cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
BRIDGING RESEARCH, POLICY, AND PRACTICE IN AFRICAN AGRICULTURE
Creators: name: Omamo, Steven Were
name: Omamo, Steven Were
Publisher: name: Unknown
Year: 2004
Subjects: International Development

description: Policy research on African agriculture is long on prescriptions on what needs to be done to reverse negative growth trends but short on how such prescriptions might be implemented in practice. This paper addresses this state of affairs, focusing on the role and impact of research in agricultural policy processes.
COMMON-PROPERTY RESOURCE USE AND OUTSIDE OPTIONS: COOPERATION ACROSS GENERATIONS IN A DYNAMIC GAME
Creators: name: Tarui, Nori
name: Tarui, Nori
Publisher: name: Unknown
Year: 2004
Subjects: Resource /Energy Economics and Policy

description: This paper presents a noncooperative dynamic game with overlapping generations of players using a common-property natural resource, and identifies conditions under which cooperation is supported as an equilibrium of the game. It explores how heterogeneity among the resource users and access to outside markets or microcredit affect local resource use in developing countries.
MIGRATION, CREDIT AVAILABILITY, AND EXPENDITURE GROWTH IN RURAL VIETNAM
Creators: name: Harigaya, Tomoko
name: De Brauw, Alan
name: Harigaya, Tomoko
name: De Brauw, Alan
Publisher: name: Unknown
Year: 2004
Subjects: International Development

description: This paper's objective is to describe and explain expenditure growth in Vietnam over the 1990s. Using two rounds of the Vietnam Living Standards Survey, we describe and explain household specific expenditure growth rates and poverty statistics. We find that while credit access does not affect growth, migration does.
ECONOMIC IMPACTS OF MANDATED GRADING AND TESTING TO AVOID A NEGATIVE FOOD SAFETY EVENT: EX ANTE ANALYSIS OF THE FEDERAL MARKETING ORDER FOR PISTACHIOS
Creators: name: Gray, Richard S.
name: Sumner, Daniel A.
name: Alston, Julian M.
name: Brunke, Henrich
name: Gray, Richard S.
name: Sumner, Daniel A.
name: Alston, Julian M.
name: Brunke, Henrich
Publisher: name: Unknown
Year: 2004
Subjects: Food Consumption/Nutrition/Food Safety

description: The California pistachio industry led an initiative to establish a federal marketing order, which mandates quality standards and an inspection program to assure food safety and consistency in the quality of California pistachios. We develop a stochastic dynamic simulation model of the pistachio market to investigate quantitatively the likely effects of such collective action enforced by government mandates. Simulation results indicate that, across the full range of parameters used in the analysis, the benefit-cost analysis was always favorable to the proposed policy. The measured benefits to producers, the nation, or the world always well exceeded the corresponding measure of costs, typically by many times.
Antiproton fluxes from light neutralinos
Creators: name: Bottino, A.
name: Donato, F.
name: Fornengo, N.
name: Salati, P.
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We analyze how the measurements of the low-energy spectrum of cosmic antiprotons can provide information on relic neutralinos. The analysis is focused on the light neutralinos which emerge in supersymmetric schemes where gaugino-mass unification is not assumed. We determine which ranges of the astrophysical parameters already imply stringent constraints on the supersymmetric configurations and those ranges which make the antiproton flux sensitive to the primary component generated by the neutralino self-annihilation. Our results are derived from some general properties of the antiproton flux proved to be valid for a generic cold dark matter candidate.
description: 12 pages, 13 figures, subm. Phys. Rev. D
Intra-Industry Trade, Imperfect Competition, Trade Integration and Invasive Species Risk
Creators: name: Tu, Anh Thuy
name: Beghin, John C.
name: Tu, Anh Thuy
name: Beghin, John C.
Publisher: name: Unknown
Year: 2004
Subjects: International Relations/Trade

description: We analyze the linkage between protectionism and invasive species hazard in the context of imperfect competition, two-way trade, and multilateral trade liberalization, three major actual features of agricultural trade and policies in the real world. We revisit the reciprocal-dumping model with differentiated products, adding trade and agricultural policies into the framework in the presence of invasive-species risk associated with agriculture. We look at joint reduction of agricultural tariffs. This type of trade integration is much more likely to increase the damage from invasive species than predicted by unilateral trade liberalization under the classical HOS framework. We document the non-monotonic relationship between policy (trade barriers and farm subsidies) and the expected damages from invasive species. We illustrate our analytical results with a stylized model of the world wheat market.
