257 research outputs found
Public and Private Enforcement of Title VII of the Civil Rights Act of 1964—A Ten-Year Perspective
The purpose of this Article is to describe the enforcement provisions of the Act and to outline the litigative activities by government agencies and private parties in the three types of cases that have characterized court action under Title VII during the ten-year period since the Act\u27s adoption. The record of enforcement compels the conclusion that effective enforcement of the Act has barely commenced. A much larger volume of litigation probably will be filed before the country approaches widespread compliance with the law against discrimination in employment
Ledoux-Convection in Protoneutron Stars --- a Clue to Supernova Nucleosynthesis?
Two-dimensional hydrodynamical simulations of the deleptonization of a newly
formed neutron star were performed. Driven by negative lepton fraction and
entropy gradients, convection starts near the neutrinosphere about 20-30 ms
after core bounce, but moves deeper into the protoneutron star, and after about
one second the whole protoneutron star is convective. The deleptonization of
the star proceeds much faster than in the corresponding spherically symmetrical
model because the lepton flux and the neutrino luminosities increase by up to a
factor of two. The convection below the neutrinosphere raises the
neutrinospheric temperatures and mean energies of the emitted neutrinos by
10-20%. This can have important implications for the supernova explosion
mechanism and changes the detectable neutrino signal from the Kelvin-Helmholtz
cooling of the protoneutron star. In particular, the enhanced electron neutrino
flux relative to the electron antineutrino flux during the early post-bounce
evolution might solve the overproduction problem of certain elements in the
neutrino-heated ejecta in models of type-II supernova explosions.Comment: 17 pages, LaTeX, 8 postscript figures, uses epsf.sty. To appear in
ApJ 473 (Letters), 1996 December 1
The Circuit Ideal of a Vector Configuration
The circuit ideal, \ica, of a configuration \A = \{\a_1, ..., \a_n\}
\subset \Z^d is the ideal generated by the binomials {\x}^{\cc^+} -
{\x}^{\cc^-} \in \k[x_1, ..., x_n] as \cc = \cc^+ - \cc^- \in \Z^n varies
over the circuits of \A. This ideal is contained in the toric ideal, \ia,
of \A which has numerous applications and is nontrivial to compute. Since
circuits can be computed using linear algebra and the two ideals often
coincide, it is worthwhile to understand when equality occurs. In this paper we
study \ica in relation to \ia from various algebraic and combinatorial
perspectives. We prove that the obstruction to equality of the ideals is the
existence of certain polytopes. This result is based on a complete
characterization of the standard pairs/associated primes of a monomial initial
ideal of \ica and their differences from those for the corresponding toric
initial ideal. Eisenbud and Sturmfels proved that \ia is the unique minimal
prime of \ica and that the embedded primes of \ica are indexed by certain
faces of the cone spanned by \A. We provide a necessary condition for a
particular face to index an embedded prime and a partial converse. Finally, we
compare various polyhedral fans associated to \ia and \ica. The Gr\"obner
fan of \ica is shown to refine that of \ia when the codimension of the
ideals is at most two.Comment: 25 page
Towards Gravitational Wave Signals from Realistic Core Collapse Supernova Models
We have computed the gravitational wave signal from supernova core collapse
using the presently most realistic input physics available. We start from
state-of-the-art progenitor models of rotating and non-rotating massive stars,
and simulate the dynamics of their core collapse by integrating the equations
of axisymmetric hydrodynamics together with the Boltzmann equation for the
neutrino transport including an elaborate description of neutrino interactions,
and a realistic equation of state. We compute the quadrupole wave amplitudes,
the Fourier wave spectra, the amount of energy radiated in form of
gravitational waves, and the S/N ratios for the LIGO and the tuned Advanced
LIGO interferometers resulting both from non-radial mass motion and anisotropic
neutrino emission. The simulations demonstrate that the dominant contribution
to the gravitational wave signal is produced by neutrino-driven convection
behind the supernova shock. For stellar cores rotating at the extreme of
current stellar evolution predictions, the core-bounce signal is detectable
with advanced LIGO up to a distance of 5kpc, whereas the signal from post-shock
convection is observable up to a distance of about 100kpc. If the core is
non-rotating its gravitational wave emission can be measured up to a distance
of 15kpc, while the signal from the Ledoux convection in the deleptonizing,
nascent neutron star can be detected up to a distance of 10kpc. Both kinds of
signals are generically produced by convection in any core collapse supernova.Comment: 9 pages, 13 figures, Latex, submitted to ApJ, error in ps-file fixed;
figures in full resolution are available upon reques
Topological String Amplitudes, Complete Intersection Calabi-Yau Spaces and Threshold Corrections
We present the most complete list of mirror pairs of Calabi-Yau complete
intersections in toric ambient varieties and develop the methods to solve the
topological string and to calculate higher genus amplitudes on these compact
Calabi-Yau spaces. These symplectic invariants are used to remove redundancies
in examples. The construction of the B-model propagators leads to compatibility
conditions, which constrain multi-parameter mirror maps. For K3 fibered
Calabi-Yau spaces without reducible fibers we find closed formulas for all
genus contributions in the fiber direction from the geometry of the fibration.
