5,775 research outputs found
Attainable entanglement of unitary transformed thermal states in liquid-state nuclear magnetic resonance with the chemical shift
Recently, Yu, Brown, and Chuang [Phys. Rev. A {\bf 71}, 032341 (2005)]
investigated the entanglement attainable from unitary transformed thermal
states in liquid-state nuclear magnetic resonance (NMR). Their research gave an
insight into the role of the entanglement in a liquid-state NMR quantum
computer. Moreover, they attempted to reveal the role of mixed-state
entanglement in quantum computing. However, they assumed that the Zeeman energy
of each nuclear spin which corresponds to a qubit takes a common value for all;
there is no chemical shift. In this paper, we research a model with the
chemical shifts and analytically derive the physical parameter region where
unitary transformed thermal states are entangled, by the positive partial
transposition (PPT) criterion with respect to any bipartition. We examine the
effect of the chemical shifts on the boundary between the separability and the
nonseparability, and find it is negligible.Comment: 9 pages, 1 figures. There were mistakes in the previous version. The
main results don't change, but our motivation has to be reconsidere
Large gauge invariant non-standard neutrino interactions
Theories beyond the Standard Model must necessarily respect its gauge
symmetry. This implies strict constraints on the possible models of
non-standard neutrino interactions, which we analyze. The focus is set on the
effective low-energy dimension six and eight operators involving four leptons,
decomposing them according to all possible tree-level mediators, as a guide for
model building. The new couplings are required to have sizeable strength, while
processes involving four charged leptons are required to be suppressed. For
non-standard interactions in matter, only diagonal tau-neutrino interactions
can escape these requirements and can be allowed to result from dimension six
operators. Large non-standard neutrino interactions from dimension eight
operators alone are phenomenologically allowed in all flavour channels and
shown to require at least two new mediator particles. The new couplings must
obey general cancellation conditions both at the dimension six and eight
levels, which result from expressing the operators obtained from the mediator
analysis in terms of a complete basis of operators. We illustrate with one
example how to apply this information to model building.Comment: 34 pages, 4 figures, 5 tables. Final version in PR
The Chandra view of the Largest Quasar Lens SDSS J1029+2623
We present results from Chandra observations of the cluster lens SDSS
J1029+2623 at z_l=0.58, which is a gravitationally lensed quasar with the
largest known image separation. We clearly detect X-ray emission both from the
lensing cluster and the three lensed quasar images. The cluster has an X-ray
temperature of kT = 8.1 (+2.0, -1.2) keV and bolometric luminosity of L_X =
9.6e44 erg s^-1. Its surface brightness is centered near one of the brightest
cluster galaxies, and it is elongated East-West. We identify a subpeak
North-West of the main peak, which is suggestive of an ongoing merger. Even so,
the X-ray mass inferred from the hydrostatic equilibrium assumption appears to
be consistent with the lensing mass from the Einstein radius of the system. We
find significant absorption in the soft X-ray spectrum of the faintest quasar
image, which can be caused by an intervening material at either the lens or
source redshift. The X-ray flux ratios between the quasar images (after
correcting for absorption) are in reasonable agreement with those at optical
and radio wavelengths, and all the flux ratios are inconsistent with those
predicted by simple mass models. This implies that microlensing effect is not
significant for this system and dark matter substructure is mainly responsible
for the anomalous flux ratios.Comment: 35 pages, 8 figures. Accepted for publication in Ap
Rings of Dark Matter in Collisions Between Clusters of Galaxies
Several lines of evidence suggest that the galaxy cluster Cl0024+17, an
apparently relaxed system, is actually a collision of two clusters, the
interaction occurring along our line of sight. Recent lensing observations
suggest the presence of a ring-like dark matter structure, which has been
interpreted as the result of such a collision. In this paper we present
-body simulations of cluster collisions along the line of sight to
investigate the detectability of such features. We use realistic dark matter
density profiles as determined from cosmological simulations. Our simulations
show a "shoulder" in the dark matter distribution after the collision, but no
ring feature even when the initial particle velocity distribution is highly
tangentially anisotropic (). Only when the initial
particle velocity distribution is circular do our simulations show such a
feature. Even modestly anisotropic velocity distributions are inconsistent with
