bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bone Morphogenetic Protein-Mediated Modulation of Lineage Diversification During Neural Differentiation of Embryonic Stem Cells
Authors: Gossrau Gudrun , Thiele Janine , Konang Rachel , Schmandt Tanja , Brüstle Oliver 
Published: January 2007

Abstract
Embryonic stem cells (ES cells) can give rise to a broad spectrum of neural cell types. The biomedical application of ES cells will require detailed knowledge on the role of individual factors modulating fate specification during in vitro differentiation. Bone morphogenetic proteins (BMPs) are known to exert a multitude of diverse differentiation effects during embryonic development. Here, we show that exposure to BMP2 at distinct stages of neural ES cell differentiation can be used to promote specific cell lineages. During early ES cell differentiation, BMP2-mediated inhibition of neuroectodermal differentiation is associated with an increase in mesoderm and smooth muscle differentiation. In fibroblast growth factor 2-expanded ES cell-derived neural precursors, BMP2 supports the generation of neural crest phenotypes, and, within the neuronal lineage, promotes distinct subtypes of peripheral neurons, including cholinergic and autonomic phenotypes. BMP2 also exerts a density-dependent promotion of astrocyte differentiation at the expense of oligodendrocyte formation. Experiments involving inhibition of the serine threonine kinase FRAP support the notion that these effects are mediated via the JAK/STAT pathway. The preservation of diverse developmental BMP2 effects in differentiating ES cell cultures provides interesting prospects for the enrichment of distinct neural phenotypes in vitro.
Disclosure of potential conflicts of interest is found at the end of this article.
Analysis of the Origin and Population Dynamics of Cardiac Progenitor Cells in a Donor Heart Model
Authors: Li Tao-Sheng , Suzuki Ryo , Ueda Kazuhiro , Murata Tomoaki , Hamano Kimikazu 
Published: January 2007

Abstract
Cardiac progenitor (stem) cells have recently been detected in and isolated from the myocardium of neonatal and adult mice, rats, and humans; however, the precise origin and characterization of these cells remain unclear. Using a heterotopic mouse heart transplantation model, we investigated the origin and population dynamics of cardiac progenitor cells. Donor hearts from wild-type C57/BL6 female mice were transplanted into green fluorescent protein (GFP)-transgenic C57/BL6 male mice. The donor hearts were collected 0, 2, 4, 8, and 12 weeks after transplantation. We used quantitative flow cytometry to analyze the number and origin of stem cells in the donor hearts and immunostaining to evaluate the time-related changes in their characteristics. Extracardiac GFP-positive stem cells immigrated into the donor hearts soon after transplantation. Immunostaining revealed that these GFP-positive stem cells in the donor hearts gradually lost expression of the hematopoietic markers of CD45 and CD34 and shifted to express the cardiac-specific transcription factors GATA-4 and NKx2.5. A few of the GFP-positive cells in the donor hearts finally acquired the mature cardiac phenotype in the absence of cell fusion with donor cardiomyocytes. Our discovery provides the first evidence that extracardiac stem cells may be of bone marrow origin, from which they can transform into cardiac progenitor cells in response to myocardial environment cues.
Disclosure of potential conflicts of interest is found at the end of this article.
Farce (TDR Document)
Authors: Meyerhold Vsevolod 
Published: January 2007

“Mystery in the Russian Theatre” is the title given by Benois to one of his “Letters on Art.” One might think that in this article he is discussing a production of one of Aleksei Remizov's plays written in the style of a medieval mystery play. Or, perhaps, Scriabin has already realized one of his dreams, and Benois is hastening to announce to the public the greatest event on the Russian stage—the appearance of a new theatrical form reviewing the mystic rites of ancient Greek culture.It seems that neither Remizov nor Scriabin has written a mystery; according to Benois the Moscow Art Theatre has produced a mystery with its performance of The Brothers Karamasov. But just what characteristics of the medieval mystery plays could be found in the performance of The Brothers Karamasov? Perhaps here the purified ancient Greek mysteries were combined with the visual edification of the medieval mystery play?
On the Psychology of Comedy
Authors: Jekels Ludwig 
Published: January 2007

