67,602 research outputs found
"Back to the Future" in Philosophical Dialogue: A Plea for Changing P4C Teacher Education
While making P4C much more easily disseminated, short-term weekend and weeklong P4C training programs not only dilute the potential laudatory impact of P4C, they can actually be dangerous. As well, lack of worldwide standards precludes the possibility of engaging in sufficiently high quality research of the sort that would allow the collection of empirical data in support the efficacy of worldwide P4C adoption. For all these reasons, the authors suggest that P4C advocates ought to insist that programs of a minimum of five philosophy courses be accepted as the recognized standard for any teacher to legitimately claim that she is teaching Philosophy for Children
Nucleon-nucleon potentials in phase-space representation
A phase-space representation of nuclear interactions, which depends on the
distance and relative momentum of the nucleons, is
presented. A method is developed that permits to extract the interaction
from antisymmetrized matrix elements given in a spherical
basis with angular momentum quantum numbers, either in momentum or coordinate
space representation. This representation visualizes in an intuitive way the
non-local behavior introduced by cutoffs in momentum space or renormalization
procedures that are used to adapt the interaction to low momentum many-body
Hilbert spaces, as done in the unitary correlation operator method or with the
similarity renormalization group. It allows to develop intuition about the
various interactions and illustrates how the softened interactions reduce the
short-range repulsion in favor of non-locality or momentum dependence while
keeping the scattering phase shifts invariant. It also reveals that these
effective interactions can have undesired complicated momentum dependencies at
momenta around and above the Fermi momentum. Properties, similarities and
differences of the phase-space representations of the Argonne and the N3LO
chiral potential, and their UCOM and SRG derivatives are discussed
Robotic observations of the most eccentric spectroscopic binary in the sky
The visual A component of the Gliese 586AB system is a double-lined
spectroscopic binary consisting of two cool stars with the exceptional orbital
eccentricity of 0.976. Such an extremely eccentric system may be important for
our understanding of low-mass binary formation. We present a total of 598
high-resolution echelle spectra from our robotic facility STELLA from 2006-2012
which we used to compute orbital elements of unprecedented accuracy. The orbit
constrains the eccentricity to 0.97608+/-0.00004 and the orbital period to
889.8195+/-0.0003d. The masses of the two components are 0.87+/-0.05 Msun and
0.58+/-0.03 Msun if the inclination is 5+/-1.5degr as determined from
adaptive-optics images, that is good to only 6% due to the error of the
inclination although the minimum masses reached a precision of 0.3%. The flux
ratio Aa:Ab in the optical is betwee n 30:1 in Johnson-B and 11:1 in I. Radial
velocities of the visual B-component (K0-1V) appear constant to within 130 m/s
over six years. Sinusoidal modulations of Teff of Aa with an amplitude of apprx
55 K are seen with the orbital period. Component Aa appears warmest at
periastron and coolest at apastron, indicating atmospheric changes induced by
the high orbital eccentricity. No light variations larger than approximately 4
mmag are detected for A, while a photometric period of 8.5+/-0.2 d with an
amplitude of 7 mmag is discovered for the active star B, which we interpret to
be its rotation period. We estimate an orbital period of approx 50,000 yr for
the AB system. The most likely age of the AB system is >=2 Gyr, while the
activity of the B component, if it were a single star, would imply 0.5 Gyr.
Both Aa and B are matched with single-star evolutionary tracks of their
respective mass
From nucleon-nucleon interaction matrix elements in momentum space to an operator representation
Starting from the matrix elements of the nucleon-nucleon interaction in
momentum space we present a method to derive an operator representation with a
minimal set of operators that is required to provide an optimal description of
the partial waves with low angular momentum. As a first application we use this
method to obtain an operator representation for the Argonne potential
transformed by means of the unitary correlation operator method and discuss the
necessity of including momentum dependent operators. The resulting operator
representation leads to the same results as the original momentum space matrix
elements when applied to the two-nucleon system and various light nuclei. For
applications in fermionic and antisymmetrized molecular dynamics, where an
operator representation of a soft but realistic effective interaction is
indispensable, a simplified version using a reduced set of operators is given
A program to evaluate dye lasers as high power, pulsed, visible light sources
Spectral emission of visible from Q switched dye laser
Recommended from our members
The major myosin-binding domain of skeletal muscle MyBP-C (C protein) resides in the COOH-terminal, immunoglobulin C2 motif.
A common feature shared by myosin-binding proteins from a wide variety of species is the presence of a variable number of related internal motifs homologous to either the Ig C2 or the fibronectin (Fn) type III repeats. Despite interest in the potential function of these motifs, no group has clearly demonstrated a function for these sequences in muscle, either intra- or extracellularly. We have completed the nucleotide sequence of the fast type isoform of MyBP-C (C protein) from chicken skeletal muscle. The deduced amino acid sequence reveals seven Ig C2 sets and three Fn type III motifs in MyBP-C. alpha-chymotryptic digestion of purified MyBP-C gives rise to four peptides. NH2-terminal sequencing of these peptides allowed us to map the position of each along the primary structure of the protein. The 28-kD peptide contains the NH2-terminal sequence of MyBP-C, including the first C2 repeat. It is followed by two internal peptides, one of 5 kD containing exclusively spacer sequences between the first and second C2 motifs, and a 95-kD fragment containing five C2 domains and three fibronectin type III motifs. The C-terminal sequence of MyBP-C is present in a 14-kD peptide which contains only the last C2 repeat. We examined the binding properties of these fragments to reconstituted (synthetic) myosin filaments. Only the COOH-terminal 14-kD peptide is capable of binding myosin with high affinity. The NH2-terminal 28-kD fragment has no myosin-binding, while the long internal 100-kD peptide shows very weak binding to myosin. We have expressed and purified the 14-kD peptide in Escherichia coli. The recombinant protein exhibits saturable binding to myosin with an affinity comparable to that of the 14-kD fragment obtained by proteolytic digestion (1/2 max binding at approximately 0.5 microM). These results indicate that the binding to myosin filaments is mainly restricted to the last 102 amino acids of MyBP-C. The remainder of the molecule (1,032 amino acids) could interact with titin, MyBP-H (H protein) or thin filament components. A comparison of the highly conserved Ig C2 domains present at the COOH-terminus of five MyBPs thus far sequenced (human slow and fast MyBP-C, human and chicken MyBP-H, and chicken MyBP-C) was used to identify residues unique to these myosin-binding Ig C2 repeats
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