomial approximation. (For standard explicit methods, if the spatial approximation is of degree p, then the time step sizes are typically proportional to 1/p(exp 2)). Fourier analyses for the one and two-dimensional cases are carried out. The property of super accuracy (or super convergence) is discussed. The implicit method is a simplified but optimal version of the discontinuous Galerkin scheme applied to time. It reduces to a collocation implicit Runge-Kutta (RK) method for ordinary differential equations (ODE) called Radau IIA. The explicit and implicit schemes are closely related since they employ the same intermediate time levels, and the former can serve as a key building block in an iterative procedure for the latter. A limiting technique for the piecewise linear scheme is also discussed. The technique can suppress oscillations near a discontinuity while preserving accuracy near extrema. Preliminary numerical results are shown
[Weizsäcker and Indian philosophy - a new beginning in negotiating the dualism of mind and matter?].
von Brück, Michael
2014-01-01
Carl Friedrich von Weizsäcker's thought is centred around the idea of the unity of reality. He tries to express this idea in his interpretation of quantum physics as well as on the background of neoplatonic thinking. Even his interest in Indian philosophies is based on this concept that would overcome the dualism of mind and matter as well as the dualism of subject and object. On this basis he also tries to reflect on his own inexpressible "mystical" experience in Tiruvannamalai, India, interpreting it with the help of the experience he has been told about by the Indian thinker Gopi Krishna. This is the concept of prana (vital energy) that he uses to find a common terminological ground for physical and mental events. According to Indian Advaita Vedanta, the non-dualistic interpretation of the Vedantic scriptures, reality is based on a non-dual oneness that is self-reflective, transparent and neither immanent nor transcendent but beyond any category. It is pure bliss in its self-expression. Human "mental" experience is a reflective mode of this one reality, subject and object coincide. The result is a holistic psycho-somatology. In view of these ideas Weizsäcker reformulates the notion of "matter". It is less an interaction of particles with specific mass than a non-dual net of interrelations and information, and this would correlate with a concept of mind (consciousness) that could be conceptualized as the energy of self-reflectivity in that very process. PMID:24974622
NASA Astrophysics Data System (ADS)
Mendicino, Giuseppe; Pedace, Jessica; Senatore, Alfonso
2015-04-01
Cellular Automata are often used for modeling the evolution in time of environmental systems mainly because they are directly compatible with parallel programming. Nevertheless, defining the optimal time step criterion for integrating forward in time numerical processes can further enhance model computational efficiency. To this aim, a numerical stability analysis of an original overland flow model, within the framework of a fully coupled eco-hydrological system based on the Macroscopic Cellular Automata paradigm, is performed. According to the other modules of the system describing soil water flow, soil-surface-atmosphere fluxes and vegetation dynamics, overland flow model equations were derived through a direct discrete formulation (i.e. no differential equations were discretized), adopting the diffusion wave model as an approximation of the full De Saint Venant equations and including the capability of accounting for specific processes, such as the increasing roughness effects due to vegetation growth or surface-soil water exchanges. Suitable formulations of robust tools usually applied in the stability analyses, such as Courant-Friedrichs-Lewy and von Neumann conditions, were initially derived for the CA-based overland flow model. Afterwards, the theoretical stability conditions were compared to experimental time step constraints through several numerical simulations of a 5-h rain event. Specifically, adopting a constant (i.e. not adaptive) time step for simulations, and discretizing head losses in a way that increases model stability, experimental upper limits preventing numerical instability were found for 13 test cases with different slopes, precipitation intensities, vegetation densities and depths of surface depressions. Even though von Neumann condition and experimental values were well positively correlated, the latter were almost always sensibly lower, excluding cases when free surface gradients tended to zero. Therefore, based on the original method
NASA Astrophysics Data System (ADS)
Guo, Y.; Xia, C.; Keppens, R.; Valori, G.
