Physical Sciences and Mathematics Commons^™

Hiv Infection And The Risk Of World Health Organization-Defined Sudden Cardiac Death, Matthew S. Freiberg, Meredith S. Duncan, Charles Alcorn, Chung-Chou H. Chang, Suman Kundu, Asri Mumpuni, Emily K. Smith, Sarah Loch, Annie Bedigian, Eric Vittinghoff, Kaku So-Armah, Priscilla Y. Hsue, Amy C. Justice, Zian H. Tseng

Biostatistics Faculty Publications

Background

People living with HIV have higher sudden cardiac death (SCD) rates compared with the general population. Whether HIV infection is an independent SCD risk factor is unclear.

Methods and Results

This study evaluated participants from the Veterans Aging Cohort Study, an observational, longitudinal cohort of veterans with and without HIV infection matched 1:2 on age, sex, race/ethnicity, and clinical site. Baseline for this study was a participant's first clinical visit on or after April 1, 2003. Participants were followed through December 31, 2014. Using Cox proportional hazards regression, we assessed whether HIV infection, CD4 cell counts, and/or HIV viral …

Heavy Metal And Contaminant Loading In The Oder River Floodplains And Consequences For Livestock Management, G. Schalitz, A. Behrendt

IGC Proceedings (1993-2023)

The predominately pristine lower Oder floodplains have experienced sedimentation and enrichment of heavy metals and contaminants since the start of industrialization in the region. With the creation of the German-Polish National Park, which included the flooded grassland area, intensive milk production has been prohibited. The objective of this research was to estimate the impact of the floodplain heavy metal and contaminant levels on the lower Oder region. Soil and plant content were analyzed for three transects according to accepted DIN methods. High content in soil did not consistently result in high plant contents; however, higher content levels were often observed …

Extended Daylength To Increase Fall/Winter Yields Of Warm-Season Perennial Grasses, P. Mislevy, T. R. Sinclair, J. D. Ray

IGC Proceedings (1993-2023)

Low forage production in fall/winter months is a severe limitation for dairy and beef cattle producers in the southeastern U.S. It was hypothesized that shrt daylengths during these months induce a physiological dormancy in grasses. Four grasses [Pensacola bahiagrass, Paspalum notatum Flugge; Tifton 85 and Florakirk bermudagrass, Cynodon dactylon (L.); Florona stargrass, C. nlemfuensis Vanderyst var. nlemfuensis] were subjected to extended daylengths during the winter/fall months in a field test. Pensacola bahiagrass and Tifton 85 bermudagrass showed especially dramatic increases in forage yield during the fall/winter season under the extended daylength. Genetic elimination of daylength sensitivity in these grasses …

Nitrogen Or Water Limitation To Grassland Growth During A Moderate Dry Season In The Humid Tropics, P. Cruz, M. Boval

IGC Proceedings (1993-2023)

The aim of this work was to compare the effects of nitrogen and water shortage on grassland production during a moderate dry season in a tropical humid environment. The results of two experiments carried out in Guadeloupe (FWI) have shown that during dry spells, the reduction in growth of natural grasslands based on Angleton grass (Dichantium aristatum) is more easily corrected by nitrogen fertiliser application than by irrigation. This shows that it is not the availability of water, but that of nitrogen, which is limiting the primary production of Angleton grass, stands. This result is less clear for …

Screening Brachiaria Introductions For Resistance To Spittlebugs (Homoptera: Cercopidae), José R. Valério, Cacilda Borges Do Valle, A. P. De Souza, M. C. M. Oliveira

IGC Proceedings (1993-2023)

Spittlebugs are the most evident and damaging pests of Signal grasses (Brachiaria) in tropical America. Damage caused by these insects can result in the complete loss of available forage, thereby reducing the carrying capacity of infested pastures. Host plant resistance is a low-cost method of controlling insects. High level of spittlebug resistance is found in the cultivar Marandu (B. brizantha), but it requires more fertile soils. Brachiaria germplasm provided by the International Center for Tropical Agriculture (CIAT) is available at National Beef Cattle Research Center of the Brazilian Agricultural Research Corporation (Embrapa Beef Cattle) and it …

