bluuebunny/crossref_metadata_2025_split huggingface dataset:
LOCAL MAXIMA IN GRADED GRAPHS OF EMBEDDINGS
Authors: Gross Jonathan L. , Tucker Thomas W. 
Published: December 2006

SummaryThis paper describes four natural ways in which the set of all orientable embeddings of a graph might be regarded as the vertices of a “graded graph.” A local maximum in any of these kinds of graded graphs is an embedding such that every “adjacent” embedding has fewer faces, and consequently, higher genus. Examples are presented to show that local maxima can arise in each of the four kinds of graded graphs, thereby undermining the hope for an obvious hill‐climbing algorithm. (Some hope for a more subtle hill‐climbing algorithm may survive.)
ON THE SPANNING TREES OF SELF‐DUAL MAPS
Authors: Tutte W. T. 
Published: December 2006

SummaryA central reflex is a map on the sphere that is transformed into its dual map by reflection in the center. It is shown in [2] that the number T(M) of spanning trees of a central reflex M is a perfect square {X(M)}2. In the present paper we determine X(M) directly as the number of spanning trees of M in which no edge is equivalent, under central reflection, to the dual edge of another.The paper is constructed as an expository article on the theory of dual planar maps. The proof that T(M) = {X(M)}2 is presented as an exercise in this theory.
ELECTRICAL FIELDS, CALCIUM GRADIENTS, AND CELL GROWTH
Authors: Robinson Kenneth R. , McCaig Colin 
Published: December 2006

SummaryWe have outlined the evidence that fucoid eggs and pollen tubes drive an electric current through themselves as they grow, alter (or initiate) their growth in response to an applied electrical field, and develop a calcium gradient during their growth with the region of highest calcium concentration being the growing point. New data have been presented to support the notion that it is this calcium gradient that is essential in the polarization process.The fucoid egg (a free‐living cell) would not normally be subjected to an externally imposed electrical field. The fact that an imposed field can mimic the endogenous current must be viewed as somewhat fortuitous, since the effects of the imposed field on the membrane and the cytoplasm must be quite different from those of the endogenous field. The case of the growing neurite is quite different; we imagine that it might well be exposed to a field during normal neurogenesis. The following intriguing possibility is raised. Might the exogenous electrical field interact with an endogenous electrical field in the growing neurite? If so, the analogy between neurite extension and plant tip growth could be very close indeed. Our preliminary evidence that the neurites curve in response to a calcium ionophore gradient adds to the suspicion that these processes are similar. The idea is that the small voltage gradient sensed by a neurite would be amplified by the neurite's production of its own current which would involve local calcium entry. We are encouraged to attempt to suitably scale down the vibrating probe in an effort to measure such self‐generated currents.Our finding that the muscle cells form their long axes at right angles to an electric field was made accidently and does not easily fit into the scheme that has been suggested for fucoid egg, pollen, and nerve. It may be that the field affects the orientation of a transverse tubule system which is somehow caused to form parallel to the field with the result that the long axis forms perpendicular to the field, but this is purely speculative at this point.Finally, we should emphasize that our notion that an epithelially generated current may play a role in the orientation of nerves and muscle in embryonic Xenopus is not an exclusive one. We envision that such currents are only crude, initial controls and that other, subtler controls (such as local chemical gradients) will undoubtedly be involved in the finer control of these processes.
CELL TYPES IN LONG‐TERM PROPAGABLE CULTURES OF RAT LIVER*
Authors: Grisham J. W. 
Published: December 2006

SUMMARYUnder the conditions of this experiment, propagable hepatic epithelial cells in long‐term culture were derived from a small, nonparenchymal precursor cell present in the liver in vivo. Progeny of the nonparenchymal precursor cell weakly expressed some hepatocyte‐like properties in culture. Hepatocytes were not clonogenic under the conditions of this experiment. Propagable hepatic epithelial cells in long‐term culture probably originate from hepatic stem cells in vivo. Terminal biliary ductular cells are facultative stem cells for hepatocytes.
The Effects of Vitamin C Supplementation on Blood and Hair Levels of Cadmium, Lead, and Mercury
Authors: CALABRESE EDWARD J. , STODDARD ANNE , LEONARD DENISE A. , DINARDI SALVATORE R. 
Published: December 2006

