Coastal sea level measurements using a single geodetic GPS receiver

This paper presents a method to derive local sea level variations using data from a single geodetic-quality Global Navigation Satellite System (GNSS) receiver using GPS (Global Positioning System) signals. This method is based on multipath theory for specular reflections and the use of Signal-to-Noise Ratio (SNR) data. The technique could be valuable for altimeter calibration and validation. Data from two test sites, a dedicated GPS tide gauge at the Onsala Space Observatory (OSO) in Sweden and the Friday Harbor GPS site of the EarthScope Plate Boundary Observatory (PBO) in USA, are analyzed. The sea level results are compared to independently observed sea level data from nearby and in situ tide gauges. For OSO, the Root-Mean-Square (RMS) agreement is better than 5 cm, while it is in the order of 10 cm for Friday Harbor. The correlation coefficients are better than 0.97 for both sites. For OSO, the SNR-based results are also compared with results from a geodetic analysis of GPS data of a two receivers/antennae tide gauge installation. The SNR-based analysis results in a slightly worse RMS agreement with respect to the independent tide gauge data than the geodetic analysis (4.8 cm and 4.0 cm, respectively). However, it provides results even for rough sea surface conditions when the two receivers/antennae installation no longer records the necessary data for a geodetic analysis.     

Monitoring coastal sea level using reflected GNSS signals

A continuous monitoring of coastal sea level changes is important for human society since it is predicted that up to 332 million people in coastal and low-lying areas will be directly affected by flooding from sea level rise by the end of the 21st century. The traditional way to observe sea level is using tide gauges that give measurements relative to the Earth’s crust. However, in order to improve the understanding of the sea level change processes it is necessary to separate the measurements into land surface height changes and sea surface height changes. These measurements should then be relative to a global reference frame. This can be done with satellite techniques, and thus a GNSS-based tide gauge is proposed. The GNSS-based tide gauge makes use of both GNSS signals that are directly received and GNSS signals that are reflected from the sea surface. An experimental installation at the Onsala Space Observatory (OSO) shows that the reflected GNSS signals have only about 3 dB less signal-to-noise-ratio than the directly received GNSS signals. Furthermore, a comparison of local sea level observations from the GNSS-based tide gauge with two stilling well gauges, located approximately 18 and 33 km away from OSO, gives a pairwise root-mean-square agreement on the order of 4 cm. This indicates that the GNSS-based tide gauge gives valuable results for sea level monitoring.     

Stable carbon isotope fractionation in the search for life on early Mars.

Isotopic measurements and, more specifically, ratios of 13C to 12C in organic relative to inorganic deposits, are useful in reconstructing past biological activity on Earth. Organic matter has a lower ratio of 13C to 12C due largely to the preferential fixation of 12C over the heavier isotope by the major carbon-fixation enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase, although other factors (e.g., availability of source carbon, fixation by other carboxylating enzymes and diagenesis of organic material) also contribute to fractionation. Would carbon isotope discrepancies between inorganic and organic carbon indicate past biological activity on Mars? In order to answer this question, we analyse what is known about terrestrial biologic and abiologic carbon fixation and its preservation in the fossil record, and suggest what the isotope discrimination during possible biologic and abiologic carbon fixation on Mars might have been like. Primarily because isotopic signatures of abiotically fixed carbon overlap with those of biotic fixation, but also because heterotrophy does not significantly alter the isotopic signature of ingested carbon, fractionation alone would not be definitive evidence for life. However, a narrow range of fractionation, including no fractionation, would suggest biotic processes. Never-the-less, isotopic ratios in organic deposits on Mars would be extremely useful in analysing prebiotic, if not biotic, carbon transformations on Mars.     

Virus protein assembly in microgravity.

The coat of polyomavirus is composed of three proteins that can self-assemble to form an icosahedral capsid. VP1 represents 75% of the virus capsid protein and the VP1 capsomere subunits are capable of self assembly to form a capsid-like structure. Ground-based and orbiter studies were conducted with VP1 protein cloned in an expression vector and purified to provide ample quantities for capsomere-capsid assembly. Flight studies were conducted on STS-37 on April 5-9, 1991. Assembly initiated when a VP1 protein solution was interfaced with a Ca+2 buffer solution (pH 5.0). After four days a second alignment terminated the assembly process and allowed for glutaraldehyde fixation. Flight and ground-based samples were analyzed by electron microscopy. Ground-based experiments revealed the assembly of VP1 into capsid-like structures and a heterogenous size array of capsomere subunits. Samples reacted in microgravity, however, showed capsomeres of a homogenous size, but lack of capsid-like assembly.     

