1,051 research outputs found

    Vertical Distribution of Dust and Water Ice Aerosols from CRISM Limb-geometry Observations

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    [1] Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars Reconnaissance Orbiter provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb enables the vertical distribution of both dust and water ice aerosols to be retrieved. More than a dozen sets of CRISM limb observations have been taken so far providing pole-to-pole cross sections, spanning more than a full Martian year. Radiative transfer modeling is used to model the observations taking into account multiple scattering from aerosols and the spherical geometry of the limb observations. Both dust and water ice vertical profiles often show a significant vertical structure for nearly all seasons and latitudes that is not consistent with the well-mixed or Conrath-v assumptions that have often been used in the past for describing aerosol vertical profiles for retrieval and modeling purposes. Significant variations are seen in the retrieved vertical profiles of dust and water ice aerosol as a function of season. Dust typically extends to higher altitudes (approx. 40-50km) during the perihelion season than during the aphelion season (<20km), and the Hellas region consistently shows more dust mixed to higher altitudes than other locations. Detached water ice clouds are common, and water ice aerosols are observed to cap the dust layer in all seasons

    Utilising EEG Signals for Modulating Neural Molecular Communications

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    A major challenge in neuronal molecular communications lies in modulating signals through the neuronal network of the cortex that will minimize interference with the natural signalling. In this paper, we propose the use of Electroencephalogram (EEG) signals as a sensing mechanism to determine spiking interval gaps that can be used to stimulate artificial data transfer in the cortical micro-column

    Novel Role of Hypoxia in Ovarian Cancer Chemo Resistance through Epigenetic Regulation of HIF1α

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    Ovarian cancer is the fifth deadliest cancer in woman, and epithelial malignancies account for 90% of cases. Tumor recurrence after chemotherapy or radiation remains a major obstacle to successful ovarian cancer treatment. Despite the large number of studies, molecular events that govern the emergence of aggressive therapy-resistant cells after chemotherapy are poorly defined. Genetic modifications, such as copy number variation (CNV), play an important role in controlling the expression of genes that are involved in chemo resistance. We analyzed CNV data that is publically available through the Cancer Genome Atlas and others. Of particular interest was the transcription factor HIF1α which plays an integral role in oxidative stress response such as those induced by chemotherapy reagents? The present study provides evidence for the rare escape of tumor cells from drug-induced cell death by entering a non-cycling senescent state. We report the adaptive response of human ovarian surface epithelium cells to CoCl2, a chemical hypoxia-mimicking agent resulting in a senescent-like state of chemo resistant cells. The effect of the treatment was evaluated on CNV of HIF-1α gene expression, cell proliferation, survival, and tumor invasiveness

    Proopiomelanocortin Neurons in Nucleus Tractus Solitarius Are Activated by Visceral Afferents: Regulation by Cholecystokinin and Opioids

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    The nucleustractus solitarius (NTS) receives dense terminations from cranial visceral afferents, including those from the gastrointestinal (GI) system. Although the NTS integrates peripheral satiety signals and relays this signal to central feeding centers, little is known about which NTS neurons are involved or what mechanisms are responsible. Proopiomelanocortin (POMC) neurons are good candidates for GI integration, because disruption of the POMC gene leads to severe obesity and hyperphagia. Here, we used POMC– enhanced green fluorescent protein (EGFP) transgenic mice to identify NTS POMC neurons. Intraperitoneal administration of cholecystokinin (CCK) induced c-fos gene expression in NTS POMC–EGFP neurons, suggesting that they are activated by afferents stimulated by the satiety hormone. We tested the synaptic relationship of these neurons to visceral afferents and their modulation by CCK and opioids using patch recordings in horizontal brain slices. Electrical activation of the solitary tract (ST) evoked EPSCs in NTS POMC–EGFP neurons. The invariant latencies, low failure rates, and substantial paired-pulse depression of the ST-evoked EPSCs indicate that NTS POMC–EGFP neurons are second-order neurons directly contacted by afferent terminals. The EPSCs were blocked by the glutamate antagonist 2,3- dihydroxy-6-nitro-7-sulfonyl-benzo[f]quinoxaline. CCK increased the amplitude of the ST-stimulated EPSCs and the frequency of miniature EPSCs, effects attenuated by the CCK1 receptor antagonist lorglumide. In contrast, the orexigenic opioid agonists [D-Ala(2), N-Me-Phe(4), Gly-ol(5)]-enkephalin and met-enkephalin inhibited both ST-stimulated EPSCs and the frequency of miniature EPSCs. These findings identify a potential satiety pathway in which visceral afferents directly activate NTS POMC–EGFP neurons with excitatory inputs that are appropriately modulated by appetite regulators

    Metagenomic Profiling of Microbial Pathogens in the Little Bighorn River, Montana

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    The Little Bighorn River is the primary source of water for water treatment plants serving the local Crow Agency population, and has special significance in the spiritual and ceremonial life of the Crow tribe. Unfortunately, the watershed suffers from impaired water quality, with high counts of fecal coliform bacteria routinely measured during run-off events. A metagenomic analysis was carried out to identify potential pathogens in the river water. The Oxford Nanopore MinION platform was used to sequence DNA in near real time to identify both uncultured and a coliform-enriched culture of microbes collected from a popular summer swimming area of the Little Bighorn River. Sequences were analyzed using CosmosID bioinformatics and, in agreement with previous studies, enterohemorrhagic and enteropathogenic Escherichia coli and other E. coli pathotypes were identified. Noteworthy was detection and identification of enteroaggregative E. coli O104:H4 and Vibrio cholerae serotype O1 El Tor, however, cholera toxin genes were not identified. Other pathogenic microbes, as well as virulence genes and antimicrobial resistance markers, were also identified and characterized by metagenomic analyses. It is concluded that metagenomics provides a useful and potentially routine tool for identifying in an in-depth manner microbial contamination of waterways and, thereby, protecting public health
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