2016-09-01
We report our implementation of the magneto-frictional method in the Message Passing Interface Adaptive Mesh Refinement Versatile Advection Code (MPI-AMRVAC). The method aims at applications where local adaptive mesh refinement (AMR) is essential to make follow-up dynamical modeling affordable. We quantify its performance in both domain-decomposed uniform grids and block-adaptive AMR computations, using all frequently employed force-free, divergence-free, and other vector comparison metrics. As test cases, we revisit the semi-analytic solution of Low and Lou in both Cartesian and spherical geometries, along with the topologically challenging Titov–Démoulin model. We compare different combinations of spatial and temporal discretizations, and find that the fourth-order central difference with a local Lax–Friedrichs dissipation term in a single-step marching scheme is an optimal combination. The initial condition is provided by the potential field, which is the potential field source surface model in spherical geometry. Various boundary conditions are adopted, ranging from fully prescribed cases where all boundaries are assigned with the semi-analytic models, to solar-like cases where only the magnetic field at the bottom is known. Our results demonstrate that all the metrics compare favorably to previous works in both Cartesian and spherical coordinates. Cases with several AMR levels perform in accordance with their effective resolutions. The magneto-frictional method in MPI-AMRVAC allows us to model a region of interest with high spatial resolution and large field of view simultaneously, as required by observation-constrained extrapolations using vector data provided with modern instruments. The applications of the magneto-frictional method to observations are shown in an accompanying paper.
Landslide-Generated Tsunami Model for Quick Hazard Assessment
NASA Astrophysics Data System (ADS)
Franz, M.; Rudaz, B.; Locat, J.; Jaboyedoff, M.; Podladchikov, Y.
2015-12-01
Alpine regions are likely to be areas at risk regarding to landslide-induced tsunamis, because of the proximity between lakes and potential instabilities and due to the concentration of the population in valleys and on the lakes shores. In particular, dam lakes are often surrounded by steep slopes and frequently affect the stability of the banks. In order to assess comprehensively this phenomenon together with the induced risks, we have developed a 2.5D numerical model which aims to simulate the propagation of the landslide, the generation and the propagation of the wave and eventually the spread on the shores or the associated downstream flow. To perform this task, the process is done in three steps. Firstly, the geometry of the sliding mass is constructed using the Sloping Local Base Level (SLBL) concept. Secondly, the propagation of this volume is performed using a model based on viscous flow equations. Finally, the wave generation and its propagation are simulated using the shallow water equations stabilized by the Lax-Friedrichs scheme. The transition between wet and dry bed is performed by the combination of the two latter sets of equations. The proper behavior of our model is demonstrated by; (1) numerical tests from Toro (2001), and (2) by comparison with a real event where the horizontal run-up distance is known (Nicolet landslide, Quebec, Canada). The model is of particular interest due to its ability to perform quickly the 2.5D geometric model of the landslide, the tsunami simulation and, consequently, the hazard assessment.
Merli, Marco; Castagna, Antonella; Salpietro, Stefania; Gianotti, Nicola; Messina, Emanuela; Poli, Andrea; Morsica, Giulia; Bagaglio, Sabrina; Cernuschi, Massimo; Bigoloni, Alba; Uberti-Foppa, Caterina; Lazzarin, Adriano; Hasson, Hamid
2016-04-01
Non-invasive assessment of liver fibrosis represents an appealing method to monitor liver disease in HCV-infected patients. Currently, transient elastography (TE) is the most accurate non-invasive tool to measure liver stiffness (LS), with the diagnostic accuracy increasing together with the stage of fibrosis (Friedrich Rust et al., 2008; Degos et al., 2010). Stiffness measurement is widely used in the assessment of fibrosis in patients with chronic hepatitis C given its good reproducibility (Fraquelli et al., 2007) and its association with the risk of liver-related complications and death in HIV/HCV-coinfected patients (Fernandez-Montero et al., 2013) and also in patients with compensated HCV-related liver cirrhosis (with or without concomitant HIV-coinfection) (Pérez-Latorre et al., 2014). In the last decade, direct and indirect biomarkers for predicting liver fibrosis have also been developed. Direct fibrosis