We are indebted to psycho-analysis for much valuable insight into the psychology of tragedy. Not only has psycho-analysis made us recognize that the “tragic guilt” of the hero, postulated by aesthetics, actually stems from the repressed Oedipus-wishes of the dramatist but it has also drawn our attention to the interrelation of dramatist and audience; that is, to the fact of a common guilt as the decisive psychological factor which, on the one hand, enables the dramatist to create his work and, on the other, produces the Aristotelian catharsis, or “purging of the passions.” Freud, in particular, established the psychological traces of the primal crime in classical tragedy and following in his tracks, Winterstein has recently subjected the origins of tragedy to intensive study and radically clarified them.By contrast, how little has psycho-analysis bothered about comedy! So far it has hardly attracted any interest worth mentioning: at most it was granted a modest domicile in that basement of research, the footnote, there to be dealt with in a cursory manner.
The Plays of John Whiting
Authors: Trussler Simon 
Published: January 2007

Only recently has the new drama begun to catch up with John Whiting, who if he were alive would now be almost fifty. He was out of sympathy with the social commitment of the early days. Whiting was not one of the cultural knight-errants who crusaded for working-class culture and against the bomb; rather, he belonged instinctively to the older tradition of the intellectual elite, writing difficult plays for a discriminating audience—an audience with which he never truly made contact, and which perhaps had long ceased to exist.Yet his lifelong preoccupations with the nature of violence and of personal responsibility foreshadowed the concern of a younger generation of dramatists with issues more elemental than the kitchen sink.
On Practical Mathematics in Schools
Authors: Steggall J.E.A. 
Published: January 2007

When, with the other members, I received a request from the Secretary, it seemed only fair to him that I should express my willingness to do whatever might be in my power towards the provision of a subject for discussion ; and therefore, with an earnest wish that he would if possible ignore my suggestions, I proposed the rather well worn subject of this paper. To my dismay he did not ignore the suggestions, and in consequence you will have to listen to the trite observations of one who, sufficiently remote from great centres of education, and in great measure precluded from intimate contact with modern methods, is nevertheless sufficiently interested in them to form theories, or rather opinions, of his own. Those to whom the element of novelty may be absent in the points that I proceed to consider will, I trust, extend a charitable reception on the great moral principle of the Western States that the pianist who does his best is not to be shot.In the ordinary course of lecturing to students who come stamped with the approval of some of the entrance examination Boards, and their name is legion, I find that, especially when they have had a more or less practical course, very great difficulties arise on account of their weak grasp of mathematical reasoning.
The Eccentric Circle of Boscovich
Authors: Langley E. M. 
Published: January 2007

Consideration of the special case in which the centre of the eccentric circle lies on the straight line whose points of intersection with the conic are required.In what follows it will be convenient to abandon the system of lettering adopted by Boscovich which we have hitherto followed, and as far as possible to use that common to modern text books.
Approximations to n√1+x where n is an integer and 0<x<1
Authors: Child J.M. 
Published: January 2007

If we seek approximations to in the formof such a nature that the fraction gives, on performing the division, an infinite series whose first 2r+1 terms are identical with the first 2r+1 terms of the Binomial Expansion for we shall obtain 2r equations of the form
The Conic through Five Given Points
Authors: Dixon A. C. 
Published: January 2007

The following discussion may be of interest on account of the way in which it leads to the axial and focal properties.I. Let the locus of a point P such that A(CDEP) = B(CDEP), where A, B, C, D, E are fixed points, be called the conic (AB, CDE). Then it is clear that permuting A, B or C, D, E does not affect the conic, and that the conic passes through C, D, E, and also through A, B. (Give BP the four positions BC, BD, BE, BA and then give AP the position AB.)
On a Continued Fraction of Stieltjes
Authors: Phillips E. G. 
Published: January 2007

1. One of the two curious self-reciprocal formulae stated by Rama-nujan,whereof which I have recently given a proof, can be established by using a result proved by Stieltjes that, if x > 0, m ≥ 0, 0≤a≤ 1,The proof only requires the above result in the case in which m = 1, a = 0. While seeking an extension of the result (1. 1), I have obtained an expression for the continued fraction (1. 3) in the form of an infinite series.
The Circle in Homogeneous Coordinates
Authors: Gibbins N. M. 
Published: January 2007

