1,601 research outputs found
The nature of GRB-selected submillimeter galaxies: hot and young
We present detailed fits of the spectral energy distributions (SEDs) of four
submillimeter (submm) galaxies selected by the presence of a gamma-ray burst
(GRB) event (GRBs 980703, 000210, 000418 and 010222). These faint ~3 mJy submm
emitters at redshift ~1 are characterized by an unusual combination of long-
and short-wavelength properties, namely enhanced submm and/or radio emission
combined with optical faintness and blue colors. We exclude an active galactic
nucleus as the source of long-wavelength emission. From the SED fits we
conclude that the four galaxies are young (ages <2 Gyr), highly starforming
(star formation rates ~150 MSun/yr), low-mass (stellar masses ~10^10 MSun) and
dusty (dust masses ~3x10^8 MSun). Their high dust temperatures (Td>45 K)
indicate that GRB host galaxies are hotter, younger, and less massive
counterparts to submm-selected galaxies detected so far. Future facilities like
Herschel, JCMT/SCUBA-2 and ALMA will test this hypothesis enabling measurement
of dust temperatures of fainter GRB-selected galaxies.Comment: 9 pages, 2 figures, submitted to ApJ, for SED templates, see
http://archive.dark-cosmology.dk
Moving embedded lattice solitons
It was recently proved that isolated unstable "embedded lattice solitons"
(ELS) may exist in discrete systems. The discovery of these ELS gives rise to
relevant questions such as the following: are there continuous families of
ELS?, can ELS be stable?, is it possible for ELS to move along the lattice?,
how do ELS interact?. The present work addresses these questions by showing
that a novel differential-difference equation (a discrete version of a complex
mKdV equation) has a two-parameter continuous family of exact ELS. The
numerical tests reveal that these solitons are stable and robust enough to
withstand collisions. The model may apply to the description of a Bose-Einstein
condensate with dipole-dipole interactions between the atoms, trapped in a deep
optical-lattice potential.Comment: 13 pages, 11 figure
New insights on the molecular recognition of imidacloprid with Aplysia californica AChBP: a computational study
The binding of imidacloprid (IMI), the forerunner of neonicotinoid insecticides, with the acetylcholine binding protein (AChBP) from Aplysia californica, the established model for the extracellular domain of insects nicotinic acetylcholine receptors, has been studied with a two-layer ONIOM partition approach (M06-2X/6-311G(d):PM6). Our calculations allow delineating the contributions of the key residues of AChBP for IMI binding. In particular, the importance of Trp147 and Cys190-191, through weak CH...pi interactions and both van der Waals and hydrogen-bond (H-bond) interactions, respectively, are highlighted. Furthermore, H-bonds between hydroxyl groups of both Ser189 and Tyr55 and the IMI nitro group are pointed out. The participation of Ile118, whose main chain NH and carbonyl group are hydrogen-bonded with the IMI pyridinic nitrogen through a water molecule, is characterized. Our simulations also indicate the presence of a significant contribution of this residue through van der Waals interactions. The various trends obtained by the calculations of the pairwise interaction energies are confirmed through a complementary noncovalent interaction (NCI) analysis of selected IMI-AChBP amino acid pairs. Indeed, the contribution of a halogen-bond interaction between IMI and AChBP, recently proposed in the literature, is corroborated by our NCI analysis
Pretreatment of the cockroach cercal afferent/giant interneuron synapses with nicotinoids and neonicotinoids differently affects acetylcholine and nicotine-induced ganglionic depolarizations
We have recently demonstrated that neonicotinoid insecticides were able to act as agonists of postsynaptic nicotinic acetylcholine receptors (nAChRs) expressed at the synapse between the cercal nerve XI and the giant interneurons, in the sixth abdominal ganglion. In this work, we demonstrated that nicotinoids such as nornicotine acted as an agonist of nicotinic acetylcholine receptors expressed at cercal afferent/giant interneurons while cotinine was a poor agonist. Indeed, nornicotine induced a ganglionic depolarization which was blocked by the nicotinic antagonist mecamylamine. In addition, we found that pretreatment of the sixth abdominal ganglion with 1 and 10 muM nornicotine and cotinine had no significant effect on acetylcholine and nicotine-induced depolarization. But pretreatment with 1 and 10 muM acetamiprid and imidacloprid had a strong effect. 1 and 10 muM acetamiprid completely blocked acetylcholine-induced depolarization, whereas imidacloprid had a partial effect. The present work therefore suggests, in agreement with previous studies, that nornicotine and cotinine bind to distinct cockroach postsynaptic nAChRs, whereas acetamiprid and imidacloprid have competitive effects with acetylcholine and nicotine on ganglionic depolarization
The very red afterglow of GRB 000418 - further evidence for dust extinction in a GRB host galaxy
We report near-infrared and optical follow-up observations of the afterglow
of the Gamma-Ray Burst 000418 starting 2.5 days after the occurrence of the
burst and extending over nearly seven weeks. GRB 000418 represents the second
case for which the afterglow was initially identified by observations in the
near-infrared. During the first 10 days its R-band afterglow was well
characterized by a single power-law decay with a slope of 0.86. However, at
later times the temporal evolution of the afterglow flattens with respect to a
simple power-law decay. Attributing this to an underlying host galaxy we find
its magnitude to be R=23.9 and an intrinsic afterglow decay slope of 1.22. The
afterglow was very red with R-K=4 mag. The observations can be explained by an
adiabatic, spherical fireball solution and a heavy reddening due to dust
extinction in the host galaxy. This supports the picture that (long) bursts are
associated with events in star-forming regions.Comment: Accepted for publication in The Astrophysical Journal. 12 pages;
citations & references updated; minor textual change
New Higgs signals induced by mirror fermion mixing effects
We study the conditions under which flavor violation arises in scalar-fermion
interactions, as a result of the mixing phenomena between the standard model
and exotic fermions. Phenomenological consequences are discussed within the
specific context of a left-right model where these additional fermions have
mirror properties under the new SU(2)_R gauge group.
