13 results on '"Johnson, Kirk A."'
Search Results
2. Reachability-Based Search for Tracking of Noncooperative Maneuvering Satellites in Data Sparse Environment.
- Author
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Hall, Zach, Singla, Puneet, and Johnson, Kirk
- Abstract
A generic Bayesian framework is presented to track lost-in-space noncooperative maneuvering satellites. The developed framework predicts the reachability set for a lost-in-space satellite given bounds on maneuver parameters such as maneuver time and maneuver magnitude. Reachability sets are represented as a desired order polynomial series as a function of maneuver parameters. Recent advances in non-product quadrature methods are utilized to compute coefficients of this polynomial series in a computationally efficient manner. A major contribution of this work is to develop quadrature methods to generate samples for spherically uniform distribution for bounded magnitude maneuvers. Samples generated from this polynomial series are used for direct particle propagation in a traditional Bayesian filter rather than solving governing equations of motion for each sample point. An important component of the developed framework is a search strategy which exploits the reachability set calculations to task the sensor to increase the detection probability of the satellite. The samples generated from initial reachability sets are updated to systematically reduce the target search region based on actual detection of the target in a Bayesian framework. Numerical simulations are performed to show the efficacy of the developed ideas for tracking a lost-in-space satellite with the help of space based sensor. Performance of the proposed method varies widely based on factors such as the reachability set polynomial order, maneuver uncertainty bounds, sensor parameters (Field of view, measurement frequency, and detection probability), and initial conditions. For numerical experiments performed, the observer gained the custody of the maneuvering target in 100 % and 96 % of Monte Carlo (MC) simulations for the single maneuver and two maneuver cases, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Semi-field and surveillance data define the natural diapause timeline for Culex pipiens across the United States.
- Author
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Field, Eleanor N., Shepard, John J., Clifton, Mark E., Price, Keith J., Witmier, Bryn J., Johnson, Kirk, Boze, Broox, Abadam, Charles, Ebel, Gregory D., Armstrong, Philip M., Barker, Christopher M., and Smith, Ryan C.
- Subjects
CULEX pipiens ,DIAPAUSE ,MOSQUITO control ,TEMPERATE climate ,POPULATION genetics ,DISEASE incidence - Abstract
Reproductive diapause serves as biological mechanism for many insects, including the mosquito Culex pipiens, to overwinter in temperate climates. While Cx. pipiens diapause has been well-studied in the laboratory, the timing and environmental signals that promote diapause under natural conditions are less understood. In this study, we examine laboratory, semi-field, and mosquito surveillance data to define the approximate timeline and seasonal conditions that contribute to Cx. pipiens diapause across the United States. While confirming integral roles of temperature and photoperiod in diapause induction, we also demonstrate the influence of latitude, elevation, and mosquito population genetics in shaping Cx. pipiens diapause incidence across the country. Coinciding with the cessation of WNV activity, these data can have important implications for mosquito control, where targeted efforts prior to diapause induction can decrease mosquito populations and WNV overwintering to reduce mosquito-borne disease incidence the following season. The combination of laboratory and semifield experiments, paired with surveillance data, demonstrate the natural timeline for mosquito diapause, highlighting the importance of latitude and population genetics. [ABSTRACT FROM AUTHOR]
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- 2022
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4. Lasmiditan mechanism of action – review of a selective 5-HT1F agonist.
- Author
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Clemow, David B., Johnson, Kirk W., Hochstetler, Helen M., Ossipov, Michael H., Hake, Ann M., and Blumenfeld, Andrew M.