1. It is necessary to challenge Mr. F H. V Gulasekharam’s Note 1448 (May, 1940) in which he claims to give simpler methods than usual for dealing with the circleS ≡ (Σlx)(Σx) − Σa2yz = 0.Objection must be taken at the very beginning where he says “Suppose the circle cuts the sides of the triangle of reference ABC at D1D2” The arguments of §§ 1 and 2 are sound when these points are real, but it is asking too much of a young student to expect him to understand what is meant by the ratios D1C/BD1 and D2C/BD2 when D1 and D2 are imaginary Moreover the writer considers that the arguments of §§ 3 and 4 are not simple but very difficult.
Rotation and Strain
Authors: Browne H. F 
Published: January 2007

The following method of introducing the ideas of rotation and strain into the study of Elasticity depends upon the identitym · n grad u=n · (m grad u + m × curl u).....(1)and upon the fact that if the straight line PQ undergoes a small rotation ω about an axis through P, the displacement of Q isConsider first of all a rigid body which undergoes a small displacement. Let the point P of the body move to P′. We shall represent PP′ by u and regard u as typical of a vector field extending throughout the space originally occupied by the body. Let Q be a point near to P and represent by m.
On the Intersections of a Central Conic and its Principal Hyperbolas
Authors: Rajagopal C. T. 
Published: January 2007

Let an ellipse or a hyperbola be given by the equationThen, following Vaidyanathaswamy [8, p. 124], we shall refer to a hyperbola H having its asymptotes parallel to the principal axes of S as a principal hyperbola of S. H is thus given by an equation of the typeand it is uniquely determined when we know three of its intersections with S. It is one of the purposes of this article to bring together some of the elementary properties of H which have been ignored, quite unjustifiably, by most of the textbooks on conic sections produced after Casey's Analytical Geometry [2]. Another purpose which it is hoped the article will serve is that of bringing within easy reach of students, who have had only a preliminary course in geometries of two and three dimensions, some of Vaidyanathaswamy's investigations into the concurrency of normals to a central conic [6].
Some Interesting Sets of Circles
Authors: Child J. M. 
Published: January 2007

The “curious” property noted by Mr. A. P. Rollett (Note 1261 in the Mathematical Gazette for December 1937), with regard to the centres of circles touching one another and inscribed in the space between two given circles, leads to an interesting general theorem on all such sets of circles.Given any two circles, and a set of circles touching one another and the two given circles, then, if r1r2, r3 are the radii of three successive circles of the set, of which r2 is known, r1 and r3 are the roots of a quadratic equation of which the coefficients are simple functions of r2 and the radii of the given circles.
The Product of Two Series
Authors: Siddons A.W. 
Published: January 2007

The followitlg is a useful introduction to the proof of the theorem about the product of two series.(1) Let Ur =u1 + u2 + .. +urand Vr = v1 + v2 + ... + vrbe two convergent series of real positive terms, and let Ur → U, Vr→V as r→∞.
Sign, and Elementary Vector ideas, in Plane Analytical Geometry and Trigonometry.
Authors: Picken D. K. 
Published: January 2007

Plane Analytical Geometry, and elementary Trigonometry, are the beginnings of the systematic application of mathematical analysis to Geometry, i.e. of systematic expression in terms of “number”—which is essentially “real” number.Complete application of the generality of the algebra (within the restriction to real number) is, of course, the power of the method; and, in particular, sign of the (real) numbers is significant throughout.
“The Teaching of Mechanics in Schools” and Other Reports
Authors: Combridge J. T. 
Published: January 2007

It is the duty of the Teaching Committee to keep under review Reports published by the Association, and accordingly members of this committee were asked last May to answer the following questions :(a) Do you consider that the Mechanics Report is sufficiently in need of revision or rewriting for a sub-committee to be appointed now for this purpose, or do you consider that any other Report needs revision more urgently?(b) Which parts of the Mechanics Report do you think are most in need of rewriting?(c) Are there any topics not included in the Mechanics Report which you consider should be put into a new report?
On the Inversion Property of the Mobius’ μ-Function II
Authors: Satyanarayana U. V. 
Published: January 2007

