Hybrid LZW compression

The Science Data Management and Science Payload Operations subpanel reports from the NASA Conference on Scientific Data Compression (Snowbird, Utah in 1988) indicate the need for both lossless and lossy image data compression systems. The ranges developed by the subpanel suggest ratios of 2:1 to 4:1 for lossless coding and 2:1 to 6:1 for lossy predictive coding. For the NASA Freedom Science Video Processing Facility it would be highly desirable to implement one baseline compression system which would meet both of these criteria. Presented here is such a system, utilizing an LZW hybrid coding scheme which is adaptable to either type of compression. Simulation results are presented with the hybrid LZW algorithm operating in each of its modes

Elastic precursor of the transformation from glycolipid-nanotube to -vesicle

By the combination of optical tweezer manipulation and digital video microscopy, the flexural rigidity of single glycolipid "nano" tubes has been measured below the transition temperature at which the lipid tubules are transformed into vesicles. Consequently, we have found a clear reduction of the rigidity obviously before the transition as temperature increasing. Further experiments of infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) have suggested a microscopic change of the tube walls, synchronizing with the precursory softening of the nanotubes.Comment: 9 pages, 6 figure

Hydrocarbons identified in extracts from estuarine water accommodated no. 2 fuel oil by gas chromatography-mass spectrometry

Results are presented on a computerized gas chromatograph-mass spectrometer analysis of methylene chloride and n-heptane extracts of a No. 2 fuel oil accommodated estuarine water sample. The analytical method is briefly described, and the limitations on the identifications are categorized. Some attempt was made to determine major and trace constituents in the water accommodate. Altogether 66 hydrocarbon compounds were identified specifically, and 75 compounds were partially identified. Seven compounds could be recognized as major constituents of the water accommodated oil and ten were present only as traces. The aromatic compounds found were alkyl benzenes, naphthalene, tetralin, indane, biphenyl, fluorene, anthracene, and some of their alkyl substituted isomers in the range of carbon numbers C7 to C15. Four n-alkanes, C10 to C13, were found along with four other assorted hydrocarbons

NERVA irradiation program. GTR 23, volume 1: Combined effects of reactor radiation and cryogenic temperature on NERVA structural materials

Specimens fabricated from structural materials that were candidates for certain NERVA applications were irradiated in liquid nitrogen (LN2), liquid hydrogen (LH2), water, and air. The specimens irradiated in LN2 were stored in LN2 and finally tested in LN2, or at some higher temperature in a few instances. The specimens irradiated in LH2 underwent an unplanned warmup while in storage so this portion of the test was lost; some specimens were tested in LN2 but none were tested in LH2. The Ground Test Reactor was the radiation source. The test specimens consisted mainly of tensile and fracture toughness specimens of several different materials, but other types of specimens such as tear, flexure, springs, and lubricant were also irradiated. Materials tested include Hastelloy X, Al, Ni steel, steel, Be, ZrC, Ti-6Al-4V, CuB, and Ti-5Al-2.5Sn

Mind the Gap: Another look at the problem of the semantic gap in image retrieval

This paper attempts to review and characterise the problem of the semantic gap in image retrieval and the attempts being made to bridge it. In particular, we draw from our own experience in user queries, automatic annotation and ontological techniques. The first section of the paper describes a characterisation of the semantic gap as a hierarchy between the raw media and full semantic understanding of the media's content. The second section discusses real users' queries with respect to the semantic gap. The final sections of the paper describe our own experience in attempting to bridge the semantic gap. In particular we discuss our work on auto-annotation and semantic-space models of image retrieval in order to bridge the gap from the bottom up, and the use of ontologies, which capture more semantics than keyword object labels alone, as a technique for bridging the gap from the top down

Dynamical matrix of two-dimensional electron crystals

In a quantizing magnetic field, the two-dimensional electron (2DEG) gas has a rich phase diagram with broken translational symmetry phases such as Wigner, bubble, and stripe crystals. In this paper, we derive a method to get the dynamical matrix of these crystals from a calculation of the density response function performed in the Generalized Random Phase Approximation (GRPA). We discuss the validity of our method by comparing the dynamical matrix calculated from the GRPA with that obtained from standard elasticity theory with the elastic coefficients obtained from a calculation of the deformation energy of the crystal.Comment: Revised version published in Phys. Rev. B. 12 pages with 11 postscripts figure

Viking orbiter stereo imaging catalog

The extremely long mission of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of these photos can be used to form stereo images allowing the student of Mars to examine a subject in three dimensional. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set

Maternal and perinatal outcome in severe preeclampsia and eclampsia at the Rivers State university teaching hospital, Nigeria

Background: Severe preeclampsia and eclampsia remain a challenge in tropical obstetric practice. It is a major contributor to feto-maternal morbidity and mortality in developing countries. This study seeks to determine the prevalence, associated risk factors and the feto-maternal outcome of severe preeclampsia and eclampsia at the rivers state university teaching hospital (RSUTH).Method: A retrospective study of all women who had severe preeclampsia and eclampsia and were delivered at the RSUTH in a two-year period, 1ST January 2018 to 31ST December 2019, was carried out. Data on patients’ age, parity, education, booking status, gestational age at delivery, diagnosis, complications, mode of delivery and fetal sex, birth weight and Apgar scores were retrieved using structured pro-forma. Data were analyzed using SPSS version 20.Results: There were 4496 deliveries of which 128 had severe preeclampsia and eclampsia, giving a prevalence of 2.85%. Of these, 94 (73.4%) had severe preeclampsia and 34 (26.6%) had eclampsia. The mean age of the women ± SD was 29.84±5.44 years, median parity was para 1, and mean gestational age ± SD was 35.38±3.84 weeks. There were 10 maternal deaths giving case fatality of 7.8%. The mean birth weight ± SD was 2.61±0.91 kg and stillborn rate was 14.4%. There was significant association with maternal age, education, booking status, method of delivery and Apgar score of the baby.Conclusion: The prevalence in this study is high with associated high maternal mortality and stillborn rates. Timely and appropriate intervention including primary management and judicious termination of pregnancy will reduce mortality of mother and fetus

Ermakov-Lewis angles for one-parameter supersymmetric families of Newtonian free damping modes

We apply the Ermakov-Lewis procedure to the one-parameter damped modes \tilde{y} recently introduced by Rosu and Reyes, which are related to the common Newtonian free damping modes y by the general Riccati solution [H.C. Rosu and M. Reyes, Phys. Rev. E 57, 4850 (1998), physics/9707019]. In particular, we calculate and plot the angle quantities of this approach that can help to distinguish these modes from the common y modesComment: 6 pages, twocolumn, 18 figs embedded, only first 9 publishe