20 results
Sub-filter-scale shear stress analysis in hypersonic turbulent Couette flow
- Takahiko Toki, Victor C.B. Sousa, Yongkai Chen, Carlo Scalo
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- Journal:
- Journal of Fluid Mechanics / Volume 984 / 10 April 2024
- Published online by Cambridge University Press:
- 08 April 2024, A53
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Direct numerical simulations of hypersonic turbulent Couette flows are performed for top-wall Mach numbers of 6, 7 and 8, inspired by non-reactive high-enthalpy wind tunnel free-stream conditions, with the goal of analysing the physical processes driving the sub-filter-scale (SFS) stresses to inform development of large-eddy simulation techniques for hypersonic wall-bounded flows. Semi-local scaling laws collapse mean profiles and second-order turbulent statistics well, in spite of the strong wall-normal gradients of temperature and density. On the other hand, the SFS shear stresses exhibit an unexpected profile characterized by a region of pronounced shear stress deficit, which becomes more pronounced for higher Mach numbers. Instantaneous visualizations suggest that the SFS shear stress deficit is induced by the counter-gradient resolved momentum transport driven by residual velocity motions at the interface between high-density low-speed streaks being ejected away from the wall, and low-density high-speed ones replacing the displaced fluid, qualifying this as a compressibility effect. It is shown that the SFS shear stresses are primarily driven by second-order interactions between residual velocities, in spite of their triply nonlinear nature. This, in turn, motivated a statistical quadrant analysis revealing the presence of a SFS shear stress deficit, that is, SFS processes driving momentum transport of the resolved field towards the top wall. Additionally, higher-Reynolds-number simulations reveal that there is an upper limit of spatial filter widths to resolve large-scale structures, and such deficit is observable at any Reynolds number when a reasonable spatial filter is applied.
3 CI Cognitive Therapy: Initial Application in a Pilot Study to Improve Cognitive Impairment in Chronic Stroke Survivors
- Edward Taub, Gitendra Uswatte, Karlene Ball, Victor W Mark, Staci McKay, Brandon Mitchell, Jason Blake, Amy Knight, Chen Lin, Gary Cutter
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 597-598
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Objective:
CI Cognitive Therapy (CICT) is a combination of behavioral techniques derived from CI Movement Therapy (CIMT) modified to apply to the cognitive domain, and Speed of (Cognitive) Processing Training (SOPT). SOPT is effective in improving cognitive function in the treatment setting and driving ability in everyday situations. The data concerning the effect of SOPT on other cognition-based instrumental activities of daily living (IADL) in everyday situations is incomplete. The strengths of CIMT, based on its Transfer Package (TP), are to facilitate 1) transfer of improved function from the treatment setting to IADL in everyday settings, and 2) long-term retention of the improved performance of IADL. This study sought to determine in a preliminary case series whether the TP of CI Movement Therapy combined with SOPT would have the same effect on a wide range of impaired cognition-based ADL.
Participants and Methods:Participants were 6 adults with chronic stroke: mean chronicity = 36.2 months, (range, 16-56 months); mean age = 59.7 years, (range, 47-55); 1 female; 3 African American and 3 European American. Five had mild cognitive impairment, while one had moderate impairment. Participants received 35 hours of outpatient treatment in 10-15 sessions distributed over 2-6 weeks, depending on the participants’ availability. Sessions began with 1 hour of SOPT training followed by training of cognition-based ADL by the process of shaping, a common method in the behavior analysis field. Other behavior analysis methods employed in the TP of CI Movement Therapy were used, including: 1) behavior contracting, daily assignment of homework, participation of a family member in the training and monitoring process, daily administration of a structured interview assessing amount and quality of performance of 30 IADL, problem solving to overcome perceived (or real) barriers to performance of IADL. Participants were given daily homework assignments in follow-up and were contacted in periodic, pre-arranged phone calls to determine status, compliance and problem-solve.
