816 research outputs found
Extinction in Lotka-Volterra model
Competitive birth-death processes often exhibit an oscillatory behavior. We
investigate a particular case where the oscillation cycles are marginally
stable on the mean-field level. An iconic example of such a system is the
Lotka-Volterra model of predator-prey competition. Fluctuation effects due to
discreteness of the populations destroy the mean-field stability and eventually
drive the system toward extinction of one or both species. We show that the
corresponding extinction time scales as a certain power-law of the population
sizes. This behavior should be contrasted with the extinction of models stable
in the mean-field approximation. In the latter case the extinction time scales
exponentially with size.Comment: 11 pages, 17 figure
Projected sensitivity to sub-GeV dark matter of next-generation semiconductor detectors
We compute the projected sensitivity to dark matter (DM) particles in the
sub-GeV mass range of future direct detection experiments using germanium and
silicon semiconductor targets. We perform this calculation within the dark
photon model for DM-electron interactions using the likelihood ratio as a test
statistic, Monte Carlo simulations, and background models that we extract from
recent experimental data. We present our results in terms of DM-electron
scattering cross section values required to reject the background only
hypothesis in favour of the background plus DM signal hypothesis with a
statistical significance, , corresponding to 3 or 5 standard
deviations. We also test the stability of our conclusions under changes in the
astrophysical parameters governing the local space and velocity distribution of
DM in the Milky Way. In the best-case scenario, when a high-voltage germanium
detector with an exposure of kg-year and a CCD silicon detector with an
exposure of kg-year and a dark current rate of
counts/pixel/day have simultaneously reported a DM signal, we find that the
smallest cross section value compatible with ()
is about cm ( cm) for contact
interactions, and cm ( cm) for
long-range interactions. Our sensitivity study extends and refine previous
works in terms of background models, statistical methods, and treatment of the
underlying astrophysical uncertainties.Comment: 17 pages, 4 figure
4,5,6,7-Tetrabromo-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)indane
The title compound (OctaInd), C18H12Br8, is a commercial brominated flame retardant (BFR). In the molecule, the five-membered ring has a slight envelope conformation, with a deviation of 0.317 (9) Å for the flap C atom from four essentially planar C atoms. The dihedral angle between the two benzene rings is 74.00 (16) Å
Toward Unbiased Galaxy Cluster Masses from Line of Sight Velocity Dispersions
We study the use of red sequence selected galaxy spectroscopy for unbiased
estimation of galaxy cluster masses. We use the publicly available galaxy
catalog produced using the semi-analytic model of De Lucia & Blaizot (2007) on
the Millenium Simulation (Springel et al. 2005). We explore the impacts on
selection using galaxy color, projected separation from the cluster center, and
galaxy luminosity. We study the relationship between cluster mass and velocity
dispersion and identify and characterize the following sources of bias and
scatter: halo triaxiality, dynamical friction of red luminous galaxies and
interlopers. We show that due to halo triaxiality the intrinsic scatter of
estimated line of sight dynamical mass is about three times larger (30-40%)
than the one estimated using the 3D velocity dispersion (~12%) and a small bias
(~1%) is induced. We find evidence of increasing scatter as a function of
redshift and provide a fitting formula to account for it. We characterize the
amount of bias and scatter introduced by dynamical friction when using
subsamples of red-luminous galaxies to estimate the velocity dispersion. We
study the presence of interlopers in spectroscopic samples and their effect on
the estimated cluster dynamical mass. Our results show that while cluster
velocity dispersions extracted from a few dozen red sequence selected galaxies
do not provide precise masses on a single cluster basis, an ensemble of cluster
velocity dispersions can be combined to produce a precise calibration of a
cluster survey mass observable relation. Currently, disagreements in the
literature on simulated subhalo velocity dispersion mass relations place a
systematic floor on velocity dispersion mass calibration at the 15% level in
mass. We show that the selection related uncertainties are small by comparison,
providing hope that with further improvements this systematic floor can be
reduced.Comment: submitted to Ap
Phase 1 Trial With the Cell-Based Immune Primer Ilixadencel, Alone, and Combined With Sorafenib, in Advanced Hepatocellular Carcinoma
Several lines of evidence support immunotherapy in hepatocellular carcinoma (HCC). We have shown that intratumoral injections of the immune primer ilixadencel (pro-inflammatory allogeneic dendritic cells) are safe in renal-cell carcinoma. Here, we assessed ilixadencel as a single agent and combined with sorafenib in advanced HCC. Of 17 HCC patients enrolled, 12 patients received ilixadencel at the dose of 10 × 106 cells (six as monotherapy and six in combination with sorafenib), and five received ilixadencel at the dose of 20 × 106 cells as monotherapy. The primary objective was to evaluate tolerability. All patients had at least one adverse event, with 30% of such events considered as treatment-related, with one single treatment-related grade three event. The most common toxicity was grade 1 and 2 fever and chills. Eleven of 15 evaluable patients (73%) showed increased frequency of tumor-specific CD8+ T cells in peripheral blood. Overall one patient had a partial response (with ilixadencel as monotherapy), and five had stable disease as overall best response per mRECIST. The median time to progression was 5.5 months, and overall survival ranged from 1.6 to 21.4 months. Our study confirms the safety of ilixadencel as single agent or in combination with sorafenib and indicates tumor-specific immunological responses in advanced HCC.Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT0197466
Propuesta de un prototipo de vivienda sustentable y sismo resistente en asentamiento humano Nueva Esperanza, Nuevo Chimbote, 2021
El distrito de Nuevo Chimbote, la mayor parte de viviendas fueron construidas con
materiales poco duraderos y esto aumenta cada día debido al bajo nivel
socioeconómico de las poblaciones vulnerables lo que los conlleva a no poder construir
una vivienda duradera y siguiendo los protocolos establecidos; nuestro proyecto fue
útil para brindar propuestas con bases teóricas para construir viviendas económicas y
seguras de una manera rápida y confiable.