Bounds on the parameters of the model are obtained from LFV processes; these
results are then used to study the LFV Higgs decays (H --> tau l_j, l_j = e,
mu), which reach branching ratios that could be detected at future colliders.Comment: 12 pages, 2 figures, ReVTex4, graphicx, to be published in Phys. Rev.
On the Afterglow of the X-ray Flash of 2003 July 23: Photometric evdence for an Off-Axis Gamma-Ray burst with an Associated Supernova
Peer reviewe
Chapter 10 - Industry
This chapter provides an update to developments on mitigation in the industry sector since the IPCC (Intergovernmental Panel on Climate Change) Fourth Assessment Report (AR4) (IPCC, 2007), but has much wider coverage. Industrial activities create all the physical products (e.g., cars, agricultural equipment, fertilizers, textiles, etc.) whose use delivers the final services that satisfy current human needs. Compared to the industry chapter in AR4, this chapter analyzes industrial activities over the whole supply chain, from extraction of primary materials (e.g., ores) or recycling (of waste materials), through product manufacturing, to the demand for the products and their services. It includes a discussion of trends in activity and emissions, options for mitigation (technology, practices, and behavioural aspects), estimates of the mitigation potentials of some of these options and related costs, co-benefits, risks and barriers to their deployment, as well as industry-specific policy instruments. Findings of integrated models (long-term mitigation pathways) are also presented and discussed from the sector perspective. In addition, at the end of the chapter, the hierarchy in waste management and mitigation opportunities are synthesized, covering key waste-related issues that appear across all chapters in the Working Group III contribution to the IPCC Fifth Assessment Report (AR5)
Two neutrino positron double beta decay of Cd for transition
The two neutrino positron double beta decay of Cd for 0
0 transition has been studied in the Hartree-Fock-Bogoliubov model in
conjunction with the summation method. In the first step, the reliability of
the intrinsic wave functions of Cd and Pd nuclei has been
tested by comparing the theoretically calculated results for yrast spectra,
reduced : transition probabilities, quadrupole moments
and gyromagnetic factors with the available experimental
data. In the second step, the nuclear transition matrix element and
the half-life for 0 0 transition have been
calculated with these wave functions. Moreover, we have studied the effect of
deformation on nuclear transition matrix element MComment: 20 page
Implications For The Origin Of GRB 051103 From LIGO Observations
We present the results of a LIGO search for gravitational waves (GWs)
associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst
(GRB) whose electromagnetically determined sky position is coincident with the
spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for
short-hard GRBs include compact object mergers and soft gamma repeater (SGR)
giant flares. A merger progenitor would produce a characteristic GW signal that
should be detectable at the distance of M81, while GW emission from an SGR is
not expected to be detectable at that distance. We found no evidence of a GW
signal associated with GRB 051103. Assuming weakly beamed gamma-ray emission
with a jet semi-angle of 30 deg we exclude a binary neutron star merger in M81
as the progenitor with a confidence of 98%. Neutron star-black hole mergers are
excluded with > 99% confidence. If the event occurred in M81 our findings
support the the hypothesis that GRB 051103 was due to an SGR giant flare,
making it the most distant extragalactic magnetar observed to date.Comment: 8 pages, 3 figures. For a repository of data used in the publication,
go to: https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=15166 . Also see
the announcement for this paper on ligo.org at:
http://www.ligo.org/science/Publication-GRB051103/index.ph
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