In a recent paper, under the same title, I proved that inversion of certain functional relations is the characteristic property of the Mobius’ μ-function, by establishing the:THEOREM I′: f(n), g(n) and μ*(n) (possibly depending on f) are three arithmetical functions with
Dividing an angle into equal parts
Authors: Buckley Stephen , MacHale Desmond 
Published: January 2007

The problem of finding a geometric construction in a finite number of steps to trisect an arbitrary angle using straightedge and compasses alone is a very old one, originally proposed by the mathematicians of ancient Greece. It was only with modern algebraic techniques in the nineteenth century that it was shown conclusively that no such construction can exist. This fact has in no way deterred a legion of crank angle-trisectors from presenting their alleged solutions to the problem! However some angles (even non-constructible ones) can be trisected: we’ll see later, for example, that given an angle π/7 it can be trisected. We can also consider the more general problem:
For which natural numbers n > 2 does there exist a geometric construction in a finite number of steps to divide an arbitrary angle into n equal parts, using straightedge and compasses alone?
A plane introduction to surfaces
Authors: Firby P. A. , Gardiner C. F. 
Published: January 2007

1. IntroductionSince Poincaré introduced algebraic or geometric topology in a series of papers during the years 1895-1901, the subject has grown rapidly to become one of the major branches of mathematics with ramifications in many other branches. However, apart from some recreational level ‘rubber-sheet’ geometry, very few students, even at first degree level, meet algebraic topology.
61.4 Basic topological concepts without intimidation
Authors: Meyers Leroy F. 
Published: January 2007

The usual basic topological concepts, as seen by students for the first time in a course such as analysis, often seem unintuitive. The following procedure may be more digestible.Virtually everyone can recognise a boundary point of a set A in a space X. It is merely a point of X all of whose neighbourhoods contain both a point belonging to A and a point not belonging to A. The boundary bA of A consists of the boundary points of A.
Identifying points of inflection
Authors: Ball A. A. 
Published: January 2007

We start with a geometric definition:A point of inflection is a point of a smooth curve at which the tangent not only touches the curve but also crosses it.Fig. 1 illustrates the definition and shows a curve, its point of inflection and the inflectional tangent (i.e. the tangent at the point of inflection) which crosses the curve. We can see that the point of inflection occurs where the curve stops bending to the left and starts bending to the right. This leads to a more descriptive definition of a point of inflection as a point where the direction of bending of a smooth curve changes sense.
Applications of the pigeon-hole principle
Authors: Bankov Kiril 
Published: January 2007

Consider the statement (whose truth is obvious):If n objects are placed in k boxes, where n = qk + r, q and r are positive integers, and 0 < r < k, then at least one box contains more than q objects.This is known as a pigeon-hole principle (or Dirichlet’s). It is one of the strategies which is often used for problem-solving. Although it is one of the most powerful tools of combinatorics, the principle can be used successfully in other branches of mathematics. Below you can find a collection of problems which can be solved easily by applying this principle to geometrical objects.
A salutary or solitary point
Authors: Hoare Graham 
Published: January 2007

Some three weeks into the academic year I presented, off the cuff, the following morsel to engage some lower-sixth formers who had polished off some routine derivatives all too quickly:Sketch the curve whose equation is given by x3 + y3 + 3xy – 1 = 0 , and find the gradient at the point (–1 , –1).Since this was near the end of a double period I thought no more of it. At the end of the next double period one student remarked that he had been having difficulty in sketching it. “It seems to be a straight line”, he said. I rashly suggested that he could well be mistaken, but promised to look at it. If my faith in the student had been greater I could have saved myself some labour searching for simple solutions of the cubic. I had noticed the solution (½ , ½) by the way. I began to have delusions of grandeur, imagining myself to be the natural successor of Diophantus, as I found the solutions (5,–4) and (–4,5).
Roll-a-penny probabilities
Authors: Hirst Ann 
Published: January 2007