Spin networks, quantum automata and link invariants
Creators: name: Garnerone, Silvano
name: Marzuoli, Annalisa
name: Rasetti, Mario
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The spin network simulator model represents a bridge between (generalized) circuit schemes for standard quantum computation and approaches based on notions from Topological Quantum Field Theories (TQFT). More precisely, when working with purely discrete unitary gates, the simulator is naturally modelled as families of quantum automata which in turn represent discrete versions of topological quantum computation models. Such a quantum combinatorial scheme, which essentially encodes SU(2) Racah--Wigner algebra and its braided counterpart, is particularly suitable to address problems in topology and group theory and we discuss here a finite states--quantum automaton able to accept the language of braid group in view of applications to the problem of estimating link polynomials in Chern--Simons field theory.
description: LateX,19 pages; to appear in the Proc. of "Constrained Dynamics and Quantum Gravity (QG05), Cala Gonone (Italy) September 12-16 2005
ACCOUNTING FOR MANAGEMENT IN COST OF LIVESTOCK DISEASE STUDIES
Creators: name: Ott, Stephen L.
name: Ott, Stephen L.
Publisher: name: Unknown
Year: 2004
Subjects: Farm Management

description: Assessing the impacts of livestock disease on productivity is enhanced when the management abilities of producers are taken into consideration. One method of doing this is to develop a management index of several production/marketing practices using correspondence analysis which can combine several practices into a few variables. Also, through correspondence analysis herds can be divided into better managed and more poorly managed herds to test the association of management on herd health, productivity, and profitability.
Constraining Velocity-dependent Self-Interacting Dark Matter with the Milky Way's dwarf spheroidal galaxies
Creators: name: Correa, Camila A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The observed anti-correlation between the central dark matter (DM) densities of the bright Milky Way (MW) dwarf spheroidal galaxies (dSphs) and their orbital pericenter distances poses a potential signature of self-interacting dark matter (SIDM). In this work we investigate this possibility by analysing the range of SIDM scattering cross section per unit mass, $σ/m_χ$, able to explain such anti-correlation. We simulate the orbital evolution of dSphs subhaloes around the MW assuming an analytical form for the gravitational potential, adopting the proper motions from the Gaia mission and including a consistent characterization of gravitational tidal stripping. The evolution of the subhaloes density profile is modelled using the gravothermal fluid formalism, where DM particle collisions induce thermal conduction that depends on $σ/m_χ$. We find that models of dSphs, such as Carina and Fornax, reproduce the observed central DM densities with fixed $σ/m_χ$ ranging between $30$ and $50$ cm$^{2}$g$^{-1}$, whereas other dSphs prefer larger values ranging between $70$ and $100$ cm$^{2}$g$^{-1}$. These cross sections correlate with the average collision velocity of DM particles within each subhalo's core, so that systems modelled with large cross sections have lower collision velocities. We fit the cross section-velocity correlation with a SIDM particle model, where a DM particle of mass $m_χ=0.648\pm 0.154$ GeV interacts under the exchange of a light mediator of mass $m_ϕ=0.636\pm 0.055$ MeV, with the self-interactions being described by a Yukawa potential. The outcome is a cross section-velocity relation that explains the diverse DM profiles of MW dSph satellites and is consistent with observational constraints on larger scales.
description: 18 pages including references, 14 figures, and 2 tables. Submitted to MNRAS, comments welcome
The NICMOS Polarimetric Calibration
Creators: name: Batcheldor, D.
name: Robinson, A.
name: Axon, D.
name: Hines, D. C.
name: Sparks, W.
name: Tadhunter, C.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The value of accurately knowing the absolute calibration of the polarizing elements in the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) becomes especially important when conducting studies which require measuring degrees of polarization of close to 1% in the near infrared. We present a comprehensive study of all previously observed polarimetric standards using the NIC2 camera on NICMOS. Considering both pre- and post-NICMOS Cooling System observations we find variations in the polarimetry consistent with the effects of sub-pixel mis-alignments and the point spread function. We also measure non-zero results from unpolarized standards indicating an instrumental polarization of p ~ 1.2%, theta ~ 88degrees. The lack of polarized and unpolarized standard stars with which to perform a comprehensive calibration study means we cannot be confident that the current calibration will be effective for a number of recent large NICMOS GO programs. Further observations of polarimetric standards are needed in order to fully characterize the behavior of NICMOS at around p=1%.
description: 9 pages, 4 figures, PASP accepted
Discovery of a Universal Correlation For Long and Short GRBs and Its Application on the Study of Luminosity Function and Formation Rate
Creators: name: Guo, Qi
name: Wei, Da-Ming
name: Wang, Yuan-Zhu
name: Jin, Zhi-Ping
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Gamma-ray bursts (GRBs) are known to be the most violent explosions in the universe, and a variety of correlations between observable GRB properties have been proposed in literature, but none of these correlations is valid for both long GRBs and short GRBs. In this paper we report the discovery of a universal correlation which is suitable for both long and short GRBs using three prompt emission properties of GRBs, i.e. the isotropic peak luminosity $L_{\rm iso}$, the peak energy of the time-integtated prompt emission spectrum $E_{\rm peak}$, and the "high signal" timescale $T_{\rm 0.45}$, $L_{\rm iso} \propto E_{\rm peak}^{1.94} T_{0.45}^{0.37}$. This universal correlation just involves properties of GRB prompt emission and does not require any information of afterglow phase, which can be used as a relatively unbiased redshift estimator. Here we use this correlation to estimate the pseudo-redshifts for short Gamma Ray Bursts and then use Lynden-Bell method to obtain a non-parametric estimate of their luminosity function and formation rate. The luminosity function is $ψ(L_0)\propto{L_0^{-0.63\pm{0.07}}}$ for dim SGRBs and $ψ(L_0)\propto{L_0^{-1.96\pm{0.28}}}$ for bright SGRBs, with the break point $6.95_{-0.76}^{+0.84}\times10^{50} erg/s$. The local formation rate of SGRBs is about 15 events $\rm Gpc^{-3}yr^{-1}$ . This universal correlation may have important implications for GRB physics, implying that the long and short GRBs should share similar radiation processes.
