218,055 results on '"Robert, F"'
Search Results
202. Results of Leveraging Pharmaceutical Patient Assistance Programs to Expand Access to High Cost Medications in a Student-Run Free Clinic
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Lee, Julie J., Sack, Daniel E., Kam, Sharon, Reed, Sarah C., Carew, Babatunde, Lloyd, Cooper, Weaver, Eleanor O., and Miller, Robert F.
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- 2023
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203. Dependency, Detachment, and Health-Related Behavior in Adult Primary Care Patients
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Bornstein, Robert F., Porcerelli, John H., and Jones, John R.
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- 2023
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204. Breast cancer cell-secreted miR-199b-5p hijacks neurometabolic coupling to promote brain metastasis
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Xianhui Ruan, Wei Yan, Minghui Cao, Ray Anthony M. Daza, Miranda Y. Fong, Kaifu Yang, Jun Wu, Xuxiang Liu, Melanie Palomares, Xiwei Wu, Arthur Li, Yuan Chen, Rahul Jandial, Nicholas C. Spitzer, Robert F. Hevner, and Shizhen Emily Wang
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Science - Abstract
Abstract Breast cancer metastasis to the brain is a clinical challenge rising in prevalence. However, the underlying mechanisms, especially how cancer cells adapt a distant brain niche to facilitate colonization, remain poorly understood. A unique metabolic feature of the brain is the coupling between neurons and astrocytes through glutamate, glutamine, and lactate. Here we show that extracellular vesicles from breast cancer cells with a high potential to develop brain metastases carry high levels of miR-199b-5p, which shows higher levels in the blood of breast cancer patients with brain metastases comparing to those with metastatic cancer in other organs. miR-199b-5p targets solute carrier transporters (SLC1A2/EAAT2 in astrocytes and SLC38A2/SNAT2 and SLC16A7/MCT2 in neurons) to hijack the neuron–astrocyte metabolic coupling, leading to extracellular retention of these metabolites and promoting cancer cell growth. Our findings reveal a mechanism through which cancer cells of a non-brain origin reprogram neural metabolism to fuel brain metastases.
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- 2024
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205. An integrative framework for mapping the psychological landscape of risk perception
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Sarah C. Jenkins, Robert F. Lachlan, and Magda Osman
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Medicine ,Science - Abstract
Abstract We vary greatly in our perception of risk, not just because of differences between risks themselves, but also because of individual, contextual and cultural differences too. To better understand and predict responses to risk, we need to (a) integrate these components, combining approaches from different psychological disciplines and (b) also consider risk tolerance – how individuals trade-off between risks and benefits. We therefore developed an ICONS (individual, contextual, cognitive, social) framework; using it across two empirical studies (n = 4228) to examine how individuals perceive and respond to the quotidian risks associated with consumer products. Three dimensions underlined risk perceptions: benefits, dread and individual responsibility. Risk tolerance was typically predicted by interactions between individual (demographic, cultural worldview, personality) and contextual (product type/category, harm information) factors. In turn, perceived dread, benefits and individual differences shaped how likely participants were to communicate risk information. Our results demonstrate for the first time how the interaction between individual, cognitive (risk tolerance, intensity), contextual, and social (risk communication) factors is key to understanding and predicting risk perceptions. Together, our findings help explain why societal responses to risks are often difficult to predict and have implications for the spread, and amplification, of risk information.
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- 2024
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206. SY-MIS Project: Biomedical Design of Endo-Robotic and Laparoscopic Training System for Surgery on the Earth and Space
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José Cornejo, Jorge Cornejo, M. Vargas, M. Carvajal, Paul Perales, G. Rodríguez, C. Macias, S. Canizares, Paola Silva, Robert F. Cubas, M. C. Jimenez, Eddy P. Lincango, Luis Serrano, Ricardo Palomares, S. Aspilcueta, Rocio Castillo-Larios, Lorna A. Evans, J. A. De La Cruz-Vargas, Marcelo Risk, Rafael J. Grossmann, and Enrique F. Elli
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engineering design ,biomedical technologies ,medical mechatronics ,surgical robotics ,aerospace medicine. ,Technology (General) ,T1-995 ,Social sciences (General) ,H1-99 - Abstract
Despite the location (Earth or Space), surgical simulation is a vital part of improving technical skills and ensuring patients' safety in the real procedure. The purpose of this study is to describe the Space System for Minimally Invasive Surgery (SY-MIS©) project, which started in 2016 under the supervision of the Center for Space Systems (C-SET). The process connects the best features of the following machines: Biomedik Surgeon, Space Biosurgeon, SP-LAP 1, and SP-LAP 2, which were defined using the VDI 2221 guidelines. This research uses methods based on 3 standards: i) Biomedical design: ISO 9001-13485 / FDA 21 CFR 820.30 / ASTM F1744-96(2016); ii) Aerospace human factors: HF-STD-001; iii) Mechatronics design: VDI 2206. The results depict the conceptual biomedical design of a novel training system named Surgical Engineering and Mechatronic System (SETY©), which integrates the use of 2 laparoscopic tools and 2 anthropomorphic mini-robotic arms (6 DOF). It has been validated by the Evaluation of Technical Criteria, getting a total score of 90% related to clinical assessment, machine adaptability, and robustness. The novelty of the research lies in the introduction of a new procedure that covers the simultaneous use of laparoscopic and robotic systems, named Hybrid Cyber-Physical Surgery (HYS©). In conclusion, the development of SY-MIS© promotes the use of advanced technologies to improve surgical procedures and human-machine medical cooperation for the next frontier of habitability on other planets. Doi: 10.28991/ESJ-2024-08-02-01 Full Text: PDF
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- 2024
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207. Intention-to-treat outcomes utilising a stringent event definition in children and young people treated with tisagenlecleucel for r/r ALL through a national access scheme
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Macarena Oporto Espuelas, Saskia Burridge, Amy A. Kirkwood, Denise Bonney, Kelly Watts, Geoff Shenton, Katarzyna A. Jalowiec, Maeve A. O’Reilly, Claire Roddie, Anna Castleton, Katherine Clesham, Emma Nicholson, Rajesh Alajangi, Shilpa Prabhu, Lindsay George, Ben Uttenthal, Maria Gabelli, Lorna Neill, Caroline Besley, Sridhar Chaganti, Robert F. Wynn, Jack Bartram, Robert Chiesa, Giovanna Lucchini, Vesna Pavasovic, Anupama Rao, Kanchan Rao, Juliana Silva, Sujith Samarasinghe, Ajay Vora, Peter Clark, Michelle Cummins, David I. Marks, Persis Amrolia, Rachael Hough, and Sara Ghorashian
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Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract CAR T-cell therapy has transformed relapsed/refractory (r/r) B-cell precursor acute lymphoblastic leukaemia (B-ALL) management and outcomes, but following CAR T infusion, interventions are often needed. In a UK multicentre study, we retrospectively evaluated tisagenlecleucel outcomes in all eligible patients, analysing overall survival (OS) and event-free survival (EFS) with standard and stringent definitions, the latter including measurable residual disease (MRD) emergence and further anti-leukaemic therapy. Both intention-to-treat and infused cohorts were considered. We collected data on feasibility of delivery, manufacture, toxicity, cause of therapy failure and followed patients until death from any cause. Of 142 eligible patients, 125 received tisagenlecleucel, 115/125 (92%) achieved complete remission (CR/CRi). Severe cytokine release syndrome and neurotoxicity occurred in 16/123 (13%) and 10/123 (8.1%), procedural mortality was 3/126 (2.4%). The 2-year intent to treat OS and EFS were 65.2% (95%CI 57.2–74.2%) and 46.5% (95%CI 37.6–57.6%), 2-year intent to treat stringent EFS was 35.6% (95%CI 28.1–44.9%). Median OS was not reached. Sixty-two responding patients experienced CAR T failure by the stringent event definition. Post failure, 1-year OS and standard EFS were 61.2% (95%CI 49.3–75.8) and 55.3% (95%CI 43.6–70.2). Investigation of CAR T-cell therapy for B-ALL delivered on a country-wide basis, including following patients beyond therapy failure, provides clinicians with robust outcome measures. Previously, outcomes post CAR T-cell therapy failure were under-reported. Our data show that patients can be successfully salvaged in this context with good short-term survival.