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BLOOD-brain barrier , *CALCITONIN , *CENTRAL nervous system , *MIGRAINE , *PERIPHERAL nervous system , *NEUROPEPTIDES , *SEROTONIN agonists , *PAIN threshold , *PHARMACODYNAMICS - Abstract
Migraine is a leading cause of disability worldwide, but it is still underdiagnosed and undertreated. Research on the pathophysiology of this neurological disease led to the discovery that calcitonin gene-related peptide (CGRP) is a key neuropeptide involved in pain signaling during a migraine attack. CGRP-mediated neuronal sensitization and glutamate-based second- and third-order neuronal signaling may be an important component involved in migraine pain. The activation of several serotonergic receptor subtypes can block the release of CGRP, other neuropeptides, and neurotransmitters, and can relieve the symptoms of migraine. Triptans were the first therapeutics developed for the treatment of migraine, working through serotonin 5-HT1B/1D receptors. The discovery that the serotonin 1F (5-HT1F) receptor was expressed in the human trigeminal ganglion suggested that this receptor subtype may have a role in the treatment of migraine. The 5-HT1F receptor is found on terminals and cell bodies of trigeminal ganglion neurons and can modulate the release of CGRP from these nerves. Unlike 5-HT1B receptors, the activation of 5-HT1F receptors does not cause vasoconstriction. The potency of different serotonergic agonists towards 5-HT1F was correlated in an animal model of migraine (dural plasma protein extravasation model) leading to the development of lasmiditan. Lasmiditan is a newly approved acute treatment for migraine in the United States and is a lipophilic, highly selective 5-HT1F agonist that can cross the blood-brain barrier and act at peripheral nervous system (PNS) and central nervous system (CNS) sites. Lasmiditan activation of CNS-located 5-HT1F receptors (e.g., in the trigeminal nucleus caudalis) could potentially block the release of CGRP and the neurotransmitter glutamate, thus preventing and possibly reversing the development of central sensitization. Activation of 5-HT1F receptors in the thalamus can block secondary central sensitization of this region, which is associated with progression of migraine and extracephalic cutaneous allodynia. The 5-HT1F receptors are also elements of descending pain modulation, presenting another site where lasmiditan may alleviate migraine. There is emerging evidence that mitochondrial dysfunction might be implicated in the pathophysiology of migraine, and that 5-HT1F receptors can promote mitochondrial biogenesis. While the exact mechanism is unknown, evidence suggests that lasmiditan can alleviate migraine through 5-HT1F agonist activity that leads to inhibition of neuropeptide and neurotransmitter release and inhibition of PNS trigeminovascular and CNS pain signaling pathways. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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5. Prayer: A Helpful Aid in Recovery from Depression.
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Johnson, Kirk A.
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COGNITIVE therapy , *CONVALESCENCE , *MENTAL depression , *MEDITATION , *PRAYER , *PSYCHOLOGY & religion , *WELL-being , *MINDFULNESS - Abstract
Depression is a growing issue within the field of medicine. It negatively impacts individuals’ lives and the people they are most connected to. For decades, medical professionals have been searching for solutions to assist those who are suffering from this illness. The use of drugs has not been a sufficient means of treatment to alleviate depression and its symptoms. There is a dire need to expand therapeutic interventions that can attribute meaningful recovery for victims of depression. One means of positive treatment is the use of prayer. Prayer, one of the most ancient forms of meditation, aligns and relaxes the mental state of the mind. The uses of drugs are limited by physiological focus, but prayer is a mechanism that brings human beings into a unique state of oneness. Oneness comprises the holistic nature of a human being and asserts the triad of well-being: mind, body, and spirit. As the emergence of humanities and holism continues in medicine, centering/meditative prayer and similar practices like mindfulness-based cognitive therapy can be useful therapeutic interventions specifically for major depressed patients. [ABSTRACT FROM AUTHOR]
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- 2018
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6. Store and share ancient rocks.
- Author
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Planavsky, Noah, Hood, Ashleigh, Tarhan, Lidya, Shuzhong Shen, and Johnson, Kirk
- Published
- 2020
7. A Black Theological Response to Race-Based Medicine: Reconciliation in Minority Communities.
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Johnson, Kirk
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BLACK people , *MINORITIES , *PATIENT advocacy , *RACE , *RELIGION , *SELF-efficacy , *SOCIAL justice , *TRANSCULTURAL medical care - Abstract
The harm race-based medicine inflicts on minority bodies through race-based experimentation and the false solutions a race-based drug ensues within minority communities provokes concern. Such areas analyze the minority patient in a physical proxy. Though the mind and body are important entities, we cannot forget about the spirit. Healing is not just a physical practice; it includes spiritual practice. Efficient medicine includes the holistic elements of the mind, body, and spirit. Therefore, the spiritual discipline of black theology can be used as a tool to mend the harms of race-based medicine. It can be an avenue of research to further particular concerns for justice in medical care . Such theology contributes to the discussion of race-based medicine indicating the need for the voice, participation, and interdependence of minorities. Black theology can be used as a tool of healing and empowerment for health equity and awareness by exploring black theology's response to race-based medicine, analyzing race in biblical literature, using biblical literature as a tool for minority patient empowerment, building on past and current black church health advocacy with personal leadership in health advocacy. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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8. Karl Schwesig's Schlegelkeller: Anatomy of a Rejected Warning of Prewar Violence at LIFE Magazine.
- Author
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Johnson, Willa and Johnson, Kirk
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HOLOCAUST, 1939-1945, in art , *IDEOLOGY , *NAZI Germany, 1933-1945 - Abstract
This essay examines the 1939 decision by Time, Inc., publisher of LIFE magazine, to reject Schlegelkeller, an eyewitness account of early pre-Holocaust violence by German artist Karl Schwesig. While scholars have suggested a number of reasons why the American press minimized or failed to report the Nazi decimation of Jews and other marginalized groups, we borrow from two influential works by sociologist C. Wright Mills to suggest that an intricate intersection of social statuses, along with ideological perspectives, institutional norms, and personal temperament, may explain why LIFE rejected Schlegelkeller. We discuss the implications of this decision in light of both the magazine's internal metrics and the response of the American news media to prewar violence in Europe. [ABSTRACT FROM AUTHOR]
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- 2017
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9. A left knee wound complication by non-Hodgkins lymphoma in bilateral total knee arthroplasties.