description: 13 pages, 6 figures, accepted for publication in ApJ
Clustering of solutions in the random satisfiability problem
Creators: name: Mezard, M.
name: Mora, T.
name: Zecchina, R.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Computational Complexity (cs.CC)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Using elementary rigorous methods we prove the existence of a clustered phase in the random $K$-SAT problem, for $K\geq 8$. In this phase the solutions are grouped into clusters which are far away from each other. The results are in agreement with previous predictions of the cavity method and give a rigorous confirmation to one of its main building blocks. It can be generalized to other systems of both physical and computational interest.
description: 4 pages, 1 figure
A vanishing theorem for T-branes
Creators: name: Marchesano, Fernando
name: Moraru, Ruxandra
name: Savelli, Raffaele
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Algebraic Geometry (math.AG)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We consider regular polystable Higgs pairs $(E, ϕ)$ on compact complex manifolds. We show that a non-trivial Higgs field $ϕ\in H^0 ({\rm End} (E) \otimes K_S)$ restricts the Ricci curvature of the manifold, generalising previous results in the literature. In particular $ϕ$ must vanish for positive Ricci curvature, while for trivial canonical bundle it must be proportional to the identity. For Kähler surfaces, our results provide a new vanishing theorem for solutions to the Vafa--Witten equations. Moreover they constrain supersymmetric 7-brane configurations in F-theory, giving obstructions to the existence of T-branes, i.e. solutions with $[ϕ, ϕ^\dagger] \neq 0$. When non-trivial Higgs fields are allowed, we give a general characterisation of their structure in terms of vector bundle data, which we then illustrate in explicit examples.
description: 40 pages, 1 grid
Precision Measurements in Few-Electron Molecules: The Ionization Energy of Metastable $\mathbf{^4}$He$\mathbf{_2}$ and the First Rotational Interval of $\mathbf{^4}$He$\mathbf{{_2}^+}$
Creators: name: Semeria, Luca
name: Jansen, Paul
name: Camenisch, Gian-Marco
name: Mellini, Federico
name: Schmutz, Hansjürg
name: Merkt, Frédéric
Publisher: name: arXiv
Year: 2020
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Molecular helium represents a benchmark system for testing $\textit{ab initio}$ calculations on few-electron molecules. We report on the determination of the adiabatic ionization energy of the $a\,^3Σ_u^+$ state of He$_2$, corresponding to the energy interval between the $a\,^3Σ_u^+$ ($v''=0$, $N''=1$) state of He$_2$ and the $X^+\,^2Σ_u^+$ ($v^+=0$, $N^+=1$) state of He${_2}^+$, and of the lowest rotational interval of He${_2}^+$. These measurements rely on the excitation of metastable He$_2$ molecules to high Rydberg states using frequency-comb-calibrated continuous-wave UV radiation in a counter-propagating-laser-beam setup. The observed Rydberg states were extrapolated to their series limit using multichannel quantum-defect theory. The ionization energy of He$_2$ ($a\,^3Σ_u^+$) and the lowest rotational interval of He${_2}^+$ ($X^+\,^2Σ_u^+$) are 34301.207002(23)$\pm 0.000037_{\mathrm{sys}}$ cm$^{-1}$ and 70.937589(23)$\pm 0.000060_{\mathrm{sys}}$ cm$^{-1}$, respectively.
The UV Luminosity Function of Protocluster Galaxies at $z\sim4$: the Bright-end Excess and the Enhanced Star Formation Rate Density
Creators: name: Ito, Kei
name: Kashikawa, Nobunari
name: Toshikawa, Jun
name: Overzier, Roderik
name: Kubo, Mariko
name: Uchiyama, Hisakazu
name: Liang, Yongming
name: Onoue, Masafusa
name: Tanaka, Masayuki
name: Komiyama, Yutaka
name: Lee, Chien-Hsiu
name: Lin, Yen-Ting
name: Marinello, Murilo
name: Martin, Crystal L.