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- 2024
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208. Parafoveal cone function in choroideremia assessed with adaptive optics optoretinography
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Peiluo Xu, Robert F. Cooper, Yu You Jiang, and Jessica I. W. Morgan
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Medicine ,Science - Abstract
Abstract Choroideremia (CHM) is an X-linked retinal degeneration leading to loss of the photoreceptors, retinal pigment epithelium (RPE), and choroid. Adaptive optics optoretinography is an emerging technique for noninvasive, objective assessment of photoreceptor function. Here, we investigate parafoveal cone function in CHM using adaptive optics optoretinography and compare with cone structure and clinical assessments of vision. Parafoveal cone mosaics of 10 CHM and four normal-sighted participants were imaged with an adaptive optics scanning light ophthalmoscope. While acquiring video sequences, a 2 s 550Δ10 nm, 450 nW/deg2 stimulus was presented. Videos were registered and the intensity of each cone in each frame was extracted, normalized, standardized, and aggregated to generate the population optoretinogram (ORG) over time. A gamma-pdf was fit to the ORG and the peak was extracted as ORG amplitude. CHM ORG amplitudes were compared to normal and were correlated with bound cone density, ellipsoid zone to RPE/Bruch’s membrane (EZ-to-RPE/BrM) distance, and foveal sensitivity using Pearson correlation analysis. ORG amplitude was significantly reduced in CHM compared to normal (0.22 ± 0.15 vs. 1.34 ± 0.31). In addition, CHM ORG amplitude was positively correlated with cone density, EZ-to-RPE/BrM distance, and foveal sensitivity. Our results demonstrate promise for using ORG as a biomarker of photoreceptor function.
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- 2024
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209. Characterization of a Southern Ocean deep chlorophyll maximum: Response of phytoplankton to light, iron, and manganese enrichment
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Pauline Latour, Sam Eggins, Pier van derMerwe, Lennart T. Bach, Philip W. Boyd, Michael J. Ellwood, Andrew R. Bowie, Kathrin Wuttig, and Robert F. Strzepek
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Oceanography ,GC1-1581 - Abstract
Abstract Southern Ocean phytoplankton growth is limited by low iron (Fe) supply and irradiance, impacting the strength of the biological carbon pump. Unfavorable upper ocean conditions, such as low nutrient concentrations, can lead to the formation of deep chlorophyll or biomass maxima (DCM/DBM). While common in the Southern Ocean, these features remain understudied due to their subsurface location. To increase our understanding of their occurrence, we studied the responses of phytoplankton communities from a Southern Ocean DCM to increasing light, Fe, and manganese (Mn) levels. The DCM communities were light‐ and Fe‐limited, but light limitation did not increase phytoplankton Fe requirements. The greatest physiological responses were observed under combined Fe/light additions, which stimulated macronutrient drawdown, biomass production and the growth of large diatoms. Combined Mn/light additions induced subtle changes in Fe uptake rates and community composition, suggesting species‐specific Mn requirements. These results provide valuable information on Southern Ocean DCM phytoplankton physiology.
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- 2024
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210. Epigenetic scores of blood-based proteins as biomarkers of general cognitive function and brain health
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Hannah M. Smith, Joanna E. Moodie, Karla Monterrubio-Gómez, Danni A. Gadd, Robert F. Hillary, Aleksandra D. Chybowska, Daniel L. McCartney, Archie Campbell, Paul Redmond, Danielle Page, Adele Taylor, Janie Corley, Sarah E. Harris, Maria Valdés Hernández, Susana Muñoz Maniega, Mark E. Bastin, Joanna M. Wardlaw, Ian J. Deary, James P. Boardman, Donncha S. Mullin, Tom C. Russ, Simon R. Cox, and Riccardo E. Marioni
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DNA methylation ,Epigenetic scores ,General cognitive function ,Brain imaging ,Dementia ,Blood-based biomarkers ,Medicine ,Genetics ,QH426-470 - Abstract
Abstract Background Epigenetic Scores (EpiScores) for blood protein levels have been associated with disease outcomes and measures of brain health, highlighting their potential usefulness as clinical biomarkers. They are typically derived via penalised regression, whereby a linear weighted sum of DNA methylation (DNAm) levels at CpG sites are predictive of protein levels. Here, we examine 84 previously published protein EpiScores as possible biomarkers of cross-sectional and longitudinal measures of general cognitive function and brain health, and incident dementia across three independent cohorts. Results Using 84 protein EpiScores as candidate biomarkers, associations with general cognitive function (both cross-sectionally and longitudinally) were tested in three independent cohorts: Generation Scotland (GS), and the Lothian Birth Cohorts of 1921 and 1936 (LBC1921 and LBC1936, respectively). A meta-analysis of general cognitive functioning results in all three cohorts identified 18 EpiScore associations (absolute meta-analytic standardised estimates ranged from 0.03 to 0.14, median of 0.04, P FDR
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- 2024
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211. The NASA Radiation Hardness Assurance (RHA) Process Standard
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Razvan Gaza, Gregory R Allen, Michael J Campola, Kenneth A LaBel, Raymond L Ladbury, Jean-Marie Lauenstein, Joshua Pritts, Ted Wilcox, Peter J Majewicz, and Robert F Hodson
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Spacecraft Instrumentation and Astrionics - Abstract
This paper presents status on the upcoming NASA Agency-level RHA Process Standard. Based on recommendations provided by the NASA Engineering and Safety Center (NESC), the NASA Electronic Parts and Packaging (NEPP) Program has led development of an agency-level standard for space flight avionics and electronics RHA. The standard introduces a novel RHA taxonomy and prescribes the process required by NASA programs and projects to baseline their RHA programs consistent with the MEAL (Mission, Environment, Application, and Lifetime) criteria including the risk tolerance posture. The standard also provides requirements for the RHA schedule integration in the program or project lifecycle and requirements for data deliverables content. Additional non-prescriptive technical content is provided in the standard appendices to guide development of RHA programs for NASA missions.
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- 2024
212. Algorithms and Bounds for Complex and Quaternionic Lattices With Application to MIMO Transmission
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Stern, Sebastian, Ling, Cong, and Fischer, Robert F. H.