No correlation between multilamellar bodies in the inner ear and further organs of mutant (backstroke, bks) and wildtype zebrafish embryos.

The origin of the proteinacious matrix of the inner ear stones (otoliths) of vertebrates has not yet been clarified. Using the backstroke mutant (bks) of the zebrafish Danio rerio, which is characterized by a complete lack of otoliths, we searched for possibly missing or aberrant structural components within the macular epithelia of the inner ears of embryos on the ultrastructural level. Numerous multilamellar bodies (MLBs) were found. The MLBs were, however, not restricted to the inner ears of mutants but were also found in wildtype individuals and in further organs such as brain and liver. MLBs have hitherto never been described from the inner ear of fish and are generally estimated to be rare structures. Their occurrence in fish liver can, however, be induced by using particular chemical substances, which seem to effect adaptive compensatory processes on the cellular level. Such a chemical treatment also affects the ultrastructure of further organelles. Since the occurrence of MLBs in the liver of zebrafish was not accompanied by an alteration of the morphology of other organelles, their occurrence seems not to be due to environmental stress. The findings indicate that the MLBs cannot be correlated with bks-inherent features as well as with missing otolith development/growth. Since the occurrence of MLBs was independent from the developmental stage of a specimen and its overall tissue preservation, it can moreover be excluded that these MLBs merely represent fixation artifacts. Their presence more likely indicates cellular remodelling processes of hitherto unknown significance.     

Changes in vacuolation in the root apex cells of soybean seedlings in microgravity.

Changes in the vacuolation in root apex cells of soybean (Glycine max L. [Merr.]) seedlings grown in microgravity were investigated. Spaceflight and ground control seedlings were grown in the absence or presence of KMnO4 (to remove ethylene) for 6 days. After landing, in order to study of cell ultrastructure and subcellular free calcium ion distribution, seedling root apices were fixed in 2.5% (w/v) glutaraldehyde in 0.1 M cacodylate buffer and 2% (w/v) glutaraldehyde, 2.5% (w/v) formaldehyde, 2% (w/v) potassium antimonate K[Sb(OH)6] in 0.1 M K2HPO4 buffer with an osmolarity (calculated theoretically) of 0.45 and 1.26 osmol. The concentrations of ethylene in all spaceflight canisters were significantly higher than in the ground control canisters. Seedling growth was reduced in the spaceflight-exposed plants. Additionally, the spaceflight-exposed plants exhibited progressive vacuolation in the root apex cells, particularly in the columella cells, to a greater degree than the ground controls. Plasmolysis was observed in columella cells of spaceflight roots fixed in solutions with relatively high osmolarity (1.26 osmol). The appearance of plasmolysis permitted the evaluation of the water status of cells. The water potential of the spaceflight cells was higher than the surrounding fixative solution. A decrease in osmotic potential and/or an increase in turgor potential may have induced increases in cell water potential. However, the plasmolysed (i.e. non-turgid) cells implied that increases in water potential were accompanied with a decrease in osmotic potential. In such cells changes in vacuolation may have been involved to maintain turgor pressure or may have been a result of intensification of other vacuolar functions like digestion and storage.     

行星际南向磁场事件与强磁暴

利用１９７８－１９８８年期间的太阳风和地磁资料对行星际磁场（ＩＭＦ）南向分量Ｂｓ事件（即Ｂｓ〉１０ｎＴ及其所驱动的错向电场ＶＢｓ〉５ｍＶ／ｍ、持续时间△Ｔ〉３ｈ的事件）与弱磁暴（Ｄｓｔ≤－１００ｎＴ）关系进行了分析。结果表明,１００％的Ｂｓ事件能能引起磁暴的发生,但其中只有８４％为强磁暴;强磁暴的发生都与较强的ＩＭＦ Ｂｓ活动密切相关,但只有６８％的强磁共伴随Ｂｓ事件而发生;Ｂｓ事件与强磁暴并不是     