name: Shibuya, Takatoshi
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We report the rest-frame ultraviolet luminosity function of $g$-dropout galaxies in 177 protocluster candidates (PC UVLF) at $z\sim4$ selected in the Hyper Suprime-Cam Subaru Strategic Program. Comparing with the UVLF of field galaxies at the same redshift, we find that the PC UVLF shows a significant excess towards the bright-end. This excess can not be explained by the contribution of only active galactic nuclei, and we also find that this is more significant in higher dense regions. Assuming that all protocluster members are located on the star formation main sequence, the PC UVLF can be converted into a stellar mass function. Consequently, our protocluster members are inferred to have a 2.8 times more massive characteristic stellar mass than that of the field Lyman break galaxies at the same redshift. This study, for the first time, clearly shows that the enhancement in star formation or stellar mass in overdense regions can generally be seen as early as at $z\sim4$. We also estimate the star formation rate density (SFRD) in protocluster regions as $\simeq 6-20\%$ of the cosmic SFRD, based on the measured PC UVLF after correcting for the selection incompleteness in our protocluster sample. This high value suggests that protoclusters make a non-negligible contribution to the cosmic SFRD at $z\sim4$, as previously suggested by simulations. Our results suggest that protoclusters are essential components for the galaxy evolution at $z\sim4$.
description: 22 pages, 16 figures, Accepted for publication in ApJ
Supersonic crack propagation in a class of lattice models of Mode III brittle fracture
Creators: name: Guozden, T. M.
name: Jagla, E. A.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We study a lattice model for mode III crack propagation in brittle materials in a stripe geometry at constant applied stretching. Stiffening of the material at large deformation produces supersonic crack propagation. For large stretching the propagation is guided by well developed soliton waves. For low stretching, the crack-tip velocity has a universal dependence on stretching that can be obtained using a simple geometrical argument.
description: 4 pages, 3 figures
The effective mitigation of greenhouse gas emissions from rice paddies without compromising yield by early-season drainage
Creators: name: Islam, S. F. U.
name: van Groenigen, J. W.
name: Jensen, L. S.
name: Sander, B. O.
name: de Neergaard, A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Geophysics (physics.geo-ph)
subject: Quantitative Methods (q-bio.QM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Global rice production systems face two opposing challenges: the need to increase production to accommodate the world's growing population while simultaneously reducing greenhouse gas (GHG) emissions. Adaptations to drainage regimes are one of the most promising options for methane mitigation in rice production. Whereas several studies have focused on mid-season drainage (MD) to mitigate GHG emissions, early-season drainage (ED) varying in timing and duration has not been extensively studied. However, such ED periods could potentially be very effective since initial available Carbon levels (and thereby the potential for methanogenesis) can be very high in paddy systems with rice straw incorporation. This study tested the effectiveness of seven drainage regimes varying in their timing and duration (combinations of ED and MD) to mitigate methane (CH4) and nitrous oxide (N2O) emissions in a 101-day growth chamber experiment. Emissions were considerably reduced by early-season drainage compared to both conventional continuous flooding (CF) and the MD drainage regime. The results suggest that ED + MD drainage may have the potential to reduce methane emissions and yield-scaled global warming potential by 85 to 90% compared to CF and by 75 to 77% compared to MD only. A combination of (short or long) ED drainage and one MD drainage episode was found to be the most effective in mitigating methane emissions without negatively affecting yield. In particular, compared with CF, the long early-season drainage treatments LE + SM and LE + LM significantly decreased yield scaled global warming potential by 85% and 87% respectively. This was associated with carbon being stabilised early in the season, thereby reducing available carbon for methanogenesis. Overall nitrous oxide emissions were small and not significantly affected by ED.
Puzzles of Large Scale Structure and Gravitation
Creators: name: Sidharth, Burra Gautam
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: We consider the puzzle of cosmic voids bounded by two dimensional structures of galactic clusters as also a puzzle pointed out by Weinberg: How can the mass of a typical elementary particle depend on a cosmic parameter like the Hubble constant? An answer to the first puzzle is proposed in terms of ``Scaled'' Quantum Mechanical like behaviour which appears at large scales. The second puzzle can be answered by showing that the Gravitational mass of an elementary particle has a Machian character.
description: 10 pages, Invited talk at Physics 2005 Symposium
Illuminating Dark Matter Halo Density Profiles Without Subhaloes
Creators: name: Fielder, Catherine E.
name: Mao, Yao-Yuan
name: Zentner, Andrew R.
name: Newman, Jeffrey A.
name: Wu, Hao-Yi
name: Wechsler, Risa
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Cold dark matter haloes consist of a relatively smooth dark matter component as well as a system of bound subhaloes. It is the prevailing practice to include all halo mass, including mass in subhaloes, in studies of halo density profiles. However, often in observational studies satellites are treated as having their own distinct dark matter density profiles in addition to the profile of the host. This difference makes comparisons between theoretical and observed results difficult. In this work we investigate density profiles of the smooth components of host haloes by excluding mass contained within subhaloes. We find that the density profiles of the smooth halo component (without subhaloes) differs substantially from the conventional halo density profile. Smooth profiles decline more rapidly at large radii and are not well characterised by the standard NFW profile. We also find that concentrations derived from smooth density profiles exhibit less scatter at fixed mass and a weaker mass dependence than standard concentrations. Both smooth and standard halo profiles can be described by a generalised Einasto profile, an Einasto profile with a modified central slope, with smaller residuals than either an NFW or Einasto profile. These results hold for both Milky Way-mass and cluster-mass haloes. This new characterisation of smooth halo profiles can be useful for many analyses, such as lensing and dark matter annihilation, in which the smooth and clumpy components of a halo should be accounted for separately.