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Computer Science - Information Theory - Abstract
Lattices are a popular field of study in mathematical research, but also in more practical areas like cryptology or multiple-input/multiple-output (MIMO) transmission. In mathematical theory, most often lattices over real numbers are considered. However, in communications, complex-valued processing is usually of interest. Besides, by the use of dual-polarized transmission as well as by the combination of two time slots or frequencies, four-dimensional (quaternion-valued) approaches become more and more important. Hence, to account for this fact, well-known lattice algorithms and related concepts are generalized in this work. To this end, a brief review of complex arithmetic, including the sets of Gaussian and Eisenstein integers, and an introduction to quaternion-valued numbers, including the sets of Lipschitz and Hurwitz integers, are given. On that basis, generalized variants of two important algorithms are derived: first, of the polynomial-time LLL algorithm, resulting in a reduced basis of a lattice by performing a special variant of the Euclidean algorithm defined for matrices, and second, of an algorithm to calculate the successive minima - the norms of the shortest independent vectors of a lattice - and its related lattice points. Generalized bounds for the quality of the particular results are established and the asymptotic complexities of the algorithms are assessed. These findings are extensively compared to conventional real-valued processing. It is shown that the generalized approaches outperform their real-valued counterparts in complexity and/or quality aspects. Moreover, the application of the generalized algorithms to MIMO communications is studied, particularly in the field of lattice-reduction-aided and integer-forcing equalization.
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- 2022
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213. TOI-836: A super-Earth and mini-Neptune transiting a nearby K-dwarf
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Hawthorn, Faith, Bayliss, Daniel, Wilson, Thomas G., Bonfanti, Andrea, Adibekyan, Vardan, Alibert, Yann, Sousa, Sérgio G., Collins, Karen A., Bryant, Edward M., Osborn, Ares, Armstrong, David J., Abe, Lyu, Acton, Jack S., Addison, Brett C., Agabi, Karim, Alonso, Roi, Alves, Douglas R., Anglada-Escudé, Guillem, Bárczy, Tamas, Barclay, Thomas, Barrado, David, Barros, Susana C. C., Baumjohann, Wolfgang, Bendjoya, Philippe, Benz, Willy, Bieryla, Allyson, Bonfils, Xavier, Bouchy, François, Brandeker, Alexis, Broeg, Christopher, Brown, David J. A., Burleigh, Matthew R., Buttu, Marco, Cabrera, Juan, Caldwell, Douglas A., Casewell, Sarah L., Charbonneau, David, Charnoz, Sébastian, Cloutier, Ryan, Cameron, Andrew Collier, Collins, Kevin I., Conti, Dennis M., Crouzet, Nicolas, Czismadia, Szilárd, Davies, Melvyn B., Deleuil, Magali, Delgado-Mena, Elisa, Delrez, Laetitia, Demangeon, Olivier D. S., Demory, Brice-Olivier, Dransfield, Georgina, Dumusque, Xavier, Egger, Jo Ann, Ehrenreich, David, Eigmüller, Philipp, Erickson, Anders, Essack, Zahra, Fortier, Andrea, Fossati, Luca, Fridlund, Malcolm, Günther, Maximilian N., Güdel, Manuel, Gandolfi, Davide, Gillard, Harvey, Gillon, Michaël, Gnilka, Crystal, Goad, Michael R., Goeke, Robert F., Guillot, Tristan, Hadjigeorghiou, Andreas, Hellier, Coel, Henderson, Beth A., Heng, Kevin, Hooton, Matthew J., Horne, Keith, Howell, Steve B., Hoyer, Sergio, Irwin, Jonathan M., Jenkins, James S., Jenkins, Jon M., Jensen, Eric L. N., Kane, Stephen R., Kendall, Alicia, Kielkopf, John F., Kiss, Laszlo L., Lacedelli, Gaia, Laskar, Jacques, Latham, David W., Etangs, Alain Lecavalier des, Leleu, Adrien, Lendl, Monika, Lillo-Box, Jorge, Lovis, Christophe, Mékarnia, Djamel, Massey, Bob, Masters, Tamzin, Maxted, Pierre F. L., Nascimbeni, Valerio, Nielsen, Louise D., O'Brien, Sean M., Olofsson, Göran, Osborn, Hugh P., Pagano, Isabella, Pallé, Enric, Persson, Carina M., Piotto, Giampaolo, Plavchan, Peter, Pollacco, Don, Queloz, Didier, Ragazzoni, Roberto, Rauer, Heike, Ribas, Ignasi, Ricker, George, Ségransan, Damien, Salmon, Sébastien, Santerne, Alexandre, Santos, Nuno C., Scandariato, Gaetano, Schmider, François-Xavier, Schwarz, Richard P., Seager, Sara, Shporer, Avi, Simon, Attila E., Smith, Alexis M. S., Srdoc, Gregor, Steller, Manfred, Suarez, Olga, Szabó, Gyula M., Teske, Johanna, Thomas, Nicolas, Tilbrook, Rosanna H., Triaud, Amaury H. M. J., Udry, Stéphane, Van Grootel, Valérie, Walton, Nicholas, Wang, Sharon X., Wheatley, Peter J., Winn, Joshua N., Wittenmyer, Robert A., and Zhang, Hui
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Astrophysics - Earth and Planetary Astrophysics - Abstract
We present the discovery of two exoplanets transiting TOI-836 (TIC 440887364) using data from TESS Sector 11 and Sector 38. TOI-836 is a bright ($T = 8.5$ mag), high proper motion ($\sim\,200$ mas yr$^{-1}$), low metallicity ([Fe/H]$\approx\,-0.28$) K-dwarf with a mass of $0.68\pm0.05$ M$_{\odot}$ and a radius of $0.67\pm0.01$ R$_{\odot}$. We obtain photometric follow-up observations with a variety of facilities, and we use these data-sets to determine that the inner planet, TOI-836 b, is a $1.70\pm0.07$ R$_{\oplus}$ super-Earth in a 3.82 day orbit, placing it directly within the so-called 'radius valley'. The outer planet, TOI-836 c, is a $2.59\pm0.09$ R$_{\oplus}$ mini-Neptune in an 8.60 day orbit. Radial velocity measurements reveal that TOI-836 b has a mass of $4.5\pm0.9$ M$_{\oplus}$ , while TOI-836 c has a mass of $9.6\pm2.6$ M$_{\oplus}$. Photometric observations show Transit Timing Variations (TTVs) on the order of 20 minutes for TOI-836 c, although there are no detectable TTVs for TOI-836 b. The TTVs of planet TOI-836 c may be caused by an undetected exterior planet.
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- 2022
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214. Composition-differentiation operators on $S^2(\mathbb{D})$
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Allen, Robert F., Heller, Katherine, and Pons, Matthew A.