Associations Of Circulating Dimethylarginines With The Metabolic Syndrome In The Framingham Offspring Study, Ibrahim Musa Yola, Carlee Moser, Meredith S. Duncan, Edzard Schwedhelm, Dorothee Atzler, Renke Maas, Juliane Hannemann, Rainer H. Böger, Ramachandran S. Vasan, Vanessa Xanthakis

Biostatistics Faculty Publications

BACKGROUND: Circulating levels of the endogenous inhibitor of nitric oxide synthase, asymmetric dimethylarginine (ADMA), are positively associated with the prevalence of metabolic syndrome (MetS) in cross-sectional investigations. It is unclear if circulating ADMA and other methylarginines are associated with incident MetS prospectively.

METHODS: We related circulating ADMA, symmetric dimethylarginine (SDMA), L-arginine (ARG) concentrations (measured with a validated tandem mass spectrometry assay) and the ARG/ADMA ratio to MetS and its components in 2914 (cross-sectional analysis, logistic regression; mean age 58 years, 55% women) and 1656 (prospective analysis, Cox regression; mean age 56 years, 59% women) individuals from the Framingham Offspring Study …

Selection Of High Yielding And Anthracnose Resistant Stylosanthes For Brazil, India And China, N. White, S. Chakraborty, Celso D. Fernandes, M. J. Charchar, N. P. Melkania, C. R. Ramesh, B. Gangaiah, Guodao Liu, D. F. Cameron, J. W. Miles

IGC Proceedings (1993-2023)

Resistance to anthracnose, dry matter yield (DMY) and seed yield (SY) was assessed for germplasm and breeding lines of Stylosanthes in Brazil, India and China. Overall, Stylosanthes guianensis produced higher DMY than S. scabra, S. capitata and S. macrocephala at most sites in Brazil. Data from China suggest that there are high yielding anthracnose resistant S. guianensis lines that can reduce the reliance on CIAT 184. S. seabrana might also prove successful. S. seabrana in India produced the highest DMY and SY and it can form nodules with native Bradyrhizobium strains. Regional differences in resistance within accessions stress the …

Bone Quality And Fractures In Women With Osteoporosis Treated With Bisphosphonates For 1 To 14 Years, Hartmut H. Malluche, Jin Chen, Florence Lima, Lucas J. Liu, Marie-Claude Monier-Faugere, David A. Pienkowski

Internal Medicine Faculty Publications

Oral bisphosphonates are the primary medication for osteoporosis, but concerns exist regarding potential bone-quality changes or low-energy fractures. This cross-sectional study used artificial intelligence methods to analyze relationships among bisphosphonate treatment duration, a wide variety of bone-quality parameters, and low-energy fractures. Fourier transform infrared spectroscopy and histomorphometry quantified bone-quality parameters in 67 osteoporotic women treated with oral bisphosphonates for 1 to 14 years. Artificial intelligence methods established two models relating bisphosphonate treatment duration to bone-quality changes and to low-energy clinical fractures. The model relating bisphosphonate treatment duration to bone quality demonstrated optimal performance when treatment durations of 1 to 8 …

Genetic Diversity In The Anthracnose Pathogen Infecting Stylosanthes In Brazil, India And China, P. Weeds, S. Chakraborty, Celso D. Fernandes, M. J. Charchar, C. R. Ramesh, Guodao Liu, S. Kelemu

IGC Proceedings (1993-2023)

This work aimed to determine the genetic diversity of Colletotrichum gloeosporioides infecting Stylosanthes spp. in Brazil, China and India. A total of 132 isolate originating from S. seabrana, S. macrocephala, S. capitata, S. scabra, and S. guianensis were used. Four major genetic groups were identified from an analysis of genetic diversity using selection-neutral DNA markers. Group 1 contained 20 isolates and this may represent a genotype that migrated from the center of diversity in Brazil and Colombia to Australia, Thailand and India. Group 2 consisted of 66 Brazilian isolates and group 3 had 19 isolates from …

Relationship Between Tree Density And Grass Dry Matter Yield In A Southern African Savanna, G. N. Smit

IGC Proceedings (1993-2023)