Nuestro proyecto es descriptivo comparativo porque realizaremos la comparación con
respecto a una vivienda tradicional. Nuestro proyecto permitió comparar en términos
de economía que tipo de vivienda es más viable destinada hacia nuestra población a
estudiar.
Una vivienda sostenible planteada en nuestro proyecto posee las siguientes
características: Económico, seguro, viable, basado en normas RNE, de menor tiempo
de construcción. Con nuestro proyecto esperamos proponer una vivienda económica
y confiable utilizando las normas correspondientes.
Por lo cual presento este proyecto para abarcar lo máximo posible en base teórica y
por consiguiente brindar un producto económico y rentable socialmente para dichas
zonas de expansión urbana en nuestra localidad
Wave function recombination instability in cold atom interferometers
Cold atom interferometers use guiding potentials that split the wave function
of the Bose-Einstein condensate and then recombine it. We present theoretical
analysis of the wave function recombination instability that is due to the weak
nonlinearity of the condensate. It is most pronounced when the accumulated
phase difference between the arms of the interferometer is close to an odd
multiple of PI and consists in exponential amplification of the weak ground
state mode by the strong first excited mode. The instability exists for both
trapped-atom and beam interferometers.Comment: 4 pages, 5 figure
Optimal simultaneous measurements of incompatible observables of a single photon
The ultimate limits of measurement precision are dictated by the laws of quantum mechanics. One of the most fascinating results is that joint or simultaneous measurements of noncommuting quantum observables are possible at the cost of increased unsharpness or measurement uncertainty. Many different criteria exist for determining what an “optimal” joint measurement is, with corresponding different trade-off relations for the measurements. It is generally a nontrivial task to devise or implement a strategy that minimizes the joint-measurement uncertainty. Here, we implement the simplest possible technique for an optimal four-outcome joint measurement and demonstrate a type of optimal measurement that has not been realized before in a photonic setting. We experimentally investigate a joint-measurement uncertainty relation that is more fundamental in the sense that it refers only to probabilities and is independent of values assigned to measurement outcomes. Using a heralded single-photon source, we demonstrate quantum-limited performance of the scheme on single quanta. Since quantum measurements underpin many concepts in quantum information science, this study is both of fundamental interest and relevant for emerging photonic quantum technologies
Estimating the frequency of Asian cytochrome B haplotypes in standard European and local Spanish pig breeds
Mitochondrial DNA has been widely used to perform phylogenetic studies in different animal species. In pigs, genetic variability at the cytochrome B gene and the D-loop region has been used as a tool to dissect the genetic relationships between different breeds and populations. In this work, we analysed four SNP at the cytochrome B gene to infer the Asian (A1 and A2 haplotypes) or European (E1 and E2 haplotypes) origins of several European standard and local pig breeds. We found a mixture of Asian and European haplotypes in the Canarian Black pig (E1, A1 and A2), German Piétrain (E1, A1 and A2), Belgian Piétrain (E1, A1), Large White (E1 and A1) and Landrace (E1 and A1) breeds. In contrast, the Iberian (Guadyerbas, Ervideira, Caldeira, Campanario, Puebla and Torbiscal strains) and the Majorcan Black pig breeds only displayed the E1 haplotype. Our results show that the introgression of Chinese pig breeds affected most of the major European standard breeds, which harbour Asian haplotypes at diverse frequencies (15–56%). In contrast, isolated local Spanish breeds, such as the Iberian and Majorcan Black pig, only display European cytochrome B haplotypes, a feature that evidences that they were not crossed with other Chinese or European commercial populations. These findings illustrate how geographical confinement spared several local Spanish breeds from the extensive introgression event that took place during the 18th and 19th centuries in Europe
PRISM: A Non-Equilibrium, Multiphase Interstellar Medium Model for Radiation Hydrodynamics Simulations of Galaxies
We introduce the PRISM interstellar medium (ISM) model for thermochemistry
and its implementation in the RAMSES-RTZ code. The model includes a
non-equilibrium primordial, metal, and molecular chemistry network for 115
species coupled to on-the-fly multifrequency radiation transport. PRISM
accurately accounts for the dominant ISM cooling and heating processes in the
low-density regime (i.e. ), including photoheating,
photoelectric heating, H heating/cooling, cosmic-ray heating, H/He cooling,
metal-line cooling, CO cooling, and dust cooling (recombination and gas-grain
collisions). We validate the model by comparing 1D equilibrium simulations
across six dex in metallicity to existing 1D ISM models in the literature. We
apply PRISM to high-resolution (4.5 pc) isolated dwarf galaxy simulations that
include state-of-the-art models for star formation and stellar feedback to take
an inventory of which cooling and heating processes dominate each different gas
phase of a galaxy and to understand the importance of non-equilibrium effects.
We show that most of the ISM gas is either close to thermal equilibrium or
exhibits a slight cooling instability, while from a chemical perspective, the
non-equilibrium electron fraction is often more than three times higher or
lower than the equilibrium value, which impacts cooling, heating, and
observable emission lines. Electron enhancements are attributed to
recombination lags while deficits are shown to be due to rapid cosmic-ray
heating. The PRISM model and its coupling to RAMSES-RTZ is applicable to a wide
variety of astrophysical scenarios, from cosmological simulations to isolated
giant molecular clouds, and is particularly useful for understanding how
changes to ISM physics impact observable quantities such as metallic emission
lines.Comment: 21 pages, 16 figures, submitted to MNRA
- …