biomarkers (e.g. FibroTest, FibroMeter) are calculated using serum molecules produced in the presence of liver fibrosis and released in the circulatory system while indirect biomarkers (e.g. APRI, FIB-4, Forns) result from the combination of routine blood tests. Even though indirect biomarkers had a lower diagnostic performance than direct biomarkers and especially TE (Sánchez-Conde et al., 2010; Degos et al., 2010; Castéra et al., 2014), the absence of additional costs and the ready availability make indirect biomarkers a quick and easy non-invasive method to periodically assess liver fibrosis. Since the early detection of liver cirrhosis has a significant impact on both clinical management and treatment decision regarding chronic hepatitis C, we evaluated the threshold and the diagnostic accuracy of APRI, FIB-4 and Forns for the diagnosis of liver cirrhosis in HIV/HCV-coinfected patients. PMID:27196548
Pain and Poppies: The Good, the Bad, and the Ugly of Opioid Analgesics
Al-Hasani, Ream; Salvemini, Daniela; Salter, Michael W.; Gutstein, Howard
2015-01-01
Treating pain is one of the most difficult challenges in medicine and a key facet of disease management. The isolation of morphine by Friedrich Sertürner in 1804 added an essential pharmacological tool in the treatment of pain and spawned the discovery of a new class of drugs known collectively as opioid analgesics. Revered for their potent pain-relieving effects, even Morpheus the god of dreams could not have dreamt that his opium tincture would be both a gift and a burden to humankind. To date, morphine and other opioids remain essential analgesics for alleviating pain. However, their use is plagued by major side effects, such as analgesic tolerance (diminished pain-relieving effects), hyperalgesia (increased pain sensitivity), and drug dependence. This review highlights recent advances in understanding the key causes of these adverse effects and explores the effect of chronic pain on opioid reward. SIGNIFICANCE STATEMENT Chronic pain is pervasive and afflicts >100 million Americans. Treating pain in these individuals is notoriously difficult and often requires opioids, one of the most powerful and effective classes of drugs used for controlling pain. However, their use is plagued by major side effects, such as a loss of pain-relieving effects (analgesic tolerance), paradoxical pain (hyperalgesia), and addiction. Despite the potential side effects, opioids remain the pharmacological cornerstone of modern pain therapy. This review highlights recent breakthroughs in understanding the key causes of these adverse effects and explores the cellular control of opioid systems in reward and aversion. The findings will challenge traditional views of the good, the bad, and the ugly of opioids. PMID:26468188
Jennette, J C
2011-01-01
Names influence how something is perceived. Diagnostic terms (diagnoses) are the names of diseases that are usually derived either from some distinctive characteristic of the disease or include an eponym recognizing someone who elucidated the disease. No matter how logical and appropriate a name may be, if it is not usable and used it is of no lasting value. This brief commentary focuses on the nomenclature of systemic vasculitides, and uses as a prime example Wegener's granulomatosis, which has been renamed recently ‘granulomatosis with polyangiitis’, in part because of concerns about the suitability of Friedrich Wegener as the source of an eponym. The most distinctive pathological feature of Wegener's granulomatosis is multi-focal necrotizing inflammation that has long been called granulomatosis. The systemic variant of Wegener's granulomatosis also is characterized by inflammation in many different vessels or different types, i.e. polyangiitis. Thus, granulomatosis with polyangiitis is a very appropriate alternative term for Wegener's granulomatosis. This term also is in accord with the name for a closely related vasculitis, i.e. microscopic polyangiitis. Terms that indicate aetiology and pathogenesis, when known, are useful to include in names for diseases (diagnoses). Anti-neutrophil cytoplasmic autoantibodies specific for myeloperoxidase (MPO-ANCA) or proteinase 3 (PR3-ANCA) are implicated in the cause of granulomatosis with polyangiitis and thus also should be specified in the diagnosis (e.g. PR3-ANCA-positive granulomatosis with polyangiitis or MPO-ANCA-positive microscopic polyangiitis). As our understanding of the clinical manifestations, pathogenesis and aetiology of vasculitides change over time, the names and approaches for diagnosing these diseases will change accordingly. PMID:21447122
Suffering for her art: the chronic pain syndrome of pianist Clara Wieck-Schumann.