The investigation was carried out on a densely wooded area in the Mopani savanna of South Africa. Seven plots were subjected to different intensities of tree thinning, ranging from a totally cleared plot (0 %) to plots thinned to the equivalent of 10 %, 20 %, 35 %, 50 % and 75 % of the leaf biomass of a control plot (100 %). The grasses responded positively to the tree thinning in terms of total dry matter yield. The yields between tree canopies were generally of the same order or higher than under tree canopies, with the yields where trees …

Seasonal Patterns Of Growth And Senescence In Cynodon Spp. Cv Tifton 85 Grazed Swards, L. F. M. Pinto, L. G. Barioni, S. C. Da Silva

IGC Proceedings (1993-2023)

Growth and senescence are very important determinants of grassland productivity and correspond to key features to be considered for grazing management purposes. The present study was carried out at ESALQ, Piracicaba, S.P., Brazil and evaluated growth and senescence as a function of sward surface height. Mathematical models generated revealed that a similar pattern of response occurred as described in the literature for temperate grass species. However, a seasonal variation in response curves for growth and senescence was also observed and could be related to climatic events. Highest herbage accumulation rates were observed within the range of 15 to 20 cm …

Yields And Sward Characteristics Of Timothy Cultivars Under Grazing, H. T. Kunelius, G. H. Dürr, K. B. Mcrae, S. A. E. Fillmore

IGC Proceedings (1993-2023)

Seven timothy (Phleum pratense L.) cultivars were evaluated over three pasture seasons under rotational grazing to 7 or 11 cm post-grazing heights and regrowth periods of four to seven weeks. There was a trend for the pasture type timothy cultivars to outyield Champ timothy (check). Dry matter yields were lower for the 7 cm than 11 cm post-grazing height. Although the overall cultivar x post-grazing height interaction was not significant (P > 0.05), there was variability in grazing tolerance among timothy cultivars. Yield of Kahu was maintained and vegetative tiller density of Kahu increased over the experimental period under 7 …

A Technique For Assessing Seed Survival Of New Pasture Legumes Following Grazing By Sheep, Caroline T. De Koning, P. E. Beale, A. J. Duncan, S. Hughes, K. Haskard

IGC Proceedings (1993-2023)

A technique for assessing the fate of seed grazed by sheep in small field plots was examined using the pasture species Trifolium michelianum cv. Paradana, Medicago truncatula cv. Mogul, Trifolium spumosum and Trigonella balansae. Trifolium spumosum lost the greatest proportion of seed from dry pasture residues (88% seed eaten), whereas Trigonella balansae, Paradana and Mogul lost 61%, 55% and 53% respectively. However, Trifolium spumosum and Paradana had high levels of seed in the faeces (56.8 kg/ha and 65.2 kg/ha respectively), whereas Mogul and Trigonella balansae had low levels (10.3 kg/ha and 11.0 kg/ha respectively). Mogul, due to it's …

Seasonal Growth Curves Of Perennial Ryegrass In Mexico, M. E. Z. Velasco, Alfonso Hernández-Garay, J. P. Pérez, V. A. González-Hernández

IGC Proceedings (1993-2023)

An experiment was established at Colegio de Postgraduados Research Station, Texcoco, México to evaluate the seasonal pattern of growth curve of perennial ryegrass (Lolium perenne) swards. Growth rate increases rapidly from a low level immediately after defoliation, and eventually reaches an equilibrium level as the amount of green leaf in the sward stabilize. The time required to reach this state varied according to the season of year, with the four seasons ranked in the order: spring (4 weeks) < summer (5 weeks) < autumn and winter (6 weeks). Once swards reached equilibrium, growth rates started to decline as a consequence of an increase in dead material and pseudostem. These increases were highest in spring and lowest in winter. The results of this study suggest that sward management to maximise herbage production and utilisation in ryegrass swards must be done once the highest green leaf mass is reached. In this trial, it was reached at 5, 6, 6 and 4 weeks in summer, autumn, winter and spring, respectively.

