Theses & Dissertations

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https://hdl.handle.net/20.500.11801/5
This collection is exclusively made up of theses, dissertations, and project reports submitted as a requirement for completing a graduate degree at UPR-Mayagüez. If you are a UPRM graduate student and you are looking for information related to the deposit process, please refer to https://libguides.uprm.edu/repositorioUPRM/tesis

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  • Publication
    Biosystematic analysis of Adiantum vivesii Proctor (Polypodaceae: Adianthoideae), a rare fern endemic to northwestern Puerto Rico
    ( 2000) Sepúlveda Orengo, Marian T. ; Kolterman, Duane A. ; College of Arts and Sciences - Sciences ; Sastre De Jesús, Inés ; Breckon, Gary J. ; Department of Biology ; González Miranda, Sally
    Adiantum vivesii Proctor is a rare fern endemic to the northwestern part of Puerto Rico, known only from its type locality on limestone substrate on privately owned land in the Municipality of Quebradillas. The distribution, abundance, morphology, and cytology of the species were studied to clarify its status as a distinct species or of hybrid or polyploid origen. The population of A. vivesii occupies a total area of 21 m x 10 m; eight sympatric species of Adiantum are found in the immediate area. Following several deep excavations it was concluded that the entire population of A. vivesii is one individual with proliferation by rhizomes. Morphological measurements and light and scanning microscopy were used to describe some parts of A. vivesii and A. tetraphyllum. Morphometric studies were conducted for 22 characters of the species and the possible parent, Adiantum tetraphyllum. Greater variability was obtained within the A. tetraphyllum population, and statistically significant differences between the two species were observed for 17 characteristics. Meiotic studies were inconclusive, but no evident difference in chromosome number was observed between the two species. The spores of A. tetraphyllum showed normal appearance and were rarely abortive, while those of A. vivesii showed greater variability in size and were almost always abortive, suggesting that A. vivesii is a sterile hybrid.
  • Publication
    Population ecology and reproductive behavior of the endangered Buxus vahlii Baillon (Buxaceae)
    ( 2001) Carrero-Rivera, Gloryvee ; Kolterman, Duane A. ; College of Arts and Sciences - Sciences ; Lewis, Allen ; Silander, Susan ; Department of Biology ; González Lagoa, Juan G.
    Buxus vahlii Baillon is an endangered plant species endemic to Puerto Rico and St. Croix (USVI). There are six known populations, four in Puerto Rico (Rincón, Isabela, two in Bayamón) and two in St. Croix (Frederiksted and Christiansted). The status of these populations was studied to provide information on the ecology of the species. The species showed the ability to adapt to different environmental conditions. Such adaptations include shrubby growth in dry areas where it grows as part of the understory (Rincón, Frederiksted and Christiansted) vs. an arborescent growth form in high precipitation areas (Isabela and Bayamón). Identified human impacts on the studied populations were: development (Frederiksted), illegal immigrants and fires (Rincón), and rock climbing and introduced species (Bayamón). The Isabela and Christiansted populations were not impacted due to their low accessibility. Actualization of the management plan is suggested to reverse the decline of this species and restore the populations.
  • Publication
    Wedelia trilobata (L.) Hitchc. (Asteraceae) como repelente de Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae) y de Cosmopolites sordidus Germar (Coleoptera: Curculionidae)
    ( 2001) Ramos Rodríguez, Olgaly ; Mari Mutt, José A. ; College of Arts and Sciences - Sciences ; Pantoja, Alberto ; Acosta, Jaime A. ; Department of Biology ; González, Ángel
    Laboratory experiments were conducted to understand the influence of Wedelia trilobata (L.) Hitchc. on the oviposition of Bemisia argentifolii Bellows & Perring over tomato leaves and on the presence of Cosmopolites sordidus Germar over plantain pseudostems. Solutions made with aqueous extracts of W. trilobata (100, 75, 50, 25 and 0 %) were applied to plants exposed to these insects. The extracts repelled adults of C. sordidus when applied to pieces of plantain pseudostem, but did not affect the oviposition rate of B. argentifolii when applied to tomato leaves. Field experiments using sticky traps compared whitefly abundance in plots surrounded by W. trilobata and control plots (without wedelia). No significant differences were obtained between treatments. Wedelia had no effect on whitefly abundance under field conditions.