the halo velocity distributions seen in cosmological simulations, and would
require highly fine-tuned initial conditions. Our investigation leaves us
without an explanation for the dark matter ring-like feature in Cl 0024+17
suggested by lensing observations.Comment: 7 pages (emulateapj), 9 figures. Expanded figures and text to match
accepted versio
L_X-T Relation and Related Properties of Galaxy Clusters
An observational approach is presented to constrain the global structure and
evolution of the intracluster medium based on the ROSAT and ASCA distant
cluster sample. From statistical analysis of the gas density profile and the
connection to the LX-T relation under the beta-model, the scaled gas profile is
nearly universal for the outer region and the LX(>0.2r500) is tightly related
to the temperature through T^3 rather than T^2. On the other hand, a large
density scatter exists in the core region and there is clearly a deviation from
the self-similar scaling for clusters with a small core size. A direct link
between the core size and the radiative cooling timescale suggest that t_cool
is a parameter to control the gas structure and the appearance of small cores
in regular clusters may be much connected with the thermal evolution. We derive
the luminosity-ambient temperature (T') relation, assuming the universal
temperature profile to find the dispersion around the relation significantly
decreases: L_1keV is almost constant for a wide range of t_cool. We further
examined the LX-Tbeta and LX-T'beta relations and showed a trend that merging
clusters segregate from the regular clusters on the planes. A good correlation
between t_cool and the X-ray morphology on the L_1keV-t_cool/t_age plane leads
us to define three phases according to the different level of cooling, and draw
a phenomenological picture: after a cluster collapses and t_cool falls below
t_age, the core cools radiatively with quasi-hydrostatic balancing in the
gravitational potential, and the central density gradually becomes higher to
evolve from an outer-core-dominant cluster to inner-core-dominant cluster.Comment: 39 pages, 37 figures. Accepted for publication in ApJ. Version with
high-quality color figures at
http://cosmic.riken.jp/ota/publications/index.htm
The published research paper: is it an important indicator of successful operational research at programme level?
Is a published research paper an important indicator of successful operational research at programme level in low-income countries? In academia, publishing in peer-reviewed scientific journals is highly encouraged and strongly pursued for academic recognition and career progression. In contrast, for those who engage in operational research at programme level, there is often no necessity or reward for publishing the results of research studies; it may even be criticized as being an unnecessary detraction from programme-related work. We present arguments to support publishing operational research from low-income countries; we highlight some of the main reasons for failure of publication at programme level and suggest ways forward
GC–MS profile, anti-seizure and anti-pyretic activities of palm kernel nut oil and its isolate, N-Octanoic acid from specially breed palm kernel Elaeis guineensis
PURPOSE: Palm kernel nut oil (PKNO) from palm fruit of a rare breed of Elaeis guineensis (virescens), and one of the species belonging to the Elaeis genre of arecaceae family was subjected to Gas chromatography - Mass spectroscopic studies as well as anti-seizure and anti-pyretic studies. It is used in South-Eastern part of Nigeria as antipyretic and anti-seizure agents especially in children. The aim of this study was to evaluate the chemical contents of PKNO using GC-MS and to investigate the antiseizure and antipyretic properties of PKNO using animal model.METHOD: 1500 g Palm Kernels (PK) of the rare breed collected from Abia State were cracked open and the nuts (1000 g) poured into steel vessel and heated until oil was produced after charring the nuts. The oil (PKNO) was analyzed using GC-MS to determine its chemical composition. Yeast induced hyperthermia method was used for anti-pyretic studies while strychnine sulphate induced method was used for anti-seizure studies. PKNO and Octanoic acid (0.5 mg/kg ,1 mg/kg, 2 mg/kg) were administered intraperitoneally (IP).Paracetamol (0.15mg/kg) was used as reference standard for anti-pyretic assay while epilim and tegretol (0.14mg/kg, resp.) were used as reference standards for anti-seizure assay.RESULTS: The major component identified in the extract include: Dodecanoic acid,2,3-dihydroxypropyl ester(19.36 %),n-Hexadecanoic acid(15.49 %),Dodecanoic acid( 12.51 %),Myristic acid ( 6.47 %), Dodecanedioic acid (3.93 %),n-Acetylpyrrolidone (3.67 %) , Thiazole (0.98 %) and Octanoic acid, OA ( 3.19 %).The anti-seizure results showed that doses of PKNO and OA used had Significant (p<0.02) anti-seizure activities by delaying the on-set of seizure from time of induction to time of first seizure observed. In yeast induced hyperthermia model, PKNO exhibited good level of anti-pyretic activities by direct reduction of pyrexia with the highest dose, 2.0 mg/kg. The PKNO and OA are proven to be safe till 3000 μl/kg as indicated by LD50 results.CONCLUSION: PKNO and its components mainly fatty acids, thiazole, and n- acetylpyrrolidone are potent and promising agents with anti-pyretic and antiseizure activities.Keywords: Anti-Seizure, anti-pyretic, Octanoic acid, elaeis virescens, GC-MS, Palm kernel nut oil (PKNO
