791 research outputs found

    StomateTutor™: An Introduction to Stomatal Control of Gas Exchange in Plants

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    This is a HyperCard implementation which includes Pascal programs. HyperCard, which requires at least 1 Megabyte of memory, must be supplied by the user. The system disk must include the Geneva 10 pt font. When using, open the HyperCard stack StomateTutor which coordinates the remaining files (StomateTutorl-3 and the two Pascal programs). When you run StomateTutor the first time with your file configuration, you must locate the Pore Width and Diffusion applications used in Modules 1 and 2, respectively

    Peroxisome proliferator-activated receptor delta limits the expansion of pathogenic Th cells during central nervous system autoimmunity.

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    Peroxisome proliferator-activated receptors (PPARs; PPAR-alpha, PPAR-delta, and PPAR-gamma) comprise a family of nuclear receptors that sense fatty acid levels and translate this information into altered gene transcription. Previously, it was reported that treatment of mice with a synthetic ligand activator of PPAR-delta, GW0742, ameliorates experimental autoimmune encephalomyelitis (EAE), indicating a possible role for this nuclear receptor in the control of central nervous system (CNS) autoimmune inflammation. We show that mice deficient in PPAR-delta (PPAR-delta(-/-)) develop a severe inflammatory response during EAE characterized by a striking accumulation of IFN-gamma(+)IL-17A(-) and IFN-gamma(+)IL-17A(+) CD4(+) cells in the spinal cord. The preferential expansion of these T helper subsets in the CNS of PPAR-delta(-/-) mice occurred as a result of a constellation of immune system aberrations that included higher CD4(+) cell proliferation, cytokine production, and T-bet expression and enhanced expression of IL-12 family cytokines by myeloid cells. We also show that the effect of PPAR-delta in inhibiting the production of IFN-gamma and IL-12 family cytokines is ligand dependent and is observed in both mouse and human immune cells. Collectively, these findings suggest that PPAR-delta serves as an important molecular brake for the control of autoimmune inflammation

    A new strategy for waterborne disease prevention

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    In many parts of the developing world, drinking water is collected from unsafe sources and is further contaminated during storage in household vessels. We have developed a simple, inexpensive system for point-of-use disinfection and storage of water which has 3 elements: for disinfection, a sodium hypochlorite solution produced from water and salt using appropriate technology; for safe storage, a 20-litre plastic vessel with a narrow mouth, lid, and spigot (referred to hereafter as the special vessel); and community education to ensure proper use of this system and to teach populations about the association between contaminated water and disease (Mintz, 1995). A field test of this system in El Alto, Bolivia, demonstrated a high level of acceptance among impoverished Aymara Indian families (Quick, 1996). Stored water in households that used the system had lower levels of contamination with E. coli than water in households that used their traditional storage systems. A second field test among vendors in the markets of Guatemala City, Guatemala, showed that there were lower levels of contamination with fecal coliform bacteria in samples of stored water and beverages from vendors using this system than from vendors not using this system (Sobel, 1997). Two field trials have been conducted in the past 3 years to test the effectiveness of this system in preventing diarrhea and its sustainability on a large scale

    Constraining Andean Propagation of Exhumation at the Limit of the Eastern Cordillera, NW Argentina, Using Low-Temperature Thermochronology in a Structural Context