  • Publication
    Stellar imaging interferometry
    ( 2003) Yance-Orcasita, Armando De J. ; Chang, Mark J.L. ; College of Arts and Science - Science ; Jiménez, Héctor ; Pabón-Ortiz, Carlos U. ; Department of Physics ; Gooransarab, Haedeh
    This thesis work, developed at the laboratories of the Department of Physics of the University of Puerto Rico, reports the first efforts to build a prototype stellar interferometer with applications to stellar astrophysics. The work is focused in the automation of the key subsystems in the interferometer: the Optical Delay Lines (ODLs). The automation of the mechanical controls that allows displacement of ODL, is achieved through the use of inexpensively built stepper motors and driver cards, using slave processors and implementing control through their parallel ports. Our Objective was to obtain precision displacement of the system that controls the ODL. We found that the motors were able to move 400 nm per step in one direction; with a maximum error of 0.5%, but bidirectional motion has a much larger error in our implementation of the system. In testing the prototype while studying the visibility of the fringes, I found that the polarization effects due to the reflections away from normal incidence are an important factor for the optical design of the interferometer.
  • Publication
    Determinación de digestibilidad y consumo de materia seca de Heno de Arachis glabrata en rumiantes
    ( 2003) Rivera-Estremera, Loures ; Ruiz-López, Teodoro M. ; College of Agricultural Sciences ; Randel, Paul F. ; Macchiavelli, Raúl ; Latorre, José R. ; Department of Animal Science ; Borges, Sonia
    The experiment was conducted to determine the digestibility of hays from two accessions of rhizoma peanut (RP;17033 and 17097) and from Bermuda grass (B) as determined by the total collection method (in vivo), with nine mixed-breed lambs randomly allotted to treatments in a 3 x 3 latin square design with three repetitions. Also, the three methods for determining forage digestibility (in vivo, in vitro and in situ) were compared. Estimates of in vitro digestibility were obtained using a Daisy II incubator (48 hours). In addition, in situ digestibility using dacron bags placed (48 hours) inside the rumen of a fistulated cow fed grass hay was determined. Daily intake of dry matter (DM), organic matter (OM) and acid detergent fiber (ADF) were similar for both RP accessions and were higher (P<0.05) than B, 1.02 vs. .7442 kg/d, .9185 vs. .6782 kg/d and .3764 vs. .2774 kg/d, respectively. In vivo DM, OM, crude protein (CP), and ADF digestibility and digestible energy (DE) of both RP accessions were higher (P<0.05) than those of B. Small, but significant differences were found between the two RP accessions in favor of 17097 in digestibility of DM, OM, and neutral detergent fiber (NDF) and in favor of 17033 in CP digestibility and DE. In vivo ADF digestibility did not differ (P>0.05) between the RP accessions. In vitro and in situ DM and NDF digestibility were higher (P<0.05) for the two RP combined as compared to B (in vitro, 66.83 vs. 44.74 % e in situ, 71.63 vs. 48.12 % of DM; in vitro, 42.21 vs. 30.01 %, e in situ, 42.25 vs. 25.14 % of NDF, respectively). However, both in vitro and in situ OM digestibility differed (P<0.05) among all three hays, being greatest for RP 17033 (65.21 %). Both in vitro and in situ methods overestimated in vivo DM and OM digestibility of both RP accessions and underestimated those of B. In vivo NDF digestibility of both RP was underestimated by both in vitro and in situ methods. According to the results, the in situ method gave the best estimates of in vivo digestibility. Because of its high voluntary intake and digestibility, as determined by three methods (in vivo, in situ and in vitro), the RP demonstrated its outstanding quality potential.
  • Publication
    Improved gray-box modeling of electric drives using neural networks
    ( 2003) Báez-Rivera, Yamilka I. ; Vélez-Reyes, Miguel ; College of Engineering ; Hunt, Shawn D. ; Venkatesan, Krishnaswami ; Department of Electrical and Computer Engineering ; Orama Exclusa, Lionel R.