Biological modulation of the terrestrial carbon cycle: Isotope clues to early organic evolution

The characteristic difference of some 20 to 30 ‰ in the ¹³C/¹²C rations of reduced (organic) and oxidized (carbonate) carbon as observed in the contemporary environment can be traced back over 3.5 (if not 3.8) Ga of recorded Earth history. There is little doubt that the enrichment of isotopically light carbon in fossil organic matter ultimately derives from the bias in favor of ¹²C during photosynthetic carbon fixation (notably the RuBP carboxylase reaction of the Calvin cycle). Accordingly, the mainstream of the sedimentary δ ¹³C_org record can be most reasonably explained as geochemical evidence of the isotope-discriminating properties of the principal CO₂-fixing enzymatic reaction of the assimilatory pathway, thus giving eloquent testimony to an extreme degree of evolutionary conservatism in the biochemistry of autotrophic carbon fixation.     

Experiments with small animals in BIOLAB and EMCS on the International Space Station.

Two ESA facilities will be available for animal research and other biological experiments on the International Space Station: the European Modular Cultivation System (EMCS) in the US Lab "Destiny" and BIOLAB in the European "Columbus" Laboratory. Both facilities use standard Experiment Containers, mounted on two centrifuge rotors allowing either research in microgravity or acceleration studies with variable g-levels from 0.001 to 2.0 x g. Standard interface plates provide each container with power and data lines, gas supply (controlled CO2, O2 concentration and relative humidity), and--for EMCS only--connectors to fresh and waste water reservoirs. The experiment hardware inside the containers will be developed by the user, but ESA conducted a feasibility study for several kinds of Experiment Support Equipment with potential use for research on small animals: design concepts for experiments with insects, with aquatic organisms like rotifers and nematodes, and with small aquatic animals (sea urchin larvae, tadpoles, fish youngsters) are described in detail in this presentation. Also ESA's initial steps to support experiments with rodents on the Space Station are presented.     

Organic solids produced from simple C/H/O/N ices by charged particles: applications to the outer solar system.

CH4, CO, and CO2 are all potential one-carbon molecular repositories in primitive icy objects. These molecules are all found in the Comet Halley coma, and are probable but, (except for CH4 detected on Triton and Pluto) undetected subsurface constituents in icy outer solar system objects. We have investigated the effects of charged particle irradiation by cold plasma discharge upon surfaces of H2O:CH4 clathrate having a 200:1 ratio, as well as upon ices composed of H2O plus C2H6 or C2H2 (sometimes plus NH3) which are also plausible constituents. These materials color and darken noticeably after a dose 10(9) - 10(10) erg cm-2, which is deposited rapidly (< or = 10(4) yr.) in solar system environments. The chromophore is a yellowish to tan organic material (a tholin) which we have studied by UV-VIS reflection and transmission, and IR transmission spectroscopy. Its yield, -1 C keV-1, implies substantial production of organic solids by the action of cosmic rays and radionuclides in cometary crusts and interiors, as well as rapid production in satellite surfaces. This material shows alkane bands which Chyba and Sagan have shown to well match the Halley infrared emission spectrum near 3.4 microns, and also bands due to aldehyde, alcohol and perhaps alkene/aromatic functional groups. We compare the IR spectral properties of these tholins with the spectra of others produced by irradiation of gases and ices containing simple hydrocarbons.     

The initiation of biological processes on Earth: summary of empirical evidence.

With the currently available geological record at band, the existence of life on this planet as from at least 3.8 Gyr ago seems so firmly established as to be virtually unassailable. Specifically, various disparate lines of evidence have merged to indicate (1) that the surface of the Archaean Earth had hosted prolific microbial ecosystems as is testified by a quasi-continuous record of microbialites ("stromatolites") and associated microfossils of prokaryotic affinity over 3.5, if not 3.8 Gyr of geological history, and (2) that the sedimentary carbon record has preserved the isotopic signature of autotrophic (notably photosynthetic) carbon fixation over the same time span. With the observed enrichment of isotopically light carbon in sedimentary organic matter largely consonant with the bias in favor of 12C during photosynthesis, the mainstream of the carbon isotope record can be best explained as geochemical manifestation of the isotope discriminating properties of the ribulose-1,5-bisphosphate (RuBP) carboxylase reaction of the Calvin cycle suggesting an extreme degree of evolutionary conservatism in the biochemistry of autotrophic carbon fixation. As a consequence, partial biological control of the geochemical carbon cycle was established already during Early Archaean times and fully operative by the time of formation of the Earth's earliest sediments.     

