A Computerized Mapping System for Forest Resource Management Planning

Large volumes of inventory data are collected and analyzed with the idea of developing resource management schemes for the future. Unless this inventory information is easily accessible, is of the type needed to make management decisions in accordance with current policy, and has a readily available updating system, the entire management plan often becomes a seldom, if ever, used document. This study deals with the application of several inventory collection and display techniques to assist in making rapid and accurate resource management decisions on a continuing basis. The objective of the study is to develop a comprehensive forest resource management plan for the U.S. Department of the Army, Corps of Engineers Philpott Reservoir Complex located on the Piedmont geomorphic province near Bassett, Virginia. Specifically the management plan is focused on increasing the value of the lands primarily for recreation and wildlife with the inclusion of other compatible uses where appropriate. A healthy and vigorous forest system is required in order to withstand the stresses imposed by man and nature. Therefore, a forest complex capable of supporting the planned recreation, wildlife, scenic attractiveness and other project uses must be maintained so as to yield the maximum social benefit and insure the ecologic integrity of the system

Vertebral elemental markers in elasmobranchs : potential for reconstructing environmental history and population structure

Differences in the chemical composition of calcified structures can be used to reveal natal origins, connectivity, metapopulation structure, and reconstruct the environmental history or movement patterns of many marine organisms. Sharks, skates, and rays (elasmobranchs) lack the calcified structures, known as otoliths, that are typically used for geochemical studies of dispersal and natal origin in fishes. If the incorporation of elements into shark and ray vertebrae is related to environmental conditions, the geochemical composition of cartilaginous vertebrae may also serve as natural tags and records of environmental history in elasmobranch populations. I used complementary laboratory and field studies to address several key assumptions regarding the incorporation of elements in elasmobranch vertebrae, providing the first detailed studies to assess relationships between water and vertebral chemical composition and the spatial and temporal variation of vertebral elemental signatures in this subclass of fishes. To validate the uptake and incorporation of elements from water to vertebrae, I conducted two laboratory studies using round stingrays, Urobatis halleri, as a model species. First, I examined the effects of temperature (16°, 18°, 24° C) on vertebral elemental incorporation (Li/Ca, Mg/Ca, Mn/Ca, Zn/Ca, Sr/Ca, Ba/Ca) and found that temperature had strong, negative effects on the uptake (measured as a partition coefficient, D[subscript Element]) of magnesium and Ba and positively influenced manganese incorporation. Second, I tested the relationship between water and vertebral elemental composition by manipulating dissolved barium (Ba) concentrations (1x, 3x, 6x ambient concentrations) and found significant differences among rays from each treament. I also evaluated the influence of natural variation in somatic growth and vertebral precipitation rates on elemental incorporation. Finally, I examined the accuracy of classifying individuals to known environmental histories (temperature and barium treatments) using vertebral elemental composition. There were no significant relationships between elemental incorporation and somatic growth or vertebral precipitation rates for any elements with the exception of Zn. Relationships between somatic growth rate and D[subscript Zn] were, however, inconsistent and inconclusive. Elemental variation of vertebrae reliably distinguished U. halleri based on temperature (85%) and [Ba] (96%) history. These results support the assumption that vertebral elemental composition reflects the environmental conditions during deposition and validates the use of vertebral elemental signatures as natural markers in an elasmobranch. To evaluate the utility of vertebral geochemistry as intrinsic markers of natal origin, I collected vertebrae of young-of-the-year scalloped hammerhead sharks (Sphyrna lewini) from artisanal fishery landings at six sites along the Pacific coast of Mexico and Costa Rica between 2007-2009. A total of 386 vertebrae were used to assess patterns of spatial and temporal variation in elemental composition using laser ablation-inductively coupled plasma mass spectrometry. A protracted pupping period was confirmed for S. lewini, with newborn pups being recorded from May through mid-October. Natal elemental signatures detected in the vertebrae of the sharks varied significantly among sites and could be used to identify source populations. All element-to-calcium ratios included in these analyses (Li/Ca, Mg/Ca, V/Ca, Cr/Ca, Mn/Ca, Rb/Ca, Sr/Ca, Ba/Ca, Pb/Ca) were useful for the discerning natal origins of sharks; however, Ba, Sr, Mn, and Mg ratios most consistently generated the greatest discriminatory power based on step-wise discriminant function analyses. Classification accuracy to putative nursery areas (natal signature) and location of capture (edge signature) based on step-wise discriminant function analysis ranged from low (30-60%) to high (80-100%) depending on the degree of spatial and temporal resolution by which the data were filtered for analysis (e.g. pooled across months, early season, late season). All classification accuracies exceeded chance expectations and assignment to putative nursery areas and sites of capture were accomplished with up to 100% accuracy in several models. I found significant intra-annual differences in natal elemental signatures within the three primary study sites, which likely contributed to the low assignment accuracies when data were grouped across months of collection. Significant differences in natal elemental signatures were also detected across years. However, pair-wise analyses revealed that site-specific inter-annual variation was driven by differences associated with samples collected in 2009. Natal elemental signatures were similar between 2007 and 2009, indicating some consistency in site-specific vertebral chemistry across years. These results confirmed that vertebral elemental signatures can be applied to distinguish individuals across small (5s km), moderate (100s km), and large spatial scales (>1000 km). The potential for intra-annual variation in natal signatures within a year-class highlights the importance of cohort-specific analyses and the development of a spatial atlas of natal vertebral elemental signatures for studies of natal origin and population connectivity. The findings of my laboratory validation experiments and field study establish that geochemical analyses of vertebrae can provide reliable information on the spatial ecology and environmental history of shark and ray populations. The use of elemental signatures offers a new approach for the study and conservation of this historically vulnerable group of fishes

