Shortcomings in ground testing, environment simulations, and performance predictions for space applications

This paper addresses the issues involved in radiation testing of devices and subsystems to obtain the data that are required to predict the performance and survivability of satellite systems for extended missions in space. The problems associated with space environmental simulations, or the lack thereof, in experiments intended to produce information to describe the degradation and behavior of parts and systems are discussed. Several types of radiation effects in semiconductor components are presented, as for example: ionization dose effects, heavy ion and proton induced Single Event Upsets (SEUs), and Single Event Transient Upsets (SETUs). Examples and illustrations of data relating to these ground testing issues are provided. The primary objective of this presentation is to alert the reader to the shortcomings, pitfalls, variabilities, and uncertainties in acquiring information to logically design electronic subsystems for use in satellites or space stations with long mission lifetimes, and to point out the weaknesses and deficiencies in the methods and procedures by which that information is obtained

Rapid progesterone actions on thymulin-secreting epithelial cells cultured from rat thymus

Many soluble factors of neural, endocrine, paracrine and autocrine origin are present in the thymus and modulate its function. Long-term effects of sex steroids have! been documented for thymocytes and cells of the thymic microenvironment. In this report we examine rapid actions of progesterone upon aspects of epithelial cell physiology. Progesterone (0.1-10 mu M) was applied to cultured thymulin-secreting thymic epithelial cells (TS-TEC) and changes in transmembrane potential, transmembrane current, intracellular calcium levels and thymulin secretion were assessed. Rapid changes in electrophysiology and intracellular calcium provide evidence for a membrane-bound progesterone receptor in these cells, in addition to classical cytoplasmic receptors. Application of progesterone to TS-TEC caused electrophysiological changes in 56% of cells (n = 40), activating an inward current (-24 +/- 9 pA at 1 mu M, n = 7, p < 0.02) and dose-dependent depolarization (7.1 +/- 1.8 mV at 1 mu M, n = 19, p < 0.01). Intracellular calcium levels, monitored by the ratiometric fluorescent calcium indicator fura-2, increased within seconds of progesterone (1 mu M) application. Progesterone(1 mu M) increased thymulin levels in supernatant, as measured by ELISA, above the levels in the preapplication period (142 +/- 16% of the preapplication period, n = 3, p < 0.02). This effect was reduced in the presence of cobalt chloride which blocks voltage-dependent calcium channels. In addition, TS-IEC in culture were immunoreactive to antibody AG7. This antibody was raised to a membrane-bound antigen involved in calcium influx subsequent to progesterone binding in sperm. thus we suggest that progesterone acts upon many aspects of TS-TEC physiology through both cytoplasmic and membrane-bound receptors

Something Was Rotten At Garden Fresh: Tax Evasion And Accounting Fraud At A Produce Wholesaler

Most fraud cases prepared for use in auditing and fraud examination courses involve theft-of-asset or financial statement misstatement types of frauds.  Based on an actual case, we present a situation where the owner of a wholesale produce business, Garden Fresh, adjusted accounting records to evade taxes.  Changes in the produce industry were threatening Garden Fresh’s business, and the owner used funds generated from the tax-evasion fraud to support purchases from the company’s buyers.  In the end, the fraud and business could not be sustained, and Garden Fresh failed.  An important learning objective of the case is to illustrate how journal entries can be used to conceal a fraud, and how understanding accounting is essential for uncovering some frauds.  The Garden Fresh case has been used in an undergraduate auditing class, and assessment results indicate that the case is effective for meeting identified learning objectives.  The case would also be appropriate for use in taxation, fraud examination, forensic accounting, and small business courses at both the undergraduate and graduate levels

Phosphorus solubilization by microorganisms at different stages of soil development

P solubilization is an important process for ecosystem nutrition that is largely driven by soil microorganisms. However, little is known about changes of P solubilization rates and mechanisms during soil formation. Therefore, we investigated P solubilization along a climosequence in the coastal range of Chile. We analysed soil samples from four study areas in order to test the hypotheses that i) higher developed soils in temperate ecosystems show higher rates of P solubilization and silicate weathering as well as higher concentrations of organic acids compared to initially developed soils in dry ecosystems; ii) topsoil horizons reveal higher rates of P solubilization than subsoil horizons; iii) P solubilization is not driven by microbial need for P, but is a side effect of microbial metabolism. To determine the rates and mechanisms of P solubilization as well as the silicate weathering, we conducted several incubation experiments (one month at 15°C) with soil extracts containing soil microorganisms and apatite or saprolite as P sources. In some experiments, a minimal growth medium (glucose + NH4Cl) was used. In others, inorganic P was added additionally in order to test whether P availability affects the P solubilization rate. Inorganic P (Pi), pH, organic acids and Si were measured at regular intervals. Our results show that up to ten times higher rates of P solubilization from the added apatite were observed in the intermediately and highly developed soils compared to the initially developed one. Si-release rates and concentrations of organic acids were higher in the intermediately and highly developed soils compared to the initially developed one. P solubilization from saprolite was small and likely masked by microbial P immobilization. Topsoil horizons generally exhibited higher rates of P solubilization than subsoil horizons and the addition of a readily available P source did not result in substantial decreases of P solubilization rates, indicating that P solubilization was not driven by microbial need for P. We conclude that the capability of microbial communities to solubilize P from apatite and Si release rates are higher at more developed soils. Moreover, our experiments showed that the availability of carbon increased the P solubilization rates