Calcium gradients in the fish inner ear sensory epithelium and otolithic membrane visualized by energy filtering transmission electron microscopy (EFTEM).

Inner ear otolith formation in fish is supposed to be performed by the molecular release of proteinacious precursor material from the sensory epithelia, followed by an undirected and diffuse precipitation of calcium carbonate (which is mainly responsible for the functionally important weight of otoliths). The pathway of calcium into the endolymph, however, still remains obscure. Therefore, the presence of calcium within the utricle of larval cichlid fish Oreochromis mossambicus was analyzed by means of energy filtering transmission electron microscopy (EFTEM). Electron spectroscopic imaging (ESI) and electron energy loss spectra (EELS) revealed discrete calcium precipitations, which were especially numerous in the proximal endolymph as compared to the distal endolymph. A decreasing proximo-distal gradient was also present within the proximal endolymph between the sensory epithelium and the otolith. Further calcium particles covered the peripheral proteinacious layer of the otolith. They were especially pronounced at the proximal surface of the otolith. Other calcium precipitates were found to be accumulated at the macular junctions. These results strongly suggest that the apical region of the macular epithelium is involved in the release of calcium and that calcium supply of the otoliths takes place in the proximal endolymph.     

Efficacy of an ototoxic aminoglycoside (gentamicin) on the differentiation of the inner ear of cichlid fish.

Previous investigations revealed that the growth of fish inner ear otoliths depends on the amplitude and the direction of gravity, thus suggesting the existence of a (negative) feedback mechanism. In the course of these experiments, it was shown that altered gravity both affected otolith size (and thus the provision of the proteinacious matrix) as well as the incorporation of calcium. It is hitherto unknown, as of whether sensory hair cells are involved either in the regulation of otolith growth or in the provision of otolithic material (such as protein or inorganic components) or even both. The ototoxic aminoglycoside gentamicin (GM) damages hair cells in many vertebrates (and is therefore used for the treatment of Meniere's disease in humans). The present study was thus designed to determine as of whether vestibular sensory cells are needed for otolith growth by applying GM in order to induce a (functionally relevant) loss of these cells. Developing cichlid fish Oreochromis mossambicus were therefore immersed in 120 mg/l GM for 10 or 21 days. At the beginning and at the end of the experimental periods, the fish were incubated in the calcium-tracer alizarin complexone (AC). After the experiment, otoliths were dissected and the area grown during GM-exposure (i.e., the area enclosed by the two AC labellings) was determined planimetrically. The results showed that incubating the animals in a GM-solution had no effect on otolith growth, but the development of otolith asymmetry was affected. Ultrastructural examinations of the sensory hair cells revealed that they had obviously not been affected by GM-treatment (no degenerative morphological features observed). Overall, the present results suggest that hair cells are not affected by GM concerning their possible role in (general) otolith growth, but that these cells indeed might have transitionally been impaired by GM resulting in a decreased capacity of regulating otolith symmetry.     

Increase in fish abundance during two typhoons in the South China Sea

A fish monitoring program was conducted in the northern region of the South China Sea from March 2009 to December 2010. During this period, two typhoons, GONI and Koppu, hit this region consecutively in August and September 2009. The fish and satellite data were analyzed to understand the influence of the typhoons on fish activities. The results showed that the fish species number (FSN) increased by approximately 14.29% and 14.81% after the two typhoons, GONI and Koppu, respectively. The five increased fish species included three estuarine species and two shallow sea species. However, one shallow sea species was also absent. In the nearshore (near the Pearl River Estuary) and offshore (along the typhoon’s track) regions after GONI, the FSN increased by approximately 24% (nearshore) and 52.63% (offshore), with estuarine species accounting for 42.86% (nearshore) and 33.33% (offshore) of the fish species; after Koppu, the FSN increased by approximately 15.38% (nearshore) and 163.64% (offshore), with estuarine species accounting for 60% (nearshore) and 26.32% (offshore) of the fish species. In the increased records, small and medium-sized fish species were dominant nearshore, and small fish species were dominant offshore. The FSN increased to a maximum value between the 5th and the 10th days after the typhoon nearshore and between the 3rd and 8th days after the typhoon offshore. The results indicated that river discharge, triggered by the typhoon’s nearshore rainfall, as well as offshore upwelling nutrients, also triggered by the typhoons, and may have played important roles in the variability of fish species. This research found that the increase in the FSN was associated with the typhoons in the northern South China Sea.     