The magnetic Bp star 36 Lyncis, I. Magnetic and photospheric properties

This paper reports the photospheric, magnetic and circumstellar gas characteristics of the magnetic B8p star 36 Lyncis (HD 79158). Using archival data and new polarised and unpolarised high-resolution spectra, we redetermine the basic physical properties, the rotational period and the geometry of the magnetic field, and the photospheric abundances of various elements.}{Based on magnetic and spectroscopic measurements, we infer an improved rotational period of $3.83475\pm 0.00002$ d. We determine a current epoch of the longitudinal magnetic field positive extremum (HJD 2452246.033), and provide constraints on the geometry of the dipole magnetic field (i\geq 56\degr, $3210 {\rm G}\leq B_{\rm d}\leq 3930$ G, $\beta$ unconstrained). We redetermine the effective temperature and surface gravity using the optical and UV energy distributions, optical photometry and Balmer line profiles ($T_{\rm eff}=13300\pm 300$ K, $\log g=3.7-4.2$), and based on the Hipparcos parallax we redetermine the luminosity, mass, radius and true rotational speed ($L=2.54\pm 0.16 L_\odot, M=4.0\pm 0.2 M_\odot, R=3.4\pm 0.7 R_\odot, v_{\rm eq}=45-61.5$ \kms). We measure photospheric abundances for 21 elements using optical and UV spectra, and constrain the presence of vertical stratification of these elements. We perform preliminary Doppler Imaging of the surface distribution of Fe, finding that Fe is distributed in a patchy belt near the rotational equator. Most remarkably, we confirm strong variations of the H$\alpha$ line core which we interpret as due to occultations of the star by magnetically-confined circumstellar gas.Comment: Accepted by Astronomy and Astrophysic

The magnetic Bp star 36 Lyncis, II. A spectroscopic analysis of its co-rotating disk

We report on the physical properties of the disk-like structure of B8 IIIp star 36 Lyncis from line syntheses of phase-resolved, high resolution spectra obtained from the IUE archives and from newly obtained ground-based H$\alpha$ spectra. This disk is highly inclined to the rotational axis and betrays its existence every half rotation cycle as one of two opposing sectors pass in front of the star. Although the disk absorption spectrum is at least ten times too weak to be visible in optical iron lines during these occultations, its properties can be readily examined in a large number of UV "iron curtain" lines because of their higher opacities. The analysis of the variations of the UV resonance lines brings out some interesting details about the radiative properties of the disks: (1) they are optically thick in the C IV and Si IV doublets, (2) the range of excitation of the UV resonance lines is larger at the primary occultation ($\phi$ = 0.00) than at the secondary one, and (3) the {\bf relative strengths of the absorption peaks} for the two occultations varies substantially from line to line. We have modeled the absorptions of the UV C IV resonance and H$\alpha$ absorptions by means of a simulated disk with opaque and translucent components. Our simulations suggest that a gap separates the star and the inner edge of the disk. The disk extends radially out to $\geq$10 R$_{*}$. The disk scale height perpendicular to the plane is $\approx$1R$_{*}$. However, the sector causing the primary occultation is about four times thicker than the opposite sector. The C IV scattering region extends to a larger height than the H$\alpha$ region does, probably because it results from shock heating far from the cooler disk plane.Comment: Accepted by Astronomy and Astrophysic