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    Within the Central Andes of NW Argentina, the spatiotemporal distribution and style of deformation is strongly influenced by pre-Cenozoic heterogeneities, mostly related to the Salta rift extension in the Cretaceous. At the enigmatic junction of the thin-skinned Subandean belt and the thick-skinned Santa Barbara System, the Tilcara Range and adjacent San Lucas block, located within the Eastern Cordillera, show thermochronological and field evidence of multiple exhumation events. Mesozoic (140-115 Ma), pre-Andean exhumation of basement highs is constrained by unconformities between basement and syn-rift strata, as well as zircon (U-Th-Sm)/He cooling ages. Cenozoic Andean exhumation is quantified by apatite (U-Th-Sm)/He and fission track cooling ages, which were reset between the Late Cretaceous and Miocene. These data show that the westernmost Tilcara Range began exhuming in the late Oligocene-early Miocene (26-16 Ma), after which exhumation propagated to the border of the Eastern Cordillera in the middle Miocene (22-10 Ma). The onset of rapid exhumation in the San Lucas block, which is located east of the Tilcara Range, occurred in the late Miocene (10-8 Ma) in its western part, and in the late Miocene-early Pliocene (6-4 Ma) in its eastern part. Internal deformation of the San Lucas block, disturbing zircon (U-Th-Sm)/He and apatite fission track age patterns, predates propagation of rapid exhumation. The here presented low-temperature thermochronology data set thus quantifies the multi-phase exhumation history of the Eastern Cordillera of NW Argentina and constrains the timing of Andean propagation of exhumation within the Eastern Cordillera and the adjacent structural transition zone.Fil: van Kooten, Willemijn S. M. T.. Universitat Potsdam; AlemaniaFil: Sobel, Edward Robert. Universitat Potsdam; AlemaniaFil: del Papa, Cecilia Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Payrola Bosio, Patricio Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta-Jujuy. Instituto de Bio y Geociencias del Noroeste Argentino. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto de Bio y Geociencias del Noroeste Argentino; ArgentinaFil: Glodny, Johannes. German Research Centre for Geosciences; Alemani

    New thermocronological data of the Cretaceous-Cenozoic clastic sequences from the VINCHINA basin: Linkage between burial, exhumation and thermal flow variations

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    New apatite fission track (AFT) and (U–Th)/He (AHe) data from two sections recording Cretaceous-Cenozoic clastic successions (La Flecha - La Troya Sur creeks) in the northern sector of the Central Precordillera of Argentina are presented. The results show that the Ciénaga del Río Huaco, Puesto la Flecha and Vallecito Fms. would have crossed the 60 °C isotherm during burial, while the middle sector of the Vinchina Fm. would not have reached temperatures higher than 55 °C. Multimethod inverse thermal modeling suggests that the AFT ages of all the studied levels would not have been completely reset and allow inferring that the partial retention zone for the AHe system (AHe-PRZ) would have been reached during the Miocene in levels between the Vallecito and Vinchina Fms. Our 1D-modeling results for the Ciénaga del Río Huaco, Puesto la Flecha and Vallecito Fms. show that the maximum temperature would have been reached at ~15 Ma, with a sedimentary thickness of ~2750 m and a heat flow of 65 mW/m2. From these data, a geothermal gradient of ~27 °C/km at this time could be inferred. In turn, the Vinchina and Zapallar Fms. would have reached their maximum temperature at ~2 Ma, under a cooler thermal regime (20 mW/m2) and with an estimated geothermal gradient of <15 °C/km. Thus, a complex time-temperature trajectory is proposed. Maximum and cooling temperatures reached by each unit do not correspond in all cases to the maximum burial and exhumation times. Comparison of the thermal modelling from this work with those carried out by other authors for sections immediately to the north allows us to infer that the thermal regime within the Vinchina basin has important lateral variations. Finally, AFT and AHe analyzes carried out in this work constitute a baseline database of the thermal regime, which is necessary for future multiproxies studies that are being done to evaluate the preservation of primary thermal signals, and thus check their reliability for pealeoclimatic and paleoenvironmental interpretations.Fil: Wunderlin, Cecilia Ayelén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Collo, Gilda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Parra, Mauricio. Universidade de Sao Paulo; BrasilFil: Ezpeleta, Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Sánchez Nassif, Francisco Gabriel Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Flores, Marlene. Universidade de Sao Paulo; BrasilFil: Sobel, Edward Robert. Universitat Potsdam; AlemaniaFil: Glodny, Johannes. Universitat Potsdam; Alemani

    Exhumation and structural evolution of the high-elevation Malcante Range, Eastern Cordillera, NW Argentina