Weekly Gridded Aquarius L-band Radiometer-Scatterometer Observations and Salinity Retrievals over the Polar Regions - Part 2: Initial Product Analysis

Following the development and availability of Aquarius weekly polar-gridded products, this study presents the spatial and temporal radiometer and scatterometer observations at L band (frequency1.4 GHz) over the cryosphere including the Greenland and Antarctic ice sheets, sea ice in both hemispheres, and over sub-Arctic land for monitoring the soil freeze-thaw state. We provide multiple examples of scientific applications for the L-band data over the cryosphere. For example, we show that over the Greenland Ice Sheet, the unusual 2012 melt event lead to an L-band brightness temperature (TB) sustained decrease of 5 K at horizontal polarization. Over the Antarctic ice sheet, normalized radar cross section (NRCS) observations recorded during ascending and descending orbits are significantly different, highlighting the anisotropy of the ice cover. Over sub-Arctic land, both passive and active observations show distinct values depending on the soil physical state (freeze-thaw). Aquarius sea surface salinity (SSS) retrievals in the polar waters are also presented. SSS variations could serve as an indicator of fresh water input to the ocean from the cryosphere, however the presence of sea ice often contaminates the SSS retrievals, hindering the analysis. The weekly grided Aquarius L-band products used a redistributed by the US Snow and Ice Data Center at http:nsidc.orgdataaquariusindex.html, and show potential for cryospheric studies

Prediction and measurement of radiation damage to CMOS devices on board spacecraft

The CMOS Radiation Effects Measurement (CREM) experiment is presently being flown on the Explorer-55. The purpose of the experiment is to evaluate device performance in the actual space radiation environment and to correlate the respective measurements to on-the-ground laboratory irradiation results. The experiment contains an assembly of C-MOS and P-MOS devices shielded in front by flat slabs of aluminum and by a practically infinite shield in the back. Predictions of radiation damage to C-MOS devices are based on standard environment models and computational techniques. A comparison of the shifts in CMOS threshold potentials, that is, those measured in space to those obtained from the on-the-ground simulation experiment with Co-60, indicates that the measured space damage is smaller than predicted by about a factor of 2-3 for thin shields, but agrees well with predictions for thicker shields

Numerical simulation of transom-stern waves

The flow field generated by a transom-stern hullform is a complex, broad-banded, three-dimensional phenomenon marked by a large breaking wave. This unsteady multiphase turbulent flow feature is difficult to study experimentally and simulate numerically. The results of a set of numerical simulations, which use the Numerical Flow Analysis (NFA) code, of the flow around the Model 5673 transom stern at speeds covering both wet- and dry-transom operating conditions are shown in the accompanying fluid dynamics video. The numerical predictions for wet-transom and dry-transom conditions are presented to demonstrate the current state of the art in the simulation of ship generated breaking waves. The interested reader is referred to Drazen et al. (2010) for a detailed and comprehensive comparison with experiments conducted at the Naval Surface Warfare Center Carderock Division (NSWCCD).Comment: Fluid Dynamics Video for 2010 APS Division of Fluid Dynamics Gallery of Fluid Motion include

Miniature High-Let Radiation Spectrometer for Space and Avionics Applications

This paper reports on the design and characterization of a small, low power, and low weight instrument, a High-LET Radiation Spectrometer (HiLRS), that measures energy deposited by heavy ions in microelectronic devices. The HILRS operates on pulse-height analysis principles and is designed for space and avionics applications. The detector component in the instrument is based on large scale arrays of p-n junctions. In this system, the pulse amplitude from a particle hit is directly proportional to the particle LET. A prototype flight unit has been fabricated and calibrated using several heavy ions with varying LETs and protons with several energies. The unit has been delivered to the Ballistic Missile Defense Organization (BMDO) c/o the Air Force Research Laboratory in Albuquerque, NM, for integration into the military Space Technology Research Vehicle (STRV), a US-UK cooperative mission. Another version of HILRS is being prepared for delivery in April to the Hubble Space Telescope (HST) project, to fly on the HST Orbital Systems Test (HOST) Platform on a shuttle mission

On the Fly GPS Tide Measurement along the Saint John River

Conventional tide measurement gives a separate reading at each tide gauge but cannot meet completely with the requirement of precise hydrographic survey for points between tide gauges. The GPS differential technique provides an alternative method for obtaining on-the-fly tides, which can only be achieved by applying latency correction, attitude correction, height transformation, draft correction and finally a data filter.La mediciôn convencional de marea proporciona una lectura separada en cada mareôgrafo pero no puede cumplir totalmente et requerimiento de los levantamientos hidrogrâficos precisos para los puntos que se encuentran entre los mareôgrafos. La técnica de GPS diferencial proporciona un método alternativo para la obtenciôn de mareas "al sobrevueio", que puede ser llevado a cabo ûnicamente aplicando la correcciôn de latencia, la correcciôn de actitudes, la transformation de alturas, la correcciôn de caiado y, finalmente, un filtro de datos.Le mesurage des marées traditionnel permet d'obtenir une lecture séparée à chaque marégraphe mais ne peut pas répondre entièrement aux exigences de levés hydrographiques précis pour les points situés entre les marégraphes. La technique du GPS différentiel fournit une autre méthode d'obtention des marées à la volée qui ne peut être réalisée qu 'en appliquant la correction du temps d'attente, la correction de l'attitude, la transformation des hauteurs, la correction du tirant d'eau et enfin un filtre de données