Lithium in garnet as a tracer of subduction zone metamorphic reactions: The record in ultrahigh-pressure metapelites at Lago di Cignana, Italy
Lithium is of great interest as a tracer of metamorphic reactions and related fluid-mineral interactions because of its potential to isotopically fractionate during inter- and intracrystalline diffusional processes. Study of its transfer through subduction zones, based on study of arc volcanic and metamorphic rocks, can yield insight regarding ocean-to-mantle chemical cycling. We investigated major- and trace-element concentrations and delta Li-7 in garnet in ultrahigh-pressure (UHP) Lago di Cignana metasedimentary rocks, relating these observations to reconstructed prograde devolatilization history. In all garnet crystals we studied, heavy rare earth elements (HREEs), Y, and Li showed strong zoning, with elevated concentrations in cores (15-50 ppm Li) and marked high-concentration anomalies (up to 117 ppm Li, 5500 ppm Y; little or no major-element shift) as growth annuli, in which some crystals showed subtle elevation in delta Li-7 greater than analytical error of similar to 3 parts per thousand (2 sigma). Rutile inclusions appeared abruptly at annuli and outward toward rims, accompanied by inclusions of a highly zoned, Ca- and rare earth element-rich phase and decreased Nb concentrations in garnet. These relationships are interpreted to reflect prograde garnet-forming reaction(s), in part involving titanite breakdown to stabilize rutile, which resulted in delivery of more abundant Y and HREEs at surfaces of growing garnet crystals to produce annuli. Co-enrichments in Li and Y + REEs are attributed to mutual incorporation via charge-coupled substitutions; thus, increased Li uptake was a passive consequence of elevated concentrations of Y + REEs. The small-scale fluctuations in delta Li-7 (overall range of similar to 9 parts per thousand) observed in some crystals may correlate with abrupt shifts in major-and trace-element concentrations, suggesting that changes in reactant phases exerted some control on the evolution of delta Li-7. For one garnet crystal, late-stage growth following partial resorption produced deviation in major- and trace-element compositions, including Li concentration, accompanied by a 10 parts per thousand-15 parts per thousand negative shift in delta Li-7, perhaps reflecting a change in the mechanism of incorporation or source of Li. These results highlight the value of measuring the major- and trace-element and isotope compositions of garnets in high-pressure and UHP metamorphic rocks in which matrix mineral assemblages are extensively overprinted by recrystallization during exhumation histories. Lithium concentrations and isotope compositions of the garnets can add valuable information regarding prograde (and retrograde) reaction history, kinetics of porphyroblast growth, intracrystalline diffusion, and fluid-rock interactions. This work, integrated with previous study of devolatilization in the Schistes Lustres/Cignana metasedimentary suite, indicates retention of a large fraction of the initially subducted sedimentary Li budget to depths approaching those beneath volcanic fronts, despite the redistribution of this Li among mineral phases during complex mineral reaction histories
Energy levels of few electron quantum dots imaged and characterized by atomic force microscopy
Strong confinement of charges in few electron systems such as in atoms,
molecules and quantum dots leads to a spectrum of discrete energy levels that
are often shared by several degenerate quantum states. Since the electronic
structure is key to understanding their chemical properties, methods that probe
these energy levels in situ are important. We show how electrostatic force
detection using atomic force microscopy reveals the electronic structure of
individual and coupled self-assembled quantum dots. An electron addition
spectrum in the Coulomb blockade regime, resulting from a change in cantilever
resonance frequency and dissipation during tunneling events, shows one by one
electron charging of a dot. The spectra show clear level degeneracies in
isolated quantum dots, supported by the first observation of predicted
temperature-dependent shifts of Coulomb blockade peaks. Further, by scanning
the surface we observe that several quantum dots may reside on what
topologically appears to be just one. These images of grouped weakly and
strongly coupled dots allow us to estimate their relative coupling strengths.Comment: 11 pages, 6 figure
- …