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  • 1
    Publication Date: 2002-12-14
    Description: The first chordates appear in the fossil record at the time of the Cambrian explosion, nearly 550 million years ago. The modern ascidian tadpole represents a plausible approximation to these ancestral chordates. To illuminate the origins of chordate and vertebrates, we generated a draft of the protein-coding portion of the genome of the most studied ascidian, Ciona intestinalis. The Ciona genome contains approximately 16,000 protein-coding genes, similar to the number in other invertebrates, but only half that found in vertebrates. Vertebrate gene families are typically found in simplified form in Ciona, suggesting that ascidians contain the basic ancestral complement of genes involved in cell signaling and development. The ascidian genome has also acquired a number of lineage-specific innovations, including a group of genes engaged in cellulose metabolism that are related to those in bacteria and fungi.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dehal, Paramvir -- Satou, Yutaka -- Campbell, Robert K -- Chapman, Jarrod -- Degnan, Bernard -- De Tomaso, Anthony -- Davidson, Brad -- Di Gregorio, Anna -- Gelpke, Maarten -- Goodstein, David M -- Harafuji, Naoe -- Hastings, Kenneth E M -- Ho, Isaac -- Hotta, Kohji -- Huang, Wayne -- Kawashima, Takeshi -- Lemaire, Patrick -- Martinez, Diego -- Meinertzhagen, Ian A -- Necula, Simona -- Nonaka, Masaru -- Putnam, Nik -- Rash, Sam -- Saiga, Hidetoshi -- Satake, Masanobu -- Terry, Astrid -- Yamada, Lixy -- Wang, Hong-Gang -- Awazu, Satoko -- Azumi, Kaoru -- Boore, Jeffrey -- Branno, Margherita -- Chin-Bow, Stephen -- DeSantis, Rosaria -- Doyle, Sharon -- Francino, Pilar -- Keys, David N -- Haga, Shinobu -- Hayashi, Hiroko -- Hino, Kyosuke -- Imai, Kaoru S -- Inaba, Kazuo -- Kano, Shungo -- Kobayashi, Kenji -- Kobayashi, Mari -- Lee, Byung-In -- Makabe, Kazuhiro W -- Manohar, Chitra -- Matassi, Giorgio -- Medina, Monica -- Mochizuki, Yasuaki -- Mount, Steve -- Morishita, Tomomi -- Miura, Sachiko -- Nakayama, Akie -- Nishizaka, Satoko -- Nomoto, Hisayo -- Ohta, Fumiko -- Oishi, Kazuko -- Rigoutsos, Isidore -- Sano, Masako -- Sasaki, Akane -- Sasakura, Yasunori -- Shoguchi, Eiichi -- Shin-i, Tadasu -- Spagnuolo, Antoinetta -- Stainier, Didier -- Suzuki, Miho M -- Tassy, Olivier -- Takatori, Naohito -- Tokuoka, Miki -- Yagi, Kasumi -- Yoshizaki, Fumiko -- Wada, Shuichi -- Zhang, Cindy -- Hyatt, P Douglas -- Larimer, Frank -- Detter, Chris -- Doggett, Norman -- Glavina, Tijana -- Hawkins, Trevor -- Richardson, Paul -- Lucas, Susan -- Kohara, Yuji -- Levine, Michael -- Satoh, Nori -- Rokhsar, Daniel S -- HD-37105/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 2002 Dec 13;298(5601):2157-67.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉U.S. Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA 94598, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12481130" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Animals ; Apoptosis ; Base Sequence ; Cellulose/metabolism ; Central Nervous System/physiology ; Ciona intestinalis/anatomy & histology/classification/*genetics/physiology ; Computational Biology ; Endocrine System/physiology ; Gene Dosage ; Gene Duplication ; Genes ; Genes, Homeobox ; *Genome ; Heart/embryology/physiology ; Immunity/genetics ; Molecular Sequence Data ; Multigene Family ; Muscle Proteins/genetics ; Organizers, Embryonic/physiology ; Phylogeny ; Polymorphism, Genetic ; Proteins/genetics/physiology ; *Sequence Analysis, DNA ; Sequence Homology, Nucleic Acid ; Species Specificity ; Thyroid Gland/physiology ; Urochordata/genetics ; Vertebrates/anatomy & histology/classification/genetics/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2001-02-22