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Mathematics - Functional Analysis - Abstract
We investigate composition-differentiation operators acting on the space $S^2$, the space of analytic functions on the open unit disk whose first derivative is in $H^2$. Specifically, we determine characterizations for bounded and compact composition-differentiation operators acting on $S^p$. In addition, for particular classes of inducing maps, we compute the norm, and identify the spectrum. Finally, for particular linear fractional inducing maps, we determine the adjoint of the composition-differentiation operator acting on weighted Bergman spaces which include $S^2, H^2$, and the Dirichlet space., Comment: in submission
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- 2022
215. On the Diophantine equation $U_n-b^m = c$
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Heintze, Sebastian, Tichy, Robert F., Vukusic, Ingrid, and Ziegler, Volker
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Mathematics - Number Theory - Abstract
Let $(U_n)_{n\in \mathbb{N}}$ be a fixed linear recurrence sequence defined over the integers (with some technical restrictions). We prove that there exist effectively computable constants $B$ and $N_0$ such that for any $b,c\in \mathbb{Z}$ with $b> B$ the equation $U_n - b^m = c$ has at most two distinct solutions $(n,m)\in \mathbb{N}^2$ with $n\geq N_0$ and $m\geq 1$. Moreover, we apply our result to the special case of Tribonacci numbers given by $T_1= T_2=1$, $T_3=2$ and $T_{n}=T_{n-1}+T_{n-2}+T_{n-3}$ for $n\geq 4$. By means of the LLL-algorithm and continued fraction reduction we are able to prove $N_0=1.1\cdot 10^{37}$ and $B=e^{438}$. The corresponding reduction algorithm is implemented in Sage., Comment: 34 pages
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- 2022
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216. CAPD: A Context-Aware, Policy-Driven Framework for Secure and Resilient IoBT Operations
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Chukkapalli, Sai Sree Laya, Joshi, Anupam, Finin, Tim, and Erbacher, Robert F.
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Computer Science - Cryptography and Security ,Computer Science - Artificial Intelligence ,Computer Science - Multiagent Systems - Abstract
The Internet of Battlefield Things (IoBT) will advance the operational effectiveness of infantry units. However, this requires autonomous assets such as sensors, drones, combat equipment, and uncrewed vehicles to collaborate, securely share information, and be resilient to adversary attacks in contested multi-domain operations. CAPD addresses this problem by providing a context-aware, policy-driven framework supporting data and knowledge exchange among autonomous entities in a battlespace. We propose an IoBT ontology that facilitates controlled information sharing to enable semantic interoperability between systems. Its key contributions include providing a knowledge graph with a shared semantic schema, integration with background knowledge, efficient mechanisms for enforcing data consistency and drawing inferences, and supporting attribute-based access control. The sensors in the IoBT provide data that create populated knowledge graphs based on the ontology. This paper describes using CAPD to detect and mitigate adversary actions. CAPD enables situational awareness using reasoning over the sensed data and SPARQL queries. For example, adversaries can cause sensor failure or hijacking and disrupt the tactical networks to degrade video surveillance. In such instances, CAPD uses an ontology-based reasoner to see how alternative approaches can still support the mission. Depending on bandwidth availability, the reasoner initiates the creation of a reduced frame rate grayscale video by active transcoding or transmits only still images. This ability to reason over the mission sensed environment and attack context permits the autonomous IoBT system to exhibit resilience in contested conditions.
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- 2022
217. Weighted composition operators from the Bloch space to weighted Banach spaces on bounded homogeneous domains
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Allen, Robert F.
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Mathematics - Functional Analysis ,primary: 47B38, secondary: 32A18 - Abstract
We study the bounded and the compact weighted composition operators from the Bloch space into the weighted Banach spaces of holomorphic functions on bounded homogeneous domains, with particular attention to the unit polydisk. For bounded homogeneous domains, we characterize the bounded weighted composition operators and determine the operator norm. In addition, we provide sufficient conditions for compactness. For the unit polydisk, we completely characterize the compact weighted composition operators, as well as provide computable estimates on the operator norm.
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- 2022
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218. Hypercyclicity of composition operators on discrete weighted Banach spaces
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Allen, Robert F., Colonna, Flavia, Martínez-Avendaño, Rubén A., and Pons, Matthew A.
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Mathematics - Functional Analysis ,primary: 47B33, 47A16, secondary: 47B38 - Abstract
In this paper, we study the hypercyclic composition operators on weighted Banach spaces of functions defined on discrete metric spaces. We show that the only such composition operators act on the "little" spaces. We characterize the bounded composition operators on the little spaces, as well as provide various necessary conditions for hypercyclicity.
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- 2022
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219. Multiplication operators between Lipschitz-type spaces on a tree
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Allen, Robert F., Colonna, Flavia, and Easley, Glenn R.
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Mathematics - Functional Analysis ,primary: 47B38, secondary: 05C05 - Abstract
Let $\mathcal{L}$ be the space of complex-valued functions $f$ on the set of vertices $T$ of an rooted infinite tree rooted at $o$ such that the difference of the values of $f$ at neighboring vertices remains bounded throughout the tree, and let $\mathcal{L}_{\textbf{w}}$ be the set of functions $f\in \mathcal{L}$ such that $|f(v)-f(v^-)|=O(|v|^{-1})$, where $|v|$ is the distance between $o$ and $v$ and $v^-$ is the neighbor of $v$ closest to $o$. In this article, we characterize the bounded and the compact multiplication operators between $\mathcal{L}$ and $\mathcal{L}_{\textbf{w}}$, and provide operator norm and essential norm estimates. Furthermore, we characterize the bounded and compact multiplication operators between $\mathcal{L}_{\textbf{w}}$ and the space $L^\infty$ of bounded functions on $T$ and determine their operator norm and their essential norm. We establish that there are no isometries among the multiplication operators between these spaces.
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- 2022
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220. Compact differences of composition operators on weighted Dirichlet spaces
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Allen, Robert F., Heller, Katherine, and Pons, Matthew A.
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Mathematics - Functional Analysis ,primary: 47B33, secondary: 46E20, 47B32 - Abstract
Here we consider when the difference of two composition operators is compact on the weighted Dirichlet spaces $\mathcal{D}_\alpha$. Specifically we study differences of composition operators on the Dirichlet space $\mathcal{D}$ and $S^2$, the space of analytic functions whose first derivative is in $H^2$, and then use Calder\'{o}n's complex interpolation to extend the results to the general weighted Dirichlet spaces. As a corollary we consider composition operators induced by linear fractional self-maps of the disk.
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- 2022
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221. Isometric composition operators on the analytic Besov spaces
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Allen, Robert F., Heller, Katherine, and Pons, Matthew A.
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Mathematics - Functional Analysis ,primary: 47B33, secondary: 30H25 - Abstract
We investigate the isometric composition operators on the analytic Besov spaces. For $1
2$, we extend previous work on the subject. Finally, we analyze this same problem for the Besov spaces with an equivalent norm.
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- 2022
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222. Multiplication operators on the weighted Lipschitz space of a tree
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Allen, Robert F., Colonna, Flavia, and Easley, Glenn R.
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Mathematics - Functional Analysis ,primary: 47B38, secondary: 05C05 - Abstract
We study the multiplication operators on the weighted Lipschitz space $\mathcal{L}_{\textbf{w}}$ consisting of the complex-valued functions $f$ on the set of vertices of an infinite tree $T$ rooted at $o$ such that $\sup_{v\neq o}|v||f(v)-f(v^-)|<\infty$, where $|v|$ denotes the distance between $o$ and $v$ and $v^-$ is the neighbor of $v$ closest to $o$. For the multiplication operator, we characterize boundedness, compactness, provide estimates on the operator norm and the essential norm, and determine the spectrum. We prove that there are no isometric multiplication operators or isometric zero divisors on $\mathcal{L}_{\textbf{w}}$., Comment: arXiv admin note: text overlap with arXiv:2207.12212
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- 2022
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223. Weighted composition operators on the Bloch space of a bounded homogeneous domain
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Allen, Robert F. and Colonna, Flavia
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Mathematics - Complex Variables ,Mathematics - Functional Analysis ,primary: 47B38, seconday: 32A18, 30D45 - Abstract
In this paper, we present the current results in the study of weighted composition operators on the Bloch space of bounded homogeneous domains in $\mathbb{C}^n$ with particular emphasis on the issues of boundedness and compactness. We also discuss the bounded and the compact weighted composition operators from the Bloch space to the Hardy space $H^\infty$.
