3,003 research outputs found
Heterogeneous Investors and their Changing Demand and Supply Schedules for Individual Common Stocks
Using 550 million limit orders submitted in the Korea Stock Exchange, we estimate demand and supply elasticities of heterogeneous investor types and their changes around the Asian financial crisis. We find that domestic individuals have substantially more inelastic demand and supply curves than domestic institutions and foreign investors. The crisis permanently reduced price elasticities of domestic individuals by 50% but had no effect on those of foreign investors. Institutional changes restricting margin purchases, implemented after the crisis, seem particularly important in explaining the dramatic drop. Information heterogeneity, availability of close substitutes and arbitrage risk also explain time-series variations in elasticities.
Lines and Boxes: Unmasking Dynamical Dark Matter through Correlations in the MeV Gamma-Ray Spectrum
Identifying signatures of dark matter at indirect-detection experiments is
generally more challenging for scenarios involving non-minimal dark sectors
such as Dynamical Dark Matter (DDM) than for scenarios involving a single dark
particle. This additional difficulty arises because the partitioning of the
total dark-matter abundance across an ensemble of different constituent
particles with different masses tends to "smear" the injection spectra of
photons and other cosmic-ray particles that are produced via dark-matter
annihilation or decay. As a result, the imprints of the dark sector on these
cosmic-ray flux spectra typically take the form of continuum features rather
than sharp peaks or lines. In this paper, however, we identify an unambiguous
signature of non-minimal dark sectors such as DDM which can overcome these
issues and potentially be observed at gamma-ray telescopes operating in the MeV
range. We discuss the specific situations in which this signature can arise,
and demonstrate that this signature can be exploited in order to significantly
enhance our ability to resolve the unique spectral features of DDM and other
non-minimal dark sectors at future gamma-ray facilities.Comment: 21 pages, LaTeX, 4 figures, 1 tabl
Boxes, Boosts, and Energy Duality: Understanding the Galactic-Center Gamma-Ray Excess through Dynamical Dark Matter
Many models currently exist which attempt to interpret the excess of gamma
rays emanating from the Galactic Center in terms of annihilating or decaying
dark matter. These models typically exhibit a variety of complicated cascade
mechanisms for photon production, leading to a non-trivial kinematics which
obscures the physics of the underlying dark sector. In this paper, by contrast,
we observe that the spectrum of the gamma-ray excess may actually exhibit an
intriguing "energy-duality" invariance under for some . As we shall discuss, such an energy
duality points back to a remarkably simple alternative kinematics which in turn
is realized naturally within the Dynamical Dark Matter framework. Observation
of this energy duality could therefore provide considerable information about
the properties of the dark sector from which the Galactic-Center gamma-ray
excess might arise, and highlights the importance of acquiring more complete
data for the Galactic-Center excess in the energy range around 1 GeV.Comment: 13 pages, LaTeX, 5 figure
Light Dark Matter Detection Prospects at Neutrino Experiments
We consider the prospects for the detection of relatively light dark matter
through direct annihilation to neutrinos. We specifically focus on the
detection possibilities of water Cherenkov and liquid scintillator neutrino
detection devices. We find in particular that liquid scintillator detectors may
potentially provide excellent detection prospects for dark matter in the 4-10
GeV mass range. These experiments can provide excellent corroborative checks of
the DAMA/LIBRA annual modulation signal, but may yield results for low mass
dark matter in any case. We identify important tests of the ratio of electron
to muon neutrino events (and neutrino versus anti-neutrino events), which
discriminate against background atmospheric neutrinos. In addition, the
fraction of events which arise from muon neutrinos or anti-neutrinos (
and ) can potentially yield information about the branching
fractions of hypothetical dark matter annihilations into different neutrino
flavors. These results apply to neutrinos from secondary and tertiary decays as
well, but will suffer from decreased detectability.Comment: 13 pages, 2 figures, pdflatex, references, one figure and comments on
electron neutrino bounds and on spin-dependent scattering limits added.
