2,590 research outputs found
NOSS altimeter algorithm specifications
A description of all algorithms required for altimeter processing is given. Each description includes title, description, inputs/outputs, general algebraic sequences and data volume. All required input/output data files are described and the computer resources required for the entire altimeter processing system were estimated. The majority of the data processing requirements for any radar altimeter of the Seasat-1 type are scoped. Additions and deletions could be made for the specific altimeter products required by other projects
A 94/183 GHz multichannel radiometer for Convair flights
A multichannel 94/183 GHz radiometer was designed, built, and installed on the NASA Convair 990 research aircraft to take data for hurricane penetration flights, SEASAT-A underflights for measuring rain and water vapor, and Nimbus-G underflights for new sea ice signatures and sea surface temperature data (94 GHz only). The radiometer utilized IF frequencies of 1, 5, and 8.75 GHz about the peak of the atmospheric water vapor absorption line, centered at 183.3 GHz, to gather data needed to determine the shape of the water molecule line. Another portion of the radiometer operated at 94 GHz and obtained data on the sea brightness temperature, sea ice signatures, and on areas of rain near the ocean surface. The radiometer used a multiple lens antenna/temperature calibration technique using 3 lenses and corrugated feed horns at 94 GHz and 183 GHz. Alignment of the feed beams at 94 GHz and 183 GHz was accomplished using a 45 deg oriented reflecting surface which permitted simultaneous viewing of the feeds on alternate cycles of the chopping intervals
Research in millimeter wave techniques
The following technical developments are described: (1) a reliable 183 GHz subharmonic mixer, (2) a precision noise figure test setup, (3) the successful deposition of SiO2 on a noncontacting backshort, and (4) sturdier whisker points used for diode contacting
A 94/183 GHz aircraft radiometer system for Project Storm Fury
A radiometer design suitable for use in NASA's WB-57F aircraft to collect data from severe storm regions was developed. The design recommended was a 94/183 GHz scanning radiometer with 3 IF channels on either side of the 183.3 GHz water vapor line and a single IF channel for a low loss atmospheric window channel at 94 GHz. The development and construction of the 94/183 GHz scanning radiometer known as the Advanced Microwave Moisture Sounder (AMMS) is presented. The radiometer scans the scene below the aircraft over an angle of + or - 45 degrees with the beamwidth of the scene viewed of approximately 2 degrees at 94 GHz and 1 degree at 183 GHz. The AMMS data collection system consists of a microcomputer used to store the radiometer data on the flight cartridge recorder, operate the stepper motor driven scanner, and collect housekeeping data such as thermistor temperature readings and aircraft time code
Dynamics of a liquid dielectric attracted by a cylindrical capacitor
The dynamics of a liquid dielectric attracted by a vertical cylindrical
capacitor is studied. Contrary to what might be expected from the standard
calculation of the force exerted by the capacitor, the motion of the dielectric
is different depending on whether the charge or the voltage of the capacitor is
held constant. The problem turns out to be an unconventional example of
dynamics of a system with variable mass, whose velocity can, in certain
circumstances, suffer abrupt changes. Under the hypothesis that the voltage
remains constant the motion is described in qualitative and quantitative
details, and a very brief qualitative discussion is made of the constant charge
case.Comment: To appear in European Journal of Physic
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International survey of Cronobacter sakazakii and other Cronobacter spp. in follow up formulas and infant food
A coordinated survey for Cronobacter and related organisms in powdered infant formula, follow up formula and infant foods was undertaken by 8 laboratories in 7 countries in recognition of and in response to the data needs identified in an FAO/WHO call for data in order to develop global risk management guidance for these products. The products (domestic and imported) were purchased from the local market and were categorised according to their principle ingredients. A total of 290 products were analysed using a standardised procedure of pre-enrichment in 225 ml Buffered Peptone Water (BPW), followed by enrichment in Enterobacteriaceae Enrichment (EE) broth, plating on the chromogenic Cronobacter Druggan–Forsythe–Iversen (DFI) agar and presumptive identification with ID 32 E. Presumptive Cronobacter isolates were identified using 16S rRNA gene sequence analysis. Aerobic plate counts (APC) of the products were also determined on nutrient agar. Fourteen samples had APC > 105 cfu/g, 3 of which contained probiotic cultures. C. sakazakii was isolated from 27 products; 3/91 (3%) follow up formulas (as defined by Codex Alimentarius Commission), and 24/199 (12%) infant foods and drinks. Hence C. sakazakii was less prevalent in follow up formula than other foods given to infants over the same age range. A range of other bacteria were also isolated from follow up formulas, including Acinetobacter baumannii, Enterobacter cloacae, Klebsiella pneumoniae, Citrobacter freundii, and Serratia ficaria. There was significant variation in the reconstitution instructions for follow up formulas. These included using water at temperatures which would enable bacterial growth. Additionally, the definition of follow up formula varied between countries
