882 research outputs found

    The use of remote sensing in solving Florida's geological and coastal engineering problems

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    LANDSAT imagery and NASA high altitude color infrared (CIR) photography were used to select suitable sites for sanitary landfill in Volusia County, Florida and to develop techniques for preventing sand deposits in the Clearwater inlet. Activities described include the acquisition of imagery, its analysis by the IMAGE 100 system, conventional photointerpretation, evaluation of existing data sources (vegetation, soil, and ground water maps), site investigations for ground truth, and preparation of displays for reports

    The use of geoscience methods for aquatic forensic searches

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    There have been few publications on the forensic search of water and fewer still on the use of geoforensic techniques when exploring aqueous environments. Here we consider what the nature of the aqueous environment is, what the forensic target(s) may be, update the geoforensic search assets we may use in light of these, and provide a search strategy that includes multiple exploration assets. Some of the good practice involved in terrestrial searches has not been applied to water to-date, water being seen as homogenous and without the complexity of solid ground: this is incorrect and a full desktop study prior to searching, with prioritized areas, is recommended. Much experimental work on the decay of human remains is focused on terrestrial surface deposition or burial, with less known about the nature of this target in water, something which is expanded upon here, in order to deploy the most appropriate geoforensic method in water-based detection. We include case studies where detecting other forensic targets have been searched for; from metal (guns, knives) to those of a nonmetallic nature, such as submerged barrels/packages of explosives, drugs, contraband and items that cause environmental pollution. A combination of the consideration of the environment, the target(s), and both modern and traditional search devices, leads to a preliminary aqueous search strategy for forensic targets. With further experimental research and criminal/humanitarian casework, this strategy will continue to evolve and improve our detection of forensic targets

    A WFC3 Grism Emission Line Redshift Catalog in the GOODS-South Field

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    We combine HST/WFC3 imaging and G141 grism observations from the CANDELS and 3D-HST surveys to produce a catalog of grism spectroscopic redshifts for galaxies in the CANDELS/GOODS-South field. The WFC3/G141 grism spectra cover a wavelength range of 1.1<lambda<1.7 microns with a resolving power of R~130 for point sources, thus providing rest-frame optical spectra for galaxies out to z~3.5. The catalog is selected in the H-band (F160W) and includes both galaxies with and without previously published spectroscopic redshifts. Grism spectra are extracted for all H-band detected galaxies with H<24 and a CANDELS photometric redshift z_phot > 0.6. The resulting spectra are visually inspected to identify emission lines and redshifts are determined using cross-correlation with empirical spectral templates. To establish the accuracy of our redshifts, we compare our results against high-quality spectroscopic redshifts from the literature. Using a sample of 411 control galaxies, this analysis yields a precision of sigma_NMAD=0.0028 for the grism-derived redshifts, which is consistent with the accuracy reported by the 3D-HST team. Our final catalog covers an area of 153 square arcmin and contains 1019 redshifts for galaxies in GOODS-S. Roughly 60% (608/1019) of these redshifts are for galaxies with no previously published spectroscopic redshift. These new redshifts span a range of 0.677 < z < 3.456 and have a median redshift of z=1.282. The catalog contains a total of 234 new redshifts for galaxies at z>1.5. In addition, we present 20 galaxy pair candidates identified for the first time using the grism redshifts in our catalog, including four new galaxy pairs at z~2, nearly doubling the number of such pairs previously identified.Comment: 25 Pages, 9 Figures, submitted to A

    Gas Accretion as a Dominant Formation Mode in Massive Galaxies from the GOODS NICMOS Survey

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    The ability to resolve all processes which drive galaxy formation is one of the most fundamental goals in extragalactic astronomy. While star formation rates and the merger history are now measured with increasingly high certainty, the role of gas accretion from the intergalactic medium in supplying gas for star formation still remains largely unknown. We present in this paper indirect evidence for the accretion of gas into massive galaxies with initial stellar masses M_*>10^{11} M_sol and following the same merger adjusted co-moving number density at lower redshifts during the epoch 1.5 < z < 3, using results from the GOODS NICMOS Survey (GNS). We show that the measured gas mass fractions of these massive galaxies are inconsistent with the observed star formation history for the same galaxy population. We further demonstrate that this additional gas mass cannot be accounted for by cold gas delivered through minor and major mergers. We also consider the effects of gas outflows and gas recycling due to stellar evolution in these calculations. We argue that to sustain star formation at the observed rates there must be additional methods for increasing the cold gas mass, and that the likeliest method for establishing this supply of gas is by accretion from the intergalactic medium. We calculate that the average gas mass accretion rate into these massive galaxies between 1.5 < z < 3.0, is \dot{M} = 96+/-19 M_sol/yr after accounting for outflowing gas. We show that during this epoch, and for these very massive galaxies, 49+/-20% of baryonic mass assembly is a result of gas accretion and unresolved mergers. However, 66+/-20% of all star formation in this epoch is the result of gas accretion. This reveals that for the most massive galaxies at 1.5< z< 3 gas accretion is the dominant method for instigating new stellar mass assembly.Comment: MNRAS in press, 11 pages, 5 figure

