1,363 research outputs found

    Markus Borner, a life at the conservation front line

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    Multiresolution spatiotemporal mechanical model of the heart as a prior to constrain the solution for 4D models of the heart.

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    In several nuclear cardiac imaging applications (SPECT and PET), images are formed by reconstructing tomographic data using an iterative reconstruction algorithm with corrections for physical factors involved in the imaging detection process and with corrections for cardiac and respiratory motion. The physical factors are modeled as coefficients in the matrix of a system of linear equations and include attenuation, scatter, and spatially varying geometric response. The solution to the tomographic problem involves solving the inverse of this system matrix. This requires the design of an iterative reconstruction algorithm with a statistical model that best fits the data acquisition. The most appropriate model is based on a Poisson distribution. Using Bayes Theorem, an iterative reconstruction algorithm is designed to determine the maximum a posteriori estimate of the reconstructed image with constraints that maximizes the Bayesian likelihood function for the Poisson statistical model. The a priori distribution is formulated as the joint entropy (JE) to measure the similarity between the gated cardiac PET image and the cardiac MRI cine image modeled as a FE mechanical model. The developed algorithm shows the potential of using a FE mechanical model of the heart derived from a cardiac MRI cine scan to constrain solutions of gated cardiac PET images

    The effects of 405 nm light on bacterial membrane integrity determined by salt and bile tolerance assays, leakage of UV absorbing material and SYTOX green labelling

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    Bacterial inactivation by 405nm light is accredited to the photo-excitation of intracellular porphyrin molecules which results in energy transfer and the generation of reactive oxygen species (ROS) which impart cellular oxidative damage. The specific mechanism of cellular damage, however, is not fully understood. Previous work has suggested that destruction of nucleic acids may be responsible for inactivation; however, microscopic imaging has suggested membrane damage as a major constituent of cellular inactivation. This study investigates the membrane integrity of Escherichia coli and Staphylococcus aureus exposed to 405nm light. Results indicated membrane damage to both species, with loss of salt and bile tolerance by S. aureus and E. coli, respectively, consistent with reduced membrane integrity. Increased nucleic acid release was also demonstrated in 405nm light-exposed cells, with up to 50% increase in DNA concentration into the extracellular media in the case of both organisms. SYTOX green fluorometric analysis however demonstrated contradictory results between the two test species. With E. coli, increasing permeation of SYTOX green was observed following increased exposure, with >500% increase in fluorescence, whereas no increase was observed with S. aureus. Overall, this study has provided good evidence that 405nm light exposure causes loss of bacterial membrane integrity in E. coli, but the results with S. aureus are more difficult to explain. Further work is required to gain greater understanding of the inactivation mechanism in different bacterial species, as there are likely to be other targets within the cell which are also impaired by the oxidative damage from photo-generated ROS

    Use of DES Modeling for Determining Launch Availability for SLS

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    The National Aeronautics and Space Administration (NASA) is developing new capabilities for human and scientific exploration beyond Earth's orbit. This effort includes the Space Shuttle derived Space Launch System (SLS), the Orion Multi-Purpose Crew Vehicle (MPCV), and the Ground Systems Development and Operations (GSDO). There are several requirements and Technical Performance Measures (TPMs) that have been levied by the Exploration Systems Development (ESD) upon the SLS, Orion, and GSDO Programs including an integrated Launch Availability (LA) TPM. The LA TPM is used to drive into the SLS, Orion and GSDO designs a high confidence of successfully launching exploration missions that have narrow Earth departure windows. The LA TPM takes into consideration the reliability of the overall system (SLS, Orion and GSDO), natural environments, likelihood of a failure, and the time required to recover from an anomaly. A challenge with the LA TPM is the interrelationships between SLS, Orion, GSDO and the natural environments during launch countdown and launch delays that makes it impossible to develop an analytical solution for calculating the integrated launch probability. This paper provides an overview of how Discrete Event Simulation (DES) modeling was used to develop the LA TPM, how it was allocated down to the individual programs, and how the LA analysis is being used to inform and drive the SLS, Orion, and GSDO designs to ensure adequate launch availability for future human exploration