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    As an integral part of the Eastern Cordillera, the fault-bounded Malcante mountain range (up to 5100 m) in the NW Argentine Andes (ca. 25°S) is located in the transition between the arid Puna Plateau to the west and the humid broken foreland to the east. At this latitude, the topographic gradient of the eastern Andean margin forms an efficient orographic barrier that causes pronounced east–west rainfall and surface-process gradients. In this setting, the Malcante Range is an important, yet poorly studied structural high formed during the Cenozoic topographic growth of the Central Andes. In this study, we combine (a) detailed field observations, (b) a two-dimensional structural reconstruction, (c) apatite fission track and (U–Th-Sm)/He thermochronology of bedrock samples from a vertical transect across the western flank of the Malcante Range, and (d) inverse thermal modelling using QTQt software with the aim of deciphering the exhumation history of this mountain range. Field data indicate the presence of an angular unconformity between Cenozoic foreland deposits and older sedimentary strata, suggesting an initial episode of deformation during the middle-late Eocene, while our thermal model constrains the onset of exhumation at ~10 Ma. We suggest that exhumation was related to the unroofing of the easily erodible sedimentary cover, which prevented significant initial surface uplift. This may have changed as more resilient bedrock was exposed at ~5 Ma according to the thermal model, promoting rapid rock uplift. In combination with published data, our thermochronology allows us to speculate on the existence of a zone of deformation concentrated in the area of the present-day Pasha (24.5°S), Malcante (25°S), and Agua de Castilla (25.4°S) mountain ranges by ca. 10 Ma.Fil: Payrola Bosio, Patricio Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Zapata, Matias Sebastian. Smithsonian Tropical Research Institute; Panamá. University of Missouri; Estados UnidosFil: Sobel, Edward Robert. Universitat Potsdam. Mathematisch Nautrwissenschaften Fakultat. Institut für Geowissenschaften; AlemaniaFil: del Papa, Cecilia Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Pingel, Heiko. Universitat Potsdam. Mathematisch Nautrwissenschaften Fakultat. Institut für Geowissenschaften; AlemaniaFil: Glodny, Johannes. German Research Centre for Geosciences; AlemaniaFil: Ledesma, Jonathan Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentin

    Bacterial Vaginosis and the Natural History of Human Papillomavirus

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    Objective. To evaluate associations between common vaginal infections and human papillomavirus (HPV). Study Design. Data from up to 15 visits on 756 HIV-infected women and 380 high-risk HIV-uninfected women enrolled in the HIV Epidemiology Research Study (HERS) were evaluated for associations of bacterial vaginosis, trichomoniasis, and vaginal Candida colonization with prevalent HPV, incident HPV, and clearance of HPV in multivariate analysis. Results. Bacterial vaginosis (BV) was associated with increased odds for prevalent (aOR = 1.14, 95% CI: 1.04, 1.26) and incident (aOR = 1.24, 95% CI: 1.04, 1.47) HPV and with delayed clearance of infection (aHR = 0.84, 95% CI: 0.72, 0.97). Whereas BV at the preceding or current visit was associated with incident HPV, in an alternate model for the outcome of incident BV, HPV at the current, but not preceding, visit was associated with incident BV. Conclusion. These findings underscore the importance of prevention and successful treatment of bacterial vaginosis

    Association between Semen Exposure and Incident Bacterial Vaginosis

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    Objective. To identify correlates of incident bacterial vaginosis (BV) diagnosed with Nugent scoring among high-risk women. Study Design. We conducted both cohort and case-crossover analyses, stratified by HIV infection status, based on 871 HIV-infected and 439 HIV-uninfected participants in the HIV Epidemiology Research Study, conducted in 4 US sites in 1993–2000. Results. BV incidence was 21% and 19% among HIV-infected and -uninfected women, respectively. Fewer correlates of BV were found with case-crossover than with cohort design. Reporting frequent coitus (regardless of consistency of condom use) was correlated with BV in cohort analyses but not in case-crossover analyses. The sole correlate of BV in both types of analyses was the detection of spermatozoa on Gram stain, which is a marker of semen exposure. Conclusion. The inconsistent association between condom use and BV in prior studies could be from reporting bias. We found evidence of a relationship between semen exposure and incident BV
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