SUMMARYFifty‐two adult male subjects were randomly assigned to one of three possible treatment groups: supplemental ascorbic acid at one of two levels, 500 mg or 1000 mg, or a placebo. Hair and blood samples were taken before vitamin C or placebo supplementation was started and at monthly intervals thereafter for three months. Samples were analyzed for cadmium, lead, and mercury. Results indicate that vitamin C did not significantly affect levels of these metals in either hair or blood samples.
Hemopoietic Cell Progenitors in the Avian Embryo: Origin and Migrations
Authors: DIETERLEN‐LIÈVRE F. 
Published: December 2006

The cellular events involved in the formation of hemopoietic progenitors during early embryogenesis are critical for the lifelong function of the blood‐forming system if, as is supposed, these progenitors arise during ontogeny and thereafter maintain their stock by self renewal. Several aspects of these events have been unravelled in recent years. Basic data on the interactions between stem cells and hemopoietic microenvironments have emerged from studies of the avian embryo by experimental approaches that are possible only in that class at the time of organogenesis. Interestingly, when it has been possible to devise appropriate experimental models, similar mechanisms have often been detected in mammals.When early developmental processes are investigated, difficulties arise from the small contingent of cells available. Cell markers have made it possible to trace individual cells and thus to follow lineages through their phenotypic changes and their extensive migrations. In the avian embryo, a cell‐marking technique devised by N. Le Douarin in 19691 has become widely used for the study of various lineages. It consists in associating cells (or tissues, rudiments, embryonic territories) from two species, the chicken and the quail. Cell nuclei have a different appearance in these two species (Figure 1). In recent years, the distinction of blood cells according to species in this heterospecific system has become refined by the availability of two monoclonal antibodies with affinity restricted to the quail species and which recognize the hemangioblastic lineage, MB12 and QH13 (Figure 2). The hemangioblastic lineage comprises, on the one hand, endothelial cells, and on the other, blood cells and their progenitors. The points to consider about the ontogeny of the blood system are the relationships between stem cells and hemopoietic organ rudiments, the spatial and chronological origins of stem cells during ontogeny, the mechanisms through which they settle into the stromas of hemopoietic organs and the nature of the relationship between endothelial and hemopoietic cells.
Studies of Cachexia in Parasitic Infection
Authors: TRACEY KEVIN J. , CERAMI ANTHONY 
Published: December 2006

Chronic illness caused by infection with parasites, viruses, or bacteria is frequently associated with a potentially fatal syndrome termed “cachexia.” The stricken host dies from progressive weight loss, anemia, immune suppression, and terminal organ injury, even when the invasive burden may be relatively small. Until recently the biochemical basis of these harmful effects of infection‐associated cachexia was not understood. They are now known to be mediated primarily by endogenous factors released in response to invasive infection. The search for these mediators led to the identification, isolation, and cloning of the cytokine known as cachectin/TNF (tumor necrosis factor).Investigation of the biological effects of cachectin/TNF subsequently confirmed its role as a mediator of cachexia. Further studies revealed that cachectin is also an important mediator of septic shock, another syndrome of injurious host responses elicited by acute bacterial infection. The realization that endogenous factors, produced acutely or chronically during infection and inflammation, may mediate lethal syndromes in the host has advanced our understanding of the pathophysiology of infectious illnesses, and led to the investigation of novel treatment modalities. In this paper we will briefly review the history of cachectin/TNF, and discuss its role as an endogenous mediator of the hosts' responses to infection.
Lower Density Topologiesa
Authors: ROSE D. A. , JANKOVIĆ D. , HAMLETT T. R. 
Published: December 2006