    Description: A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Venter, J C -- Adams, M D -- Myers, E W -- Li, P W -- Mural, R J -- Sutton, G G -- Smith, H O -- Yandell, M -- Evans, C A -- Holt, R A -- Gocayne, J D -- Amanatides, P -- Ballew, R M -- Huson, D H -- Wortman, J R -- Zhang, Q -- Kodira, C D -- Zheng, X H -- Chen, L -- Skupski, M -- Subramanian, G -- Thomas, P D -- Zhang, J -- Gabor Miklos, G L -- Nelson, C -- Broder, S -- Clark, A G -- Nadeau, J -- McKusick, V A -- Zinder, N -- Levine, A J -- Roberts, R J -- Simon, M -- Slayman, C -- Hunkapiller, M -- Bolanos, R -- Delcher, A -- Dew, I -- Fasulo, D -- Flanigan, M -- Florea, L -- Halpern, A -- Hannenhalli, S -- Kravitz, S -- Levy, S -- Mobarry, C -- Reinert, K -- Remington, K -- Abu-Threideh, J -- Beasley, E -- Biddick, K -- Bonazzi, V -- Brandon, R -- Cargill, M -- Chandramouliswaran, I -- Charlab, R -- Chaturvedi, K -- Deng, Z -- Di Francesco, V -- Dunn, P -- Eilbeck, K -- Evangelista, C -- Gabrielian, A E -- Gan, W -- Ge, W -- Gong, F -- Gu, Z -- Guan, P -- Heiman, T J -- Higgins, M E -- Ji, R R -- Ke, Z -- Ketchum, K A -- Lai, Z -- Lei, Y -- Li, Z -- Li, J -- Liang, Y -- Lin, X -- Lu, F -- Merkulov, G V -- Milshina, N -- Moore, H M -- Naik, A K -- Narayan, V A -- Neelam, B -- Nusskern, D -- Rusch, D B -- Salzberg, S -- Shao, W -- Shue, B -- Sun, J -- Wang, Z -- Wang, A -- Wang, X -- Wang, J -- Wei, M -- Wides, R -- Xiao, C -- Yan, C -- Yao, A -- Ye, J -- Zhan, M -- Zhang, W -- Zhang, H -- Zhao, Q -- Zheng, L -- Zhong, F -- Zhong, W -- Zhu, S -- Zhao, S -- Gilbert, D -- Baumhueter, S -- Spier, G -- Carter, C -- Cravchik, A -- Woodage, T -- Ali, F -- An, H -- Awe, A -- Baldwin, D -- Baden, H -- Barnstead, M -- Barrow, I -- Beeson, K -- Busam, D -- Carver, A -- Center, A -- Cheng, M L -- Curry, L -- Danaher, S -- Davenport, L -- Desilets, R -- Dietz, S -- Dodson, K -- Doup, L -- Ferriera, S -- Garg, N -- Gluecksmann, A -- Hart, B -- Haynes, J -- Haynes, C -- Heiner, C -- Hladun, S -- Hostin, D -- Houck, J -- Howland, T -- Ibegwam, C -- Johnson, J -- Kalush, F -- Kline, L -- Koduru, S -- Love, A -- Mann, F -- May, D -- McCawley, S -- McIntosh, T -- McMullen, I -- Moy, M -- Moy, L -- Murphy, B -- Nelson, K -- Pfannkoch, C -- Pratts, E -- Puri, V -- Qureshi, H -- Reardon, M -- Rodriguez, R -- Rogers, Y H -- Romblad, D -- Ruhfel, B -- Scott, R -- Sitter, C -- Smallwood, M -- Stewart, E -- Strong, R -- Suh, E -- Thomas, R -- Tint, N N -- Tse, S -- Vech, C -- Wang, G -- Wetter, J -- Williams, S -- Williams, M -- Windsor, S -- Winn-Deen, E -- Wolfe, K -- Zaveri, J -- Zaveri, K -- Abril, J F -- Guigo, R -- Campbell, M J -- Sjolander, K V -- Karlak, B -- Kejariwal, A -- Mi, H -- Lazareva, B -- Hatton, T -- Narechania, A -- Diemer, K -- Muruganujan, A -- Guo, N -- Sato, S -- Bafna, V -- Istrail, S -- Lippert, R -- Schwartz, R -- Walenz, B -- Yooseph, S -- Allen, D -- Basu, A -- Baxendale, J -- Blick, L -- Caminha, M -- Carnes-Stine, J -- Caulk, P -- Chiang, Y H -- Coyne, M -- Dahlke, C -- Mays, A -- Dombroski, M -- Donnelly, M -- Ely, D -- Esparham, S -- Fosler, C -- Gire, H -- Glanowski, S -- Glasser, K -- Glodek, A -- Gorokhov, M -- Graham, K -- Gropman, B -- Harris, M -- Heil, J -- Henderson, S -- Hoover, J -- Jennings, D -- Jordan, C -- Jordan, J -- Kasha, J -- Kagan, L -- Kraft, C -- Levitsky, A -- Lewis, M -- Liu, X -- Lopez, J -- Ma, D -- Majoros, W -- McDaniel, J -- Murphy, S -- Newman, M -- Nguyen, T -- Nguyen, N -- Nodell, M -- Pan, S -- Peck, J -- Peterson, M -- Rowe, W -- Sanders, R -- Scott, J -- Simpson, M -- Smith, T -- Sprague, A -- Stockwell, T -- Turner, R -- Venter, E -- Wang, M -- Wen, M -- Wu, D -- Wu, M -- Xia, A -- Zandieh, A -- Zhu, X -- New York, N.Y. -- Science. 2001 Feb 16;291(5507):1304-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Celera Genomics, 45 West Gude Drive, Rockville, MD 20850, USA. humangenome@celera.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11181995" target="_blank"〉PubMed〈/a〉