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- 2022
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224. Multiplication operators between iterated logarithmic Lipschitz spaces of a tree
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Allen, Robert F., Colonna, Flavia, and Prudhom, Andrew
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Mathematics - Functional Analysis ,primary: 47B38, 05C05 - Abstract
In this article, we characterize the bounded and the compact multiplication operators between distinct iterated logarithmic Lipschitz spaces, and between the Lipschitz space and an iterated logarithmic Lipschitz space of an infinite tree. In addition, we provide operator norm estimates and show that there are no isometries among such operators. %We obtain a new characterization of the bounded multiplication operators acting on an iterated logarithmic Lipschitz space and the compact multiplication operators between the weighted Lipschitz space and the Lipschitz space.
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- 2022
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225. Multiplication operators on $S^2(\mathbb D)$
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Allen, Robert F., Heller, Katherine, and Pons, Matthew A.
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Mathematics - Complex Variables ,Mathematics - Functional Analysis ,primary: 47B38, secondary: 46E20, 47B32, 30H1 - Abstract
In this paper, we study the multiplication operators on $S^2$, the space of analytic functions on the open unit disk $\mathbb D$ whose first derivative is in $H^2$. Specifically, we characterize the bounded and the compact multiplication operators, establish estimates on the operator norm, and determine the spectrum. Finally, we prove that the isometric multiplication operators are precisely those induced by a constant function of modulus one.
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- 2022
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226. Multiplication operators on the iterated logarithmic Lipschitz spaces of a tree
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Allen, Robert F., Colonna, Flavia, and Easley, Glenn R.
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Mathematics - Functional Analysis ,primary: 47B38, 05C05 - Abstract
We introduce a class of iterated logarithmic Lipschitz spaces $\mathcal{L}^{(k)}$, $k\in\mathbb{N}$, on an infinite tree which arise naturally in the context of operator theory. We characterize boundedness and compactness of the multiplication operators on $\mathcal{L}^{(k)}$ and provide estimates on their operator norm and their essential norm. In addition, we determine the spectrum, characterize the multiplication operators that are bounded below, and prove that on such spaces there are no nontrivial isometric multiplication operators and no isometric zero divisors.
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- 2022
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227. Perturbations in epidemiological models: When zombies attack, we can survive!
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Allen, Robert F., Jens, Cassandra, and Wendt, Theodore J.
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Quantitative Biology - Populations and Evolution ,Mathematics - Dynamical Systems ,primary: 92D30, secondary: 92B05 - Abstract
In this paper, we investigate the existence of stability-changing bifurcations in epidemiological models used to study the spread of zombiism through a human population. These bifurcations show that although linear instability of disease-free equilibria may exist in a model, perturbations of model parameters may result in stability. Thus, we show that humans can survive a zombie outbreak.
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- 2022
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228. The differentiation operator on discrete function spaces of a tree
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Allen, Robert F. and Jackson, Colin M.
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Mathematics - Functional Analysis ,primary: 47B38, secondary: 05C05 - Abstract
In this paper, we study the differentiation operator acting on discrete function spaces; that is spaces of functions defined on an infinite rooted tree. We discuss, through its connection with composition operators, the boundedness and compactness of this operator. In addition, we discuss the operator norm and spectrum, and consider when such an operator can be an isometry. We then apply these results to the operator acting on the discrete Lipschitz space and weighted Banach spaces, as well as the Hardy spaces defined on homogeneous trees.
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- 2022
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229. Composition-differentiation operators on the Dirichlet space
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Allen, Robert F., Heller, Katherine, and Pons, Matthew A.
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Mathematics - Functional Analysis ,primary: 47B33 - Abstract
We investigate composition-differentiation operators acting on the Dirichlet space of the unit disk. Specifically, we determine characterizations for bounded, compact, and Hilbert-Schmidt composition-differentiation operators. In addition, for particular classes of inducing maps, we derive an adjoint formula, compute the norm, and identify the spectrum.
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- 2022
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230. Topological structure of the space of composition operators on $L^\infty$ of an unbounded, locally finite metric space
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Allen, Robert F., George, Whitney, and Pons, Matthew A.
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Mathematics - Functional Analysis ,Mathematics - General Topology ,primary: 47B33, secondary: 47B38 - Abstract
We study properties of the topological space of composition operators on the Banach algebra of bounded functions on an unbounded, locally finite metric space in the operator norm topology and essential norm topology. Moreover, we characterize the compactness of differences of two such composition operators., Comment: in submission
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- 2022
231. Weighted composition operators on discrete weighted Banach spaces
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Allen, Robert F. and Pons, Matthew A.
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Mathematics - Functional Analysis ,primary: 47B33, secondary: 05C05 - Abstract
We present the current results in the study of weighted composition operators on weighted Banach spaces of an unbounded, locally finite metric space. Specifically, we determine characterizations of bounded and compact weighted composition operators, including the operator and essential norms. In addition, we characterize the weighted composition operators that are injective, are bounded below, have closed range, and have bounded inverse. We characterize the isometries and surjective isometries among the weighted composition operators, as well as those that satisfy the Fredholm condition. Lastly, we provide numerous interesting examples of the richness of these operators acting on the discrete weighted Banach spaces., Comment: to appear, Acta Sci. Math. (Szeged)
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- 2022
232. Composition operators on weighted Banach spaces of a tree
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Allen, Robert F. and Pons, Matthew A.
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Mathematics - Functional Analysis ,primary: 47B33, secondary: 05C05 - Abstract
We study composition operators on the weighted Banach spaces of an infinite tree. We characterize the bounded and the compact operators, as well as determine the operator norm and the essential norm. In addition, we study the isometric composition operators.
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- 2022
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233. Analysis of SIR epidemic models with sociological phenomenon
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Allen, Robert F., Heller, Katherine, and Pons, Matthew A.
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Mathematics - Dynamical Systems ,Physics - Physics and Society ,Quantitative Biology - Populations and Evolution ,primary: 92D30, secondary: 92B05 - Abstract
We propose two SIR models which incorporate sociological behavior of groups of individuals. It is these differences in behaviors which impose different infection rates on the individual susceptible populations, rather than biological differences. We compute the basic reproduction number for each model, as well as analyze the sensitivity of $R_0$ to changes in sociological parameter values.
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- 2022
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234. Spectrum of a composition operator with automorphic symbol
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Allen, Robert F., Le, Thong M., and Pons, Matthew A.
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Mathematics - Functional Analysis ,primary: 47B33, 47A10, secondary: 30H05 - Abstract
We give a complete characterization of the spectrum of composition operators, induced by an automorphism of the open unit disk, acting on a family of Banach spaces of analytic functions that includes the Bloch space and BMOA. We show that for parabolic and hyperbolic automorphisms, the spectrum is the unit circle. For the case of elliptic automorphisms, the spectrum is either the unit circle or a finite cyclic subgroup of the unit circle.
