Extended Benefit-Cost Analysis of Management Alternatives: Pagbilao Mangrove Forest

Mangroves are important fish hatcheries. It prevents coastal erosion and provides timber resources. However, it limits land access to coastal and fishpond areas. This article presents a cost-benefit analysis on mangrove preservation.natural resources and environment, environmental issues

Subhalo accretion through filaments

We track subhalo orbits of galaxy and group sized halos in cosmological simulations. We identify filamentary structures around halos and we use these to define a sample of subhalos accreted from filaments as well as a control sample of subhalos accreted from other directions. We use these samples to study differences in satellite orbits produced by filamentary accretion. Our results depend on host halo mass. We find that for low masses, subhalos accreted from filaments show $\sim10\%$ shorter lifetimes compared to the control sample, they show a tendency towards more radial orbits, reach halo central regions earlier, and are more likely to merge with the host. For higher mass halos this lifetime difference dissipates and even reverses for cluster sized halos. This behavior appears to be connected to the fact that more massive hosts are connected to stronger filaments with higher velocity coherence and density, with slightly more radial subhalo orbits. Because subhalos tend to follow the coherent flow of the filament, it is possible that such thick filaments are enough to shield the subhalo from the effect of dynamical friction at least during their first infall. We also identify subhalo pairs/clumps which merge with one another after accretion. They survive as a clump for only a very short time, which is even shorter for higher subhalo masses, suggesting that the Magellanic Clouds and other Local group satellite associations, may have entered the MW virial radius very recently and probably are in their first infall. Filaments boost the accretion of satellite associations.Comment: Accepted for publication in Ap

Bioeconomic Analysis of Management Options for Tropical Fisheries Using a Bicriteria Programming Model

A possible approach to the management of the multispecies multi-gear fishery in a developing country was explored. The small petagics fishery in central Philippines was analyzed in three stages. A dynamic pool model represented the dynamics of the stocks. The optimal allocation of catch across competing fleets was modeled having regard for the pursuit of two conflicting objectives, maximizing employment and fishing profits. Alternative management schemes were then explored. On the basis of the criteria used, the optimal fleet size was a small fraction of the existing fleet size. Calculation of increased target yields through regulation of fishing mortality and selectivity showed that the increase in optimal feet size would be moderate because the current level of exploitation is close to that producing the maximum yield-per-recruit. An agenda for exploration of further management alternatives appropriate to the social and economic policy objectives of a developing country is discussed.bioeconomics, Philippines, small pelagics, multicriteria decision making, fishery economics, fishery management, tropical fisheries, Environmental Economics and Policy, Production Economics,

Cosmic web alignments with the shape, angular momentum and peculiar velocities of dark matter haloes

We study the alignment of dark matter haloes with the cosmic web characterized by the tidal and velocity shear fields. We focus on the alignment of their shape, angular momentum and peculiar velocities. We use a cosmological N-body simulation that allows to study dark matter halos spanning almost five orders of magnitude in mass ($10^{9}$-$10^{14}$) $h^{-1}$$M_{\odot}$ and spatial scales of $(0.5$-$1.0)$ $h^{-1}$ Mpc to define the cosmic web. We find that the halo shape presents the strongest alignment along the smallest tidal eigenvector, e.g. along filaments and walls, with a signal that gets stronger as the halo mass increases. In the case of the velocity shear field only massive halos $>10^{12}$ $h^{-1}$$M_{\odot}$ tend to have their shapes aligned along the largest tidal eigenvector; that is, perpendicular to filaments and walls. For the angular momentum we find alignment signals only for halos more massive than $10^{12}$ $h^{-1}$$M_{\odot}$ both in the tidal and velocity shear webs where the preferences are for it to be parallel to the middle eigenvector; perpendicular to filaments and parallel to walls. Finally, the peculiar velocities show a strong alignment along the smallest tidal eigenvector for all halo masses; halos move along filaments and walls. In the velocity shear the same alignment is present but weaker and only for haloes less massive than $10^{12}$ $h^{-1}$$M_{\odot}$. Our results clearly show that the two different algorithms we used to define the cosmic web describe different physical aspects of non-linear collapse and should be used in a complementary way to understand the effect of the cosmic web on galaxy evolution.Comment: 14 pages, 5 figures, MNRAS accepte

Water Quality and Fisheries Issues Accompanying Population Growth in the Philippines

Fishing should be an employment of last resort. This article argues why through analysis of water quality and fisheries in conjunction to the role of human population and overfishing on yields.fisheries sector, water sector, population and family relation

MEXICAN-U.S. FRESH TOMATO TRADE: AN ANALYSIS OF VOLUME, PRICES AND TRANSACTION COSTS

Tomato trade between the U.S. and Mexico has grown significantly during the past decade. Although the tariff reductions accorded under NAFTA may explain part of his increase, there are other supply and demand factors that affect trade flows. This study develops a U.S.-Mexico tomato trade model, with special focus on the interdependence between trading costs and the volume of Mexican imports. As expected, the exchange rate is a significant determinant of trading costs, but the level of tariffs was insignificant in both the trading and tomato supply equations. The shipping point price level and volume of imports also appear to affect these costs. For the import supply and demand models, there appears to be a significant share of imports that rely on previous levels of imports, rather than the expected economic factors (prices, income, and producer price index). We conclude that the structure and performance of the tomato trading market is changing, and may be more influential than tariff reductions in explaining increased trade flows.Crop Production/Industries, International Relations/Trade,

Resonance in Asymmetric Warped Geometry

We study the spectrum of an asymmetric warped braneworld model with different AdS curvatures on either side of the brane. In addition to the RS-like modes we find a resonance state. Its mass is proportional to the geometric mean of the two AdS curvature scales, while the difference between them determines the strength of the resonance peak. There is a complementarity between the RS zero-mode and the resonance: making the asymmetry stronger weakens the zero-mode but strengthens the resonance, and vice versa. We calculate numerically the braneworld gravitational potential and discuss the holographic correspondence for the asymmetric model.Comment: 17 pages, 9 figures; v2 references with comments added; v3 two references added, JHEP versio