The status of shark and ray fishery resources in the Gulf of California: applied research to improve management and conservation

Seasonal surveys were conducted during 1998–1999 in Baja California, Baja California Sur, Sonora, and Sinaloa to determine the extent and activities of artisanal elasmobranch fisheries in the Gulf of California. One hundred and forty–seven fishing sites, or camps, were documented, the majority of which (n = 83) were located in Baja California Sur. Among camps with adequate fisheries information, the great majority (85.7%) targeted elasmobranchs during some part of the year. Most small, demersal sharks and rays were landed in mixed species fisheries that also targeted demersal teleosts, but large sharks were usually targeted in directed drift gillnet or, to a lesser extent, surface longline fisheries. Artisanal fishermen were highly opportunistic, and temporally switched targets depending on the local productivity of teleost, invertebrate, and elasmobranch fishery resources. Major fisheries for small sharks ( 1.5 m, “tiburón”) were minor components of artisanal elasmobranch fisheries in Sonora and Sinaloa, but were commonly targeted during summer and early autumn in Baja California and Baja California Sur. The pelagic thresher shark (Alopias pelagicus) and silky shark (Carcharhinus falciformis) were most commonly landed in Baja California, whereas a diverse assemblage of pelagic and large coastal sharks was noted among Baja California Sur landings. Rays dominated summer landings in Baja California and Sinaloa, when elevated catch rates of the shovelnose guitarfish (Rhinobatos productus, 13.2 individuals/vessel/trip) and golden cownose ray (Rhinoptera steindachneri, 11.1 individuals/vesse/trip) primarily supported the respective fisheries. The Sonoran artisanal elasmobranch fishery was the most expansive recorded during this study, and rays (especially R. productus) dominated spring and summer landings in this state. Seasonal catch rates of small demersal sharks and rays were considerably greater in Sonora than in other surveyed states. Many tiburón populations (e.g., C. leucas, C. limbatus, C. obscurus, Galeocerdo cuvier) have likely been overfished, possibly shifting effort towards coastal populations of cazón and rays. Management recommendations, including conducting demographic analyses using available life history data, determining and protecting nursery areas, and enacting seasonal closures in areas of elasmobranch aggregation (e.g., reproduction, feeding), are proposed. Without effective, enforceable management to sustain or rebuild targeted elasmobranch populations in the Gulf of California, collapse of many fisheries is a likely outcome. (PDF contains 243 pages

Activities and Catch Composition of Artisanal Elasmobranch Fishing Sites on the Eastern Coast of Baja California Sur, Mexico

Eighty–three artisanal fishing sites were documented from seasonal surveys of the Gulf of California coast of Baja California Sur conducted during El Nin˜o (1998) and La Nin˜a (1999) conditions. The direct targeting of elasmobranchs was observed at approximately half (48.2%) of these sites. Sharks numerically dominated sampled landings (71.3%, n 5 693), and exceeded those of batoids during all seasons. Among the primary species in observed landings were the scalloped hammerhead, Sphyrna lewini (15.2%, n 5148), Pacific angel shark, Squatina californica (11.6%, n 5 113), blue shark, Prionace glauca (11.4%, n 5 111), Pacific sharpnose shark, Rhizoprionodon longurio (11.3%, n 5 110), and pygmy devil ray, Mobula munkiana (8.6%, n 5 84)