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- 2022
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235. Weighted composition operators from $H^\infty$ to the Bloch space of a bounded homogeneous domain
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Allen, Robert F. and Colonna, Flavia
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Mathematics - Functional Analysis ,primary: 47B38, secondary: 32A18, 30D45 - Abstract
Let $D$ be a bounded homogeneous domain in $\mathbb{C}^n$. In this paper, we study the bounded and the compact weighted composition operators mapping the Hardy space $H^\infty(D)$ into the Bloch space of $D$. We characterize the bounded weighted composition operators, provide operator norm estimates, and give sufficient conditions for compactness. We prove that these conditions are necessary in the case of the unit ball and the polydisk. We then show that if $D$ is a bounded symmetric domain, the bounded multiplication operators from $H^\infty(D)$ to the Bloch space of $D$ are the operators whose symbol is bounded.
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- 2022
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236. Power Injection Measurements are more Vulnerable to Data Integrity Attacks than Power Flow Measurements
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Ye, Xiuzhen, Esnaola, Iñaki, Perlaza, Samir M., and Harrison, Robert F.
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Electrical Engineering and Systems Science - Systems and Control - Abstract
A novel metric that describes the vulnerability of the measurements in power system to data integrity attacks is proposed. The new metric, coined vulnerability index (VuIx), leverages information theoretic measures to assess the attack effect on the fundamental limits of the disruption and detection tradeoff. The result of computing the VuIx of the measurements in the system yields an ordering of the measurements vulnerability based on the level of exposure to data integrity attacks. This new framework is used to assess the measurements vulnerability of IEEE test systems and it is observed that power injection measurements are overwhelmingly more vulnerable to data integrity attacks than power flow measurements. A detailed numerical evaluation of the VuIx values for IEEE test systems is provided., Comment: 6 pages, 9 figures, Submitted to IEEE International Conference on Communications, Control, and Computing Technologies for Smart Grids
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- 2022
237. Association of cancer and outcomes of patients hospitalized for COVID-19 between 2020 and 2023 [version 1; peer review: awaiting peer review]
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Abdulai Tejan Jalloh, Laura Merson, Divya Nair, Shermarke Hassan, Ibrahim Franklyn Kamara, Innocent Nuwagira, Sia Morenike Tengbe, Yusuf Sheku Tejan, Mustapha Kabba, Sulaiman Lakoh, Donald S Grant, Robert J Samuels, Rugiatu Z Kamara, and Robert F Terry
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Research Article ,Articles ,COVID-19 ,cancer ,comorbidities ,mortality ,hazard ratio ,risk factor ,ISARIC ,SORT IT - Abstract
Background The coronavirus disease 2019 (COVID-19) has caused substantial morbidity and mortality on a global scale. A strong correlation has been found between COVID-19 treatment outcomes and noncommunicable diseases such as cancers. However, there is limited information on the outcomes of cancer patients who were hospitalised for COVID-19. Methods We conducted an analysis on data collected in a large prospective cohort study set-up by the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC). All patients with laboratory-confirmed or clinically-diagnosed SARS-CoV-2 infection were included. Cancer was defined as having a current solid organ or haematological malignancy. The following outcomes were assessed; 30-day in-hospital mortality, intensive care unit (ICU) admission, length of hospitalization and receipt of higher-level care. Results Of the 560,547 hospitalised individuals who were analysed, 27,243 (4.9%) had cancer. Overall, cancer patients were older and had more comorbidities than non-cancer patients. Patients with cancer had higher 30-day in-hospital mortality than non-cancer patients (29.1.3% vs 18.0%) and longer hospital stays (median of 12 days vs 8 days). However, patients with cancer were admitted less often to intensive care units than non-cancer patients (12.6% vs 17.1%) and received less invasive mechanical ventilation than non-cancer patients (4.5% vs 7.6%). The hazard ratio of dying from cancer, adjusted for age, sex and country income level was 1.18 (95%CI: 1.15-1.2). Conclusions This study’s findings underscore the heightened vulnerability of hospitalized COVID-19 patients with cancer, revealing a higher mortality rate, longer hospital stays, and an unstructured pattern of care that reflects the complexity of managing severely ill patients during a public health crisis like the COVID-19 pandemic.
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- 2024
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238. Monoclonal antibody therapy demonstrates increased virulence of a lineage VII strain of Lassa virus in nonhuman primates
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Courtney Woolsey, Robert W. Cross, Abhishek N. Prasad, Krystle N. Agans, Viktoriya Borisevich, Daniel J. Deer, Natalie S. Dobias, Alyssa C. Fears, Mack B. Harrison, Megan L. Heinrich, Karla A. Fenton, Robert F. Garry, Luis M. Branco, and Thomas W. Geisbert
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Lassa virus ,arenavirus ,monoclonal antibodies ,haemorrhagic fever ,nonhuman primates ,Infectious and parasitic diseases ,RC109-216 ,Microbiology ,QR1-502 - Abstract
ABSTRACTLassa virus (LASV) is a World Health Organization (WHO) priority pathogen that causes high morbidity and mortality. Recently, we showed that a combination of three broadly neutralizing human monoclonal antibodies known as Arevirumab-3 (8.9F, 12.1F, 37.2D) based on the lineage IV Josiah strain protected 100% of cynomolgus macaques against heterologous challenge with lineage II and III strains of LASV when therapy was initiated beginning at day 8 after challenge. LASV strains from Benin and Togo represent a new lineage VII that are more genetically diverse from lineage IV than strains from lineages II and III. Here, we tested the ability of Arevirumab-3 to protect macaques against a LASV lineage VII Togo isolate when treatment was administered beginning 8 days after exposure. Unexpectedly, only 40% of treated animals survived challenge. In a subsequent study we showed that Arevirumab-3 protected 100% of macaques from lethal challenge when treatment was initiated 7 days after LASV Togo exposure. Based on our transcriptomics data, successful Arevirumab-3 treatment correlated with diminished neutrophil signatures and the predicted development of T cell responses. As the in vitro antiviral activity of Arevirumab-3 against LASV Togo was equivalent to lineage II and III strains, the reduced protection in macaques against Togo likely reflects the faster disease course of LASV Togo in macaques than other strains. This data causes concern regarding the ability of heterologous vaccines and treatments to provide cross protection against lineage VII LASV isolates.
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- 2024
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239. Enabling selective zinc-ion intercalation by a eutectic electrolyte for practical anodeless zinc batteries
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Li, Chang, Kingsbury, Ryan, Thind, Arashdeep Singh, Shyamsunder, Abhinandan, Fister, Timothy T, Klie, Robert F, Persson, Kristin A, and Nazar, Linda F
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Engineering ,Materials Engineering ,Chemical Sciences ,Physical Chemistry ,Affordable and Clean Energy - Abstract
Two major challenges hinder the advance of aqueous zinc metal batteries for sustainable stationary storage: (1) achieving predominant Zn-ion (de)intercalation at the oxide cathode by suppressing adventitious proton co-intercalation and dissolution, and (2) simultaneously overcoming Zn dendrite growth at the anode that triggers parasitic electrolyte reactions. Here, we reveal the competition between Zn2+ vs proton intercalation chemistry of a typical oxide cathode using ex-situ/operando techniques, and alleviate side reactions by developing a cost-effective and non-flammable hybrid eutectic electrolyte. A fully hydrated Zn2+ solvation structure facilitates fast charge transfer at the solid/electrolyte interface, enabling dendrite-free Zn plating/stripping with a remarkably high average coulombic efficiency of 99.8% at commercially relevant areal capacities of 4 mAh cm-2 and function up to 1600 h at 8 mAh cm-2. By concurrently stabilizing Zn redox at both electrodes, we achieve a new benchmark in Zn-ion battery performance of 4 mAh cm-2 anode-free cells that retain 85% capacity over 100 cycles at 25 °C. Using this eutectic-design electrolyte, Zn | |Iodine full cells are further realized with 86% capacity retention over 2500 cycles. The approach represents a new avenue for long-duration energy storage.