description: 19 pages, 9 figures, appendices, submitted to MNRAS
The effect of pre-impact spin on the Moon-forming collision
Creators: name: Ruiz-Bonilla, Sergio
name: Eke, Vincent R.
name: Kegerreis, Jacob A.
name: Massey, Richard J.
name: Teodoro, Luis F. A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We simulate the hypothesised collision between the proto-Earth and a Mars-sized impactor that created the Moon. Amongst the resulting debris disk in some impacts, we find a self-gravitating clump of material. It is roughly the mass of the Moon, contains $\sim1\%$ iron like the Moon, and has its internal composition resolved for the first time. The clump contains mainly impactor material near its core but becomes increasingly enriched in proto-Earth material near its surface. A graduated composition has recently been measured in the oxygen isotope ratios of Apollo samples, suggesting incomplete mixing between proto-Earth and impactor material that formed the Moon. However, the formation of the Moon-sized clump depends sensitively on the spin of the impactor. To explore this, we develop a fast method to construct models of multi-layered, rotating bodies and their conversion into initial conditions for smoothed particle hydrodynamical (SPH) simulations. We use our publicly available code to calculate density and pressure profiles in hydrostatic equilibrium, then generate configurations of over a billion particles with SPH densities within $1\%$ of the desired values. This algorithm runs in a few minutes on a desktop computer, for $10^7$ particles, and allows direct control over the properties of the spinning body. In comparison, relaxation or spin-up techniques that take hours on a supercomputer before the structure of the rotating body is even known. Collisions that differ only in the impactor's initial spin reveal a wide variety of outcomes: a merger, a grazing hit-and-run, or the creation of an orbiting proto-Moon.
description: Submitted to MNRAS. 11 pages, 9 figures
The Role of Active Galactic Nuclei in the Quenching of Massive Galaxies in the SQuiGGLE Survey
Creators: name: Greene, Jenny E.
name: Setton, David
name: Bezanson, Rachel
name: Suess, Katherine A.
name: Kriek, Mariska
name: Spilker, Justin S.
name: Feldmann, Robert
name: Goulding, Andy D.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We study the incidence of nuclear activity in a large sample of massive post-starburst galaxies at z~0.7 selected from the Sloan Digital Sky Survey, and identify active galactic nuclei based on radio continuum and optical emission lines. Over our mass range of 10^10.6-10^11.5 Msun, the incidence of radio activity is weakly dependent on stellar mass and independent of stellar age, while radio luminosity depends strongly on stellar mass. Optical nuclear activity incidence depends most strongly on the Dn4000 line index, a proxy for stellar age, with an active fraction that is ~ten times higher in the youngest versus oldest post-starburst galaxies. Since a similar trend is seen between age and molecular gas fractions, we argue that, like in local galaxies, the age trend reflects a peak in available fueling rather than feedback from the central black hole on the surrounding galaxy.
description: 10 pages, 4 figures, posted after review by ApJL
Evaluating the Merger Rate of Binary Black Holes from Direct Captures and Third-Body Soft Interactions Using the Milky Way Globular Clusters
Creators: name: Kritos, Konstantinos
name: Cholis, Ilias
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The multitude of binary black hole coalescence detections in gravitational waves has renewed our interest on environments that can be the cradle of these mergers. In this work we study merger rates of binary black holes in globular clusters that are among the most dense stellar environments and a natural place for the creation of black hole binaries. To model these systems with all their variations we rely on the observational properties of the known Milky Way globular clusters. We consider direct capture events between black holes, as well as soft interactions of black hole binaries with stars as third bodies that accelerate the evolution of these binaries. We find that binary black holes from direct captures merge at an averaged rate of $0.3-5 \times 10^{-11}$ yr$^{-1}$ per cluster. Third body soft interactions are a much more prominent channel giving an averaged rate of $2-4 \times 10^{-10}$ yr$^{-1}$ per cluster. Those rates in globular clusters can lead to a cumulative merger rate of about 100 mergers per year up to redshift of 1, i.e. a significant fraction of the detectable in the near future binary black hole coalescence events. Further observations of cluster properties both in terms of their masses, profile properties, velocity dispersion of stars and their cosmological distribution, will allow us to better constrain the contribution of these environments to the detectable coalescence events rate.
description: 16 pages, 6 figures and 2 appendices
Field-induced magnetoelastic instabilities in antiferromagnetic molecular wheels
Creators: name: Waldmann, O.
name: Dobe, C.
name: Ochsenbein, S. T.
name: Güdel, H. U.
name: Sheikin, I.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: The magnetic torque of the antiferromagnetic molecular wheel CsFe8 was studied down to 50 mK and in fields up to 28 T. Below ca. 0.5 K phase transitions were observed at the field-induced level-crossings (LCs). Intermolecular magnetic interactions are very weak excluding an explanation in terms of field-induced magnetic ordering. A magneto-elastic coupling was considered. A generic model shows that the wheel structure is unconditionally unstable at the LCs, and the predicted torque curves explain the essential features of the data well.