    Depression and functioning in relation to health care use in sickle cell disease

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    The purpose of the current study was to investigate depression and health care use in patients with sickle cell disease (SCD). Forty-four adults with SCD were interviewed and data from 43 participants, both with (n = 11) and without (n = 32) depression, were used for further analyses. Data from one potential subject were excluded on the basis of diagnosis. The full evaluation included the Structured Clinical Interview for DSM-III-R Disorders (SCID) and the Center for Epidemiologic Studies–Depression Scale (CES-D), as well as measures of psychosocial and behavioral functioning. Good between-instrument agreement was found between the self-report and interview-based measures of depression. However, the functioning data did not entirely support the use of a more stringent cutoff score on the CES-D. Findings suggest that the purpose of the evaluation should be factored into the decision-making process when determining which cutoff score should be utilized (i.e. what is the cost–benefit ratio for false-positives vs. false-negatives). A series of hierarchical regression analyses supported the finding that disease severity alone does not explain the level of functioning displayed by patients. More importantly, the patient’s perceived functioning was the best indicator of health care use within a 1-year period. Furthermore, specific interventions that target negative thinking and distorted cognitions, as well as provide psychoeducation, such as cognitive–behavioral therapy, need to be further explored within this population

    Perceptions of Precision Agriculture Technologies in the U.S. Fresh Apple Industry

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    Advances in precision agriculture technologies provide opportunities to improve the efficiency of agricultural production systems, especially for high-value specialty crops such as fresh apples (Malus domestica). We distributed an online survey to apple growers in Washington, New York, and Michigan to elicit stakeholder perceptions of precision agriculture technologies. Findings from this study demonstrated that growers are willing to adopt precision agriculture technologies when they receive results from applied research projects and are engaged with active extension programs. The availability of customized services and purchasing and rental options may minimize the effects of the economies of size that create barriers to adopting increasing access to technologies. Finally, respondents deemed collaborative efforts between industry and academic institutions crucial for adapting the innovation to better address the needs of growers

    Genome sequencing data for wild and cultivated bananas, plantains and abacá

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    We performed shotgun genome sequencing on a total of 19 different Musa genotypes including representatives of wild banana species Musa acuminata and M. balibisiana, allopolyploid bananas and plantains, Fe'i banana, pink banana (also known as hairy banana) and abacá (also known as hemp banana). We aligned sequence reads against a previously sequenced reference genome and assessed ploidy and, in the case of allopolyploids, the contributions of the A and B genomes; this provides important quality-assurance data about the taxonomic identities of the sequenced plant material. These data will be useful for phylogenetics, crop improvement, studies of the complex story of intergenomic recombination in AAB and ABB allotriploid bananas and plantains and can be integrated into resources such as the Banana Genome Hub

    Infection control, occupational and public health measures including mRNA-based vaccination against SARS-CoV-2 infections to protect healthcare workers from variants of concern : a 14-month observational study using surveillance data

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    The article reviews evidence regarding exposure to COVID-19 in health care workers (HCW) and rates of transmission in Vancouver (Canada). Results of the study indicate that rigorous droplet-contact precautions with N95 masks for aerosol-generating procedures are effective in preventing occupational infection in HCWs, with one dose of mRNA vaccination further reducing infection risk, despite variants of concern (VOC) and transmissibility concerns. Delaying second doses to allow more widespread vaccination against severe disease, with strict public health, occupational health and infection control measures, has been effective in protecting the healthcare workforce

    Assessing molecular simulation for the analysis of lipid monolayer reflectometry

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    Using molecular simulation to aid in the analysis of neutron reflectometry measurements is commonplace. However, reflectometry is a tool to probe large-scale structures, and therefore the use of all-atom simulation may be irrelevant. This work presents the first direct comparison between the reflectometry profiles obtained from different all-atom and coarse-grained molecular dynamics simulations. These are compared with a traditional model layer structure analysis method to determine the minimum simulation resolution required to accurately reproduce experimental data. We find that systematic limits reduce the efficacy of the MARTINI potential model, while the Berger united-atom and Slipids all-atom potential models agree similarly well with the experimental data. The model layer structure gives the best agreement, however, the higher resolution simulation-dependent methods produce an agreement that is comparable. Finally, we use the atomistic simulation to advise on possible improvements that may be offered to the model layer structures, creating a more realistic monolayer model.Comment: Electronic Supplementary Information (ESI) available: All analysis/plotting scripts and figure files, allowing for a fully reproducible, and automated, analysis workflow for the work presented is available at \url{https://github.com/arm61/sim_vs_trad} (DOI: 10.5281/zenodo.2600729) under a CC BY-SA 4.0 licens
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