    Conformational Studies on Some Inhibitors of Thermolysin and EC 3.4.24.11

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    Molecular modeling is an exciting new approach in the field of drug design. A molecule's activity as a drug is dependent upon its conformation i.e. the three dimensional arrangement of its functional groups. Molecular mechanics coupled with interactive computer graphics is an excellent technique for studying the conformations of small molecules and this thesis presents a discussion of this technique and its application to some inhibitors of the enzymes Thermolysin and EC 3.4. 24.11. An introduction to the role of molecular mechanics in computer assisted drug design is given in Chapter One. Chapter Two describes the calculation of steric energies and the potential functions used to do this, while the procedures used for conformation generation and energy minimisation are discussed in Chapter Three (Appendix A lists one of the programs used for the conformation generation). The MOL software package is an interactive modeling system for small molecules which has been developed at Glasgow and Chapter Four contains a description of this system and its options. The structure and function of many enzymes is of prime importance in drug design since drugs often act by inhibition of enzymic pathways. Since very few enzyme structures are known from X-ray crystallography the primary source of information is enzyme kinetics and Chapter Five discusses some important properties of enzymes, such as their functions as catalysts, substrate and inhibitor kinetics and evolutionary pathways. EC 3.4.24.11. (a mammalian enzyme) and Thermolysin (EC 3.4.24.4, a bacterial enzyme) have very similar substrate specificities and are inhibited at comparable rates by several inhibitors. Very little is known about the active site of EC 3.4.24.11. , however, the structure of Thermolysin is well known from X-ray crystallography and in Chapter Six the known features of active sites of both enzymes are discussed and compared. It is known that two isosteric inhibitors of Thermolysin, B-Phenylpropionyl-L-Phe and Carbobenzyoxy-L-Phe, bind in completely opposite orientations. This unexpected phenomenancan be explained by conformational studies on the two inhibitors. In both cases the enzyme does not bind the lowest energy conformer, however in each case it binds the conformer which has both low energy and gives a good fit to the active site. The results of conformational studies of inhibitors of EC 3.4.24.11. are also discussed in Chapter Six and comparison of the low energy conformers with inhibitors of Thermolysin (from X-ray data) point to differences in the positions and sizes of the S1 and S2' subsites of the two enzymes. Both enzymes are highly specific for hydrophobic groups in the S1' site, with Phe being the most favoured residue. From the X-ray studies of Thermolysin it is known that the Phe side chain is bound with torsion angles of roughly 170 and 80. It is interesting to note that these torsion angle values are very common in many of the low energy conformers and it seems reasonable to assume that the high level of specificity arises from the fact that the side chain of the Phe, Leu etc. are normally in the most favourable position for binding to the S1 hydrophobic pocket without rearrangement. Several other differences between the two enzymes lead to the conclusion that their functional similarity is more likely to be a product of evolutionary convergence on function than of divergence from a common ancestor. Chapter Seven contains a brief summary of the programming which was done during the course of this project paying particular attention to both the motivation and methods involved in programming an array processor and as previously mentioned Appendix A contains a listing of the GLOMIN program - a conformation generation program which was modified to run on an array processor during the course of this project. Finally, Chapter Eight contains a discussion of work carried out in conjunction with Professor A. Y. Meyer while he was on sabbatical leave at Glasgow University. This work shows that force fields can be modified quite simply to give more transferable non-bonding parameters by the inclusion of an electrostatic term. A paper on this work has been published in the Journal of Computational Chemistry and a copy of this paper is given in Appendix B

    Returning home: heritage work among the Stl'atl'imx of the Lower Lillooet River Valley

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    This article focusses on heritage practices in the tensioned landscape of the Stl’atl’imx (pronounced Stat-lee-um) people of the Lower Lillooet River Valley, British Columbia, Canada. Displaced from their traditional territories and cultural traditions through the colonial encounter, they are enacting, challenging and remaking their heritage as part of their long term goal to reclaim their land and return ‘home’. I draw on three examples of their heritage work: graveyard cleaning, the shifting ‘official’/‘unofficial’ heritage of a wagon road, and marshalling of the mountain named Nsvq’ts (pronounced In-SHUCK-ch) in order to illustrate how the past is strategically mobilised in order to substantiate positions in the present. While this paper focusses on heritage in an Indigenous and postcolonial context, I contend that the dynamics of heritage practices outlined here are applicable to all heritage practices