description: 4 pages, 3 figures, REVTEX4, to appear in PRL
Kinematic modelling of clusters with Gaia: the Death Throes of the Hyades
Creators: name: Oh, Semyeong
name: Evans, N. Wyn
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The precision of the Gaia data offers a unique opportunity to study the internal velocity field of star clusters. We develop and validate a forward-modelling method for the internal motions of stars in a cluster. The model allows an anisotropic velocity dispersion matrix and linear velocity gradient describing rotation and shear, combines radial velocities available for a subset of stars, and accounts for contamination from background sources via a mixture model. We apply the method to Gaia DR2 data of the Hyades cluster and its tidal tails, dividing and comparing the kinematics of stars within and beyond 10 pc, which is roughly the tidal radius of the cluster. While the velocity dispersion for the cluster is nearly isotropic, the velocity ellipsoid for the tails is clearly elongated with the major axis pointing towards the Galactic centre. We find positive and negative expansion at $\approx 2σ$ significance in Galactic azimuthal and vertical direction for the cluster but no rotation. The tidal tails are stretching in a direction tilted from the Galactic centre while equally contracting as the cluster in Galactic vertical direction. The tails have a shear (A) of $16.90\pm 0.92$ m/s/pc and a vorticity (B) of $-6.48\pm1.15$ m/s/pc, values distinct from the local Oort constants.
description: 15 pages, 9 figures + appendix
Single Intermediate Vector Boson production in e+e- collisions at sqrt(s) = 183 - 209 GeV
Creators: name: The DELPHI Collaboration
name: Abdallah, J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The production of single charged and neutral intermediate vector bosons in e+e- collisions has been studied in the data collected by the DELPHI experiment at LEP at centre-of-mass energies between 183 and 209 GeV, corresponding to an integrated luminosity of about 640 pb^{-1}. The measured cross-sections for the reactions, determined in limited kinematic regions, are in agreement with the Standard Model predictions.
description: 30 pages, 8 figures
What Drives Galaxy Quenching? Resolving Molecular Gas and Star Formation in the Green Valley
Creators: name: Brownson, Simcha
name: Belfiore, Francesco
name: Maiolino, Roberto
name: Lin, Lihwai
name: Carniani, Stefano
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We study quenching in seven green valley galaxies on kpc scales by resolving their molecular gas content using \textsuperscript{12}CO(1-0) observations obtained with NOEMA and ALMA, and their star-formation rate using spatially resolved optical spectroscopy from the MaNGA survey. We perform radial stacking of both datasets to increase the sensitivity to molecular gas and star formation, thereby avoiding biases against strongly quenched regions. We find that both spatially resolved gas fraction ($\rm {f_{gas}}$) and star formation efficiency ($\rm {SFE}$) are responsible for quenching green valley galaxies at all radii: both quantities are suppressed with respect to typical star-forming regions. $\rm {f_{gas}}$ and $\rm {SFE}$ have roughly equal influence in quenching the outer disc. We are, however, unable to identify the dominant mechanism in the strongly quenched central regions. We find that $\rm {f_{gas}}$ is reduced by $\rm \sim 1~dex$ in the central regions, but the star formation rate is too low to be measured, leading to upper limits for the $\rm {SFE}$. Moving from the outer disc to central regions, the reduction in $\rm {f_{gas}}$ is driven by an increasing $\rm Σ_{\star}$ profile rather than a decreasing $\rm Σ_{H_{2}}$ profile. The reduced $\rm {f_{gas}}$ may therefore be caused by a decrease in the gas supply rather than molecular gas ejection mechanisms, such as winds driven by active galactic nuclei. We warn more generally that studies investigating $\rm {f_{gas}}$ may be deceiving in inferring the cause of quenching, particularly in the central (bulge-dominated) regions of galaxies.
description: 8 pages, 11 figures, Accepted for publication in MNRAS Letters
Ultrasensitive Photoresponse of Graphene Quantum Dot in the Coulomb Blockade Regime to THz Radiation
Creators: name: Riccardi, E.
name: Massabeau, S.
name: Valmorra, F.
name: Messelot, S.
name: Rosticher, M.
name: Tignon, J.
name: Watanabe, K.
name: Taniguchi, T.
name: Delbecq, M.
name: Dhillon, S.
name: Ferreira, R.
name: Balibar, S.
name: Kontos, T.
name: Mangeney, J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Graphene quantum dots (GQDs) have recently attracted considerable attention, with appealing properties for terahertz (THz) technology. This includes the demonstration of large thermal bolometric effects in GQDs when illuminated by THz radiation. However, the interaction of THz photons with GQDs in the Coulomb blockade regime - single electron transport regime - remains unexplored. Here, we demonstrate the ultrasensitive photoresponse to THz radiation (from <0.1 to 10 THz) of a hBN-encapsulated GQD in the Coulomb blockade regime at low temperature (170 mK). We show that THz radiation of $\sim$10 pW provides a photocurrent response in the nanoampere range, resulting from a renormalization of the chemical potential of the GQD of $\sim$0.15 meV. We attribute this photoresponse to an interfacial photogating effect. Furthermore, our analysis reveals the absence of thermal effects, opening new directions in the study of coherent quantum effects at THz frequencies in GQDs.