    Keywords: Algorithms ; Animals ; Chromosome Banding ; Chromosome Mapping ; Chromosomes, Artificial, Bacterial ; Computational Biology ; Consensus Sequence ; CpG Islands ; DNA, Intergenic ; Databases, Factual ; Evolution, Molecular ; Exons ; Female ; Gene Duplication ; Genes ; Genetic Variation ; *Genome, Human ; *Human Genome Project ; Humans ; Introns ; Male ; Phenotype ; Physical Chromosome Mapping ; Polymorphism, Single Nucleotide ; Proteins/genetics/physiology ; Pseudogenes ; Repetitive Sequences, Nucleic Acid ; Retroelements ; *Sequence Analysis, DNA/methods ; Species Specificity
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2002-12-10
    Description: Circadian clocks are influenced by social interactions in a variety of species, but little is known about the sensory mechanisms underlying these effects. We investigated whether social cues could reset circadian rhythms in Drosophila melanogaster by addressing two questions: Is there a social influence on circadian timing? If so, then how is that influence communicated? The experiments show that in a social context Drosophila transmit and receive cues that influence circadian time and that these cues are likely olfactory.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Levine, Joel D -- Funes, Pablo -- Dowse, Harold B -- Hall, Jeffrey C -- GM-33205/GM/NIGMS NIH HHS/ -- NS-44232/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 2002 Dec 6;298(5600):2010-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Brandeis University, Waltham, MA 02454, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12471264" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal ; *Circadian Rhythm ; *Cues ; Darkness ; Drosophila Proteins/genetics/physiology ; Drosophila melanogaster/genetics/*physiology ; Light ; Male ; Motor Activity ; Mutation ; Nuclear Proteins/genetics/physiology ; Period Circadian Proteins ; Smell/physiology ; Social Behavior ; Sodium Channels/genetics/physiology ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2004-06-12
    Description: Cells regulate the biophysical properties of their membranes by coordinated synthesis of different classes of lipids. Here, we identified a highly dynamic feedback mechanism by which the budding yeast Saccharomyces cerevisiae can regulate phospholipid biosynthesis. Phosphatidic acid on the endoplasmic reticulum directly bound to the soluble transcriptional repressor Opi1p to maintain it as inactive outside the nucleus. After the addition of the lipid precursor inositol, this phosphatidic acid was rapidly consumed, releasing Opi1p from the endoplasmic reticulum and allowing its nuclear translocation and repression of target genes. Thus, phosphatidic acid appears to be both an essential ubiquitous metabolic intermediate and a signaling lipid.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Loewen, C J R -- Gaspar, M L -- Jesch, S A -- Delon, C -- Ktistakis, N T -- Henry, S A -- Levine, T P -- BBS/E/B/0000F969/Biotechnology and Biological Sciences Research Council/United Kingdom -- GM-19629/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2004 Jun 11;304(5677):1644-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Cell Biology, Institute of Ophthalmology, Bath Street, London EC1V 9EL, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15192221" target="_blank"〉PubMed〈/a〉