Figures updated
Heterogeneous investors and their changing demand and supply schedules for individual common stocks
Exogenous GDF11, but not GDF8, reduces body weight and improves glucose homeostasis in mice
Insulin resistance is associated with aging in mice and humans. We have previously shown that administration of recombinant GDF11 (rGDF11) to aged mice alters aging phenotypes in the brain, skeletal muscle, and heart. While the closely related protein GDF8 has a role in metabolism, limited data are available on the potential metabolic effects of GDF11 or GDF8 in aging. To determine the metabolic effects of these two ligands, we administered rGDF11 or rGDF8 protein to young or aged mice fed a standard chow diet, short-term high-fat diet (HFD), or long-term HFD. Under nearly all of these diet conditions, administration of exogenous rGDF11 reduced body weight by 3-17% and significantly improved glucose tolerance in aged mice fed a chow (~30% vs. saline) or HF (~50% vs. saline) diet and young mice fed a HFD (~30%). On the other hand, exogenous rGDF8 showed signifcantly lesser effect or no effect at all on glucose tolerance compared to rGDF11, consistent with data demonstrating that GFD11 is a more potent signaling ligand than GDF8. Collectively, our results show that administration of exogenous rGDF11, but not rGDF8, can reduce diet-induced weight gain and improve metabolic homeostasis
Band Gap Engineering with Ultralarge Biaxial Strains in Suspended Monolayer MoS2
We demonstrate the continuous and reversible tuning of the optical band gap
of suspended monolayer MoS2 membranes by as much as 500 meV by applying very
large biaxial strains. By using chemical vapor deposition (CVD) to grow
crystals that are highly impermeable to gas, we are able to apply a pressure
difference across suspended membranes to induce biaxial strains. We observe the
effect of strain on the energy and intensity of the peaks in the
photoluminescence (PL) spectrum, and find a linear tuning rate of the optical
band gap of 99 meV/%. This method is then used to study the PL spectra of
bilayer and trilayer devices under strain, and to find the shift rates and
Gr\"uneisen parameters of two Raman modes in monolayer MoS2. Finally, we use
this result to show that we can apply biaxial strains as large as 5.6% across
micron sized areas, and report evidence for the strain tuning of higher level
optical transitions.Comment: Nano Lett., Article ASA
A systematic review and meta-analysis of childhood health utilities
Background:
A common feature of most reviews or catalogues of health utilities has been their focus on adult health states or derivation of values from adult populations. More generally, utility measurement in or on behalf of children has been constrained by a number of methodological concerns. The objective of this study was to conduct the first comprehensive systematic review and meta-analysis of primary utility data for childhood conditions and descriptors and to determine the effects of methodological factors on childhood utilities.
Methods:
The review followed PRISMA guidelines. PubMed, Embase, Web of Science, PsycINFO, EconLit, CINAHL and Cochrane Library were searched for primary studies reporting health utilities for childhood conditions or descriptors using direct or indirect valuation methods. The Pediatric Economic Database Evaluation (PEDE) was also searched for cost-utility analyses with primary utility values. Mean or median utilities for each of the main samples were catalogued, whilst weighted averages of utilities for each health condition were estimated, by valuation method. Mixed-effects meta-regression using hierarchical linear modelling was conducted for the most common valuation methods to estimate the utility decrement for each health condition category relative to general childhood population health, as well as the independent effects of methodological factors.
Results:
The literature searches resulted in 272 eligible studies. These yielded 3,414 utilities when all sub-groups were considered, covering all ICD-10 chapters relevant to childhood health, 19 valuation methods, 12 respondent types, 8 modes of administration, and data from 36 countries. A total of 1,191 utility values were obtained when only main study samples were considered and these were catalogued by health condition or descriptor, and methodological characteristics. 1,073 mean utilities for main samples were used for fixed-effects meta-analysis by health condition and valuation method. Mixed-effects meta-regressions estimated that 53 of 76 ICD-10 delineated health conditions valued using the HUI3 were associated with statistically significant utility decrements relative to general population health, whilst 38 of 57 valued using a Visual Analogue Scale (VAS) were associated with statistically significant VAS decrements. For both methods, parental proxy-assessment was associated with overestimation of values, whilst adolescents reported lower values than children under 12 years. VAS responses were more heavily influenced by mode of administration than the HUI3
Novel model for end-neuroma formation in the amputated rabbit forelimb
<p>Abstract</p> <p>Background</p> <p>The forelimb amputee poses many reconstructive challenges in the clinical setting, and there is a paucity of established surgical models for study. To further elucidate the pathogenic process in amputation neuroma formation, we created a reproducible, well-tolerated rabbit forelimb amputation model.</p> <p>Methods</p> <p>Upon approval from the Institutional Animal Care and Use Committee, 5 New Zealand White rabbits underwent left forelimb amputation. During this initial surgery, the median, radial and ulnar nerves were transected 1.6-2.5 (mean 2.0) cm distal to the brachial plexus, transposed onto the anterior chest wall and preserved at length. Six weeks subsequent to the amputation, the distal 5 mm of each neuroma was excised, and the remaining stump underwent histomorphometric analysis.</p> <p>Results</p> <p>The nerve cross sectional areas increased by factors of 1.99, 3.17, and 2.59 in the median (p = 0.077), radial (p < 0.0001) and the ulnar (p = 0.0026) nerves, respectively. At the axonal level, the number and cross-sectional area of myelinated fibers demonstrated an inverse relationship whereby the number of myelinated fibers in the median, radial and ulnar nerves increased by factors of 5.13 (p = 0.0043), 5.25 (p = 0.0056) and 5.59 (p = 0.0027), and the cross-sectional areas of these myelinated fibers decreased by factors of 4.62 (p < 0.001), 3.51 (p < 0.01), and 4.29 (p = 0.0259), respectively.</p> <p>Conclusion</p> <p>Given that the surgical model appears well-tolerated by the rabbits and that patterns of morphologic change are consistent and reproducible, we are encouraged to further investigate the utility of this model in the pathogenesis of neuroma formation.</p
- …