825 research outputs found
Descriptions, truth value intuitions, and questions
International audienceSince the famous debate between Russell (Mind 14: 479–493, 1905, Mind 66: 385–389, 1957) and Strawson (Mind 59: 320–344, 1950; Introduction to logical theory, 1952; Theoria, 30: 96–118, 1964) linguistic intuitions about truth values have been considered notoriously unreliable as a guide to the semantics of definite descriptions. As a result, most existing semantic analyses of definites leave a large number of intuitions unexplained. In this paper, I explore the nature of the relationship between truth value intuitions and non-referring definites. Inspired by comments in Strawson (Introduction to logical theory, 1964), I argue that given certain systematic considerations, one can provide a structured explanation of conflicting intuitions. I show that the intuitions of falsity, which proponents of a Russellian analysis often appeal to, result from evaluating sentences in relation to specific questions in context. This is shown by developing a method for predicting when sentences containing non-referring definites elicit intuitions of falsity. My proposed analysis draws importantly on Roberts (in: Yoon & Kathol (eds.) OSU working papers in Linguistics: vol. 49: Papers in Semantics 1998; in: Horn & Ward (eds.) Handbook of pragmatics, 2004) and recent research in the semantics and pragmatics of focus
Caspase-8 and c-FLIPL associate in lipid rafts with NF-kappaB adaptors during T cell activation.
Humans and mice lacking functional caspase-8 in T cells manifest a profound immunodeficiency syndrome due to defective T cell antigen receptor (TCR)-induced NF-kappaB signaling and proliferation. It is unknown how caspase-8 is activated following T cell stimulation, and what is the caspase-8 substrate(s) that is necessary to initiate T cell cycling. We observe that following TCR ligation, a small portion of total cellular caspase-8 and c-FLIP(L) rapidly migrate to lipid rafts where they associate in an active caspase complex. Activation of caspase-8 in lipid rafts is followed by rapid cleavage of c-FLIP(L) at a known caspase-8 cleavage site. The active caspase.c-FLIP complex forms in the absence of Fas (CD95/APO1) and associates with the NF-kappaB signaling molecules RIP1, TRAF2, and TRAF6, as well as upstream NF-kappaB regulators PKC theta, CARMA1, Bcl-10, and MALT1, which connect to the TCR. The lack of caspase-8 results in the absence of MALT1 and Bcl-10 in the active caspase complex. Consistent with this observation, inhibition of caspase activity attenuates NF-kappaB activation. The current findings define a link among TCR, caspases, and the NF-kappaB pathway that occurs in a sequestered lipid raft environment in T cells
Modelling knowledge in Electronic Study Books
Knowledge graphs are a new form of knowledge representation. They are closely related to semantic networks and can be looked upon as in line with Schank's conceptual dependency theory and Sowa's conceptual graphs. The special feature of knowledge graphs is the use of a very restricted set of types of relations, that is considered to be the basic set of primitive relations. The theory of knowledge graphs is outlined in the first part of the paper. In the second part the possibilities of knowledge graphs for solving problems posed by Electronic (Study) Books will be discussed
An overview of jets and outflows in stellar mass black holes
In this book chapter, we will briefly review the current empirical
understanding of the relation between accretion state and and outflows in
accreting stellar mass black holes. The focus will be on the empirical
connections between X-ray states and relativistic (`radio') jets, although we
are now also able to draw accretion disc winds into the picture in a systematic
way. We will furthermore consider the latest attempts to measure/order jet
power, and to compare it to other (potentially) measurable quantities, most
importantly black hole spin.Comment: Accepted for publication in Space Science Reviews. Also to appear in
the Space Sciences Series of ISSI - The Physics of Accretion on to Black
Holes (Springer Publisher
Long-term perturbations due to a disturbing body in elliptic inclined orbit
In the current study, a double-averaged analytical model including the action
of the perturbing body's inclination is developed to study third-body
perturbations. The disturbing function is expanded in the form of Legendre
polynomials truncated up to the second-order term, and then is averaged over
the periods of the spacecraft and the perturbing body. The efficiency of the
double-averaged algorithm is verified with the full elliptic restricted
three-body model. Comparisons with the previous study for a lunar satellite
perturbed by Earth are presented to measure the effect of the perturbing body's
inclination, and illustrate that the lunar obliquity with the value 6.68\degree
is important for the mean motion of a lunar satellite. The application to the
Mars-Sun system is shown to prove the validity of the double-averaged model. It
can be seen that the algorithm is effective to predict the long-term behavior
of a high-altitude Martian spacecraft perturbed by Sun. The double-averaged
model presented in this paper is also applicable to other celestial systems.Comment: 28 pages, 6 figure
Livestock grazing and vegetative filter strip buffer effects on runoff sediment, nitrate, and phosphorus losses
Selecting simultaneous actions of different durations to optimally manage an ecological network
Stellar structure and compact objects before 1940: Towards relativistic astrophysics
Since the mid-1920s, different strands of research used stars as "physics
laboratories" for investigating the nature of matter under extreme densities
and pressures, impossible to realize on Earth. To trace this process this paper
is following the evolution of the concept of a dense core in stars, which was
important both for an understanding of stellar evolution and as a testing
ground for the fast-evolving field of nuclear physics. In spite of the divide
between physicists and astrophysicists, some key actors working in the
cross-fertilized soil of overlapping but different scientific cultures
formulated models and tentative theories that gradually evolved into more
realistic and structured astrophysical objects. These investigations culminated
in the first contact with general relativity in 1939, when J. Robert
Oppenheimer and his students George Volkoff and Hartland Snyder systematically
applied the theory to the dense core of a collapsing neutron star. This
pioneering application of Einstein's theory to an astrophysical compact object
can be regarded as a milestone in the path eventually leading to the emergence
of relativistic astrophysics in the early 1960s.Comment: 83 pages, 4 figures, submitted to the European Physical Journal
Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares
The extreme ultraviolet portion of the solar spectrum contains a wealth of
diagnostic tools for probing the lower solar atmosphere in response to an
injection of energy, particularly during the impulsive phase of solar flares.
These include temperature and density sensitive line ratios, Doppler shifted
emission lines and nonthermal broadening, abundance measurements, differential
emission measure profiles, and continuum temperatures and energetics, among
others. In this paper I shall review some of the advances made in recent years
using these techniques, focusing primarily on studies that have utilized data
from Hinode/EIS and SDO/EVE, while also providing some historical background
and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the
Topical Issue on Solar and Stellar Flare
Conceitos básicos sobre a física da formação de tubos de fluxo magnético nas proximidades da Terra
- …