1,156 research outputs found
A simplified method for calculating the atmospheric heating rate by absorption of solar radiation in the stratosphere and mesosphere
Calculations of the atmospheric heating rate by absorption of solar radiation by O3, H2O, and CO2 are reported. The method needs only seven parameters for each molecule and is particularly useful for heating calculations in three-dimensional global circulation models below 80 km. Applying the formula to the observed distributions of O3, H2O, and CO2 produces reasonable latitudinal and seasonal variations in the heating rate. The calculated heating rate, however, is sensitive to the global distributions of the absorbing gases, and uncertainties in the O3 distribution above approximately 50 km and the H2O distribution below approximately 20 km may seriously affect the global distributions of the heating rate in these regions
Simplified methods for calculating photodissociation rates
Simplified methods for calculating the transmission of solar UV radiation and the dissociation coefficients of various molecules are compared. A significant difference sometimes appears in calculations of the individual band, but the total transmission and the total dissociation coefficients integrated over the entire SR (solar radiation) band region agree well between the methods. The ambiguities in the solar flux data affect the calculated dissociation coefficients more strongly than does the method. A simpler method is developed for the purpose of reducing the computation time and computer memory size necessary for storing coefficients of the equations. The new method can reduce the computation time by a factor of more than 3 and the memory size by a factor of more than 50 compared with the Hudson-Mahle method, and yet the result agrees within 10 percent (in most cases much less) with the original Hudson-Mahle results, except for H2O and CO2. A revised method is necessary for these two molecules, whose absorption cross sections change very rapidly over the SR band spectral range
Integration of geological and seismological data for the analysis of seismic hazard: A case study of Japan
Seismic hazard analyses are associated with large uncertainties when historical data are insufficient to define secular rates of seismicity. Such uncertainties may be decreased with geological data in areas where seismicity is shallow and produced by Quaternary faulting. To illustrate, we examine intraplate Japan. Large intraplate earthquakes in Japan characteristically produce surface ruptures along mappable Quaternary faults and show a systematic relation between seismic moment, M_0 and rupture length I (log M_0 = 23.5 + 1.94 × log I). It is observed that, within the bounds placed by geologically assessed slip rates, the mean regional moment release rate M_0 resulting from slip on mapped Quaternary faults is in accord with estimates of M_0 determined with the 400-yr record of seismicity. Recent work also shows that when the repeat time T of earthquakes on Quaternary faults in southwest Japan is assumed to equal M_0/M_0^g (where M_0 is estimated for rupture extended over the entire fault length and M_0^g is the geologically assessed moment release rate of each fault), the moment frequency distribution of earthquakes predicted from the geologic record is virtually identical to that seen with the 400-yr record of seismicity. These observations indicate that the geologic record of Quaternary fault offsets contains sufficient information to predict both the spatial and size distribution of intraplate earthquakes in Japan. A contour map of the average recurrence time of ground shaking of JMA intensity ≧V is thus computed using an empirical relation between seismic moment and the areal distribution of seismic intensity and assuming that the repeat time T of earthquakes on each Quaternary fault equals M_0/M_0^g. The map demonstrates how Quaternary fault data may be used to assess long-term seismic hazard in areas of active faulting where historical records of seismicity are relatively short or absent. Another shortcoming of conventional seismic hazard analysis is that hazard is not considered a function of the time since each fault in a region last ruptured. A simple procedure is used to demonstrate how the time-dependent nature of the earthquake cycle affects the evaluation of seismic hazard. The distribution of seismic shaking characteristic of large interplate earthquakes offshore of Japan is estimated from published isoseismal maps. The observed average repeat times of ruptures along specific segments of the plate boundaries then provide the basis to make probabilistic estimates of the next expected time of seismic shaking due to plate boundary earthquakes. When data are too few to document the average repeat times of rupture, the estimates of probability are calculated with data relating to the relative coseismic slip during past earthquakes and the rate of interseismic strain accumulation, interpreted within the framework of the time predictable model of earthquake occurrence. Results are displayed as maps of instantaneous seismic hazard: the probability that seismic shaking will occur conditional to knowledge of where in time each fault in a region presently resides with respect to the earthquake cycle
The NASA Ames Research Center one- and two-dimensional stratospheric models. Part 2: The two-dimensional model