    Keywords: Active Transport, Cell Nucleus ; Animals ; Binding Sites ; COS Cells ; Cell Membrane/metabolism ; Cell Nucleus/metabolism ; Cercopithecus aethiops ; Cytidine Diphosphate Diglycerides/metabolism ; Endoplasmic Reticulum/metabolism ; Inositol/*metabolism ; Liposomes/metabolism ; Mutation ; Nuclear Envelope/metabolism ; Phosphatidic Acids/*metabolism ; Phosphatidylinositols/metabolism ; Phospholipids/biosynthesis/*metabolism ; Recombinant Fusion Proteins/metabolism ; Repressor Proteins/chemistry/genetics/*metabolism ; Saccharomyces cerevisiae/genetics/*metabolism ; Saccharomyces cerevisiae Proteins/chemistry/genetics/*metabolism ; Signal Transduction
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2003-09-06
    Description: Both dauer formation (a stage of developmental arrest) and adult life-span in Caenorhabditis elegans are negatively regulated by insulin-like signaling, but little is known about cellular pathways that mediate these processes. Autophagy, through the sequestration and delivery of cargo to the lysosomes, is the major route for degrading long-lived proteins and cytoplasmic organelles in eukaryotic cells. Using nematodes with a loss-of-function mutation in the insulin-like signaling pathway, we show that bec-1, the C. elegans ortholog of the yeast and mammalian autophagy gene APG6/VPS30/beclin1, is essential for normal dauer morphogenesis and life-span extension. Dauer formation is associated with increased autophagy and also requires C. elegans orthologs of the yeast autophagy genes APG1, APG7, APG8, and AUT10. Thus, autophagy is a cellular pathway essential for dauer development and life-span extension in C. elegans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Melendez, Alicia -- Talloczy, Zsolt -- Seaman, Matthew -- Eskelinen, Eeva-Liisa -- Hall, David H -- Levine, Beth -- CA84254/CA/NCI NIH HHS/ -- RR 12596/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 2003 Sep 5;301(5638):1387-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, Columbia University College of Physicians & Surgeons, 630 West 168th Street, New York, NY 10032, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12958363" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Animals, Genetically Modified ; Apoptosis Regulatory Proteins ; Autophagy/*genetics ; Caenorhabditis elegans/*genetics/*growth & development/metabolism/ultrastructure ; Caenorhabditis elegans Proteins/chemistry/*genetics/metabolism/physiology ; Genes, Fungal ; *Genes, Helminth ; Humans ; Longevity ; Membrane Proteins ; Morphogenesis ; Mutation ; Phagosomes/ultrastructure ; Phenotype ; Proteins/chemistry/genetics/physiology ; RNA Interference ; Receptor, Insulin/genetics/metabolism ; Recombinant Fusion Proteins/metabolism ; Saccharomyces cerevisiae/genetics/physiology ; Signal Transduction ; Vesicular Transport Proteins
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2019-07-18
    Description: Microwave remote sensing in the window at 1.413 GHz (L-band) set aside for passive use only is important for monitoring sea surface salinity and soil moisture. These parameters are important for understanding ocean dynamics and energy exchange between the surface and atmosphere, and both NASA and ESA plan to launch satellite sensors to monitor these parameters at L-band (Aquarius, Hydros and SMOS). The ionosphere is an important source of error for passive remote sensing at this frequency. In addition to Faraday rotation, emission from the ionosphere is also a potential source of error at L-band. As an aid for correcting for emission, a regression model is presented that relates ionosphere emission to the integrated electron density (TEC). The goal is to use TEC from sources such as TOPEX, JASON or GPS to obtain estimates of emission over the oceans where the electron density profiles needed to compute emission are not available. In addition, data will also be presented to evaluate the use of the IRI for computing emission over the ocean.
