419 research outputs found

    Inference of the boundary layer structure over the oceans from satellite infrared measurements

    Get PDF
    The characteristics of the boundary layer of the atmosphere over the global oceans between about 50 deg N to 40 deg S were remotely sensed for three different periods, about 3 months each, during the year 1970. The spectral measurements made by Nimbus 4 Infrared Interferometer Spectrometer were used for this purpose

    Rain retrieval method for mesoscale convective systems

    Get PDF
    The analysis of recent high-resolution aircraft observations over the ocean made by radar and passive microwave radiometer reveals significant problems in relating the brightness temperature measurements of the radiometer with the radar-derived rain rates. A predominant cause of this problem is that the information on rain drops contained in the radiometric measurements is contaminated by scattering and emission from other hydrometeors present in the field of view (fov) of the radiometer. Extensive observations of rain rate made by ship-borne radars and by the multichannel Special Sensor Microwave Imager (SSM/I), with a much larger fov, lead to similar conclusions. Considering the variability in the meteorological conditions, and in the hydrometeors spatial distribution, we developed an empirical method to estimate rain rate based on two parameters derived from the SSM/I data, which are related to the convective dynamics. The calibration of this empirical algorithm was performed with radar ground truth for November 1992, available over the TOGA-COARE (Tropical Ocean Global Atmosphere-Coupled Ocean Atmosphere Response Experiment) region. Then the algorithm was applied to the same TOGA-COARE region for the remaining three months available. The comparison between the estimated rain rate and the radar observations gives a correlation coefficient of about 0.85, and the monthly total estimated rainfall has an error of about 13%. This rain retrieval method, tuned for Mesoscale Convective Systems (MCSs), is applicable to the Tropical Rain Measuring Mission (TRMM), where microwave radiometric observations and simultaneous radar observations are available

    Air-sea interaction in the tropical Pacific Ocean

    Get PDF
    Charts of 3-month sea surface temperature (SST) anomalies in the eastern tropical Pacific Ocean were produced for the period 1949 to 1970. The anomalies along the United States and South American west coasts and in the eastern tropical Pacific appeared to be oscillating in phase during this period. Similarly, the satellite-derived cloudiness for each of four quadrants of the Pacific Ocean (130 deg E to 100 deg W, 30 deg N to 25 deg S) appeared to be oscillating in phase. In addition, a global tropical cloudiness oscillation from 30 deg N to 30 deg S was noted from 1965 to 1970, by using monthly satellite television nephanalyses. The SST anomalies were found to have a good degree of correlation both positive and negative with the following monthly geophysical parameters: (1) satellite-derived cloudiness, (2) strength of the North and South Pacific semipermanent anticyclones, (3) tropical Pacific island rainfall, and (4) Darwin surface pressure. Several strong direct local and crossequatorial relationships were noted. In particular, the high degree of correlation between the tropical island rainfall and the SST anomalies (r = +0.93) permitted the derivation of SST's for the tropical Pacific back to 1905. The close occurrence of cold tropical SST and North Pacific 700-mb positive height anomalies with central United States drought conditions was noted

    The Nimbus 4 Infrared Spectroscopy Experiment, IRIS-D. Part 1: Calibrated Thermal Emission Spectra

    Get PDF
    Calibrated infrared emission spectra of earth and atmosphere using high resolution interferometer spectrophotometer on Nimbus 4 satellit

    Control of Progressive Collapse of the Structure Using Shear Wall

    Get PDF
    The vulnerability of reinforced concrete (RC) building systems to progressive collapse has turned out to be a challenging trouble for professionalstructural engineers so as to prevent total failure on account of nearby damage. The goal of this paper is to enhance the knowledge of such buildings’behavior underneath several scenarios of misplaced columns at differentfloor stages, and their capacity for progressive collapse. The homes hadbeen analyzed following the guidelines for progressive collapse evaluation and design organized by means of the general services administrationguidelines (GSA). The progressive collapse of a ten story structure subjected to a simplest gravity load is taken into consideration and the columnhas been eliminated at one place and the spread damage is evaluated. Theprogressive collapse study has been carried out by way of removing thecolumn at a diagnosed crucial locations (at corner, middle and at interior) as in line with GSA guidelines. Static analysis is done using analysisprogram ETABS. For each case, the consequences were taken in terms ofdemand capacity ratio (DCR) at critical section, and as a result the structurehas been assessed for it’s susceptible to progressive collapse. The availability of shear wall is made on the component wherein collapse occurred andDCR values are mentioned. After imparting the shear wall to the structure,the progressive collapse of the structure because of accidental load maybe controlled in order that the GSA guidelines recommended DCR valuewould be within the range

    Radiographic evaluation of tibial component alignment in total knee arthroplasty following extramedullary and intramedullary tibial referencing