The Effects Of Planting Density On The Dry Matter Yield And The Overwintering Ability Of The Dwarf And Normal Napiergrasses In Two Years After Planting, Yasuyuki Ishii, M. M. Mukhtar, Sayan Tudsri

IGC Proceedings (1993-2023)

The objective of this study is to determine the optimum planting density in napiergrass (Pennisetum purpureum Schumach) among two dwarf varieties introduced from Thailand and two normal ones under three levels of density. Dwarf varieties showed lower plant height and mean tiller weight, and higher leaf area index (LAI) and leaf blade percentage. Crop growth rate was positively correlated with LAI, and net assimilation rate and canopy extinction coefficient (K) were negatively correlated with LAI in the second year, including all dwarf and normal varieties, while K tended to be lower in the dwarf varieties. With the increase in …

Light Interception And Dry Matter Yield In Grass/Legume Mixtures, H. A. Jönsson

IGC Proceedings (1993-2023)

The influence of grass variety on light interception and dry matter yield in a grass/clover mixture was studied. Two varieties of timothy (Phleum pratense L.) and five varieties of ryegrass (Lolium spp) as components in a mixture were compared during the spring period up to the first cut of the third harvest year. By replacing the timothy variety in the mixture both light interception and dry matter yield were significantly affected. The leaf orientation was thought to be a contributing factor with erect leaves intercepting less light. There were no significant differences neither in light interception nor …

Photosynthetic Light Response Of Tanzania Grass Under Four Levels Of Leaf Temperature, A. C. L. De Mello, P. M. Santos, Carlos G. S. Pedreira, M. Corsi, C. T. Dos S. Dias

IGC Proceedings (1993-2023)

The purpose of this paper is to establish photosynthetic light response curves for Tanzania grass (Panicum maximum Jacq.) under four leaf temperature levels. Photosynthetic rate was measured as a response to levels of photosynthetic photon flux density (PPFD) on the youngest fully expanded leaves of 12 representative tillers with an infra red gas analyzer. The effect of PPFD was tested for each leaf temperature level in a randomized complete block design. Photosynthetic light response curves were adjusted for each leaf temperature using a non-linear hyperbolic model. The maximum photosynthetic response was 25,59; 31,43; 34,57 and 27,53 µmol CO_{2 …}

Nonstructural Carbohydrate Reserves Of Temperate Perennial Grasses In Autumn Early Growth, Y. Tamura, K. Matoba, A. Fushimi, M. Moriyama

IGC Proceedings (1993-2023)

The objective of this study was to determine levels of nonstructural carbohydrate reserves of four temperate perennial grasses: Orchardgrass (Dactylis glomerata L.), Timothy (Phleum pratense L.), Perennial ryegrass (Lolium perenne L.), and Reed canarygrass (Phalaris arundinacea L.) in their early growth stages during the cool autumn temperatures in northern Japan. At the time of sampling, all grasses were in their vegetative stage, and Reed canarygrass was not forming rhizomes. Fructosan concentration in reed canarygrass roots (8.04%) was 22 times that of the leaf blade (0.36%) and twice that of the stem (3.40%); the concentration in reed …

Effect Of Cutting Height On Tiller Population Density And Herbage Biomass Of Buffel Grass, L. S. Beltrán, P. J. Pérez, G. A. Hernández, M. E. García, S. J. Kohashi, H. J. G. Herrera

IGC Proceedings (1993-2023)

The aim of this trial was to investigate the effect of different cutting heights on tiller population density and herbage biomass of Buffel grass (Cenchrus ciliaris L) grown in miniature swards in a greenhouse. Four treatments with five replicates: five cm, ten cm, and 20 cm cutting height, and control (without cut) were randomly allocated. Intensity of defoliation affected the cumulative herbage harvested; the ten cm cutting height was greater (404.1 g DM m^-2) than 5 cm (317.6 g DM m^-2) and 20 cm (263.9 g DM m^-2), respectively. Cumulative herbage harvested in …

Leaf Appearance Rate In Brachiaria Decumbens Grown In Nitrogen And Potassium Rates, M. D. C. Ferragine, F. A. Monteiro, S. C. Da Silva

IGC Proceedings (1993-2023)