    Electric drives are used in many industrial and commercial applications. High performance control of electric drives requires the accurate modeling of the motor and mechanical load. In many industrial applications, it is desirable that the electric drive has the capability of self-tuning controller parameters to be able to drive different mechanical loads. One way to achieve this flexibility is by direct identification of the drive and mechanical load. Modeling and identification of Electric drive coupled to a load can be a challenging task. This research investigates the use of gray box models to identify electric drive systems connected to an unknown load. In the proposed model, the electrical subsystem of the machine is modeled using physical principles while the mechanical subsystem is modeled using a black box model based on neural networks. A two-stage identification approach that separates electrical subsystem parameter estimation from mechanical subsystem identification is presented. At each stage the parameters are estimated using the linear least squares approach. Simulation results are presented to demonstrate the feasibility of the approach.
  • Publication
    Genetic algorithm approach for reorder cycle time determination in multi-stage systems
    ( 2003) Romero-Encarnación, Heidi L. ; Cesaní-Vázquez, Viviana I. ; College of Engineering ; Bartolomei Suárez, Sonia M. ; Hernández Rivera, William ; Department of Industrial Engineering ; Seguí Figueroa, Miguel A.
    The objective of this research is to provide a genetic algorithm to determine the reorder cycle time for multi-stage serial and assembly systems. Demand for end item is assumed to occur at a constant and continuous rate. Production is instantaneous and no backorders are allowed. Both setup and echelon holding costs are charged at each stage. The attention is on nested and stationary policies. Furthermore, the reorder interval for each echelon is restricted to be not only integer, but also a power of two times a base planning period. The performance of the genetic algorithm is evaluated in comparison with an optimal approach proposed by Maxwell and Muckstadt (1985), obtaining solutions from zero to five percent from the optimum for small problems. Experimentation is conducted to determine the genetic algorithm parameters and in addition to evaluate the robustness of the proposed methodology.
  • Publication
    Dinámica poblacional de Spoladea recurvalis (F.) (Lepidoptera: pyralidae) y sus relaciones tritróficas con variaciones en la densidad poblacional de la peseta, Trianthema portulacastrum (L.).
    ( 2003) Figueroa-Pérez, Lorimar ; González-Rodríguez, Ángel L. ; College of Agricultural Sciences ; González, Lizzette ; Semidey, Nelson ; Department of Crops and Agro-Environmental Sciences ; Berríos, Ángel
    The weed “horse purslane” (Trianthema portulacastrum [L.]) may be completely defoliated by Spoladea recurvalis (F.) larva, but the lack of a temporal synchrony between them precludes that the competition exerted by the weed on vegetable crops is avoided. In field studies (2001-02) with varying densities of the weed conducted in the Agricultural Experiment Station in Juana Díaz and in studies in fallow plots located in Juana Diaz, Santa Isabel and Lajas, it was found that the population densities of S. recurvalis were directly related to the population density of the weed. The herbivore reached regulating densities when the weed attained almost a hundred percent ground coverage. Applications of Bt-based products reduced S. recurvalis larval densities, however, the reduction in larval densities did not preclude the eventual defoliation of the weed. The insect is present, with an aggregated distribution, throughout the year in the localities studied. In choice tests, larvae preferred to feed on “horse purslane” than on other weeds and did not feed on crops, except for sugar beet. The following hymenopterans parasitoids were identified attacking S. recurvalis: the braconids Apanteles sp., Cremnops sp. and Chelonus cautus Cresson, and the pteromalid Catolaccus sp. The chalcidid Spilochalcis sp. and the elasmid Elasmus sp. were found as hyperparasites of Apanteles.
  • Publication
    Puerto Rico deployable radar network design; site survey and radar design
    ( 2003) Trabal-del Valle, Jorge M. ; Colom-Ustáriz, José G. ; College of Engineering ; Cruz-Pol, Sandra L. ; Rodríguez-Solís, Rafael ; Department of Electrical and Computer Engineering ; Gilbes, Fernando
    The Microwave Remote Sensing Laboratory (MIRSL) at the University of Massachusetts at Amherst and the Clouds Microwave Measurements of Atmospheric Events (CLiMMATE) Laboratory at the University of Puerto Rico at Mayagüez are collaborating to modify marine radars for use as meteorological radar nodes in a proposed weather radar network. This will be the first network to measure lower atmospheric phenomena in Puerto Rico. The radar consists of an antenna, a rotator, and a transceiver placed at the top of a tower or building, along with a data processing system. This thesis describes the survey method used in the MIRSL Tilson Farm field site, and the eleven campuses of the University of Puerto Rico backbone and justifies their fixed offset antennas’ elevation angle and location. A new dual-polarization Xband Doppler radar modification design with an internal calibration loop and a method to stabilize the magnetron thermal frequency drift is also described.