The two-dimensional model of stratospheric constituents is presented in detail. The derivation of pertinent transport parameters and the numerical solution of the species continuity equations, including a technique for treating the stiff differential equations that represent the chemical kinetic terms, and appropriate methods for simulating the diurnal variations of the solar zenith angle and species concentrations are discussed. Predicted distributions of tracer constituents (ozone, carbon 14, nitric acid) are compared with observed distributions
Fluorophotometry as a diagnostic tool for the evaluation of dry eye disease
BACKGROUND: Dry eye disease is a common debilitating ocular disease. Current diagnostic tests used in dry eye disease are often neither sensitive nor reproducible, making it difficult to accurately diagnose and determine end points for clinical trials, or evaluate the usefulness of different medications in the treatment of dry eye disease. The recently developed fluorophotometer can objectively detect changes in the corneal epithelium by quantitatively measuring its barrier function or permeability. The purpose of the study is to investigate the use of corneal fluorescein penetration measured by the fluorophotometer as a diagnostic tool in the evaluation of dry eye patients. METHODS: Dry eye patients (16 eyes), who presented with a chief complaint of ocular irritation corresponding with dry eye, low Schirmer's one test (<10 mm after 5 minutes) and corneal fluorescein staining score of more than two, were included in the study. Normal subjects (16 eyes), who came for refraction error evaluation, served as controls. Institutional Review Board (IRB) approved consent was obtained before enrolling the subjects in the study and all questions were answered while explaining the risks, benefits and alternatives. All Fluorophotometry of the central corneal epithelium was done utilizing the Fluorotron Master (TradeMark). Each eye had a baseline fluorescein scan performed, after which 50 l of 1% sodium fluorescein dye was instilled. Three minutes later, the fluorescein was washed with 50 ml of normal saline. Fluorescein scans were then started immediately after washing and were recorded at 10, 20, 40, and 60 minutes thereafter. The corneal peak values of fluorescein concentration were recorded within the central cornea in both dry eyes and in controls. RESULTS: Ten minutes after fluorescein installition, patients with dry eye disease averaged a five-fold increase in corneal tissue fluorescein concentration (mean = 375.26 ± 202.67 ng/ml) compared with that of normal subjects (mean = 128.19 ± 85.84 ng/ml). Sixty minutes after dye installation, patients with dry eye disease still revealed higher corneal tissue fluorescein concentration (mean = 112.87 ± 52.83 ng/ml) compared with that of controls (mean = 40.64 ± 7.96 ng/ml), averaging a three-fold increase. CONCLUSION: Patients with dry eye disease demonstrated an increased corneal permeability and a slower rate of elimination to topically administered fluorescein when measured by the fluorophotometer. This suggests that fluorophotometry may serve as a valuable quantitative and objective tool for the diagnosis of dry eye disease, and in following patients' response to new treatment modalities. Fluorophotometry may serve as an objective non-invasive tool for end-point analysis in clinical trials of new treatments for dry eye disease
Mineralogía, geoquímica y algunos aspectos genéticos de la mina El Diamante- Nariño (Colombia).
The Diamante mine is located in the southwestern part of Colombia on the west flank of the Occidental Andes Cordillera. The fluid associated with gold mineralization has a range of salinity between 1.7 to 5.8 wt % NaCl equivalent. Densities vary from 0.58 to 0.92 g/cc. Homogenization temperature averages range between 228-340°C. d34Spyrite values of –7.1 to –5.3‰ and d34SSS = -5.7‰ suggest a mixing of sulfur with sedimentary and magmatic origin. The d18O and dD values for the fluids are 7.6 to 9.6‰ and -74 to -83‰, respectively. The isotopic and fluid inclusion data of ore fluids suggest that the gold mineralization at the Diamante mine may have evolved from mixing of magmatic and meteoric fluids possibly related to intrusion of the nearby Piedrancha Granodiorite of late Miocene age. The gold deposition is attributed to destabilization of the bisulfide complex as a result of decrease of the sulfur activity, through sulfide deposition and/or H2S loss.La mina El Diamante, localizada en la parte Suroccidental de Colombia, se encuentra compuesta por venas cuarzosas enriquecidas en oro. Análisis de inclusiones fluidas, han permitido establecer que el fluido asociado con la mineralización tiene un rango que varía entre 1.7 a 5.8 NaCl equivalente en peso, con un rango de temperatura de homogeneización entre 228-340°C. Los valores de d34Spyrite obtenidos con Isótopos estables de - 7.1 a - 5.3‰ y el valor de d34SSS = -5.7‰ indican para el azufre un origen mixto: sedimentario y magmático. Los valores de d18O y dD de los fluidos fluctúan entre 7.6 a 9.6‰ y -74 a - 83‰ respectivamente. Los datos de isótopos e inclusiones fluidas sugieren que la mineralización aurífera de la mina El Diamante se desarrolló a partir de la mezcla de aguas meteóricas con aguas magmáticas, y posiblemente relacionada a la intrusión del Stock de Piedrancha de edad Mioceno Tardío. La deposición del oro es atribuida a la desestabilización del complejo bisulfuro, como resultado de la disminución de actividad del azufre a través de la deposición y/o perdida de H2S
Mineralogía, geoquímica y algunos aspectos genéticos de la mina El Diamante- Nariño (Colombia).