A greenhouse experiment was carried out with Brachiaria decumbens Stapf. cv. Basilisk grown in nutrient solution. Five nitrogen rates (42; 140; 238; 336 and 434 mg/L) and three potassium rates (78; 234 and 390 mg/L) were studied in a factorial experiment, in a randomized complete block design, with four replications. Green leaf number was evaluated in six times in the first period of growth (27, 30, 33, 36, 39 and 42 days after transplanting) and nine times in the second period (45, 48, 51, 54, 57, 60, 63, 66 and 69 days after transplanting). Data was registered in three plants …

Variability In Herbage Mass And Chemical Composition Within A Timothy Sward, O. Niemeläinen, E. Miettinen, P. Virkajärvi, L. Alakukku, K. Hakala

IGC Proceedings (1993-2023)

Variability in herbage mass (HM) and chemical composition of timothy (Phleum pratense L.) sward was studied in a three-hectare field. The field, which was flat, was divided into twelve sections and a sampling site was randomly selected in each. The study was carried out in Sotkamo (64^o 01’N, 28^o22’E) research station in Finland. Snow depth and frost conditions were measured in winter and soil water content was monitored in the growing season at each sampling site. Observations on the crop included assessment of herbage ground cover and winter damage percentage, stand height and HM and analysis …

Morphogenesis And Defoliation Frequency Of Italian Ryegrass (Lolium Multiflorum) And Paspalum Urvillei In Lowland Under Three Levels Of P And K, Fernando L. F. De Quadros, A. G. S. Pigatto, D. G. Bandinelli, E. Marchezan, Marta G. Da Rocha

IGC Proceedings (1993-2023)

This trial was conducted to evaluate growth dynamics and defoliation frequency of Italian ryegrass (Lolium multiflorum) and Paspalum urvillei in a lowland area under three levels of P and K. Using randomization tests we observed that, in a general way, fertilizer treatments were not the determinant factors of leaf appearance and elongation rates for both species. Only the leaf appearance rate of Paspalum urvillei at 100 % of recommendation level and the elongation rate for Italian ryegrass, in the same treatment, was different. Probably other factors, like drainage, are contributing to these results. I. ryegrass phyllochron ranged from …

Effects Of Temperature, Nitrogen Fertilisation And Leaf And Tiller Age On Specific Leaf Area Of Brachiaria Decumbens, J. Busqué, M. Herrero

IGC Proceedings (1993-2023)

Signal grass (Brachiaria decumbens Stapf) micro-swards were grown under controlled environmental conditions at different temperatures and nitrogen fertilisation rates. Specific leaf area was responsive both to temperature and nitrogen, but did not change with the level of insertion of the leaf in the tiller. Senescing leaves had higher specific leaf area than old extended green leaves and these had higher values than new extended green leaves. Changes in specific leaf area were more related to changes in leaf area and more exactly to changes in leaf width.

The Use Of Cover Crops After A Maize Crop In The North Of Spain, D. Báez, M. Pinto, M. Rodríguez, G. Besga, J. M. Estavillo

IGC Proceedings (1993-2023)

This work intends to study N leaching losses in a field assay when crimson clover (Trifolium incarnatum) and italian ryegrass (Lolium multiflorum) was incorporated into the soil and quantify the their effect on N₂O, N total gaseous losses under controlled soil moisture and temperature conditions. Field assay: A split-plot design where main plot was the cover crop and the subplot was the rate of fertilizer (0 and 150 kg N ha^-1) applied to the subsequent maize crop. Laboratory assay: Residues of italian ryegrass and crimson clover were mixed with soil in containers, …

Multi-Year Application Of Dairy Slurry On Grassland: Effects On Crop, Soil Biota, Soil Nutrients, And N2O Emission, Shabtai Bittman, C. G. Kowalenko, D. E. Hunt, N. Patni, J. Paul, D. Raworth, J. Hountin, T. A. Forge, C. M. Monreal, O. Schmidt

IGC Proceedings (1993-2023)

