Policy determinants of growth : survey of theory and evidence

This paper explores the broad themes of the literature on economic growth. It makesthe following two broad conclusions. First, it notes that the efficiency of investment is as important as the level of investment in determining growth performance. Secondly, it states that keeping to a minimum the distortion of resource allocation by government policies makes saving and investment more efficient and promotes long-term economic growth. Policies that contribute to the efficiency of investment and that lower distortions in resource allocation will thus generally encourage growth. Policies that promote investment, liberalize trade restrictions and remove distortions in financial markets are likely to raise a country's long-run rate of growth. It is noted, however, that more research is needed to formulate structural models of growth that give clear guidance on the effect of various policy measures.Achieving Shared Growth,Economic Theory&Research,Environmental Economics&Policies,Economic Growth,Governance Indicators

Star Formation Quenching Timescale of Central Galaxies in a Hierarchical Universe

Central galaxies make up the majority of the galaxy population, including the majority of the quiescent population at $\mathcal{M}_* > 10^{10}\mathrm{M}_\odot$. Thus, the mechanism(s) responsible for quenching central galaxies plays a crucial role in galaxy evolution as whole. We combine a high resolution cosmological $N$-body simulation with observed evolutionary trends of the "star formation main sequence," quiescent fraction, and stellar mass function at $z < 1$ to construct a model that statistically tracks the star formation histories and quenching of central galaxies. Comparing this model to the distribution of central galaxy star formation rates in a group catalog of the SDSS Data Release 7, we constrain the timescales over which physical processes cease star formation in central galaxies. Over the stellar mass range $10^{9.5}$ to $10^{11} \mathrm{M}_\odot$ we infer quenching e-folding times that span $1.5$ to $0.5\; \mathrm{Gyr}$ with more massive central galaxies quenching faster. For $\mathcal{M}_* = 10^{10.5}\mathrm{M}_\odot$, this implies a total migration time of $\sim 4~\mathrm{Gyrs}$ from the star formation main sequence to quiescence. Compared to satellites, central galaxies take $\sim 2~\mathrm{Gyrs}$ longer to quench their star formation, suggesting that different mechanisms are responsible for quenching centrals versus satellites. Finally, the central galaxy quenching timescale we infer provides key constraints for proposed star formation quenching mechanisms. Our timescale is generally consistent with gas depletion timescales predicted by quenching through strangulation. However, the exact physical mechanism(s) responsible for this still remain unclear.Comment: 16 pages, 11 figure

Public finance, trade, and development : what have we learned?

Interdependence of trade and public finance policy are important considerations in designing macroeconomic policy, public revenue policy, and public expenditure policy. A competitive real exchange rate, improved trade performance, and trade liberalization are all built on the base of sound fiscal management. Trade policies and trade liberalization may, however have a negative effect on fiscal balances, which must be considered and compensated for. Improving competitiveness and reducing protection is likely to involve reform of both trade tariffs and domestic taxation. Greater reliance on efficiently designed user charges will also help make a country more competitive internationally. Correct priorities should be set for public expenditures - whether they are rising or falling - to ensure that they are supportive of trade and of tradeable goods production.Public Sector Economics&Finance,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Banks&Banking Reform,Environmental Economics&Policies,Economic Theory&Research

Evaluation of RI Middle School Science Kits in Regards to the RI Grade Span Expectations

Evaluation of Rhode Island Middle School Science Kits in Regards to Rhode Island Grade Span Expectations Melissa Wetzel Faculty Sponsor: Jay Fogleman, Education The Rhode Island Department of Education provides a set of Grade Span Expectations (GSEs) that outline major ideas in science, including physical, life, and earth and space science. Students in Rhode Island schools are expected to be able to demonstrate understanding of each GSE in order to graduate high school with proficiency in science. Educators do not always have the time to “unpack” the GSEs that line up with the grade level they teach. Unpacking a GSE refers to determining what prior knowledge students should possess, what misconceptions students may have, and what students need to be able to do in order to demonstrate understanding of the material the particular GSE covers. Rhode Island middle school science teachers are provided with kits that contain all the materials needed for a particular unit. These kits have lessons designed to engage students in mostly teacher directed activities that address each GSE for that particular grade level. However, many kits do not address the misconceptions students may have about a certain topic or provide enough background information about the material being taught. Therefore teachers must supplement these kits with filler lessons that address these issues. Experienced teachers can do this easily and almost naturally, but relatively new science teachers may struggle with deciding what sorts of instruction to intertwine within the lessons of the kits. I have taken a common middle school science kit entitled “Ecosystems” and unpacked each of the five separate GSEs aligned with it to determine what information that students should have is missing from the kits. The second portion of my project examines the effectiveness of the Ecosystems kit in preparing students for the New England Common Assessment Program (NECAP) exam. This exam tests thirteen progressive levels of inquiry and I have found that the Ecosystems kit is lacking in regards to exposing students to a wide range of inquiry-based activities to adequately prepare them for this particular assessment. I have compiled lessons that can be added to the Ecosystems kit to more effectively address each of the thirteen levels of inquiry. The products and results of this project will be displayed on the Rhode Island Science Teacher wikispace. My hope is that this work will be useful to both current and incoming science teachers

