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1.
Rev Sci Instrum ; 88(3): 034702, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28372400

ABSTRACT

This paper presents the principal considerations when designing DC-DC converters for space instruments, in particular for the power converter module as part of the first European space laser altimeter: "BepiColombo Laser Altimeter" on board the European Space Agency-Japan Aerospace Exploration Agency (JAXA) mission BepiColombo. The main factors which determine the design of the DC-DC modules in space applications are printed circuit board occupation, mass, DC-DC converter efficiency, and environmental-survivability constraints. Topics included in the appropriated DC-DC converter design flow are hereby described. The topology and technology for the primary and secondary stages, input filters, transformer design, and peripheral components are discussed. Component selection and design trade-offs are described. Grounding, load and line regulation, and secondary protection circuitry (under-voltage, over-voltage, and over-current) are then introduced. Lastly, test results and characterization of the final flight design are also presented. Testing of the inrush current, the regulated output start-up, and the switching function of the power supply indicate that these performances are fully compliant with the requirements.

2.
Science ; 355(6332): 1392-1395, 2017 03 31.
Article in English | MEDLINE | ID: mdl-28325842

ABSTRACT

The Rosetta spacecraft spent ~2 years orbiting comet 67P/Churyumov-Gerasimenko, most of it at distances that allowed surface characterization and monitoring at submeter scales. From December 2014 to June 2016, numerous localized changes were observed, which we attribute to cometary-specific weathering, erosion, and transient events driven by exposure to sunlight and other processes. While the localized changes suggest compositional or physical heterogeneity, their scale has not resulted in substantial alterations to the comet's landscape. This suggests that most of the major landforms were created early in the comet's current orbital configuration. They may even date from earlier if the comet had a larger volatile inventory, particularly of CO or CO2 ices, or contained amorphous ice, which could have triggered activity at greater distances from the Sun.

3.
Science ; 327(5962): 190-3, 2010 Jan 08.
Article in English | MEDLINE | ID: mdl-20056887

ABSTRACT

The European Space Agency's Rosetta mission encountered the main-belt asteroid (2867) Steins while on its way to rendezvous with comet 67P/Churyumov-Gerasimenko. Images taken with the OSIRIS (optical, spectroscopic, and infrared remote( )imaging system) cameras on board Rosetta show that Steins is an oblate body with an effective spherical diameter of 5.3 kilometers. Its surface does not show color variations. The morphology of Steins is dominated by linear faults and a large 2.1-kilometer-diameter crater near its south pole. Crater counts reveal a distinct lack of small craters. Steins is not solid rock but a rubble pile and has a conical appearance that is probably the result of reshaping due to Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) spin-up. The OSIRIS images constitute direct evidence for the YORP effect on a main-belt asteroid.

4.
Neuroimage ; 47 Suppl 2: T5-9, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19362154

ABSTRACT

UNLABELLED: A proof-of-concept study was done to determine whether an electronic nose developed for air quality monitoring at the Jet Propulsion Laboratory (JPL) could be used to distinguish between the odors of organ and tumor tissues, with an eye to using such a device as one of several modes in multi-modal imaging and tumor differentiation during surgery. HYPOTHESIS: We hypothesized that the JPL electronic nose (ENose) would be able to distinguish between the odors of various organ and tumor tissues. MATERIALS AND METHODS: The odor signatures, or array response, of two organs, chicken heart and chicken liver, and cultured glioblastoma and melanoma tumor cell lines were recorded using the JPL Electronic Nose. The overall array responses were compared to determine whether they were sufficiently different to allow the organs and cell lines to be identified by their array responses. RESULTS: The ENose was able to distinguish between the two types of organ tissue and between the two types of tumor cell lines. The variation in array response for the organ tissues was 19% and between the two types of cultured cell lines was 22%. CONCLUSION: This study shows that it is possible to use an electronic nose to distinguish between two types of tumor cells and between two types of organ tissue. As we conducted the experiment with a sensor array built for air quality monitoring rather than for medical purposes, it may be possible to select an array that is optimized to distinguish between different types of cells and organ tissues. Further focused studies are needed to investigate the odor signatures of different cells as well as cellular proliferation, growth, differentiation and infiltration.