Results:All six participants showed marked improvement on the SOPT test similar to that in the Ball et al studies. However, here transfer to IADL outside the treatment setting was substantial. On the main real-world outcome, the Canadian Occupational Performance Measure (COPM), there were increases of 2.7±1.3 and 2.1±1.6 on the two scales (d’s = 1.9 & 1.3, respectively). (Changes on the COPM > 2 points are considered clinically meaningful and changes in d’ >.8 are considered large). On two other real-word measures, the Cognitive Task Activity Log (CTAL) and inventory of Improved and New Cognitive Activities (INCA), there was a marked increase during the acquisition phase of training. There was no loss in retention over the 6-16 months (mean = 12.2) of follow-up to date. Instead, the INCA showed strong further improvement after the end of treatment-setting training, especially in the New Activities Not Performed Since Before Stroke Onset category, going from a mean of 8.2 after training to 14.6 at the end of follow-up.
Conclusions:These very preliminary results suggest that CICT may be an efficacious therapy for mild to moderate cognitive impairment in chronic stroke and possibly other disorders.
The psychological impact of instrumental activities of daily living on people with simulated age-related macular degeneration
- Anne Macnamara, Scott Coussens, Celia Chen, Victor R. Schinazi, Tobias Loetscher
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- Journal:
- BJPsych Open / Volume 8 / Issue 5 / September 2022
- Published online by Cambridge University Press:
- 08 August 2022, e152
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Background
People with age-related macular degeneration (AMD) can report reduced mental health. There is also evidence that they struggle with daily tasks because of vision loss.
AimsThe purpose of this study was to assess the psychological impact of instrumental activities of daily living on people with simulated AMD.
MethodTwenty-four normally sighted participants completed 12 household tasks, in a simulated home environment, under a moderate-to-severe AMD simulation. Participants’ psychological state was measured through self-report questionnaires and physiological measurements related to anxiety and stress. Tasks were completed twice, under counterbalanced vision conditions (normal and simulated AMD).
ResultsLinear mixed models on vision condition (normal versus simulated AMD) and trial order (trial 1 versus trial 2) revealed a significant large negative effect of the AMD simulation on time to complete tasks, and the anxiety, task engagement and distress self-reports (all P < 0.024, all ω2 > 0.177). There were also significant medium-large effects of trial order on time, task incompletion, task errors, and the anxiety and task engagement self-reports (all P < 0.047, all ω2 > 0.130), whereby the results improved during the second attempt at the tasks. No physiological measures were significant (all P > 0.05).
ConclusionsCompleting instrumental activities of daily living under an AMD simulation had a negative impact on participants’ self-reported mental state. The observed trial order effects also illuminated how practice with tasks could ease anxiety and stress over time.
CryoVR: a Virtual Reality Training System for CryoEM Hands-on Operations
- Daoyi Li, Jiahui Dong, Kadir Ozcan, Dayu Wan, Yingjie Victor Chen, Wen Jiang
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- Journal:
- Microscopy and Microanalysis / Volume 28 / Issue S1 / August 2022
- Published online by Cambridge University Press:
- 22 July 2022, pp. 1212-1214
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- August 2022
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The Changing Profile of Tenure-Track Faculty in Archaeology
- Justin Cramb, Brandon T. Ritchison, Carla S. Hadden, Qian Zhang, Edgar Alarcón-Tinajero, Xianyan Chen, K. C. Jones, Travis Jones, Katharine Napora, Matthew Veres, Victor D. Thompson
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- Journal:
- Advances in Archaeological Practice / Volume 10 / Issue 4 / November 2022
- Published online by Cambridge University Press:
- 05 May 2022, pp. 371-381
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The goal for many PhD students in archaeology is tenure-track employment. Students primarily receive their training by tenure-track or tenured professors, and they are often tacitly expected—or explicitly encouraged—to follow in the footsteps of their advisor. However, the career trajectories that current and recent PhD students follow may hold little resemblance to the ones experienced by their advisors. To understand these different paths and to provide information for current PhD students considering pursuing a career in academia, we surveyed 438 archaeologists holding tenured or tenure-track positions in the United States. The survey, recorded in 2019, posed a variety of questions regarding the personal experiences of individual professors. The results are binned by the decade in which the respondent graduated. Evident patterns are discussed in terms of change over time. The resulting portraits of academic pathways through the past five decades indicate that although broad commonalities exist in the qualifications of early career academics, there is no singular pathway to obtaining tenure-track employment. We highlight the commonalities revealed in our survey to provide a set of general qualifications that might provide a baseline set of skills and experiences for an archaeologist seeking a tenure-track job in the United States.