Template coexistence in prebiotic vesicle models

The coexistence of distinct templates is a common feature of the diverse proposals advanced to resolve the information crisis of prebiotic evolution. However, achieving robust template coexistence turned out to be such a difficult demand that only a class of models, the so-called package models, seems to have met it so far. Here we apply Wright's Island formulation of group selection to study the conditions for the coexistence of two distinct template types confined in packages (vesicles) of finite capacity. In particular, we show how selection acting at the level of the vesicles can neutralize the pressures towards the fixation of any one of the template types (random drift) and of the type with higher replication rate (deterministic competition). We give emphasis to the role of the distinct generation times of templates and vesicles as yet another obstacle to coexistence.Comment: 7 pages, 8 figure

Revisiting the Rigidly Rotating Magnetosphere model for sigma Ori E. I. Observations and Data Analysis

We have obtained 18 new high-resolution spectropolarimetric observations of the B2Vp star sigma Ori E with both the Narval and ESPaDOnS spectropolarimeters. The aim of these observations is to test, with modern data, the assumptions of the Rigidly Rotating Magnetosphere (RRM) model of Townsend & Owocki (2005), applied to the specific case of sigma Ori E by Townsend et al. (2005). This model includes a substantially offset dipole magnetic field configuration, and approximately reproduces previous observational variations in longitudinal field strength, photometric brightness, and Halpha emission. We analyze new spectroscopy, including H I, He I, C II, Si III and Fe III lines, confirming the diversity of variability in photospheric lines, as well as the double S-wave variation of circumstellar hydrogen. Using the multiline analysis method of Least-Squares Deconvolution (LSD), new, more precise longitudinal magnetic field measurements reveal a substantial variance between the shapes of the observed and RRM model time-varying field. The phase resolved Stokes V profiles of He I 5876 A and 6678 A lines are fit poorly by synthetic profiles computed from the magnetic topology assumed by Townsend et al. (2005). These results challenge the offset dipole field configuration assumed in the application of the RRM model to sigma Ori E, and indicate that future models of its magnetic field should also include complex, higher-order components.Comment: 13 pages, 8 figures. Accepted for publication in MNRA

Single cell fluorescence imaging of glycan uptake by intestinal bacteria

Microbes in the intestines of mammals degrade dietary glycans for energy and growth. The pathways required for polysaccharide utilization are functionally diverse; moreover, they are unequally dispersed between bacterial genomes. Hence, assigning metabolic phenotypes to genotypes remains a challenge in microbiome research. Here we demonstrate that glycan uptake in gut bacteria can be visualized with fluorescent glycan conjugates (FGCs) using epifluorescence microscopy. Yeast α-mannan and rhamnogalacturonan-II, two structurally distinct glycans from the cell walls of yeast and plants, respectively, were fluorescently labeled and fed to Bacteroides thetaiotaomicron VPI-5482. Wild-type cells rapidly consumed the FGCs and became fluorescent; whereas, strains that had deleted pathways for glycan degradation and transport were non-fluorescent. Uptake of FGCs, therefore, is direct evidence of genetic function and provides a direct method to assess specific glycan metabolism in intestinal bacteria at the single cell level.</p

No detection of large-scale magnetic fields at the surfaces of Am and HgMn stars

We investigate the magnetic dichotomy between Ap/Bp and other A-type stars by carrying out a deep spectropolarimetric study of Am and HgMn stars. Using the NARVAL spectropolarimeter at the Telescope Bernard Lyot (Observatoire du Pic du Midi, France), we obtained high-resolution circular polarisation spectroscopy of 12 Am stars and 3 HgMn stars. Using Least Squares Deconvolution (LSD), no magnetic field is detected in any of the 15 observed stars. Uncertaintiies as low as 0.3 G (respectively 1 G) have been reached for surface-averaged longitudinal magnetic field measurements for Am (respectively HgMn) stars. Associated with the results obtained previously for Ap/Bp stars, our study confirms the existence of a magnetic dichotomy among A-type stars. Our data demonstrate that there is at least one order of magnitude difference in field strength between Zeeman detected stars (Ap/Bp stars) and non Zeeman detected stars (Am and HgMn stars). This result confirms that the spectroscopically-defined Ap/Bp stars are the only A-type stars harbouring detectable large-scale surface magnetic fields.Comment: 6 pages, 3 figures, accepted for publication in A&