AbstractBy considering lower density operators and their induced topologies in a general setting, some results of S. Scheinberg and E. Ľazarow et al. are unified and generalized. It is also shown that every σ‐finite complete measure space (X, M, m) has a lower density operator and that every such operator induces a topology making X a category measure space in the sense of J. C. Oxtoby, except that the measure need not be finite. One consequence is that category σ‐finite measure spaces must have the countable chain condition. Also, for every topological space (X, |Gt), there is a lower density operator on the σ‐field of sets having the property of Baire (relative to the σ‐ideal of meager sets). Further, in both the “measure” and “category” contexts, all induced lower density topologies have simple form. Finally, it is shown that the deep. J‐density operator on the σ‐field of subsets of the real line having the property of Baire is not a lower density operator.
Weighted Quasi‐Metrics
Authors: KÜNZI HANS‐PETER A. , VAJNER VÁCLAV 
Published: December 2006

ABSTRACT: We study the class of topologies which are induced by weighted quasi‐metrics (equivalently, partial metrics). Partial metrics were introduced by S. Matthews in his study of topological models appropriate for the denotational semantics of programming languages.It follows from our results that each T0‐space with a s̀‐disjoint base admits a weightable quasi‐metric and that each weightable quasi‐metric space is quasi‐developable. Those partially ordered sets whose Alexandrov topology admits a weightable quasi‐metric are characterized. We also show that the Pixley‐Roy space over the reals does not admit a weightable quasi‐metric.
Particle Physics and Cosmology
Authors: ELLIS John 
Published: December 2006

ABSTRACTThe agreement between the observed light element abundances and calculations of homogeneous cosmological nucleosynthesis constrains inhomogenequs models, and suggests that most of the matter in the Universe is invisible Dark Matter. This could be in the form of neutrinos, lightest supersymmetric particles (LSPs) or axions. Interactions between LSPs or axions and nuclear matter are controlled by the spin decomposition of the nucleon.
EGRET Observations of Gamma‐Ray Bursts
Authors: SCHNEID E J , BERTSCH D L , FICHTEL C E , HARTMAN R C , HUNTER S D , THOMPSON D J , KANBACH G , MAYER‐HASSELWANDER H A , LIN Y C , MICHELSON P F , NOLAN P L , DINGUS B L , VON MONTIGNY C , SREEKUMAR P , KNIFFEN D A 
Published: December 2006

ABSTRACTThe Energetic Gamma‐Ray Experiment Telescope (EGRET) has observed gamma‐rays bursts with the highest energy gamma‐rays and the longest high energy emission to date. EGRET measures the high energy gamma‐rays with its large NaI scintillator (1 to 200 MeV) and its spark chamber (30 MeV to 30 GeV). The spark chamber also measures time and arrival directions of individual photons allowing locations for the energetic bursts to be determined. Since the Compton Gamma Ray Observatory launch in 1991, EGRET has observed five bursts in the spark chamber with several having gamma‐ray energies grater than 1 GeV. The recording breaking burst, GRB940217, had gamma‐rays up to 18 GeV and lasted over 5000 seconds. The results for the energetic bursts are presented. The high energies observed from these gamma‐ray bursts set constraints for the burst distances.
Gamma‐ray Burst Models: General Requirements and Predictions
Authors: MÉSZÁROS P. 
Published: December 2006

ABSTRACTWhatever the ultimate energy source of gamma‐ray bursts turns out to be, the resulting sequence of physical events is likely to lead to a fairly generic, almost unavoidable scenario: a relativistic fireball that dissipates its energy after it has become optically thin. This is expected both for cosmological and halo distances. Here we explore the observational motivation of this scenario, and the consequences of the resulting models for the photon production in different wavebands, the energetics and the time structure of classical gamma‐ray bursters.
LISA
Authors: DANZMANN KARSTEN 
Published: December 2006

AbstractLISA (Laser Interferometer Space Antenna) is designed to observe gravitational waves from violent events in the Universe in a frequency range from 10−4 to 10−1 Hz which is totally inaccessible to ground based experiments. It uses highly stabilised laser light (Nd:YAG, λ= 1.064 μm) in a Michelson‐type interferometer arrangement.A cluster of six spacecraft with two at each vertex of an equilateral triangle is placed in an Earth‐like orbit at a distance of 1 AU from the Sun, and 20° behind the Earth. Three subsets of four adjacent spacecraft each form an interferometer comprising a central station, consisting of two relatively adjacent spacecraft (200 km apart), and two spacecraft placed at a distance of 5x106 km from the centre to form arms which make an angle of 60° with each other. Each spacecraft is equipped with a laser.A descoped LISA with only four spacecraft has undergone an ESA assessment study in the M3 cycle, and the full 6‐spacecraft LISA mission has now been selected as a cornerstone in the ESA Horizon 2000‐plus programme.
Activity of Rotating Magnetospheres in AGNs: Collimated Propagation of MHD Waves near a Black Hole
Authors: HIROTANI Kouichi , TOMIMATSU Akira 
Published: December 2006

