4,516 research outputs found
Embryo Exchanges and Adoption Tax Credits
The “Option of Adoption Act,” a Georgia law that was introduced by a staunchly anti-abortion Georgia state representative, establishes procedures for genetic donors to relinquish their rights to embryos before birth and permits, but does not require, embryo recipients to petition a court for recognition that they are the legal parents of a child born to them as a result of an embryo transfer. This article clears up what seems to be widespread confusion about a fairly straightforward question of tax law related to such embryo “adoptions.” Notwithstanding various sources\u27 claims to the contrary, neither a Georgia adoption tax credit nor a federal adoption tax credit is available for “adopting” an embryo
A systematic phenomenological study of the asymmetry in unpolarized semi--inclusive DIS
We study the azimuthal asymmetry in unpolarized semi-inclusive
DIS, taking into account both the perturbative contribution (gluon emission and
splitting) and the non perturbative effects arising from intrinsic transverse
motion and transverse spin of quarks. In particular we explore the possibility
to extract from some information about the Boer--Mulders
function $h_1^{\perp}$, which represents a transverse--polarization asymmetry
of quarks inside an unpolarized hadron. Predictions are presented for the
HERMES, COMPASS and JLab kinematics, where is dominated by the
kinematical higher--twist contribution, and turns to be of order of few
percent. We show that a larger asymmetry in production, compared to
production, would represent a signature of the Boer--Mulders effect.Comment: 14 pages, 12 figure
The W_L W_L scattering at the LHC: improving the selection criteria
We present a systematic study of the different mechanisms leading to WW pair
production at the LHC, both in the same-sign and opposite-sign channels, and we
emphasize that the former offers much better potential for investigating
non-resonant W_L W_L scattering. We propose a new kinematic variable to isolate
the W_L W_L scattering component in same-sign WW production at the LHC.
Focusing on purely leptonic W decay channels, we show that it considerably
improves the LHC capabilities to shed light on the electroweak symmetry
breaking mechanism after collecting 100 fb^{-1} of data at sqrt{s} = 14 TeV.
The new variable is less effective in the opposite-sign WW channel due to
different background composition.Comment: 25 pages, 32 figure
Higgs signals and hard photons at the Next Linear Collider: the -fusion channel in the Standard Model
In this paper, we extend the analyses carried out in a previous article for
-fusion to the case of Higgs production via -fusion within the Standard
Model at the Next Linear Collider, in presence of electromagnetic radiation due
real photon emission. Calculations are carried out at tree-level and rates of
the leading order (LO) processes e^+e^-\rightarrow e^+e^- H \ar e^+e^- b\bar b
and e^+e^-\rightarrow e^+e^- H \ar e^+e^- WW \ar e^+e^- \mathrm{jjjj} are
compared to those of the next-to-leading order (NLO) reactions
e^+e^-\rightarrow e^+e^- H (\gamma)\ar e^+e^- b\bar b \gamma and
e^+e^-\rightarrow e^+e^- H (\gamma)\ar e^+e^- WW (\gamma) \ar e^+e^-
\mathrm{jjjj}\gamma, in the case of energetic and isolated photons.Comment: 12 pages, LaTeX, 5 PostScript figures embedded using epsfig and
bitmapped at 100dpi, complete paper including high definition figures
available at ftp://axpa.hep.phy.cam.ac.uk/stefano/cavendish_9611.ps or at
http://www.hep.phy.cam.ac.uk/theory/papers
Sivers and Boer-Mulders functions in Light-Cone Quark Models
Results for the naive-time-reversal-odd quark distributions in a light-cone
quark model are presented. The final-state interaction effects are generated
via single-gluon exchange mechanism. The formalism of light-cone wave functions
is used to derive general expressions in terms of overlap of wave-function
amplitudes describing the different orbital angular momentum components of the
nucleon. In particular, the model predictions show a dominant contribution from
S- and P-wave interference in the Sivers function and a significant
contribution also from the interference of P and D waves in the Boer-Mulders
function. The favourable comparison with existing phenomenological
parametrizations motivates further applications to describe azimuthal
asymmetries in hadronic reactions.Comment: references and explanations added; version to appear in Phys. Rev.