    Keywords: Oceanography
    Type: Advanced in Space Research; Feb 01, 2004 - Feb 28, 2004; United States
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  • 7
    Publication Date: 2019-07-17
    Description: The salinity of the open ocean is important for understanding ocean circulation, for understanding energy exchange with the atmosphere and for improving models to predict weather and climate. Passive microwave sensors at L-band (1.4 GHz) operating from aircraft have demonstrated that salinity can be measured with sufficient accuracy (1 psu) to be scientifically meaningful in coastal waters. However, measuring salinity in the open ocean presents unresolved issues largely because of the much greater accuracy (approx. 0.1 psu) required to be scientifically viable. In the summer of 1999 a series of measurements called, The Gulf Stream Experiment, were conducted as part of research at the Goddard Space Flight Center to test the potential for passive microwave remote sensing of salinity in the open ocean. The measurements consisted of a compliment of airborne microwave instruments (radiometers and scatterometer) and ships and drifters for surface truth. The study area was a 200 km by 100 km rectangle about 250 km east of Delaware Bay between the continental shelf waters and north wall of the Gulf Stream. The primary passive instruments were the ESTAR radiometer (L-band, H-pol) and the SLFMR radiometer (L-band, V-pol). In addition, the compliment of instruments on the aircraft included a C-band radiometer (ACMR), an ocean wave scatterometer (ROWS) and an infrared radiometer. A GPS backscatter experiment was also part of the package. These instruments were mounted on the NASA P-3 Orion aircraft. Surface salinity measurements were provided by the RN Cape Henlopen and MN Oleander (thermosalinographs) plus salinity and temperature sensors on three surface drifters deployed from the RN Cape Henopen. The primary experiment period was August 26-September 2, 1999. During this period the salinity field within the study area consisted of a gradient on the order of 2-3 psu in the vicinity of the shelf break and a warm core ring with a gradient of 1-2 psu. Detailed maps were made with the airborne sensors on August 28 and 29 and on September 2 flights were made over the surface drifters to look for effects due to a change in surface roughness resulting from the passage of Hurricane Dennis. Preliminary results show a good agreement between the microwave measurements and ship measurements of salinity. The features of the brightness temperature maps correspond well with the features of the salinity field measured by the ship and drifters and a preliminary retrieval of salinity compares well with the ship data.
    Keywords: Oceanography
    Type: Geoscience and Remote Sensing; Jul 24, 2000 - Jul 28, 2000; Honolulu, HI; United States
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  • 8
    Publication Date: 2019-07-18
    Description: This paper describes a resonant cavity technique for the measurement of the dielectric constant of seawater as a function of its salinity. Accurate relationships between salinity and dielectric constant (which determines emissivity) are needed for sensor systems such as SMOS and Aquarius that will monitor salinity from space in the near future. The purpose of the new measurements is to establish the dependence of the dielectric constant of seawater on salinity in contemporary units (e.g. psu) and to take advantage of modern instrumentation to increase the accuracy of these measurements. The measurement device is a brass cylindrical cavity 16cm in diameter and 7cm in height. The seawater is introduced into the cavity through a slender glass tube having an inner diameter of 0.1 mm. By assuming that this small amount of seawater slightly perturbs the internal fields in the cavity, perturbation theory can be employed. A simple formula results relating the real part of the dielectric constant to the change in resonant frequency of the cavity. In a similar manner, the imaginary part of the dielectric constant is related to the change in the cavity s Q. The expected accuracy of the cavity technique is better than 1% for the real part and 1 to 2% for the imaginary part. Presently, measurements of methanol have been made and agree with precision measurements in the literature to within 1% in both real and imaginary parts. Measurements have been made of the dielectric constant of seawater samples from Ocean Scientific in the United Kingdom with salinities of 10, 30, 35 and 38 psu. All measurements were made at room temperature. Plans to make measurements at a range of temperatures and salinities will be discussed.