UV properties of early-type galaxies in the Virgo cluster
Creators: name: Boselli, A.
name: Cortese, L.
name: Deharveng, J. M.
name: Gavazzi, G.
name: Yi, K. S.
name: de Paz, A. Gil
name: Seibert, M.
name: Boissier, S.
name: Donas, J.
name: Lee, Y. -W.
name: Madore, B. F.
name: Martin, D. C.
name: Rich, R. M.
name: Sohn, Y. -J.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study the UV properties of a volume limited sample of early-type galaxies in the Virgo cluster combining new GALEX far- (1530 A) and near-ultraviolet (2310 A) data with spectro-photometric data available at other wavelengths. The sample includes 264 ellipticals, lenticulars and dwarfs spanning a large range in luminosity (M(B)
description: 5 pages, 2 figures, 1 table. Accepted for publication in Astrophysical Journal Letters
Continuum Limit of the Integrable sl(2/1) 3-\bar{3} Superspin Chain
Creators: name: Essler, Fabian H. L.
name: Frahm, Holger
name: Saleur, Hubert
Publisher: name: arXiv
Year: 2005
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: By a combination of analytical and numerical techniques, we analyze the continuum limit of the integrable 3\otimes\bar{3}\otimes 3\otimes\bar{3}... sl(2/1) superspin chain. We discover profoundly new features, including a continuous spectrum of conformal weights, whose numerical evidence is infinite degeneracies of the scaled gaps in the thermodynamic limit. This indicates that the corresponding conformal field theory has a non compact target space (even though our lattice model involves only finite dimensional representations). We argue that our results are compatible with this theory being the level k=1, `SU(2/1) WZW model' (whose precise definition requires some care). In doing so, we establish several new results for this model. With regard to potential applications to the spin quantum Hall effect, we conclude that the continuum limit of the 3\otimes\bar{3}\otimes 3\otimes\bar{3}... sl(2/1) integrable superspin chain is {\sl not} the same as (and is in fact very different from) the continuum limit of the corresponding chain with two-superspin interactions only, which is known to be a model for the spin quantum Hall effect. The study of possible RG flows between the two theories is left for further study.
description: 49 pages, 16 figures
Constraining the X-ray - Infrared spectral index of second-timescale flares from SGR1935+2154 with Palomar Gattini-IR
Creators: name: De, Kishalay
name: Ashley, Michael C. B.
name: Andreoni, Igor
name: Kasliwal, Mansi M.
name: Soria, Roberto
name: Srinivasaragavan, Gokul P.
name: Cai, Ce
name: Delacroix, Alexander
name: Greffe, Tim
name: Hale, David
name: Hankins, Matthew J.
name: Li, Chengkui
name: McKenna, Daniel
name: Moore, Anna M.
name: Ofek, Eran O.
name: Smith, Roger M.
name: Soon, Jamie
name: Travouillon, Tony
name: Zhang, Shuangnan
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The Galactic magnetar SGR1935+2154 has been reported to produce the first known example of a bright millisecond duration radio burst (FRB 200428) similar to the cosmological population of fast radio bursts (FRBs), bolstering the association of FRBs to active magnetars. The detection of a coincident bright X-ray burst has revealed the first observed multi-wavelength counterpart of a FRB. However, the search for similar emission at optical wavelengths has been hampered by the high inferred extinction on the line of sight. Here, we present results from the first search for second-timescale emission from the source at near-infrared wavelengths using the Palomar Gattini-IR observing system in J-band, made possible by a recently implemented detector read-out mode that allowed for short exposure times of 0.84 s with 99.9% observing efficiency. With a total observing time of 12 hours (47728 images) on source, we place median $3\,σ$ limits on the second-timescale emission of $< 20$ mJy (13.1 AB mag). We present non-detection limits from epochs of four simultaneous X-ray bursts detected by the Insight-{\it HXMT} and {\it NuSTAR} telescopes during our observing campaign. The limits translate to an extinction corrected fluence limit of $< 125$ Jy ms for an estimated extinction of $A_J = 2.0$ mag. These limits provide the most stringent constraints to date on the fluence of flares at frequencies of $\sim 10^{14}$ Hz, and constrain the ratio of the near-infrared (NIR) fluence to that of coincident X-ray bursts to $R_{\rm NIR} < 2.5 \times 10^{-2}$. Our observations were sensitive enough to easily detect a near-infrared counterpart of FRB 200428 if the NIR emission falls on the same power law as that observed across its radio to X-ray spectrum. The non-detection of NIR emission around the coincident X-ray bursts constrains the fluence index of the brightest burst to be steeper than $0.35$.