In exploring the probabilities involved in a roll-a-penny game, some properties turned out to be a little more complicated than expected. The main aim here is to find the probability that the player will lose after a certain number of rolls.Suppose we have a board upon which squares are drawn, and that the side of each square is four times the radius of a penny. (In practice, this means that the squares are of side 4 cm.) The first question is, “What is the probability that the penny lands entirely within a square, assuming that the dividing lines are of negligible thickness?”
Mr. Taylor in Chaldaea.
Authors: Sollberger E. 
Published: January 2007

The very first reports on excavations at sites in southern Sumer appeared in the Journal of the Royal Asiatic Society for 1855 under the name of ‘J. E. Taylor, Esq.’ A typographer's misreading thus gave Taylor the wrong initials under which he is usually mentioned. His middle name was in fact George. It may, of course, seem surprising that the author himself did not bother to correct the error. One can only suppose that, postal communications being what they were at the time (see below, §6), he never had a chance of seeing his articles in proof.
Very little seems to be known of John George Taylor's life and career. According to information kindly supplied by Miss S. Johnson, India Office Records, he was the son of R. Taylor, “almost certainly Colonel R. Taylor”, Rawlinson's predecessor at Baghdad. If so, it is remarkable that the latter does not seem to mention the fact in his correspondence with the British Museum. What is certain is that J. G. Taylor was The Hon. East India Company's Agent and H.M. Vice-Consul at Basrah from 1851 to 1859. In 1853 he started his explorations of the “Chaldaean Marshes” for and on behalf of the British Museum under the very strict instructions and supervision of Rawlinson who, as The Hon. East India Company's Political Agent in Turkish Arabia and H.M. Consul-General at Baghdad, was then presiding over Mesopotamian archaeology with truly vice-regal grandeur and an almost proprietary interest.
Eine frühurartäische Siegesdarstellung
Authors: Calmeyer P. , Seidl U. 
Published: January 2007

Die einstmals kreisrunde, flache Bronzescheibe, angeblich aus Ostanatolien, die hier vorgestellt wird (Pl. XXX–XXXI), befand sich 1981 für kurze Zeit im Labor der Prähistorischen Staatssammlung, München. Die Form des Bleches, die bisher bekannten Beschlagblechen nicht genau entspricht, die historische Darstellung auf dem umlaufenden Fries und das Mittelemblem verdienen eine genauere Behandlung.Die Scheibe: Die durchschnittlich auf eine Dicke von ungefähr 1/2 mm. ausgehämmerte Bronzescheibe wird durch 4 konzentrische getriebene Wülste in einen mittleren Kreis, drei Zonen und einen Rand aufgeteilt (Fig. 1, Pl. XXXa). Im Übrigen ist sie ganz flach, und das dürfte auch ihrem antiken Zustand entsprechen: sie muß allerdings einmal brutal quer gefaltet gewesen sein, wovon eine Reihe von Rissen und Knicken herrühren, die von links unten nach rechts oben verlaufen (Pl. XXXa); an den Enden dieser Faltung ist auch der Rand am weitesten ausgerissen. Die nachträgliche Begradigung dieser Partie ist wohl modern. Links oben und rechts unten jedoch ist der offenbar ursprünglache flache Zustand bewahrt.
Two New Milestones from Pisidia
Authors: Horsley G. H. R. 
Published: January 2007

By the end of 1987 three successive seasons had been spent by a team co-directed by Dr. S. Mitchell and Professor M. Waelkens at the Augustan colony of Cremna, and two (plus a brief initial season in 1985) at Pisidia's chief city in Roman Imperial times, Sagalassos. The permit for a surface survey has provided the opportunity to locate and check a considerable percentage of the texts previously known. It has also made possible the discovery of several new inscriptions from these sites and their territory. Two new milestones are presented here, one pertaining to each city.In early August 1987, on the last evening of my stay with the team working at Sagalassos, I was taken by two men from Aǧlasun 4 km. along the Aǧlasun–Isparta road. Turning right into a lane, after some 300 m. we came to a small bridge over a stream. Nearby was a large cylindrical stone (Pl. XVII(a)) which had recently been recovered from the stream during excavations for another bridge.