Image reconstruction from discrete samples is fundamental in remote sensing. The reconstruction problem is more complicated when the sample locations are irregularly spaced and employ different ...aperture functions. Further, not all 2-D sampling configurations permit full image reconstruction of band-limited signals. In this article, 2-D signal reconstruction from irregular samples with variable apertures is considered using theory and examples. Exact reconstruction requires that the signal be band-limited and the sampling matrix be invertable. The results are sensitive to the sample locations and noise in the measurements. Illustrative examples are provided using simulation and actual data from the L-band Soil Moisture Active Passive (SMAP) radiometer. The general approach can be employed with other sensors.
RAG initiates antibody V(D)J recombination in developing lymphocytes by generating “on-target” DNA breaks at matched pairs of bona fide recombination signal sequences (RSSs). We employ bait ...RAG-generated breaks in endogenous or ectopically inserted RSS pairs to identify huge numbers of RAG “off-target” breaks. Such breaks occur at the simple CAC motif that defines the RSS cleavage site and are largely confined within convergent CTCF-binding element (CBE)-flanked loop domains containing bait RSS pairs. Marked orientation dependence of RAG off-target activity within loops spanning up to 2 megabases implies involvement of linear tracking. In this regard, major RAG off-targets in chromosomal translocations occur as convergent RSS pairs at enhancers within a loop. Finally, deletion of a CBE-based IgH locus element disrupts V(D)J recombination domains and, correspondingly, alters RAG on- and off-target distributions within IgH. Our findings reveal how RAG activity is developmentally focused and implicate mechanisms by which chromatin domains harness biological processes within them.
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•Linear tracking within CBE-based loops restricts RAG off-target activity genome-wide•ATM deficiency allows RAG-initiated DSBs to escape from loop domains and translocate•RAG off-target activity marks certain IgH locus V(D)J recombination domains•Robust RAG off-targets occur in pairs in highly accessible regions within a loop
The 3D architecture of the genome harnesses RAG endonuclease activity by allowing it to directionally locate convergent recombination signal sequences and related CAC-containing motifs within individual chromatin loop domains.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Wind scatterometer measurements are collected over an irregular grid, and processing is required to generate backscatter images on an Earth-centered grid. The most common algorithms used for this are ..."drop in the bucket" (DIB) and variations of the scatterometer image reconstruction (SIR) algorithm. These algorithms are also used for radiometer brightness temperature imaging. The Backus-Gilbert (BG) algorithm has been used for radiometer imaging but has not been applied to scatterometer backscatter imaging. In this paper, the application of BG to scatterometer backscatter imaging is explored and its performance is compared to DIB and SIR. Like SIR, optimally tuned BG is capable of producing higher resolution images than DIB, though its noise performance is slightly inferior to SIR's. While BG and SIR produce similar results for radiometer data, the higher relative noise level of scatterometer data increases the differences between the SIR and BG algorithm performance, and limits the performance of BG relative to SIR in scatterometer imaging. Comparison of the SIR and BG algorithms in scatterometer imaging offers important insights into the inversion/reconstruction problem.
Doxorubicin is an effective and widely used cancer chemotherapeutic agent, but its application is greatly compromised by its cumulative dose-dependent side effect of cardiotoxicity. A gold ...nanoparticle-based drug delivery system has been designed to overcome this limitation. Five novel thiolated doxorubicin analogs were synthesized and their biological activities evaluated. Two of these analogs and PEG stabilizing ligands were then conjugated to gold nanoparticles, and the resulting Au-Dox constructs were evaluated. The results show that release of native drug can be achieved by the action of reducing agents such as glutathione or under acidic conditions, but reductive drug release gave the cleanest drug release. Gold nanoparticles (Au-Dox) were prepared with different loadings of PEG and doxorubicin, and one formulation was evaluated for mammalian stability and toxicity. Plasma levels of doxorubicin in mice treated with Au-Dox were significantly lower than in mice treated with the same amount of doxorubicin, indicating that the construct is stable under physiological conditions. Treatment of mice with Au-Dox gave no histopathologically observable differences from mice treated with saline, while mice treated with an equivalent dose of doxorubicin showed significant histopathologically observable lesions.
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IJS, KILJ, NUK, PNG, UL, UM
During Cook's 1772–75 Antarctic circumnavigation on the HMS Resolution, he recorded the positions of hundreds of icebergs. This paper compares Cook's observations and those of Halley in 1700, Bouvet ...in 1739 and Riou in 1789, with the Brigham Young University/National Ice Center (BYU/NIC) and the Alfred Wegener Institute datasets. Cook's description of the iceberg plume east of the Amery Ice Shelf and the iceberg distributions in the Weddell, Ross and Amundsen Seas agree with modern data. In January 1774, Cook reached his farthest south on the shelf of the Amundsen Sea Embayment, the site of the current International Thwaites Glacier Collaboration field study. Cook's largest iceberg had a 2.5 km diameter, where power-law models show that icebergs of this size or smaller comprise 92% of their total number. In the eastern Weddell, Cook's observation of a sea-ice tongue with a much greater extent than in satellite imagery remains unexplained. Although Riou's icebergs lie 1000 km east of the BYU/NIC trajectories, application of the England and others (2020) fracture and drift model to the trajectories removes the discrepancy and means that all the ship observations are consistent with modern observations and theory.