  • Publication
    Consumo voluntario y digestibilidad de nutrientes de heno de gramíneas tropicales nativas y ensilaje de sorgo y el efecto de la suplementación con residuos fermentados de pescadería
    ( 2003) León-Álamo, Felix J. ; Rodríguez-Carías, Abner A. ; College of Agricultural Sciences ; Randel, Paul F. ; Ruiz, Teodoro ; Latorre, José R. ; Department of Animal Science ; Valencia, Elíde
    Se llevaron a cabo tres ensayos con el objetivo de evaluar el consumo voluntario y digestibilidad de nutrientes de heno de gramíneas tropicales nativas (GTN) y ensilaje de sorgo (ES) con o sin suplementación de dos residuos fermentados de pescadería, residuos de la producción de filete de tilapia (RFPT) y lodos fermentados de la industria atunera (LFIA). Además, se evaluó la estabilidad aeróbica de éstos. En el primer ensayo metabólico se determinó el consumo voluntario de forraje y la digestibilidad ``in vivo´´ de la materia seca (MS), proteína bruta (PB) y fibra detergente neutro (FDN) de GTN y ES. Cuatro ovejos criollos adultos se distribuyeron a los tratamientos según un diseño completamente aleatorizado (DCA). Los resultados indicaron un mayor consumo voluntario por parte de los animales alimentados con heno de GTN. La digestibilidad aparente fue mayor para heno de GTN que ES, pero estas diferencias no alcanzaron significaciones estadísticas. En el segundo y tercer ensayos metabólicos se evaluó el efecto de la suplementación con RFPT y LFIA, a niveles de 30% del consumo de MS sobre el consumo y digestibilidad de los forrajes conservados. En ambos experimentos, se utilizaron 8 ovejos adultos distribuidos según un DCA. Se observó que al suplementar los ovejos con RFPT y LFIA aumentó (P <0.05) el consumo voluntario de MS y PB en relación al consumo solo de forraje. Se alcanzaron mayores consumos de MS (P<0.05) con heno de GTN que con ES. La suplementación con ambos residuos fermentados de pescadería tendió a aumentar la digestibilidad aparente de la MS, PB y FDN en el ES. Además, los residuos fermentados de pescadería aumentaron la digestibilidad aparente de la PB y el LFIA aumentó la digestibilidad aparente de la MS en el heno de GTN y solo se observó un efecto negativo en la digestibilidad aparente de FDN cuando se suplemento con LFIA. Por ende, el uso de RFPT y LFIA representa una alternativa para promover el consumo voluntario y en algunos casos aumentar la digestibilidad aparente en rumiantes consumiendo dietas basadas en forrajes tropicales conservados como heno de GTN y ES. Para determinar la estabilidad aeróbica de los residuos fermentados, muestras en triplicado de RFPT y LFIA se expusieron al aire durante 5 días y se analizaron para determinar cambios en pH, temperatura y poblaciones microbianas (bacterias totales y hongos y levaduras). Se observó la temperatura diariamente después de 1, 3 y 5 días de exposición aeróbica y se cuantificó el porcentaje de residuo fermentado recuperado. No se observaron diferencias marcadas en el pH, temperatura, composición química y características fermentativas de los LFIA y RFPT expuestos al aire durante 5 días, lo que sugiere que ambos residuos fermentados de pescadería son aeróbicamente estables.
  • Publication
    Estatus de Atlantea tulita (Dewitz, 1877) en Puerto Rico
    ( 2003) Carrión-Cabrera, Juan E. ; Acosta-Martínez, Jaime A. ; College of Arts and Sciences - Sciences ; Ramos Biaggi, Stuart J. ; Berríos, Ángel ; Department of Biology ; Inglés, Rafael
    The genus Atlantea is endemic to the Greater Antilles (Cuba, Hispaniola, Jamaica and Puerto Rico) with an endemic species in each of the islands. In Puerto Rico it is represented by Atlantea tulita (Dewitz) 1877, a medium sized butterfly (with a wing spread of more or less 6 cm) and singular characteristics. Among these characteristics stand out its sedentary habits, its fidelity to its habitat, the fragility of its imagoes and above all, its monophagy. The butterfly has a close relationship with plants of the genus Oplonia, the only plants used in oviposition and caterpillars food. Habitat destruction has reduced the distribution A. tulita to two extant populations in the island, one in Quebradillas and other in Maricao. The Pollard methodology was slightly modified and used to study population dynamics of tulita in the Puente Blanco area of Quebradillas, Puerto Rico. For fifty-three weeks the area was weekly visited in the morning hours, and in a predetermined route, the number individuals in each instar was recorded. The number of imagoes increases when the number of immature stages decreases, and vice versa, in alternate manner. Male imagoes are always much more common than female imagoes. Inferences and recommendations are made about the situation of A. tulita in Puerto Rico.