description: 10 pages, 4 figures, submitted to ApJL. Comments welcome
IMPROVING IRRIGATION WATER ALLOCATION EFFICIENCY USING ALTERNATIVE POLICY OPTIONS IN EGYPT
Creators: name: He, Lixia
name: Tyner, Wallace E.
name: Siam, Gamal
name: He, Lixia
name: Tyner, Wallace E.
name: Siam, Gamal
Publisher: name: Unknown
Year: 2004
Subjects: Resource /Energy Economics and Policy

description: This study provides an empirical perspective on alternative irrigation policies for allocating limited water to agricultural production in Egypt. Positive mathematical programming is used for model calibration. Three policy options for Egypt are tested: water pricing, water complementary input factor taxes, and output taxes. The results of the research show that: 1) water pricing needs to be much higher than the recovery cost in order to be effective in limiting irrigation water use; 2) at a higher tax rate, fertilizer and energy taxes are effective in reducing the irrigation water demand while maintaining adequate welfare levels; 3) a pesticide tax is less effective than fertilizer or energy taxes; and 4) an output tax on sugar cane and rice would decrease irrigation water demand substantially while allocating land to other crops which are less water intensive and have higher market values.
A PORTFOLIO OF NUTRIENTS: SOIL AND SUSTAINABILITY
Creators: name: Bond, Craig A.
name: Farzin, Y. Hossein
name: Bond, Craig A.
name: Farzin, Y. Hossein
Publisher: name: Unknown
Year: 2004
Subjects: Farm Management

description: This paper develops a basic dynamic economic model that can be used for theoretical and numerical analysis of optimal soil management practices. A dynamic biophysical/economic optimal control model is developed in a multi-disciplinary framework, treating soil as a multi-pool portfolio of a particular limiting mobile nutrient (e.g. nitrogen). This specification allows for fertilizer to directly enter the active pool, while tillage initially affects the decadal pool, reflecting the realities of agricultural production. We examine the properties of the steady-state and the time paths of the optimal solutions. In addition, alternative sustainability criteria of farm-level agricultural practices are presented, and the optimal solution of the problem is evaluated to determine if it meets any or all of the definitions of sustainability.
Lessons in Failure: The Rice Growers Association Cooperative
Creators: name: Keeling Bond, Jennifer J.
name: Carter, Colin A.
name: Keeling Bond, Jennifer J.
name: Carter, Colin A.
Publisher: name: Unknown
Year: 2004
Subjects: Agribusiness

description: This empirical study investigates a large California cooperative's closure and identifies lessons learned that might be useful to other cooperatives. It was found that the cooperative's directors failed to effectively supervise management. In turn, management fell short of expectations to fully evaluate complex business decisions.
On the force-free magnetosphere of aligned rotator
Creators: name: Timokhin, A. N.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We investigate in details properties of stationary force-free magnetosphere of aligned rotator assuming the last closed field line lying in equatorial plane at large distances from pulsar. The pulsar equations is solved numerically using multigrid code with high numerical resolution, physical properties of the magnetosphere are obtained with high accuracy. We found a set of solutions with different sizes of the closed magnetic field line zone and verify the applicability of the force-free approximation. We discuss the role of electron-positron cascades in supporting of the force-free magnetosphere and argue that the closed field line zone should grow with time slower than the light cylinder. This yield the pulsar breaking index less than 3. It is shown, that models of aligned rotator magnetosphere with widely accepted configuration of magnetic field, like one considered in this paper, have serious difficulties. We discuss solutions of this problem and argue that in any case pulsar energy losses should evolve with time differently than predicted by the magnetodipolar formula.
description: 19 pages, 14 figures; accepted for publication in MNRAS. Discussion part of the paper is rewritten, several minor changes in the main text of the article; several references added and typos corrected
BASIS RISK FOR RICE
Creators: name: Lord, Yoshie Saito
name: Turner, Steven C.
name: Lord, Yoshie Saito
name: Turner, Steven C.
Publisher: name: Unknown
Year: 1998
Subjects: Financial Economics
Risk and Uncertainty

description: The objective of this paper is to develop a cross hedging model for rice that minimizes basis risk and accounts for the existence of the nonstationary nature of basis. Basis is treated as an endogenous variable and model for basis risk are developed.
FARM-HOUSEHOLD ANALYSIS OF POLICIES AFFECTING PEANUT PRODUCTION IN SENEGAL
Creators: name: Akobundu, Eberechukwu
name: Norton, George W.
name: Gaye, Matar
name: Bertelsen, Michael
name: Akobundu, Eberechukwu
name: Norton, George W.
name: Gaye, Matar
name: Bertelsen, Michael
Publisher: name: Unknown
Year: 1998
Subjects: Agricultural and Food Policy
Demand and Price Analysis

description: A farm-level survey of 150 households was conducted in the peanut basin of Senegal, and a profit function system estimated, for the purpose of analyzing the effects of policies affecting the peanut sector. Producer price of peanuts has relatively little effect on production, but producer price of millet influences peanut seed demand.