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- 2023
240. Machine learning models inaccurately predict current and future high-latitude C balances
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Shirley, Ian A, Mekonnen, Zelalem A, Grant, Robert F, Dafflon, Baptiste, and Riley, William J
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Climate Change Impacts and Adaptation ,Environmental Sciences ,Climate Action ,machine learning ,upscaling ,forecasting ,independent evaluation ,carbon cycle ,high-latitudes ,climate change ,Meteorology & Atmospheric Sciences - Abstract
The high-latitude carbon (C) cycle is a key feedback to the global climate system, yet because of system complexity and data limitations, there is currently disagreement over whether the region is a source or sink of C. Recent advances in big data analytics and computing power have popularized the use of machine learning (ML) algorithms to upscale site measurements of ecosystem processes, and in some cases forecast the response of these processes to climate change. Due to data limitations, however, ML model predictions of these processes are almost never validated with independent datasets. To better understand and characterize the limitations of these methods, we develop an approach to independently evaluate ML upscaling and forecasting. We mimic data-driven upscaling and forecasting efforts by applying ML algorithms to different subsets of regional process-model simulation gridcells, and then test ML performance using the remaining gridcells. In this study, we simulate C fluxes and environmental data across Alaska using ecosys, a process-rich terrestrial ecosystem model, and then apply boosted regression tree ML algorithms to training data configurations that mirror and expand upon existing AmeriFLUX eddy-covariance data availability. We first show that a ML model trained using ecosys outputs from currently-available Alaska AmeriFLUX sites incorrectly predicts that Alaska is presently a modeled net C source. Increased spatial coverage of the training dataset improves ML predictions, halving the bias when 240 modeled sites are used instead of 15. However, even this more accurate ML model incorrectly predicts Alaska C fluxes under 21st century climate change because of changes in atmospheric CO2, litter inputs, and vegetation composition that have impacts on C fluxes which cannot be inferred from the training data. Our results provide key insights to future C flux upscaling efforts and expose the potential for inaccurate ML upscaling and forecasting of high-latitude C cycle dynamics.
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- 2023
241. The JPL-GIM algorithm and products: multi-GNSS high-rate global mapping of total electron content
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Martire, Léo, Runge, Thomas F., Meng, Xing, Krishnamoorthy, Siddharth, Vergados, Panagiotis, Mannucci, Anthony J., Verkhoglyadova, Olga P., Komjáthy, Attila, Moore, Angelyn W., Meyer, Robert F., Ijima, Byron A., and Green, Donald W.
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- 2024
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242. Correction: Feminization of a mixed-stock foraging aggregation of immature green turtles (Chelonia mydas), 1975–2018
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Meylan, Anne B., Brost, Beth, Conrad, Liza J., Denison, Steven H., Flaherty, Denise B., Gray, Jennifer A., Hardy, Robert F., Meylan, Peter A., Schwenter, Jeffrey A., Tornwall, Brett, and Owens, David W.
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- 2024
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243. Tomographic flow measurements over additively manufactured cooling channel roughness
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Boldt, Ryan, McClain, Stephen T., Kunz, Robert F., and Yang, Xiang
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- 2024
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244. Bioavailable iron titrations reveal oceanic Synechococcus ecotypes optimized for different iron availabilities
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Gilbert, Naomi E, LeCleir, Gary R, Strzepek, Robert F, Ellwood, Michael J, Twining, Benjamin S, Roux, S, Pennacchio, C, Boyd, Philip W, and Wilhelm, Steven W
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Microbiology ,Biological Sciences ,Ecology - Abstract
The trace metal iron (Fe) controls the diversity and activity of phytoplankton across the surface oceans, a paradigm established through decades of in situ and mesocosm experimental studies. Despite widespread Fe-limitation within high-nutrient, low chlorophyll (HNLC) waters, significant contributions of the cyanobacterium Synechococcus to the phytoplankton stock can be found. Correlations among differing strains of Synechococcus across different Fe-regimes have suggested the existence of Fe-adapted ecotypes. However, experimental evidence of high- versus low-Fe adapted strains of Synechococcus is lacking, and so we investigated the transcriptional responses of microbial communities inhabiting the HNLC, sub-Antarctic region of the Southern Ocean during the Spring of 2018. Analysis of metatranscriptomes generated from on-deck incubation experiments reflecting a gradient of Fe-availabilities reveal transcriptomic signatures indicative of co-occurring Synechococcus ecotypes adapted to differing Fe-regimes. Functional analyses comparing low-Fe and high-Fe conditions point to various Fe-acquisition mechanisms that may allow persistence of low-Fe adapted Synechococcus under Fe-limitation. Comparison of in situ surface conditions to the Fe-titrations indicate ecological relevance of these mechanisms as well as persistence of both putative ecotypes within this region. This Fe-titration approach, combined with transcriptomics, highlights the short-term responses of the in situ phytoplankton community to Fe-availability that are often overlooked by examining genomic content or bulk physiological responses alone. These findings expand our knowledge about how phytoplankton in HNLC Southern Ocean waters adapt and respond to changing Fe supply.
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- 2022
245. Site-specific field management adaptation is key to feeding the world in the 21st century
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Woo, Dong Kook, Riley, William J, Grant, Robert F, and Wu, Yuxin
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Agriculture ,Land and Farm Management ,Agricultural ,Veterinary and Food Sciences ,Crop and Pasture Production ,Zero Hunger ,Climate Action ,Wheat ,Yield ,Climate change ,Adaptation ,Earth Sciences ,Biological Sciences ,Agricultural and Veterinary Sciences ,Meteorology & Atmospheric Sciences ,Agricultural ,veterinary and food sciences ,Biological sciences ,Earth sciences - Abstract
Rapid climate change and growing population threaten global food security across the globe. Several studies have proposed early planting, increased irrigation, and increased fertilizer applications as climate adaptation strategies, yet none have considered combined and site-specific field management strategies as a comprehensive solution. Here, we analyzed non-irrigated wheat yield responses to climate change and field management adaptation using a mechanistic crop model evaluated against observed global non-irrigated wheat-yield over 3-year intervals spanning 13 years at 3749 sites (RMSE = 36 gC m−2). Early planting with later-maturing varieties provided the most benefit to future yields among the proposed field management adaptation strategies. Improved water use efficiency from increased CO2 led to relatively low benefits of additional irrigation. We estimated that spatially heterogeneous adaption strategies had the potential to improve global wheat yields by 91% by 2100 compared to the present day. The yield improvements from combined field adaptation strategies were larger than the sum of improvements from the individual strategies. These synergistic benefits were shown to result from complementary processes regulating nutrient and water uptake, physiological tolerance to heat stress, and internal carbon and nutrient cycling.