    Keywords: Oceanography
    Type: IGARSS Conference; Jul 21, 2003 - Jul 25, 2003; Toulouse; France
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  • 9
    Publication Date: 2019-07-17
    Description: Passive microwave sensors at L-band (1.4 GHz) operating from aircraft have demonstrated that salinity can be measured with sufficient accuracy (I psu) to be scientifically meaningful in coastal waters. However, measuring salinity in the open ocean presents unresolved issues largely because of the much greater accuracy (approximately 0.2 psu) required of global maps to be scientifically viable. The development of a satellite microwave instrument to make global measurements of SSS (Sea Surface Salinity) is the focus of a joint JPL/GSFC/NASA ocean research program called Aquarius. In the summer of 1999 a series of measurements called, The Gulf Stream Experiment, were conducted as part of research at the Goddard Space Flight Center to test the potential for passive microwave remote sensing of salinity in the open ocean. The measurements consisted of airborne microwave instruments together with ships and drifters for surface truth. The study area was a 200 km by 100 km rectangle about 250 km east of Delaware Bay between the continental shelf waters and north wall of the Gulf Stream. The primary passive instruments were the ESTAR radiometer (L-band, H-pol) and the SLFMR radiometer (L-band, V-pol). In addition, the instruments on the aircraft included a C-band radiometer (ACMR), an ocean wave scatterometer (ROWS) and an infrared radiometer (for surface temperature). These instruments were mounted on the NASA P-3 Orion aircraft. Sea surface measurements consisted of thermosalinograph data provided by the R/V Cape Henlopen and the MN Oleander, and data from salinity and temperature sensors on three surface drifters deployed from the R/V Cape Henlopen. The primary experiment period was August 26-September 2, 1999. During this period the salinity field within the study area consisted of a gradient on the order of 2-3 psu in the vicinity of the shelf break and a warm core ring with a gradient of 1-2 psu. Detailed maps were made with the airborne sensors on August 28 and 29 and on September 2 flights were made over the surface drifters to look for effects due to a change in surface roughness resulting from the passage of Hurricane Dennis. Results show a good agreement between the microwave measurements and ship measurements of salinity. The features of the brightness temperature maps correspond well with the features of the salinity field measured by the ship and drifters and a preliminary retrieval of salinity compares well with the ship data.
    Keywords: Oceanography
    Type: NASA Ocean Salinity Meeting; Apr 03, 2001 - Apr 05, 2001; Miami, FL; United States
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  • 10
    Publication Date: 2019-07-13
    Description: The RadSTAR instrument combines an L-band, digital beam-forming radar with an L-band synthetic aperture, thinned array (STAR) radiometer. The RadSTAR development will support NASA Earth science goals by developing a novel, L-band scatterometer/ radiometer that measures Earth surface bulk material properties (surface emissions and backscatter) as well as surface characteristics (backscatter). Present, real aperture airborne L-Band active/passive measurement systems such as the JPUPALS (Wilson, et al, 2000) provide excellent sampling characteristics, but have no scanning capabilities, and are extremely large; the huge JPUPALS horn requires a the C-130 airborne platform, operated with the aft loading door open during flight operation. The approach used for the upcoming Aquarius ocean salinity mission or the proposed Hydros soil mission use real apertures with multiple fixed beams or scanning beams. For real aperture instruments, there is no upgrade path to scanning over a broad swath, except rotation of the whole aperture, which is an approach with obvious difficulties as aperture size increases. RadSTAR will provide polarimetric scatterometer and radiometer measurements over a wide swath, in a highly space-efficient configuration. The electronic scanning approaches provided through STAR technology and digital beam forming will enable the large L-band aperture to scan efficiently over a very wide swath. RadSTAR technology development, which merges an interferometric radiometer with a digital beam forming scatterometer, is an important step in the path to space for an L-band scatterometer/radiometer. RadSTAR couples a patch array antenna with a 1.26 GHz digital beam forming radar scatterometer and a 1.4 GHz STAR radiometer to provide Earth surface backscatter and emission measurements in a compact, cross-track scanning instrument with no moving parts. This technology will provide the first L-band, emission and backscatter measurements in a compact aircraft instrument and will be ideally suited to large apertures, possibly at GEO, and could possibly be implemented on a swarm of micro-satellites. This instrument will have wide application for validation studies, and will have application for other microwave frequencies.
    Keywords: Oceanography
    Type: 31st Conference on Radar Meteorology; Aug 06, 2003 - Aug 12, 2003; Seattle, WA; United States
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