Altenmüller, Eckart; Kopiez, Reinhard
2010-01-01
Clara Schumann was an outstanding pianist, systematically trained as a child prodigy by her father Friedrich Wieck. Married to the composer Robert Schumann she gave birth to 8 children, however, was able to continue performing regularly in public. After the mental breakdown of her husband, she had to increase her public performance activities due to the need to earn a living for her large family. In this time, the first pains in the right arm occurred, which at the beginning were of shorter duration, however increasingly required prolonged periods of rest. Later, when attempting to work on the highly demanding piano works of Johannes Brahms, especially on his first piano concerto, she developed chronic pain, which forced her to interrupt any concert activities for more than 1 year. Obviously, Brahms' modern treatment of the piano in an almost orchestral way imposed technical difficulties which Clara Schumann was not properly prepared to deal with. Finally, she underwent a multimodal pain therapy in the private sanatorium of Dr. Esmarch, which consisted of an integrated interdisciplinary approach comprising pain medication, psychotherapy, physiotherapy and modification of playing habits. She fully recovered and successfully continued her career as an internationally renowned concert pianist. The case report impressively demonstrates the stressors an outstanding female elite musician had to cope with in the 19th century. Furthermore, it is a convincing example of how the intuition and mere experience of a sensitive and understanding doctor lead to the right conclusions and to a modern multimodal pain therapy in chronic overuse injury. Furthermore the case report demonstrates the important role of prevention, including physical exercises, self-awareness, and reasonable practice schedules. PMID:20375525
Electronic structure from relativistic quasiparticle self-consistent GW calculations
NASA Astrophysics Data System (ADS)
Blügel, Stefan
Most theoretical studies of topological insulators (TIs) are based on tight-binding descriptions and density functional theory (DFT). But recently, many-body calculations within the GW approximation attract much attention in the study of these materials. We present an implementation of the quasiparticle self-consistent (QS) GW method where the spin-orbit coupling (SOC) is fully taken into account in each iteration rather than added a posteriori. Within the all-electron FLAPW formalism, we show DFT, one-shot GW , and QS GW calculations for several, well-known TIs. We present a comparison of the calculations to photoemission spectroscopy and show that the GW corrected bands agree much better with experiment. For example, we show that Bi2Se3 is a direct gap semiconductor, in contrast to what was believed for many years by interpreting experimental results on the basis of DFT and that small strains in Bi can lead to a semimetal-to-semiconductor or trivial-to-topological transitions. Quasiparticle calculations for low-dimensional systems are still very demanding. In order to study the topological surface states with an approach based on GW , we use Wannier functions to construct a Hamiltonian that reproduces the many-body band structure of the bulk, and that is used to construct a slab Hamiltonian. With this approach, we discuss the effect of quasiparticle corrections on the surface states of TIs and on the interaction between bulk and surface states Work was funded by the Virtual Institute for Topological Insulators of the Helmholtz Association and carried out in collaboration with Irene Aguilera, Gustav Bihlmayer, and Christoph Friedrich.
NASA Astrophysics Data System (ADS)
Arshed, Ghulam M.; Hoffmann, Klaus A.
2013-08-01
approximation of the spatial derivative is performed by means of a conservative and consistent finite difference method based on monotone local Lax-Friedrichs Riemann solver. The resulting scheme is then integrated by the optimal third-order TVD Runge-Kutta method to ensure the nonlinear stability of the overall numerical method. A variety of benchmark problems, ranging from non-broadband to broadband, are solved using the proposed schemes and compared with the existing ones. Most test problems are validated against exact or reference data. The numerical results with bandwidth optimization and modification of the nonlinear weights are consistently superior.
NASA Astrophysics Data System (ADS)
Cavalcanti, José Rafael; Dumbser, Michael; Motta-Marques, David da; Fragoso Junior, Carlos Ruberto
2015-12-01
In this article we propose a new conservative high resolution TVD (total variation diminishing) finite volume scheme with time-accurate local time stepping (LTS) on unstructured grids for the solution of scalar transport problems, which are typical in the context of water quality simulations. To keep the presentation of the new method as simple as possible, the algorithm is only derived in two space dimensions and for purely convective transport problems, hence neglecting diffusion and reaction terms. The new numerical method for the solution of the scalar transport is directly coupled to the hydrodynamic model of Casulli and Walters (2000) that provides the dynamics of the free surface and the velocity vector field based on a semi-implicit discretization of the shallow water equations. Wetting and drying is handled rigorously by the nonlinear algorithm proposed by Casulli (2009). The new time-accurate LTS algorithm allows a different time step size for each element of the unstructured grid, based on an element-local Courant-Friedrichs-Lewy (CFL) stability condition. The proposed method does not need any synchronization between different time steps of different elements and is by construction locally and globally conservative. The LTS scheme is based on a piecewise linear polynomial reconstruction in space-time using the MUSCL-Hancock method, to obtain second order of accuracy in both space and time. The new algorithm is first validated on some classical test cases for pure advection problems, for which exact solutions are known. In all cases we obtain a very good level of accuracy, showing also numerical convergence results; we furthermore confirm mass conservation up to machine precision and observe an improved computational efficiency compared to a standard second order TVD scheme for scalar transport with global time stepping (GTS). Then, the new LTS method is applied to some more complex problems, where the new scalar transport scheme has also been coupled to