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- 2022
246. TERT promoter C228T mutation in neural progenitors confers growth advantage following telomere shortening in vivo
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Miki, Shunichiro, Koga, Tomoyuki, Mckinney, Andrew M, Parisian, Alison D, Tadokoro, Takahiro, Vadla, Raghavendra, Marsala, Martin, Hevner, Robert F, Costello, Joseph F, and Furnari, Frank
- Subjects
Biomedical and Clinical Sciences ,Oncology and Carcinogenesis ,Stem Cell Research - Induced Pluripotent Stem Cell - Human ,Stem Cell Research - Induced Pluripotent Stem Cell ,Stem Cell Research - Nonembryonic - Non-Human ,Rare Diseases ,Neurosciences ,Genetics ,Brain Cancer ,Brain Disorders ,Stem Cell Research ,Cancer ,2.1 Biological and endogenous factors ,Humans ,Mice ,Animals ,Telomere Shortening ,Induced Pluripotent Stem Cells ,Telomerase ,Telomere ,Glioblastoma ,Mutation ,Carcinogenesis ,genome editing ,glioma ,neural progenitor cell ,telomerase ,TERT promoter ,Oncology & Carcinogenesis ,Oncology and carcinogenesis - Abstract
BackgroundHeterozygous TERT (telomerase reverse transcriptase) promoter mutations (TPMs) facilitate TERT expression and are the most frequent mutation in glioblastoma (GBM). A recent analysis revealed this mutation is one of the earliest events in gliomagenesis. However, no appropriate human models have been engineered to study the role of this mutation in the initiation of these tumors.MethodWe established GBM models by introducing the heterozygous TPM in human induced pluripotent stem cells (hiPSCs) using a two-step targeting approach in the context of GBM genetic alterations, CDKN2A/B and PTEN deletion, and EGFRvIII overexpression. The impact of the mutation was evaluated through the in vivo passage and in vitro experiment and analysis.ResultsOrthotopic injection of neuronal precursor cells (NPCs) derived from hiPSCs with the TPM into immunodeficient mice did not enhance tumorigenesis compared to TERT promoter wild type NPCs at initial in vivo passage presumably due to relatively long telomeres. However, the mutation recruited GA-Binding Protein and engendered low-level TERT expression resulting in enhanced tumorigenesis and maintenance of short telomeres upon secondary passage as observed in human GBM. These results provide the first insights regarding increased tumorigenesis upon introducing a TPM compared to isogenic controls without TPMs.ConclusionOur novel GBM models presented the growth advantage of heterozygous TPMs for the first time in the context of GBM driver mutations relative to isogenic controls, thereby allowing for the identification and validation of TERT promoter-specific vulnerabilities in a genetically accurate background.
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- 2022
247. Systems genomics in age-related macular degeneration
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Hollander, Anneke I den, Mullins, Robert F, Orozco, Luz D, Voigt, Andrew P, Chen, Hsu-Hsin, Strunz, Tobias, Grassmann, Felix, Haines, Jonathan L, Kuiper, Jonas JW, Tumminia, Santa J, Allikmets, Rando, Hageman, Gregory S, Stambolian, Dwight, Klaver, Caroline CW, Boeke, Jef D, Chen, Hao, Honigberg, Lee, Katti, Suresh, Frazer, Kelly A, Weber, Bernhard HF, and Gorin, Michael B
- Subjects
Biomedical and Clinical Sciences ,Ophthalmology and Optometry ,Macular Degeneration ,Neurosciences ,Eye Disease and Disorders of Vision ,Human Genome ,Stem Cell Research ,Neurodegenerative ,Biotechnology ,Genetics ,Stem Cell Research - Induced Pluripotent Stem Cell ,Aging ,Stem Cell Research - Induced Pluripotent Stem Cell - Human ,2.1 Biological and endogenous factors ,Aetiology ,Eye ,Humans ,Retinal Pigment Epithelium ,Complement System Proteins ,Choroid ,Proteins ,Genomics ,Polymorphism ,Single Nucleotide ,Complement Factor H ,High-Temperature Requirement A Serine Peptidase 1 ,Age-related macular degeneration ,Omics ,Systems genomics ,Single cell sequencing ,Expression quantitative trait locus ,Complement system ,iPSc-RPE ,Induced pluripotent stem cells ,Clinical trial ,Polygenic risk scores ,Medical Biochemistry and Metabolomics ,Opthalmology and Optometry ,Ophthalmology & Optometry ,Ophthalmology and optometry - Abstract
Genomic studies in age-related macular degeneration (AMD) have identified genetic variants that account for the majority of AMD risk. An important next step is to understand the functional consequences and downstream effects of the identified AMD-associated genetic variants. Instrumental for this next step are 'omics' technologies, which enable high-throughput characterization and quantification of biological molecules, and subsequent integration of genomics with these omics datasets, a field referred to as systems genomics. Single cell sequencing studies of the retina and choroid demonstrated that the majority of candidate AMD genes identified through genomic studies are expressed in non-neuronal cells, such as the retinal pigment epithelium (RPE), glia, myeloid and choroidal cells, highlighting that many different retinal and choroidal cell types contribute to the pathogenesis of AMD. Expression quantitative trait locus (eQTL) studies in retinal tissue have identified putative causal genes by demonstrating a genetic overlap between gene regulation and AMD risk. Linking genetic data to complement measurements in the systemic circulation has aided in understanding the effect of AMD-associated genetic variants in the complement system, and supports that protein QTL (pQTL) studies in plasma or serum samples may aid in understanding the effect of genetic variants and pinpointing causal genes in AMD. A recent epigenomic study fine-mapped AMD causal variants by determing regulatory regions in RPE cells differentiated from induced pluripotent stem cells (iPSC-RPE). Another approach that is being employed to pinpoint causal AMD genes is to produce synthetic DNA assemblons representing risk and protective haplotypes, which are then delivered to cellular or animal model systems. Pinpointing causal genes and understanding disease mechanisms is crucial for the next step towards clinical translation. Clinical trials targeting proteins encoded by the AMD-associated genomic loci C3, CFB, CFI, CFH, and ARMS2/HTRA1 are currently ongoing, and a phase III clinical trial for C3 inhibition recently showed a modest reduction of lesion growth in geographic atrophy. The EYERISK consortium recently developed a genetic test for AMD that allows genotyping of common and rare variants in AMD-associated genes. Polygenic risk scores (PRS) were applied to quantify AMD genetic risk, and may aid in predicting AMD progression. In conclusion, genomic studies represent a turning point in our exploration of AMD. The results of those studies now serve as a driving force for several clinical trials. Expanding to omics and systems genomics will further decipher function and causality from the associations that have been reported, and will enable the development of therapies that will lessen the burden of AMD.
- Published
- 2022
248. 304 channel MicroLED based CMOS transceiver IC with aggregate 1 Tbps and sub-pJ per bit capability.
- Author
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Bardia Pezeshki, Suresh Rangarajan, Alex Tselikov, Emad Afifi, Ivan Huang, Jeff Pepper, Sarah Zou, Howard Rourke, Rowan Pocock, Alasdair Fikouras, Farzad Khoeini, Vahid Mirkhani, Steve Novak, and Robert F. Kalman
- Published
- 2024
249. Low-Complexity Non-Binary Forward Error Correction for Lattice-Based 4D Constellations.
- Author
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Sebastian Stern, Mahmoud Sallam, and Robert F. H. Fischer
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- 2024
250. Rethinking Disorder
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Carley, Robert F., primary
- Published
- 2024
- Full Text
- View/download PDF
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