  • Publication
    Purification and characterization of trypsin from intestinal and pyloric caecal tissues from the silk snapper, Lutjanus vivanus (Cuvier, 1828)
    ( 2003) Rivera-Santos, Mishelle ; Uscian, John M. ; College of Arts and Sciences - Sciences ; Navas, Vivian ; Bunkley-Williams, Lucy ; Department of Biology ; Kubaryk, John
    In an effort to better understand the chemical digestion of proteins in the silk snapper, Lutjanus vivanus (Cuvier, 1828), and thereby obtain a deeper understanding of how this fish meets its dietary needs for amino acids through its trophic environment, trypsin was purified 10-fold from intestinal and pyloric caecal tissues by sequential application of ammonium sulfate fractionation, size exclusion chromatography, and affinity chromatography. Standard kinetic characteristics of this enzyme were determined. The enzyme displayed optimal activity at pH 8 and 60oC. It was completely or nearly completely inhibited by soybean trypsin inhibitor (SBTI) at a concentration of 0.1% or higher. SDS-PAGE analysis of the purified enzyme revealed a single band with an estimated molecular weight of 26.1 kDa.
  • Publication
    Fast piecewise linear predictors for lossless compression of hyperspectral imagery
    ( 2003) Rodríguez-del Río, Leila S. ; Hunt, Shawn D. ; College of Engineering ; Rodríguez, Domingo ; Vélez Reyes, Miguel ; Department of Electrical and Computer Engineering ; Acuña Fernández, Edgar
    Image compression of hyperspectral is necessary because of the large storage requirements. The main objective of this research is to develop and implement fast and good predictors, for use in lossless compression of hyperspectral images. The algorithms developed in this research are compared in terms of compression performance and computational complexity against the best existent algorithms. These benchmark algorithms are LOCO-I and CALIC-Extended. Lossless compression algorithms are typically divided into two stages, a prediction stage to eliminate redundancy and a coding stage. The predictors can utilize pixels of the same spectral band, adjacent bands or both in order to perform the prediction. Algorithms found in documented research use information of their same band or an adjacent band, but not at the same time. An example of this type of algorithm is algorithm LOCO-I, which only uses the information in the same band in order to predict. However, the CALICExtended algorithm alternates between the information in the same band and that of the adjacent one. The algorithms developed during this research use pixels of both bands in order to do the prediction. The best lossless compression predictor implemented in this research, gave better compression than the state of the art along with a low computational complexity.
  • Publication
    Tunable folded-slot antenna with thin film ferroelectric material Ferroelectric material
    ( 2003) Castro-Vilaró, Amada M. ; Rodríguez-Solís, Rafael A. ; College of Engineering ; Colom, José ; Fernández, Félix ; Department of Electrical and Computer Engineering ; Orama, Lionel
    In this work, the modeled performance of gold (Au)/ Ba0.60Sr0.40TiO3 (BSTO) ferroelectric/ magnesium oxide (MgO) two-layered tunable coplanar waveguide (CPW) fed folded–slot antenna (FSA) is presented. BSTO materials have electric field dependent dielectric properties. Upon application of electric fields the dielectric constant can be tuned over a wide frequency range. The Finite Difference Time Domain (FDTD) method is applied to analyze the output responses. The return loss, input impedance and elevation patterns of the CPW-fed FSA design are included. The designed antenna structure is operational at Ka-band, matched at 50 ohms with minimum reflections and tunable bandwidth of 7.10 GHz for 23.33% around 30.47 GHz. A total frequency shift of 4 GHz and input resistance shift of 28.54 ohms are obtained. The gain is approximately 2.98 dBi. This thesis research demonstrates another advantageous application for ferroelectric thin-films for enhancing the performance of a CPW-fed FSA designed for Ka-band frequencies.