The long-term effects of using manure as the principal nutrient source in intensive crop production systems are not well known. This paper reports on the effects of multi-year application of fertilizer or dairy slurry on a tall fescue (Festuca arundinacea Schreb.) sward. Slurry sustained greater grass yield than chemical fertilizer. Unlike fertilizer, slurry supplied 70 to 120 kg N/ha one year after application but little after one year; 4-years of manure applications built up the stable organic matter pool in the soil. Manure-N was less prone to leaching but more prone to N₂O emissions than fertilizer-N. Manured …

Sewage Sludge As An Alternative Fertilizer For Tropical Pasture Grasses, M. B. Adjei, J. E. Rechcigl

IGC Proceedings (1993-2023)

This study was conducted to determine the effects of source (Liquid sludge at pH 7 (LS7) or pH 11 (LS11), cake biosolid (CB) or ammonium nitrate (AM)) by rate (0, 80 or 160 kg ha^-1) of N application on bahiagrass forage yield, quality and tissue composition. Same plots were fertilized in March 1998 and 1999. Forage yield was measured at 30 d intervals from May through November and subsamples were dried and ground for quality analyses. The 2-year mean forage yield was similar for AM, LS7 and LS 11 fertilizer applications. Forage yield from CB application was 30% …

Phosphorus Fertilizer And Stocking Rate Effects On Soil Microbial Biomass Of A Long-Term Dairy Farmlet Experiment, S. R. Aarons, C. R. O’Connor, C. J. P. Gourley

IGC Proceedings (1993-2023)

The effects of a range of P fertilizer rates and dairy cow stocking rates on microbial biomass carbon and phosphorus were compared in a long-term farmlet trial in southeastern Australia. Pastures were stocked at 2, 3, or 4 cows/ha and received fertilizer at rates of 0, 35, 70 or 140 kgP/ha. There was no effect of either P fertilizer rate or stocking rate on microbial biomass C from 1995 to 1998. Increasing P application rate significantly increased the chloroform-released microbial P flush measured, but stocking rate had no effect on microbial P. There were significant temporal changes, with the seasonal …

Dry Matter Accumulation And Partitioning Between Vegetative And Reproductive Organs In Alfalfa (Medicago Sativa L.), E. D. Bolaños-Aguilar, Christian Huyghe, B. Julier, C. Ecalle

IGC Proceedings (1993-2023)

This work investigated the partitioning of dry matter between vegetative and reproductive plant organs in alfalfa during the reproductive period under field conditions. Two French varieties (Europe and Magali) were studied. Both varieties showed similar growth pattern of the different plant organs in 1998 and 1999. The mean dry matter of vegetative organs (shoots and leaves) over the two years was higher in Europe (567g/m²) than Magali (470g/m²). No vegetative growth was observed during the reproductive period. The root organs (measured to a depth of 0.20 m) and the reproductive organs showed an increase in dry …

Herbage Seed Production Possibilities In Finland, O. Niemeläinen, M. Kinnari

IGC Proceedings (1993-2023)

In the seed production variety experiments in Finland from 1977 to 1992 the mean seed yield of timothy (Phleum pratense) cultivar Alma was 717 kg ha^-1, of meadow fescue (Festuca pratensis) cv. Boris 622 kg ha^-1, of tall fescue (Festuca arundinacea) cv. Retu 350 kg ha^-1, of perennial ryegrass (Lolium perenne) cv. Riikka, of cocksfoot (Dactylis glomerata) cv. Haka 295 kg ha^-1, and red clover (Trifolium pratense) cv. Hankkijan Venla 403 kg ha^-1. From 1988 to 1998 annual …

Aqueous Photochemistry Of 2-Oxocarboxylic Acids: Evidence, Mechanisms, And Atmospheric Impact, Marcelo I. Guzman, Alexis J. Eugene

Chemistry Faculty Publications

Atmospheric organic aerosols play a major role in climate, demanding a better understanding of their formation mechanisms by contributing multiphase chemical reactions with the participation of water. The sunlight driven aqueous photochemistry of small 2-oxocarboxylic acids is a potential major source of organic aerosol, which prompted the investigations into the mechanisms of glyoxylic acid and pyruvic acid photochemistry reviewed here. While 2-oxocarboxylic acids can be contained or directly created in the particles, the majorities of these abundant and available molecules are in the gas phase and must first undergo the surface uptake process to react in, and on the surface, …