The Diamante mine is located in the southwestern part of Colombia on the west flank of the Occidental Andes Cordillera. The fluid associated with gold mineralization has a range of salinity between 1.7 to 5.8 wt % NaCl equivalent. Densities vary from 0.58 to 0.92 g/cc. Homogenization temperature averages range between 228-340°C. d34Spyrite values of –7.1 to –5.3‰ and d34SSS = -5.7‰ suggest a mixing of sulfur with sedimentary and magmatic origin. The d18O and dD values for the fluids are 7.6 to 9.6‰ and -74 to -83‰, respectively. The isotopic and fluid inclusion data of ore fluids suggest that the gold mineralization at the Diamante mine may have evolved from mixing of magmatic and meteoric fluids possibly related to intrusion of the nearby Piedrancha Granodiorite of late Miocene age. The gold deposition is attributed to destabilization of the bisulfide complex as a result of decrease of the sulfur activity, through sulfide deposition and/or H2S loss.La mina El Diamante, localizada en la parte Suroccidental de Colombia, se encuentra compuesta por venas cuarzosas enriquecidas en oro. Análisis de inclusiones fluidas, han permitido establecer que el fluido asociado con la mineralización tiene un rango que varía entre 1.7 a 5.8 NaCl equivalente en peso, con un rango de temperatura de homogeneización entre 228-340°C. Los valores de d34Spyrite obtenidos con Isótopos estables de - 7.1 a - 5.3‰ y el valor de d34SSS = -5.7‰ indican para el azufre un origen mixto: sedimentario y magmático. Los valores de d18O y dD de los fluidos fluctúan entre 7.6 a 9.6‰ y -74 a - 83‰ respectivamente. Los datos de isótopos e inclusiones fluidas sugieren que la mineralización aurífera de la mina El Diamante se desarrolló a partir de la mezcla de aguas meteóricas con aguas magmáticas, y posiblemente relacionada a la intrusión del Stock de Piedrancha de edad Mioceno Tardío. La deposición del oro es atribuida a la desestabilización del complejo bisulfuro, como resultado de la disminución de actividad del azufre a través de la deposición y/o perdida de H2S
Properties of Proton Pumping in Response to Blue Light and Fusicoccin in Guard Cell Protoplasts Isolated from Adaxial Epidermis of Vicia Leaves
The Arabidopsis PHYTOCHROME KINASE SUBSTRATE2 protein is a phototropin signaling element that regulates leaf flattening and leaf positioning.
In Arabidopsis (Arabidopsis thaliana), the blue light photoreceptor phototropins (phot1 and phot2) fine-tune the photosynthetic status of the plant by controlling several important adaptive processes in response to environmental light variations. These processes include stem and petiole phototropism (leaf positioning), leaf flattening, stomatal opening, and chloroplast movements. The PHYTOCHROME KINASE SUBSTRATE (PKS) protein family comprises four members in Arabidopsis (PKS1-PKS4). PKS1 is a novel phot1 signaling element during phototropism, as it interacts with phot1 and the important signaling element NONPHOTOTROPIC HYPOCOTYL3 (NPH3) and is required for normal phot1-mediated phototropism. In this study, we have analyzed more globally the role of three PKS members (PKS1, PKS2, and PKS4). Systematic analysis of mutants reveals that PKS2 (and to a lesser extent PKS1) act in the same subset of phototropin-controlled responses as NPH3, namely leaf flattening and positioning. PKS1, PKS2, and NPH3 coimmunoprecipitate with both phot1-green fluorescent protein and phot2-green fluorescent protein in leaf extracts. Genetic experiments position PKS2 within phot1 and phot2 pathways controlling leaf positioning and leaf flattening, respectively. NPH3 can act in both phot1 and phot2 pathways, and synergistic interactions observed between pks2 and nph3 mutants suggest complementary roles of PKS2 and NPH3 during phototropin signaling. Finally, several observations further suggest that PKS2 may regulate leaf flattening and positioning by controlling auxin homeostasis. Together with previous findings, our results indicate that the PKS proteins represent an important family of phototropin signaling proteins
- …