The search for nitrogen compounds on the surface of Mars

Nitrogen is an essential element for life. Specifically, “fixed nitrogen” (i.e., NH₃, NH₄⁺, NO_x, or N that is chemically bound to either inorganic or organic molecules and is releasable by hydrolysis to NH₃ or NH₄⁺) is the form of nitrogen useful to living organisms. To date no direct analysis of Martian soil nitrogen content, or content of fixed nitrogen compounds has been done. Consequently, the planet's total inventory of nitrogen is unknown. What is known is that the N₂ content of the present-day Martian atmosphere is 0.2 mbar. It has been hypothesized that early in Mars' history (3 to 4 billion years ago) the Martian atmosphere contained much more N₂ than it does today. The values of N₂ proposed for this early Martian atmosphere, however, are not well constrained and range from 3 to 300 mbar of N₂. If the early atmosphere of Mars did contain much more N₂ than it does today the question to be answered is, Where did it go? The two main processes that could have removed it rapidly from the atmosphere include: 1) nonthermal escape of N-atoms to space; and 2) burial within the regolith as nitrates and nitrites. Nitrate will be stable in the highly oxidized surface soil of Mars, and will tend to accumulate in the soil. Such accumulations are observed in certain desert environments on Earth. Some NH₄⁺---N may also be fixed and stabilized in the soil by inclusion as a structural cation in the crystal lattices of certain phyllosilicates replacing K. Analysis of the Martian soil for traces of NO₃⁻ and NH₄⁺ during future missions will supply important information regarding the nitrogen abundance on Mars, its past climate as well as its potential for the evolution of life.     

Dorsal light response and changes of its responses under varying acceleration conditions.

In order to improve our understanding about functions of the gravity sensors, we have conducted four experiments in goldfish: 1) To define the effect of visual information influx on the static labyrinthine response, the dorsal light response (DLR) which had been proposed by von Holst as a model for postural adjustment in fish was reexamined with a newly designed, rotatory illumination device. The fish responded to illumination from the upper half of the visual field and a narrow range around 180 degrees of the lower half visual field. The maximal tilting angle of normal fish was about 40 degrees under horizontal illumination. 2) Under the changes of the gravito-inertial force level produced by a linear sled, the threshold of the gravity sensors was determined from postural adjustment responses. 3) Under hypogravic conditions during the parabolic flight of an airplane, the light-dependent behavior was investigated in intact and labyrinthectomized goldfish. 4) As one of the most likely candidates of the neural centers for the DLR, the valvula cerebelli, which receives its visual information not through the optic tectum but through the pretectal areas, is confirmed by the brain lesion experiments.     

Use of an otolith-deficient mutant in studies of fish behavior in microgravity.

The mutant strain (ha) of medaka (Oryzias latipes) lack utricular otoliths as fry, and some never form otoliths for life. The cross (F1 generation) between the strain having good eyesight and another strain having ordinary eyesight augmented visual acuity of the F1 generation. Crossing the good eyesight strain and ha mutant produced fish having good eyesight and less sensitivity to gravity in the F2 population. Their tolerance to microgravity was tested by parabolic flight using an airplane. The fish exhibited less looping and no differences in degree of looping between light and dark conditions, suggesting that loss of eyesight (in darkness) is not a direct cause for looping behavior in microgravity. The ha embryos could not form utricular otoliths. They did form saccular otoliths, but with a delay. Fry of the mutant fish lacking the utricular otoliths are highly dependent on light upon hatching and exhibit a perfect dorsal-light response (DLR). As they grow, they eventually shift from being light-dependent to being gravity-dependent. Continuous treatment of the fry with altered light direction suppressed this shift to gravity dependence. Being less dependent on gravity, these fish can serve as models in studying the differences expected for the vestibular system of fish reared in microgravity. When these fish were exposed to microgravity (parabolic flights) of an airplane, they spent far less time looping than fish reared in an ordinary light regimen.     