AbstractWe have studied non‐stationary and axisymmetric perturbations of a magnetohydrodynamic accretion onto a rotating (Kerr) black hole. Assuming that the magnetic field dominates the plasma accretion, we find that the meridional current becomes large near the fast‐magnetosonic surface located close to the horizon. This is due to the effects of the particle's inertia and the strong gravity near the horizon. As a consequence, the fluid suffers a large radial acceleration resulting from the Lorentz force, and becomes highly variable compared with the electromagnetic field there. In fact, we further find an interesting perturbed structure of the plasma velocity with a large peak in some narrow region just beyond the fast‐magnetosonic surface. If the critical surface has an oblate shape for radial poloidal field lines, this perturbation of plasma motion is induced by outgoing waves propagating from the equatorial super‐fast‐magnetosonic region to the polar sub‐fast‐magnetosonic one. Thus, the effective acceleration of particles due to the outgoing fast‐magnetosonic waves will work mainly in the polar direction as a mechanism of trigger of jet production in active galactic nuclei.
Occurrence of Interleukin‐6 in Cortical Plaques of Alzheimer's Disease Patients May Precede Transformation of Diffuse into Neuritic Plaquesa
Authors: HÜLL M. , BERGER M. , VOLK B. , BAUER J. 
Published: December 2006

Interleukin‐6 (IL‐6) immunoreactivity has previously been shown in plaques in Alzheimer's disease (AD), and elevated IL‐6 concentrations have been measured biochemically in brains of AD patients. In this report, we present data on the appearance of IL‐6 immunoreactivity in AD plaques according to the stage of plaque formation. Diffuse plaques are found in the early stages of plaque formation, whereas primitive and classic plaques are thought to represent later stages of plaque pathology. We classified plaques using the Bielschowsky silver stain method in serial sections of paraffin‐embedded cortices of clinically diagnosed and histopathologically confirmed AD patients and patients with no clinical history of dementia. In the brains of nondemented and demented persons, we found plaques using the silver staining method or immunohistochemistry with antibodies against the amyloid precursor protein. In the nondemented group, diffuse plaques were the predominant plaque type, whereas primitive plaques formed the larger proportion of lesions in the group of AD brains.IL‐6 was only detectable in plaques of demented patients. In AD cases, IL‐6 was found in a significantly higher ratio in diffuse plaques as would have been expected from a random distribution of IL‐6 in all plaque types.We conclude that the presence of IL‐6 immunoreactivity correlates with clinically detectable dementia. In addition to the ubiquitous presence of amyloid in nondemented and demented brains, an IL‐6‐related immunological mechanism may be involved both in the transformation from diffuse to primitive plaques in AD and in the development of dementia.
On MAD Families and Sequential Order
Authors: DOW ALAN 
Published: December 2006

ABSTRACTWe investigate the question of the existence of a compact sequential space with sequential order more than 2. We establish a connection with an interesting problem about maximal families of almost disjoint subsets of w. We also obtain a partial result by showing that it is consistent that every countably tight compact space of weight b is Fréchet‐Urysohn. The main task is to work with Shelah's forcing for obtaining a model of b < s=a.
The Intermediate Value Theorem for Polynomials over Lattice‐ordered Rings of Functions
Authors: HENRIKSEN MELVIN , LARSON SUZANNE , MARTINEZ JORGE 
Published: December 2006