  • Publication
    A case study approach to the supplier selection process
    ( 2003) Suárez-Bello, Marlene J. ; Cesaní-Vázquez, Viviana I. ; College of Engineering ; Deliz Alvarez, José R. ; Vázquez Ruiz, Rita ; Department of Industrial Engineering ; Ruiz Vargas, Yolanda
    This work presents a comparative evaluation of supplier selection processes in different corporate environments using a multiple exploratory case study approach and the ISO 9000 standards. The corporate environments examined were a pharmaceutical, an agricultural equipment company, and an injection molding organization. This research indicates that the supplier performance measurement criteria most commonly used by these industries are quality, delivery and service. Also, depending on the corporate environment of these industries, the importance of these performance metrics can vary. In general, quality is the most important criterion in the organizations studied. Delivery is a critical supplier’s performance measure in the pharmaceutical industry, since the reliability of the suppliers is affected in case of delivery failure in this sensitive market. Finally, these organizations continuously review and implement effective quality systems following the rigorous ISO 9000 series of standards and most companies have developed inhouse procedures and softwares for the supplier selection process.
  • Publication
    Rejilla de defoco
    ( 2003) Vidarte-Quintero, Zugel P. ; Chang, Mark J.L. ; College of Arts and Science - Science ; Jiménez, Héctor ; Pabón-Ortiz, Carlos U. ; Department of Physics ; Walker-Ramos,Uroyoán R.
    This thesis describes the design and manufacture of a non-conventional diffraction grating, referred to as a Defocus Grating. It was designed by adding to the equation of the lines of a standard grating, a function of quadratic phase, which generated a family of off-set concentric circles . The pattern of lines is determined by a parameter of defocus W20, that controls the line’s curvature. The grating was made photographically by reducing a printed object onto a 35 mm transparent slide. In combination with a lens, the system maps a single object plane into a series of im- ages, each with a different level of defocus. The images are produced simultaneously in the different diffraction orders. The proper functionality of the grating was confirmed qualitatively. The distances between image planes of first order was measured. The diffraction orders remain spatially separated along the optical axis according to the level of defocus W20 of the grating. Although symmetry is predicted, little symmetry about the zeroth order was observed.
  • Publication
    Analysis of conduction heat transfer in semi-infinite slabs and infinite quadrants with discrete heat generation sources using green's function integral methods
    ( 2003) Meza-Castillo, Omar E. ; Venkataraman, Nellore S. ; College of Engineering ; Coutín Rodicio, Sandra ; González Cruz, Jorge E. ; Department of Mechanical Engineering ; Rinaldi Ramos, Carlos M.
    The problem of steady state heat conduction in semi-infinite plates and infinite quadrants of constant thermal conductivity, with discrete heat generating sources and Dirichlet boundary conditions (temperature specified on the boundary) was solved using the method of Green’s functions using the integral techniques. The Green’s functions for the geometries were found by the method of images. These functions were then employed for the solution of five cases for semi-infinite slabs with heat generation sources of different geometry. These were: a thin plate heating source, a hollow box heating source, a square prismatic heating source, finite line heating source and a thin cylindrical heating source. For infinite quadrants a heat generation source of the form of a thin current carrying wire in the form a square was considered. The heat sources were idealized as internal thermal energy generation. Solutions found with this method always yield closed form algebraic expressions or analytical solutions or “almost analytical” solutions (in the form of an integral). Results found in this work were validated and compared with the numerical method of finite elements in Ansys 6.0. It was concluded that, for the cases considered here, the method used in the present work is elegant and is superior in terms of computational requirements.
  • Publication
    Characterization and detection by In situ gene amplification of marine denitrifying bacteria
    ( 2003) Cordero-Rodríguez, César ; Massol-Deyá, Arturo A. ; College of Arts and Sciences - Sciences ; Castillo, Carlos ; Diffoot, Nanette ; Department of Biology ; Schroder, Eduardo C.