    Get PDF
    Background: Long term survivorship of total knee arthroplasty (TKA) is significantly dependant on prostheses alignment. The debate on optimal referencing for femoral component is largely resolved with Intra-medullary jigs reproducing superior alignment. However there is still a contention about whether intramedullary or extramedullary jigs are better for tibial referencing. This study aims to compare the accuracy of tibial component alignment in TKA using intramedullary and extramedullary tibial referencing jigs.Methods: Between December 2012 and September 2014, 66 primary conventional cemented TKAs were performed using Nexgen-LPS Flex (Zimmer) implants in 55 patients, 50-80 y old (mean 65.54 y) with osteoarthritis/rheumatoid arthritis. Intramedullary and extramedullary tibial referencing was used in alternate patients undergoing TKA after excluding patients with BMI >35 kg/m2, knee deformity >150,excessive tibial bowing, previous fractures/surgeries/retained metalwork around knee. Postoperatively, tibial component alignment (TCA) in coronal plane was assessed using AP radiograph of leg. A 3º cutoff from neutral mechanical axis (i.e., 90o±3o) was considered acceptable.Results: The intramedullary group (n=33) had 4 outliers (TCA >93º or <87º) whereas the extramedullary group (n=33) had 7 outliers (p=0.511). The difference in mean TCA between intramedullary and extramedullary groups was not statistically significant [90.70±2.43 and 90.55±2.17 (p=0.790)]. There were no significant per-operative/post-operative complications in either group.Conclusions: We conclude that both intramedullary and extramedullary tibial referencing guides can be used to achieve desired tibial component alignment (90±3º) in TKA. However the surgeon should appreciate the benefits and deficiencies of either types of tibial referencing and use whichever is suited in a particular case.

    Atomistic to continuum model for studying mechanical properties of RNA nanotubes

    Get PDF
    With rapid advancements in the emerging field of RNA nanotechnology, its current and potential applications, new important problems arise in our quest to better understand properties of RNA nanocomplexes. In this paper, our focus is on the modeling of RNA nanotubes which are important for many biological processes. These RNA complexes are also important for human beings, with their theurapeuti- cal and biomedical applications discussed vigorously in the literature over the recent years. Here, we develop a continuum model of RNA nanotubes, originally obtained from self assembly of RNA building blocks in the molecular dynamics simulation. Based on the finite element method, we calculate the elastic properties of these nanostructures and provide a relationship between stress and strain induced in the RNA nanotube. We also analyze the variations in the displacement vector along the assembly axis for RNA nanotubes of different sizes. In particular, we show that os- cillations in the amplitudes of strains and displacements significantly differ for such RNA nanotubes. These findings are discussed in the context of atomistic simulations and experimental results in this field

    Bdellovibrio bacteriovorus Inhibits Staphylococcus aureus Biofilm Formation and Invasion into Human Epithelial Cells

    Get PDF
    Bdellovibrio bacteriovorus HD100 is a predatory bacterium that attacks many Gram-negative human pathogens. A serious drawback of this strain, however, is its ineffectiveness against Gram-positive strains, such as the human pathogen Staphylococcus aureus. Here we demonstrate that the extracellular proteases produced by a host-independent B. bacteriovorus (HIB) effectively degrade/inhibit the formation of S. aureus biofilms and reduce its virulence. A 10% addition of HIB supernatant caused a 75% or greater reduction in S. aureus biofilm formation as well as 75% dispersal of pre-formed biofilms. LC-MS-MS analyses identified various B. bacteriovorus proteases within the supernatant, including the serine proteases Bd2269 and Bd2321. Tests with AEBSF confirmed that serine proteases were active in the supernatant and that they impacted S. aureus biofilm formation. The supernatant also possessed a slight DNAse activity. Furthermore, treatment of planktonic S. aureus with the supernatant diminished its ability to invade MCF-10a epithelial cells by 5-fold but did not affect the MCF-10a viability. In conclusion, this study illustrates the hitherto unknown ability of B. bacteriovorus to disperse Gram-positive pathogenic biofilms and mitigate their virulence.open6

    Chemical Reaction and Radiation Effects on the Hydro-Magnetic Free Convection Flow of Visco-Elastic Fluid along an Infinite Vertical Porous Plate in a Porous Medium

    Get PDF
    An unsteady hydro magnetic laminar free convection heat and mass transfer flow of a visco-elastic, dissipative fluid along an infinite vertical Porous plate through porous medium is analyzed in the presence of chemical reaction and thermal radiation.  The solution of the problem is obtained in the form of power series of  which is very small. Analytical expressions for the velocity, temperature and concentration fields are given, as well as for the skin friction, the rate of heat transfer and the rate of mass transfer coefficient at the plate.  The influence.......
    corecore