    Nuclear and Extended Spectra of NGC 1068 - I: Hints from Near-Infrared Spectroscopy

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    We report the first simultaneous zJHK spectroscopy on the archetypical Seyfert 2 Galaxy NGC 1068 covering the wavelength region 0.9 to 2.4 micron. The slit, aligned in the NS direction and centred in the optical nucleus, maps a region 300 pc in radius at sub-arcsec resolution, with a spectral resolving power of 360 km s^-1. This configuration allow us to study the physical properties of the nuclear gas including that of the north side of the ionization cone, map the strong excess of continuum emission in the K-band and attributed to dust and study the variations, both in flux and profile, in the emission lines. Our results show that (1) Mid- to low-ionization emission lines are splitted into two components, whose relative strengths vary with the position along the slit and seem to be correlated with the jet. (2) The coronal lines are single-peaked and are detected only in the central few hundred of parsecs from the nucleus. (3) The absorption lines indicate the presence of intermediate age stellar population, which might be a significant contributor to the continuum in the NIR spectra. (4) Through some simple photoionization models we find photoionization as the main mechanism powering the emitting gas. (5) Calculations using stellar features point to a mass concentration inside the 100 - 200 pc of about 10^10 solar masses.Comment: 19 Pages, 14 figures. Accepted for publication in MNRA

    Distribution of ancestral proto-Actinopterygian chromosome arms within the genomes of 4R-derivative salmonid fishes (Rainbow trout and Atlantic salmon)

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    Background: Comparative genomic studies suggest that the modern day assemblage of ray-finned fishes have descended from an ancestral grouping of fishes that possessed 12-13 linkage groups. All jawed vertebrates are postulated to have experienced two whole genome duplications (WGD) in their ancestry (2R duplication). Salmonids have experienced one additional WGD (4R duplication event) compared to most extant teleosts which underwent a further 3R WGD compared to other vertebrates. We describe the organization of the 4R chromosomal segments of the proto-rayfinned fish karyotype in Atlantic salmon and rainbow trout based upon their comparative syntenies with two model species of 3R ray-finned fishes.Results: Evidence is presented for the retention of large whole-arm affinities between the ancestral linkage groups of the ray-finned fishes, and the 50 homeologous chromosomal segments in Atlantic salmon and rainbow trout. In the comparisons between the two salmonid species, there is also evidence for the retention of large whole-arm homeologous affinities that are associated with the retention of duplicated markers. Five of the 7 pairs of chromosomal arm regions expressing the highest level of duplicate gene expression in rainbow trout share homologous synteny to the 5 pairs of homeologs with the greatest duplicate gene expression in Atlantic salmon. These regions are derived from proto-Actinopterygian linkage groups B, C, E, J and K.Conclusion: Two chromosome arms in Danio rerio and Oryzias latipes (descendants of the 3R duplication) can, in most instances be related to at least 4 whole or partial chromosomal arms in the salmonid species. Multiple arm assignments in the two salmonid species do not clearly support a 13 proto-linkage group model, and suggest that a 12 proto-linkage group arrangement (i.e., a separate single chromosome duplication and ancestral fusion/fissions/recombination within the putative G/H/I groupings) may have occurred in the more basal soft-rayed fishes. We also found evidence supporting the model that ancestral linkage group M underwent a single chromosome duplication following the 3R duplication. In the salmonids, the M ancestral linkage groups are localized to 5 whole arm, and 3 partial arm regions (i.e., 6 whole arm regions expected). Thus, 3 distinct ancestral linkage groups are postulated to have existed in the G/H and M lineage chromosomes in the ancestor of the salmonids.</p

    Monitoring sedentary patterns in office employees: validity of an m-health tool (Walk@Work-App) for occupational health.

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    OBJECTIVE: This study validated the Walk@Work-Application (W@W-App) for measuring occupational sitting and stepping. METHODS: The W@W-App was installed on the smartphones of office-based employees (n=17; 10 women; 26±3 years). A prescribed 1-hour laboratory protocol plus two continuous hours of occupational free-living activities were performed. Intra-class correlation coefficients (ICC) compared mean differences of sitting time and step count measurements between the W@W-App and criterion measures (ActivPAL3TM and SW200Yamax Digi-Walker). RESULTS: During the protocol, agreement between self-paced walking (ICC=0.85) and active working tasks step counts (ICC=0.80) was good. The smallest median difference was for sitting time (1.5seconds). During free-living conditions, sitting time (ICC=0.99) and stepping (ICC=0.92) showed excellent agreement, with a difference of 0.5minutes and 18 steps respectively. CONCLUSIONS: The W@W-App provided valid measures for monitoring occupational sedentary patterns in real life conditions; a key issue for increasing awareness and changing occupational sedentariness
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