Subject(s)
Brain Neoplasms/diagnosis , Electronics , Glioblastoma/diagnosis , Melanoma/diagnosis , Odorants , Animals , Brain Neoplasms/physiopathology , Cell Line, Tumor , Cells, Cultured , Chickens , Electronics/instrumentation , Glioblastoma/physiopathology , Heart/physiology , Humans , Liver/physiology , Melanoma/physiopathology , Pilot Projects
5.
Biochim Biophys Acta ; 1396(2): 148-52, 1998 Mar 09.
Article in English | MEDLINE | ID: mdl-9540829

ABSTRACT

The single sspE genes coding for gamma-type small, acid-soluble spore proteins (SASP) of three round-spore-forming bacteria, Bacillus aminovorans, Sporosarcina halophila and S. ureae, have been cloned and sequenced. While the deduced amino acid sequences of these three gamma-type SASP show clear homology to those from six Bacillus species that do not form round spores, there are no residues conserved completely among the 9 sequences known. In addition, the 139 residue B. aminovorans protein is 35 residues larger than any other while the 60 residue S. halophila protein is one of the smallest. These data suggest that the sspE genes have been under little selective pressure in recent evolutionary time.


Subject(s)
Bacterial Proteins/genetics , Genes, Bacterial , Gram-Positive Endospore-Forming Bacteria/genetics , Sigma Factor , Transcription Factors , Amino Acid Sequence , Bacillus/genetics , Base Sequence , Molecular Sequence Data , Phylogeny , Repetitive Sequences, Nucleic Acid , Spores, Bacterial
6.
Adv Space Res ; 17(12): 157-60, 1996.
Article in English | MEDLINE | ID: mdl-11542251

ABSTRACT

We compute the input of meteoric materials expected on Titan, and integrate this dust model with an ablation model and a comprehensive chemical model, investigating the effects on the atmosphere and surface. We find that a water deposition of approximately 10-100 times the expected interplanetary dust flux, or a recent large impact, is required to produce the observed CO2 abundance. Ionisation due to meteoric activity is not likely to be higher than that due to other sources.


Subject(s)
Atmosphere/chemistry , Cosmic Dust , Meteoroids , Models, Chemical , Models, Theoretical , Saturn , Atmosphere/analysis , Carbon Dioxide/analysis , Carbon Dioxide/chemistry , Electrons , Extraterrestrial Environment , Silicates/analysis
7.
Rev Invest Clin ; 47(4): 297-302, 1995.
Article in Spanish | MEDLINE | ID: mdl-8525132

ABSTRACT

The ablation of cardiac arrhythmias by radiofrequency has changed radically the treatment of arrhythmias. We present the case of a woman with cirrhosis and no structural heart disease, who was severely limited in her activities because of drug-refractory paroxysmal supraventricular tachyarrhythmias. She underwent an atrio-ventricular node ablation by radiofrequency. She was discharged with no antiarrhythmic drugs and on a permanent cardiac pacing. She showed obvious improvement in her quality of life.


Subject(s)
Atrioventricular Node/surgery , Catheter Ablation , Liver Cirrhosis/complications , Tachycardia, Paroxysmal/surgery , Tachycardia, Supraventricular/surgery , Bundle-Branch Block/complications , Cardiac Pacing, Artificial , Electrocardiography , Female , Heart Block/complications , Hepatitis C/complications , Humans , Middle Aged
8.
Arch Inst Cardiol Mex ; 47(1): 95-100, 1977.
Article in Spanish | MEDLINE | ID: mdl-883868

ABSTRACT

In the patient in a critical state there are numerous conditions which alter the COP (Coloidosmotic pressure), which is important for the exchange of liquids at the capillary level of the entire organism. As a consequence for these changes, problems occur with the accumulation of water in the intersticia and a malfunction of organs. A device to measure the COP in a reliable, rapid, and economical form is described. Its simple operation is of great use in the intensive care units for the rapid diagnosis and adequate management of the alterations in the water balance of the critical patient.


Subject(s)
Colloids , Manometry/instrumentation , Water-Electrolyte Imbalance/diagnosis , Humans , Methods , Osmotic Pressure
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