Antimicrobial Stewardship-Driven Monoclonal Antibody Treatment Program for COVID-19 Patients in the Bronx, New York
- Yi Guo, Victor Chen, Lauren Allen, Kelsie Cowman, Una Hopkins, Carol Sheridan, Edwin A Torres, Patricia Davis, Susan Sakalian, Frank Sosnowski, Priya Nori, Liise-anne Pirofski, Adam Haviland, James Rossi, Hongkai (Jack) Bao
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- Journal:
- Antimicrobial Stewardship & Healthcare Epidemiology / Volume 1 / Issue S1 / July 2021
- Published online by Cambridge University Press:
- 29 July 2021, p. s57
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Background: In November 2020, bamlanivimab received emergency use authorization (EUA) to treat patients with early, mild-to-moderate COVID-19 who are at high risk of progression. Montefiore Medical Center serves an economically underserved community of >1.4 million residents in the Bronx, New York. Montefiore’s antimicrobial stewardship team (AST) developed a multidisciplinary treatment pathway for patients meeting EUA criteria: (1) outpatients and hospital associates and (2) acute-care patients (EDs or inpatient). Methods: The Montefiore AST established a centralized process for screening high-risk COVID-19 patients 7 days a week. Referrals were sent by e-mail from occupational health, primary care practices, specialty practices, emergency departments, and urgent care centers. Patients were screened in real time and were treated in the ED or a newly established infusion center within 24 hours. After infusion, all patients received phone calls from nurses and had an infectious diseases televisit. Demographics, clinical symptoms, subsequent ED visit or hospital admission, and timing from infusion to ED or hospitalization were obtained from the electronic health record. Results: In total, 281 high-risk patients (median age, 62 years; 57% female) received bamlanivimab at the infusion center or in the acute-care setting between December 2, 2020, and January 27, 2021 (Table 1). The number of treated patients increased weekly (Figure 1). Also, 62% were Hispanic or black, and 96% met EUA criteria. Furthermore, 51 (18%) were referred from occupational health, 205 (73%) were referred from the community, and 25 (9%) were inpatients (https://www.fda.gov/media/143605/download). All patients were successfully infused without adverse reactions. In addition, 23 patients (8.2%) were hospitalized and 6 (2.1%) visited EDs within 30 days of treatment. The average number of days between symptom onset and infusion was 4.9. The median age of admitted versus nonadmitted patients was 68 years versus 61.5 years (P = .07). Conclusions: An AST-coordinated bamlanivimab treatment program successfully treated multiple high-risk COVID-19 patients and potentially reduced hospitalizations. However, the effort, personnel, and resources required are significant. Dedicated hospital investment is necessary for maximal success.
Funding: No
Disclosures: None
Table 1. Figure 1.
Emotion perception and theory of mind in adolescents with major depression
- Chen Dror, Victor Portnoy, Shomrit Dayan-Rosenblum, Yari Gvion, Yuval Bloch, Dennis Boyle, Hagai Maoz
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- Acta Neuropsychiatrica / Volume 33 / Issue 5 / October 2021
- Published online by Cambridge University Press:
- 21 June 2021, pp. 261-266
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Background:
The research of theory of mind (ToM) and emotion perception (EP) in adolescents with major depressive disorder (MDD) is scarce, and no study to date has investigated the association between EP and long-term outcomes of adolescents with MDD. The aim of the current study was to evaluate ToM and EP in adolescents with MDD, as compared to healthy controls (HCs). In addition, we aimed to assess the association between impairment in ToM and EP, depressive symptom severity, and long-term outcome in the MDD group.
Methods:We compared the performance of 14 adolescents with MDD and 25 HC in the Facial Expression Recognition Task (FERT) and the Interpersonal Perception Task. We followed up with the MDD group 2 years later to assess the level of their depressive symptoms using the Children’s Depression Rating Scale–Revised (CDRS-R).
Results:No differences were found between adolescents with MDD and HC in the ToM and FERT tasks. Also, within the MDD group, there was no association between the severity of depressive symptoms and task performance. In the MDD group, there was a significant correlation between lower levels of accuracy in the FERT during the index depressive episode and lower CDRS-R scores on follow-up 2 years later (r2 = 0.35, p = 0.021).