Plasticity of visual attention in Isha yoga meditation practitioners before and after a 3-month retreat.
Meditation has lately received considerable interest from cognitive neuroscience. Studies suggest that daily meditation leads to long lasting attentional and neuronal plasticity. We present changes related to the attentional systems before and after a 3 month intensive meditation retreat. We used three behavioral psychophysical tests - a Stroop task, an attentional blink task, and a global-local letter task-to assess the effect of Isha yoga meditation on attentional resource allocation. 82 Isha yoga practitioners were tested at the beginning and at the end of the retreat. Our results showed an increase in correct responses specific to incongruent stimuli in the Stroop task. Congruently, a positive correlation between previous meditation experience and accuracy to incongruent Stroop stimuli was also observed at baseline. We also observed a reduction of the attentional blink. Unexpectedly, a negative correlation between previous meditation experience and attentional blink performance at baseline was observed. Regarding spatial attention orientation as assessed using the global-local letter task, participants showed a bias toward local processing. Only slight differences in performance were found pre- vs. post- meditation retreat. Biasing toward the local stimuli in the global-local task and negative correlation of previous meditation experience with attentional blink performance is consistent with Isha practices being focused-attention practices. Given the relatively small effect sizes and the absence of a control group, our results do not allow clear support nor rejection of the hypothesis of meditation-driven neuronal plasticity in the attentional system for Isha yoga practice
Physical Structure of Planetary Nebulae. I. The Owl Nebula
The Owl Nebula is a triple-shell planetary nebula with the outermost shell
being a faint bow-shaped halo. We have obtained deep narrow-band images and
high-dispersion echelle spectra in the H-alpha, [O III], and [N II] emission
lines to determine the physical structure of each shell in the nebula. These
spatio-kinematic data allow us to rule out hydrodynamic models that can
reproduce only the nebular morphology. Our analysis shows that the inner shell
of the main nebula is slightly elongated with a bipolar cavity along its major
axis, the outer nebula is a filled envelope co-expanding with the inner shell
at 40 km/s, and the halo has been braked by the interstellar medium as the Owl
Nebula moves through it. To explain the morphology and kinematics of the Owl
Nebula, we suggest the following scenario for its formation and evolution. The
early mass loss at the TP-AGB phase forms the halo, and the superwind at the
end of the AGB phase forms the main nebula. The subsequent fast stellar wind
compressed the superwind to form the inner shell and excavated an elongated
cavity at the center, but has ceased in the past. At the current old age, the
inner shell is backfilling the central cavity.Comment: 10 pages, 6 figures, 1 table, to appear in the Astronomical Journa
The Stability of the Gauge Hierarchy in
It has been shown that the Dimopoulos-Wilczek (or missing-VEV) mechanism for
doublet-triplet splitting can be implemented in models,
which requires no adjoint Higgs fields. This is an advantage from the point of
view of string theory construction. Here the stability of the gauge hierarchy
is examined in detail, and it is shown that it can be guaranteed much more
simply than in . In fact a symmetry ensures the stability of the
DW form of the expectation values to all orders in GUT-scale VEVs. It is also
shown that models based on have the advantages of while permitting complete quark-lepton unification as in
.Comment: 13 pages, LaTe
White Paper: Measuring the Neutrino Mass Hierarchy
This white paper is a condensation of a report by a committee appointed
jointly by the Nuclear Science and Physics Divisions at Lawrence Berkeley
National Laboratory (LBNL). The goal of this study was to identify the most
promising technique(s) for resolving the neutrino mass hierarchy. For the most
part, we have relied on calculations and simulations presented by the
proponents of the various experiments. We have included evaluations of the
opportunities and challenges for these experiments based on what is available
already in the literature.Comment: White paper prepared for Snowmass-201
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