Polar Applications of Spaceborne Scatterometers Long, David G.
IEEE journal of selected topics in applied earth observations and remote sensing,
05/2017, Volume:
10, Issue:
5
Journal Article
Peer reviewed
Open access
Wind scatterometers were originally developed for observation of near-surface winds over the ocean. They retrieve wind indirectly by measuring the normalized radar cross section (σ°) of the surface, ...and estimating the wind via geophysical model function relating σ° to the vector wind. The σ° measurements have proven to be remarkably capable in studies of the polar regions where they can map snow cover; detect the freeze/thaw state of forest, tundra, and ice; map and classify sea ice; and track icebergs. Further, a long time series of scatterometer σ° observations is available to support climate studies. In addition to fundamental scientific research, scatterometer data are operationally used for sea-ice mapping to support navigation. Scatterometers are, thus, invaluable tools for monitoring the polar regions. In this paper, a brief review of some of the polar applications of spaceborne wind scatterometer data is provided. The paper considers both C-band and Ku-band scatterometers, and the relative merits of fan-beam and pencil-beam scatterometers in polar remote sensing are discussed.
The climate research community uses atmospheric reanalysis data sets to understand a wide range of processes and variability in the atmosphere, yet different reanalyses may give very different ...results for the same diagnostics. The Stratosphere–troposphere Processes And their Role in Climate (SPARC) Reanalysis Intercomparison Project (S-RIP) is a coordinated activity to compare reanalysis data sets using a variety of key diagnostics. The objectives of this project are to identify differences among reanalyses and understand their underlying causes, to provide guidance on appropriate usage of various reanalysis products in scientific studies, particularly those of relevance to SPARC, and to contribute to future improvements in the reanalysis products by establishing collaborative links between reanalysis centres and data users. The project focuses predominantly on differences among reanalyses, although studies that include operational analyses and studies comparing reanalyses with observations are also included when appropriate. The emphasis is on diagnostics of the upper troposphere, stratosphere, and lower mesosphere. This paper summarizes the motivation and goals of the S-RIP activity and extensively reviews key technical aspects of the reanalysis data sets that are the focus of this activity. The special issue The SPARC Reanalysis Intercomparison Project (S-RIP) in this journal serves to collect research with relevance to the S-RIP in preparation for the publication of the planned two (interim and full) S-RIP reports.
This paper considers some of the issues of radiometer brightness image formation and reconstruction for use in the NASA-sponsored Calibrated Passive Microwave Daily Equal-Area Scalable Earth Grid 2.0 ...Brightness Temperature Earth System Data Record project, which generates a multisensor multidecadal time series of high-resolution radiometer products designed to support climate studies. Two primary reconstruction algorithms are considered: the Backus-Gilbert approach and the radiometer form of the scatterometer image reconstruction (SIR) algorithm. These are compared with the conventional drop-in-the-bucket (DIB) gridded image formation approach. Tradeoff study results for the various algorithm options are presented to select optimum values for the grid resolution, the number of SIR iterations, and the BG gamma parameter. We find that although both approaches are effective in improving the spatial resolution of the surface brightness temperature estimates compared to DIB, SIR requires significantly less computation. The sensitivity of the reconstruction to the accuracy of the measurement spatial response function (MRF) is explored. The partial reconstruction of the methods can tolerate errors in the description of the sensor measurement response function, which simplifies the processing of historic sensor data for which the MRF is not known as well as modern sensors. Simulation tradeoff results are confirmed using actual data.
Duane retraction syndrome (DRS) is a congenital eye-movement disorder defined by limited outward gaze and retraction of the eye on attempted inward gaze. Here, we report on three heterozygous ...loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness. Using genotype-phenotype correlations in humans and Mafb-knockout mice, we propose a threshold model for variable loss of MAFB function. Postmortem studies of DRS have reported abducens nerve hypoplasia and aberrant innervation of the lateral rectus muscle by the oculomotor nerve. Our studies in mice now confirm this human DRS pathology. Moreover, we demonstrate that selectively disrupting abducens nerve development is sufficient to cause secondary innervation of the lateral rectus muscle by aberrant oculomotor nerve branches, which form at developmental decision regions close to target extraocular muscles. Thus, we present evidence that the primary cause of DRS is failure of the abducens nerve to fully innervate the lateral rectus muscle in early development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper describes the development of, and the methodology for, a new, consolidated Brigham Young University (BYU)/National Ice Center (NIC) Antarctic iceberg tracking database. The new database ...combines daily positional data from the original BYU daily iceberg tracking database derived from scatterometers, and the NIC's weekly Antarctic iceberg tracking database derived mostly from optical and infrared sensors. Interpolation methods and statistical analyses of iceberg locations are discussed. A new, automated method of using positional data and scatterometer backscatter images to estimate sizes and rotational patterns of icebergs is also developed. This information is included in the new database.
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