Conclusions:EP impairments in adolescents with MDD might predict worse long-term outcome. Further research is needed to verify our findings and to assess for a possible neurobiological underpinning for the state and trait impairments in EP in adolescents with MDD.
Leveraging Local Expertise in Stewardship, Hospital Epidemiology and Public Health to Enrich Postgraduate Training in NYC
- Kelsie Cowman, Belinda Ostrowsky, Susan Seo, Victor Chen, Rachel Bartash, Priya Nori
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- Journal:
- Infection Control & Hospital Epidemiology / Volume 41 / Issue S1 / October 2020
- Published online by Cambridge University Press:
- 02 November 2020, pp. s311-s312
- Print publication:
- October 2020
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Background: New York City is a gateway for emerging pathogens and global threats. In 2013, faculty from Montefiore Medical Center and Memorial Sloan Kettering developed a free half-day workshop for postgraduate trainees in antimicrobial stewardship (AS), infection prevention (IP), hospital epidemiology, and public health. This annual workshop, sponsored by the Infectious Diseases Society of New York (IDSNY), incorporates case studies and expert panel discussions on timely topics such as Ebola, Candida auris, Clostridiodes difficile, measles, nosocomial influenza, drug shortages, and AS/IP “big data.” Methods: From 2013 through 2017, the workshop involved 10–15 interactive AS/IP cases with audience response questions and panel discussions. In 2018–2019, based on feedback, the format was revised to emphasize breakout sessions in which participants actively practiced AS/IP tools, (eg, medication utilization evaluations, epidemiologic curves, and performance improvement devices). Examples of 2018–2019 cases are shown in Figure 1. A pre- and postseminar paper survey was conducted yearly to understand baseline training in AS/IP, desire for future AS/IP careers, and self-reported effectiveness of the workshop. Results: Initially, the primary audience was NYC ID fellows. From 2018 onward, we opened enrollment to pharmacy residents. Approximately 45 NYC ID fellows were eligible for the course each year. Results from 2013 to 2016 surveys were reported previously (Fig. 2). There were 32 attendees in 2018, 42 in 2019. The survey response rate was 88% in 2018 and 95% in 2019, with 68 (92%) total participants. Most participants had received previous training in IP (82%) and AS (94%) (Fig. 3). Most participants reported that the program was a good supplement to their ID training (98%) and that case studies were an effective means of learning IP (100%) and AS (98%). Furthermore, 92% stated they would like additional AS/IP training, and many since 2013 have requested a full-day course. Self-reported interest in future involvement in AS/IP increased after the workshop: IP, 68%–83% (P =.04) and AS, 88%–91% (P = .61). Conclusions: Most trainees reported satisfaction with the workshop and case-study learning method; interest in future AS/IP careers increased after the seminar. We intend to explore Funding: to expand to a full-day program for all NYC postgraduate trainees and AS/IP junior faculty. As such, we hope to obtain the endorsement of professional societies such as SHEA. This workshop could address a crucial educational gap in AS/IP postgraduate training and help sustain our future workforce.
Funding: None
Disclosures: None
Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in respiratory cultures and diagnostic performance of the MRSA nasal polymerase chain reaction (PCR) in patients hospitalized with coronavirus disease 2019 (COVID-19) pneumonia
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- Chitra D. Punjabi, Theresa Madaline, Inessa Gendlina, Victor Chen, Priya Nori, Liise-anne Pirofski
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- Infection Control & Hospital Epidemiology / Volume 42 / Issue 9 / September 2021
- Published online by Cambridge University Press:
- 26 August 2020, pp. 1156-1158
- Print publication:
- September 2021
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Bacterial and fungal coinfections in COVID-19 patients hospitalized during the New York City pandemic surge
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- Priya Nori, Kelsie Cowman, Victor Chen, Rachel Bartash, Wendy Szymczak, Theresa Madaline, Chitra Punjabi Katiyar, Ruchika Jain, Margaret Aldrich, Gregory Weston, Philip Gialanella, Marilou Corpuz, Inessa Gendlina, Yi Guo
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- Journal:
- Infection Control & Hospital Epidemiology / Volume 42 / Issue 1 / January 2021
- Published online by Cambridge University Press:
- 24 July 2020, pp. 84-88
- Print publication:
- January 2021
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We observed bacterial or fungal coinfections in COVID-19 patients admitted between March 1 and April 18, 2020 (152 of 4,267, 3.6%). Among these patients, mortality was 57%; 74% were intubated; 51% with bacteremia had central venous catheters. Time to culture positivity was 6–7 days, and 79% had received prior antibiotics. Metallo-β-lactamase–producing E. cloacae coinfections occurred in 5 patients.