Sustainability of water resources management in the Indus Basin under changing climatic and socio economic conditions
Pakistan is highly dependent on water resources originating in the mountain sources of the upper Indus for irrigated agriculture which is the mainstay of its economy. Hence any change in available resources through climate change or socio-economic factors could have a serious impact on food security and the environment. In terms of both ratio of withdrawals to runoff and per-capita water availability, Pakistan's water resources are already highly stressed and will become increasingly so with projected population changes. Potential changes to supply through declining reservoir storage, the impact of waterlogging and salinity or over-abstraction of groundwater, or reallocations for environmental remediation of the Indus Delta or to meet domestic demands, will reduce water availability for irrigation. <br><br> The impact of climate change on resources in the Upper Indus is considered in terms of three hydrological regimes – a nival regime dependent on melting of winter snow, a glacial regime, and a rainfall regime dependent on concurrent rainfall. On the basis of historic trends in climate, most notably the decline in summer temperatures, there is no strong evidence in favour of marked reductions in water resources from any of the three regimes. Evidence for changes in trans-Himalayan glacier mass balance is mixed. Sustainability of water resources appears more threatened by socio-economic changes than by climatic trends. Nevertheless, analysis and the understanding of the linkage of climate, glaciology and runoff is still far from complete; recent past climate experience may not provide a reliable guide to the future
Equity of access to renal transplant waiting list and renal transplantation in Scotland: cohort study
Objective To examine the access to the renal transplant waiting list and renal transplantation in Scotland. Design Cohort study. Setting Renal and transplant units in Scotland. Participants 4523 adults starting renal replacement therapy in Scotland between 1 January 1989 and 31 December 1999. Main outcome measures Impact of age, sex, social deprivation, primary renal disease, renal or transplant unit, and geography on access to the waiting list and renal transplantation. Results 1736 of 4523 (38.4%) patients were placed on the waiting list for renal transplantation and 1095 (24.2%) underwent transplantation up to 31 December 2000, the end of the study period. Patients were less likely to be placed on the list if they were female, older, had diabetes, were in a high deprivation category, and were treated in a renal unit in a hospital with no transplant unit. Patients living furthest away from the transplant centre were listed more quickly. The only factors governing access to transplantation once on the list were age, primary renal disease, and year of listing. A significant centre effect was found in access to the waiting list and renal transplantation. Conclusions A major disparity exists in access to the renal transplant waiting list and renal transplantation in Scotland. Comorbidity may be an important factor
Solving the radial Dirac equations: a numerical odyssey
We discuss, in a pedagogical way, how to solve for relativistic wave
functions from the radial Dirac equations. After an brief introduction, in
Section II we solve the equations for a linear Lorentz scalar potential,
V_s(r), that provides for confinement of a quark. The case of massless u and d
quarks is treated first, as these are necessarily quite relativistic. We use an
iterative procedure to find the eigenenergies and the upper and lower component
wave functions for the ground state and then, later, some excited states.
Solutions for the massive quarks (s, c, and b) are also presented. In Section
III we solve for the case of a Coulomb potential, which is a time-like
component of a Lorentz vector potential, V_v(r). We re-derive, numerically, the
(analytically well-known) relativistic hydrogen atom eigenenergies and wave
functions, and later extend that to the cases of heavier one-electron atoms and
muonic atoms. Finally, Section IV finds solutions for a combination of the V_s
and V_v potentials. We treat two cases. The first is one in which V_s is the
linear potential used in Sec. II and V_v is Coulombic, as in Sec. III. The
other is when both V_s and V_v are linearly confining, and we establish when
these potentials give a vanishing spin-orbit interaction (as has been shown to
be the case in quark models of the hadronic spectrum).Comment: 39 pages (total), 23 figures, 2 table
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