Environmental Studies at Newton Lake, Illinois: Tasks 4, 5, and 7

ID: 8658; issued March 1, 1991INHS Technical Report prepared for Marathon Oil Compan

Hydrological connectivity inferred from diatom transport through the riparian-stream system

Funding for this research was provided by the Luxembourg National Research Fund (FNR) in the framework of the BIGSTREAM (C09/SR/14), ECSTREAM (C12/SR/40/8854) and CAOS (INTER/DFG/11/01) projects. We are most grateful to the Administration des Services Techniques de l’Agriculture (ASTA) for providing meteorological data. We also acknowledge Delphine Collard for technical assistance in diatom sample treatment and preparation, François Barnich for the water chemistry analyses, and Jean-François Iffly, Christophe Hissler, Jérôme Juilleret, Laurent Gourdol and Julian Klaus for their constructive comments on the project and technical assistance in the field.Peer reviewedPublisher PD

Synchronization in the presence of time delays and inertia: Stability criteria

Linear stability of synchronized states in networks of delay-coupled oscillators depends on the type of interaction, the network, and oscillator properties. For inert oscillator response, found ubiquitously from biology to engineering, states with time-dependent frequencies can arise. These generate side bands in the frequency spectrum or lead to chaotic dynamics. The time delay introduces multistability of synchronized states and an exponential term in the characteristic equation. Stability analysis using the resulting transcendental characteristic equation is a difficult task and is usually carried out numerically. We derive criteria and conditions that enable fast and robust analytical linear stability analysis based on the system parameters. These apply to arbitrary network topologies, identical oscillators, and delays

Galaxy evolution in groups and clusters: satellite star formation histories and quenching timescales in a hierarchical Universe

Satellite galaxies in groups and clusters are more likely to have low star formation rates (SFR) and lie on the red-sequence than central (field) galaxies. Using galaxy group/cluster catalogs from SDSS DR7, together with a cosmological N-body simulation to track satellite orbits, we examine the star formation histories and quenching timescales of satellites of M_star > 5 x 10^9 M_sun at z=0. We first explore satellite infall histories: group preprocessing and ejected orbits are critical aspects of satellite evolution, and properly accounting for these, satellite infall typically occurred at z~0.5, or ~5 Gyr ago. To obtain accurate initial conditions for the SFRs of satellites at their time of first infall, we construct an empirical parametrization for the evolution of central galaxy SFRs and quiescent fractions. With this, we constrain the importance and efficiency of satellite quenching as a function of satellite and host halo mass, finding that satellite quenching is the dominant process for building up all quiescent galaxies at M_star < 10^10 M_sun. We then constrain satellite star formation histories, finding a 'delayed-then-rapid' quenching scenario: satellite SFRs evolve unaffected for 2-4 Gyr after infall, after which star formation quenches rapidly, with an e-folding time of < 0.8 Gyr. These quenching timescales are shorter for more massive satellites but do not depend on host halo mass: the observed increase in satellite quiescent fraction with halo mass arises simply because of satellites quenching in a lower mass group prior to infall (group preprocessing), which is responsible for up to half of quenched satellites in massive clusters. Because of the long time delay before quenching starts, satellites experience significant stellar mass growth after infall, nearly identical to central galaxies. This fact provides key physical insight into the subhalo abundance matching method.Comment: 25 pages, 13 figures. Accepted for publication in MNRAS, matches published versio