Child and adolescent psychiatry training curriculum: a global trainee's perspective
- Sundar Gnanavel, Pawan Sharma, Antonin Sebela, Teresa Gomez Alemany, Jane Pei-Chen Chang, Mauro Victor de Medeiros Filho, Kwabena Kusi-Mensah, Fransiska Kaligis, Hidekazu Kato, Huu Kim Le, Kana Morimoto, Dmytro Martsenkovskyi, Darpan Kaur Mohinder Singh, Aditya Pawar, Asilay Seker, Napat Sittanomai, Sifat-e Syed, Utkarsh Karki, Arpit Parmar, Marcus Tan
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- Journal:
- BJPsych International / Volume 17 / Issue 3 / August 2020
- Published online by Cambridge University Press:
- 26 February 2020, pp. 69-71
- Print publication:
- August 2020
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This article is a summary of perspectives on training curricula from child and adolescent psychiatry trainees globally. We aimed to identify the relative strengths, weaknesses and gaps in learning needs from a trainee's perspective. The 20 early-career child psychiatrists who contributed are from 16 countries and represent all the five continents. We could identify some global challenges as well as local/regional challenges that need to be addressed to develop competent child psychiatrists.
Key role of the REC lobe during CRISPR–Cas9 activation by ‘sensing’, ‘regulating’, and ‘locking’ the catalytic HNH domain
- Giulia Palermo, Janice S. Chen, Clarisse G. Ricci, Ivan Rivalta, Martin Jinek, Victor S. Batista, Jennifer A. Doudna, J. Andrew McCammon
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- Quarterly Reviews of Biophysics / Volume 51 / 2018
- Published online by Cambridge University Press:
- 03 August 2018, e9
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Understanding the conformational dynamics of CRISPR (clustered regularly interspaced short palindromic repeat)–Cas9 is of the utmost importance for improving its genome editing capability. Here, molecular dynamics simulations performed using Anton-2 – a specialized supercomputer capturing micro-to-millisecond biophysical events in real time and at atomic-level resolution – reveal the activation process of the endonuclease Cas9 toward DNA cleavage. Over the unbiased simulation, we observe that the spontaneous approach of the catalytic domain HNH to the DNA cleavage site is accompanied by a remarkable structural remodeling of the recognition (REC) lobe, which exerts a key role for DNA cleavage. Specifically, the significant conformational changes and the collective conformational dynamics of the REC lobe indicate a mechanism by which the REC1–3 regions ‘sense’ nucleic acids, ‘regulate’ the HNH conformational transition, and ultimately ‘lock’ the HNH domain at the cleavage site, contributing to its catalytic competence. By integrating additional independent simulations and existing experimental data, we provide a solid validation of the activated HNH conformation, which had been so far poorly characterized, and we deliver a comprehensive understanding of the role of REC1–3 in the activation process. Considering the importance of the REC lobe in the specificity of Cas9, this study poses the basis for fully understanding how the REC components control the cleavage of off-target sequences, laying the foundation for future engineering efforts toward improved genome editing.
Translating clinical trials into clinical practice: a survey assessing the potential impact of the Pediatric Heart Network Infant Single Ventricle Trial
- Victor Zak, Daphne T. Hsu, Victoria L. Pemberton, Jami C. Levine, Andrew M. Atz, James F. Cnota, Chitra Ravishankar, Piers Barker, Linda M. Lambert, Brian W. McCrindle, Michele A. Frommelt, Karen Altmann, Shan Chen, Richard V. Williams, for the Pediatric Heart Network Investigators
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- Journal:
- Cardiology in the Young / Volume 27 / Issue 7 / September 2017
- Published online by Cambridge University Press:
- 10 February 2017, pp. 1265-1270
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Background
A few studies have evaluated the impact of clinical trial results on practice in paediatric cardiology. The Infant Single Ventricle (ISV) Trial results published in 2010 did not support routine use of the angiotensin-converting enzyme inhibitor enalapril in infants with single-ventricle physiology. We sought to assess the influence of these findings on clinical practice.