- Author
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Eskander, Mark S., McPhee, Erika, Eskander, Jonathan P., Nascimento, Robert, McCormick, Jeremy J., Suyang Hao, Shepro, David, and Johnson, Kirk
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JOINTS (Anatomy) ,STIFLE joint ,HODGKIN'S disease ,WOMEN'S history ,LYMPHOMAS - Abstract
A 70-year-old woman with a history of bilateral primary knee osteoarthritis presented with a left knee wound complication, a non-Hodgkins lymphoma, after bilateral total knee arthroplasties. After exploring several etiologies, the evidence in this unusual case suggests a coincidental preexisting lymphoma. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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10. Revision of the Proteaceae Macrofossil Record from Patagonia, Argentina.
- Author
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Gonzalez, Cynthia C., Gandolfo, Maria A., Zamaloa, Maria C., Cúneo, Nestor R., Wilf, Peter, and Johnson, Kirk R.
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FOSSIL proteaceae ,FOSSIL catalogs & collections ,FOSSIL plant classification ,PROTEACEAE ,SHRUBS ,PALEOBOTANY - Abstract
Copyright of Botanical Review is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2007
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11. The Circulating Common Gamma Chain (CD132) in Inflammatory Bowel Disease.
- Author
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Nielsen, Ole Haagen, Kirman, Irena, Johnson, Kirk, Giedlin, Martin, and Ciardelli, Thomas
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INFLAMMATORY bowel diseases ,T cells ,INTERLEUKIN-2 ,CROHN'S disease ,ULCERATIVE colitis ,ENZYME-linked immunosorbent assay ,CLINICAL pathology ,DIAGNOSIS - Abstract
Objective: Inflammatory bowel disease (IBD) is characterized by T cell activation. Activated T cells shed interleukin-2 receptors (IL-2R) in a soluble form. A positive correlation between sIL-2Rα (CD25) and disease activity is well documented in IBD, whereas IL-2Rγ (CD132) has not been investigated in this respect. Sera from 42 patients with ulcerative colitis (UC), 34 with Crohn's disease (CD), 31 healthy volunteers, and 12 patients with infectious enterocolitis were obtained. Methods: Disease activity was scored according to a semiquantitative score for UC and CD. sIL-2R α chain and γ chain were assessed by sandwich ELISA techniques using monoclonal antibodies specific for CD25 and CD132, respectively. Results: The concentration of IL-2Rα chain (CD25) was found to be median 3.8 ng/ml in healthy volunteers versus 7.0 ng/ml in UC patients (p < 0.001), and 9.6 ng/ml in CD patients (p < 0.001). With respect to IL-2Rγ (CD132), significantly higher amounts were found in CD patients: 6.6 ng/ml as compared with healthy controls <1.0 ng/ml (p < 0.004). A Kruskal-Wallis test revealed a significant correlation between a chain and disease activity in CD (p < 0.001), and further significantly higher γ chain levels were found in active CD (p = 0.03). For UC patients, a statistically significant increase of the α chain with increasing disease activity (p < 0.01) was observed, whereas no significant changes of the γ chain levels were found (p > 0.05). A difference of γ chain levels were found between CD and UC in moderate and severe disease activity (p < 0.05). Further analyses revealed that mesalazine did not influence the IL-2Rα or -γ concentration either in UC or in CD patients. Conctusion: An increased circulating level of the soluble common γ chain (CD132) seems to be found in CD, and an overlap exists between CD and UC. [ABSTRACT FROM AUTHOR]
- Published
- 1998
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12. Palaeobotany: Forests frozen in time.
- Author
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Johnson, Kirk R.
- Subjects
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FORESTS & forestry , *EARTHQUAKE damage , *DISASTERS & the environment , *NATURAL resources , *FOREST productivity , *FOREST management , *FOSSIL plants - Abstract
The article discusses the economic and social effects of a forest that was dropped below sea level by an earthquake. Such disasters provide the images of lost ecosystems on a huge spatial scale. With this, fossil plants preserve a vast amount of information about ancient ecosystems and climates. However, some information are difficult to retrieve since plants fall apart both during this rapid event.
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- 2007
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13. Extinctions at the antipodes.
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Johnson, Kirk R.
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CRETACEOUS-Paleogene boundary - Abstract
Proposes that the effects of the Cretaceous/Tertiary (K/T) event on life near the ancient South Pole were not particularly severe, and in some cases were hardly noticeable. Evidence from a range of palaeolatitudes that large scale plant, mollusc and nannofossil extinctions preceded the K/T boundary event by several million years; Inability of the bolide impact to singly explain mass extinction.
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- 1993
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