    Recent studies suggest that the oceanic nitrogen budget is unbalanced, primarily due to a high nitrogen removal in contrast to the fixation rate. This imbalance likely results from denitrification activity in continental shelf sediments. Denitrifying bacteria play a major role in marine sediment nitrogen balance. In order to assess the nitrogen balance characteristic, this study utilized slow-growth enrichment microcosms. These consisted of Puget Sound, WA seawater and sediment samples enriched with dimethyl sulfoxide (DMSO) as carbon source, and nitrate in order to stimulate denitrifying activity. Two sets of microcosms were prepared and incubated in the dark for 6 months at 25oC and 4oC. Of 82 strains isolated, 18 were positive for both nitrate reduction and gas production. Amplified ribosomal DNA restriction analysis (ARDRA) was performed to compare and establish similarities between the Puget Sound isolates and control cultures. The novel in situ reverse transcription PCR (RT-PCR) method has been optimized to study the expression of the nirS gene in denitrifying bacteria. Pure cultures of reference denitrifying isolates from marine sediments were used to optimize the in situ RT-PCR protocol. We performed cell fixation after visible gas production was observed. In situ RT-PCR was performed after cell fixation and enzymatic permeabilization. The nirS 1F and nirS 6R primers were used for the amplification of cDNA and subsequently fluorescent in situ hybridization (FISH) was done to increase the detection specificity of the amplification product. Only active denitrifying cells were detected by this approach using fluorescence microscopy.
  • Publication
    Efecto de la adición en el alimento de aguas residuales de una planta productora de caramelo sobre el desempeño de cerdos desde el destete hasta terminado
    ( 2003) Jiménez-Cabán, Esbal ; Latorre-Acevedo, José R. ; College of Agricultural Sciences ; Rodríguez Catias, Abner A. ; Fernández Van Cleve, John A. ; Latorre Acevedo, José R. ; Santana Nieves, Carmen S. ; Department of Animal Science ; Mari Mutt, José A.
    Twenty-four crossbred pigs (Duroc X Yorkshire), of 28 days of age with an average live weight of 6.9 kg, were used to evaluate the addition to the diet of 0 (control), 5, and 7.5 % of wastewater from a caramel production plant (WWCP) on the pigs’ performance, blood metabolites, and carcass characteristics from weaning to finishing (82 kg average live weight). A completely randomized block design was used (n=4). Pigs were fed on an 8 % body weight basis during the post-weaning phase (21 days) and on a 6 % basis for the rest of the investigation. Dry matter intake, weight gain and feed efficiency were improved with 7.5 % addition of WWCP during the post-weaning phase (P≤.08). Over the fattening-finishing phase, the daily dry matter intake and daily weight gain were greater in the control group, while feed efficiency improved with the addition of WWCP during the finishing period (P≤.08). Longissimus dorsi area and ham weight were greater in females compared with barrows (P≤.08), but no differences were detected by the addition of WWCP. Blood samples were taken by jugular venipuncture on day 1 and 8 of the post-weaning phase, and on the day before slaughter to determine glucose and sodium concentrations; both concentrations were greater in the bleeding previous to slaughter (P≤.08). WWCP’s aerobic stability was evaluated in a 4-week trial and it was found that butyric acid concentration was reduced in the third week, while pH gradually decreased over the four weeks (P≤.08). The results obtained in this research suggest that pig’s performance at weaning can be improved with the addition for 21 days of WWCP to the diet in levels up to 7.5 % for 21 days during this phase. On the other hand, more research is required about the use of this wastewater during the fattening-finising phase before giving any recommendation.
  • Publication
    Sre: search and retrieval engine of the terrascope database middleware system
    ( 2003) Coronado-Pacora, Enna Z. ; Rodríguez-Martínez, Manuel ; College of Engineering ; Velez-Rivera, Bienvenido ; Rivera Vega, Pedro ; Department of Electrical and Computer Engineering ; Toledo, Freya
    Our research emerged from the need to know how to recover and to visualize graphical/textual information of images that are stored in multiple data sources. We are focused on a system for recovering, merging, and displaying data, metadata, and images from heterogeneous distributed data sources for purposes of providing end-users with an unique entry point to those data sources. We present the Search and Retrieval Engine (SRE) developed as part of TerraScope, a Web-based Earth Science Database Middleware System. SRE is the execution engine based on Java Servlet technology and the Peer–to–Peer architecture that makes possible the transformation of the server into a client of data at any moment. SRE allows for the communication among others Web Servers, such that multiple data sources can be integrated into a coherent system. SRE also supports the execution of different queries that gather useful data from each distributed data source.