ABSTRACTThe classical intermediate value theorem for polynomials with real coefficients is generalized to the case of polynomials with coefficients in a lattice‐ordered ring that is a subdirect product of totally ordered rings. Several candidates for a generalization are investigated, and particular attention is paid to the case when the lattice‐ordered ring is the algebra C(X) of continuous real‐valued functions on a completely regular topological space X. For all but one of these generalizations, the intermediate value theorem holds only if X is an F‐space in the sense of Gillman and Jerison. Surprisingly, for the most interesting of these generalizations, if X is compact, the intermediate value theorem holds only if X is an F‐space and each component of X is an hereditarily indecomposable continuum. It is not known if there is an infinite compact connected space in which this version of the intermediate value theorem holds.
The Gδ‐topology, Light Compactness, and Pseudocompleteness
Authors: TODD AARON R. 
Published: December 2006

ABSTRACTBaire category arguments generally support far stronger properties. In particular, these properties, such as Oxtoby's pseudocompleteness, are generally productive, whereas the Baire property is not. We show in the main theorem that the Gδ‐expansion of a regular lightly compact space is pseudocomplete. This leads to intrinsic proofs of some cardinality results of Comfort and Robertson for pseudocompact topological groups—they had noted and used the fact that the Gδ‐expansion of such a group topology is Baire. In particular, these new proofs avoid the Weyl completion, which, in this context, is the Stone‐Čech compactification. The paper also contains an example of a topological group of smallest cardinality whose Gδ‐expansion is not Baire, as well as some related questions.
Derrida and the Truth of Drawing: Another Copernican Revolution?
Authors: Escoubas Eliane 
Published: December 2006

AbstractI begin with the hypothesis that Jacques Derrida's Memoirs of the Blind: The Self-Portrait and Other Ruins is in a way the illustration of Speech and Phenomena and therefore Derrida's critique of phenomenology, intuition, perception, and seeing. I also want to show in this regard parallels with both Husserl and Kant. I emphasize that what is at issue in Memoirs of the Blind is art, visual arts; and in the great thematic richness of this text, I note the high points as well as the low points concerning the arts of the "visible." The fundamental question is: Does Derrida "see" the drawing, the painting, and indeed listen to the music?
Life after Derrida: Anacoluthia and the Agrammaticality of Following
Authors: Dillon Sarah 
Published: December 2006

AbstractWritten on Derrida's "'Le Parjure,' Perhaps: Storytelling and Lying," this essay takes the concept of the anacoluthon from Derrida's text (as he has done from J. Hillis Miller, as he did from Proust) and—commenting on the figure of the woman in this male lineage—further invents the concept of the anacoluthon by demonstrating how its formal linguistic definition provides a model for the event of reading and writing—of thinking—that Derrida so admires in Hillis Miller's work and practices in his own. By employing this same reading practice in its own thinking, this essay does not respond to Derrida's death in mourning, nor in thinking about mourning, but in the memory of thought. Produced out of Derrida's work, the essay remains faithful to him only by simultaneously being faithful and unfaithful, thereby enacting the agrammaticality of following represented in and by the anacoluthon.
Derrida and the Question of Presence
Authors: Dastur Françoise 
Published: December 2006

AbstractIt has often been considered that the most important part of Derrida's work consisted in the five books published between 1967 and 1972. This paper intends, by way of a re-reading of Derrida's most powerful text from this period, Speech and Phenomena, to bring to light Derrida's specific manner of uniting the question of the disruption of presence to the question of writing. What is therefore questioned is Derrida's emphasis on death, considered as the very condition of possibility of language and writing. As Derrida rightfully shows, Husserl, in spite of the importance he conferred upon writing in the process of idealization, was not aware of the fact that the relationship to death constitutes the concrete structure of the living present. But on the other hand, by still opposing in a too dualistic manner presence and absence, life and death, Derrida himself was not able to see that the condition of language is not so much the death of the subject as the being toward death and the finitude of Dasein.
Oversights
Authors: Llewelyn John 
Published: December 2006

AbstractAddressed here are addressing and the address of the here and the there: the direction and indirection of words, whether written or spoken in prayer; but also of pictures, one of them sent to Derrida, one of them an icon presumably destined from God, and a third, the one reproduced on the cover of The Post Card from Socrates to Freud and Beyond, that attends to the difficulty of locating the threshold between the to and the from, perhaps a secular version of the problem of grace—unless that is not a problem but an aporia, wherever the threshold between these has its place. The chance of oversight, επισκoπη, is addressed, and the words Derrida addressed to his friends from the grave.