If the heterotic dual to this geometry is known, the higher genus invariants
can be identified with the degeneracies of BPS states contributing to
gravitational threshold corrections and all genus checks on string duality in
the perturbative regime are accomplished. We find, however, that the BPS
degeneracies do not uniquely fix the non-perturbative completion of the
heterotic string. For these geometries we can write the topological partition
function in terms of the Donaldson-Thomas invariants and we perform a
non-trivial check of S-duality in topological strings. We further investigate
transitions via collapsing D5 del Pezzo surfaces and the occurrence of free Z2
quotients that lead to a new class of heterotic duals.Comment: 117 pages, 1 Postscript figur
Dihydropyrimidine Dehydrogenase Testing prior to Treatment with 5-Fluorouracil, Capecitabine, and Tegafur: A Consensus Paper
Background: 5-Fluorouracil (FU) is one of the most commonly used cytostatic drugs in the systemic treatment of
cancer. Treatment with FU may cause severe or life-threatening side effects and the treatment-related mortality rate is 0.2–1.0%. Summary: Among other risk factors associated
with increased toxicity, a genetic deficiency in dihydropyrimidine dehydrogenase (DPD), an enzyme responsible for
the metabolism of FU, is well known. This is due to variants
in the DPD gene (DPYD). Up to 9% of European patients carry a DPD gene variant that decreases enzyme activity, and
DPD is completely lacking in approximately 0.5% of patients.
Here we describe the clinical and genetic background and
summarize recommendations for the genetic testing and
tailoring of treatment with 5-FU derivatives. The statement
was developed as a consensus statement organized by the
German Society for Hematology and Medical Oncology in
cooperation with 13 medical associations from Austria, Germany, and Switzerland. Key Messages: (i) Patients should be
tested for the 4 most common genetic DPYD variants before
treatment with drugs containing FU. (ii) Testing forms the
basis for a differentiated, risk-adapted algorithm with recommendations for treatment with FU-containing drugs. (iii)
Testing may optionally be supplemented by therapeutic
drug monitorin
Identifying key questions in the ecology and evolution of cancer
The application of evolutionary and ecological principles to cancer prevention and treatment, as well as recognizing cancer as a selection force in nature, has gained impetus over the last 50 years. Following the initial theoretical approaches that combined knowledge from interdisciplinary fields, it became clear that using the eco‐evolutionary framework is of key importance to understand cancer. We are now at a pivotal point where accumulating evidence starts to steer the future directions of the discipline and allows us to underpin the key challenges that remain to be addressed. Here, we aim to assess current advancements in the field and to suggest future directions for research. First, we summarize cancer research areas that, so far, have assimilated ecological and evolutionary principles into their approaches and illustrate their key importance. Then, we assembled 33 experts and identified 84 key questions, organized around nine major themes, to pave the foundations for research to come. We highlight the urgent need for broadening the portfolio of research directions to stimulate novel approaches at the interface of oncology and ecological and evolutionary sciences. We conclude that progressive and efficient cross‐disciplinary collaborations that draw on the expertise of the fields of ecology, evolution and cancer are essential in order to efficiently address current and future questions about cancer
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