Influence of long-term altered gravity on the swimming performance of developing cichlid fish: including results from the 2nd German Spacelab Mission D-2.

This study presents qualitative and quantitative data concerning gravity-dependent changes in the swimming behaviour of developing cichlid fish larvae (Oreochromis mossambicus) after a 9 resp. 10 days exposure to increased acceleration (centrifuge experiments), to reduced gravity (fast-rotating clinostat), changed accelerations (parabolic aircraft flights) and to near weightlessness (2nd German Spacelab Mission D-2). Changes of gravity initially cause disturbances of the swimming performance of the fish larvae. With prolonged stay in orbit a step by step normalisation of the swimming behaviour took place in the fish. After return to 1g earth conditions no somersaulting or looping could be detected concerning the fish, but still slow and disorientated movements as compared to controls occurred. The fish larvae adapted to earth gravity within 3-5 days. Fish seem to be in a distinct early developmental stages extreme sensitive and adaptable to altered gravity; However, elder fish either do not react or show compensatory behaviour e.g. escape reactions.     

Elevated CO2: impact on diurnal patterns of photosynthesis in natural microbial ecosystems.

Algae, including blue-green algae (cyanobacteria), are the major source of fixed carbon in many aquatic ecosystems. Previous work has shown that photosynthetic carbon fixation is often enhanced in the presence of additional carbon dioxide (CO2). This study was undertaken to determine if this CO2 fertilization effect extended to microbial mats, and, if so, at what times during the day might the addition of CO2 affect carbon fixation. Four microbial mats from diverse environments were selected, including mats from a hypersaline pond (area 5, Exportadora de Sal, Mexico), the marine intertidal (Lyngbya, Laguna Ojo de Liebre, Mexico), an acidic hotspring (Cyanidium, Nymph Creek, Yellowstone National Park), and an acidic stream at ambient temperature (Zygogonium, Yellowstone National Park). Carbon fixation in the absence of additional CO2 essentially followed the rising and falling sunlight levels, except that during the middle of the day there was a short dip in carbon fixation rates. The addition of CO2 profoundly enhanced carbon fixation rates during the daylight hours, including during the midday dip. Therefore, it is unlikely that the midday dip was due to photoinhibition. Surprisingly, enhancement of carbon fixation was often greatest in the early morning or late afternoon, times when carbon fixation would be most likely to be light limited.     

The C.E.B.A.S.-Minimodule: behaviour of an artificial aquatic ecological system during spaceflight.

The C.E.B.A.S.-Minimodule, a closed aquatic ecosystem integrated into a middeck locker and consisting of a Zoological (animal tanks), a Botanical (plant bioreactor), a Microbial (bacteria filter) and an Electronic Component (data acquisition/control system) was flown on the STS-89 spaceshuttle mission in January 1998 for 9 days. Preflight the plant bioreactor was loaded with 53 g of Ceratophyllum demersum (coontail) and the animal tanks with 4 adult pregnant females of the fish, Xiphophorus helleri (sword-tails), 200 juveniles of the same species less than 1 week of age, 38 large and 30 juvenile Biomphalaria glabrata water snails. The filter compartment was filled with 200 g of lava grain inoculated with laboratory strains of ammonia-oxidizing bacteria. A ground reference was undertaken with the same biological setup with a delay of 4 d. After an adaptation period of 5 d the system was closed and integrated into the spaceshuttle one day before launch. Video recordings of the animals were automatically taken for 10 minutes in 2-hour periods; the tapes were changed daily by the astronauts. The chemical and physical data for the aquatic system were within the expected range and were closely comparable in comparison to the ground reference. After 9 d under space conditions, the plant biomass increased to 117 g. The plants were all found in very good condition. All 4 adult female fish were retrieved in a good physiological condition. The juvenile fishes had a survival rate of about 33%. Almost 97% of the snails had survived and produced more than 250 neonates and 40 spawning packs. All samples were distributed according to a defined schedule and satisfied all scientific needs of the involved 12 principal investigators. This was the first successful spaceflight of an artificial aquatic ecosystem containing vertebrates, invertebrates, higher plants and microorganisms self-sustained by its inhabitants only. C.E.B.A.S. in a modified form and biological setup is a promising candidate for the early space station utilization as a first midterm experiment.