MethodsA web-based survey was distributed via e-mail to over 2000 paediatric cardiologists, intensivists, cardiothoracic surgeons, and cardiac advance practice nurses during three distribution periods. The results were analysed using McNemar’s test for paired data and Fisher’s exact test.
ResultsThe response rate was 31.5% (69% cardiologists and 65% with >10 years of experience). Among respondents familiar with trial results, 74% reported current practice consistent with trial findings versus 48% before trial publication (p<0.001); 19% used angiotensin-converting enzyme inhibitor in this population “almost always” versus 36% in the past (p<0.001), and 72% reported a change in management or improved confidence in treatment decisions involving this therapy based on the trial results. Respondents familiar with trial results (78%) were marginally more likely to practise consistent with the trial results than those unfamiliar (74 versus 67%, p=0.16). Among all respondents, 28% reported less frequent use of angiotensin-converting enzyme inhibitor over the last 3 years.
ConclusionsWithin 5 years of publication, the majority of respondents was familiar with the Infant Single Ventricle Trial results and reported less frequent use of angiotensin-converting enzyme inhibitor in single-ventricle infants; however, 28% reported not adjusting their clinical decisions based on the trial’s findings.
A “Black Cult” in Early Medieval China: Iranian-Zoroastrian Influence in the Northern Dynasties*
- SANPING CHEN, VICTOR H MAIR
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- Journal:
- Journal of the Royal Asiatic Society / Volume 27 / Issue 2 / April 2017
- Published online by Cambridge University Press:
- 24 January 2017, pp. 201-224
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- April 2017
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Through an analysis of Chinese theophoric names - a genre that emerged in the early medieval period largely under heavy Iranian-Sogdian influence - we suggest that there was a contemporary ‘black worship’ or ‘black cult’ in northern China that has since vanished. The followers of this ‘black cult’ ranged from common people living in ethnically mixed frontier communities to the ruling echelons of the Northern Dynasties. By tapping into the fragmentary pre-Islamic Iranian-Sogdian data, we link this ‘black cult’ to the now nearly forgotten ancient Iranic worship of the Avestan family of heroes centered around Sāma. This religio-cultural exchange prompts an examination of the deliberate policy by the ethnic rulers of the Northern Dynasties to attract Central Asian immigrants for political reasons, a precursor to the Semu, the Mongols’ ‘assistant conquerors’ in the Yuan dynasty.
Contributors
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- By Rose Teteki Abbey, K. C. Abraham, David Tuesday Adamo, LeRoy H. Aden, Efrain Agosto, Victor Aguilan, Gillian T. W. Ahlgren, Charanjit Kaur AjitSingh, Dorothy B E A Akoto, Giuseppe Alberigo, Daniel E. Albrecht, Ruth Albrecht, Daniel O. Aleshire, Urs Altermatt, Anand Amaladass, Michael Amaladoss, James N. Amanze, Lesley G. Anderson, Thomas C. Anderson, Victor Anderson, Hope S. Antone, María Pilar Aquino, Paula Arai, Victorio Araya Guillén, S. Wesley Ariarajah, Ellen T. Armour, Brett Gregory Armstrong, Atsuhiro Asano, Naim Stifan Ateek, Mahmoud Ayoub, John Alembillah Azumah, Mercedes L. García Bachmann, Irena Backus, J. Wayne Baker, Mieke Bal, Lewis V. Baldwin, William Barbieri, António Barbosa da Silva, David Basinger, Bolaji Olukemi Bateye, Oswald Bayer, Daniel H. Bays, Rosalie Beck, Nancy Elizabeth Bedford, Guy-Thomas Bedouelle, Chorbishop Seely Beggiani, Wolfgang Behringer, Christopher M. Bellitto, Byard Bennett, Harold V. Bennett, Teresa Berger, Miguel A. Bernad, Henley Bernard, Alan E. Bernstein, Jon L. Berquist, Johannes Beutler, Ana María Bidegain, Matthew P. Binkewicz, Jennifer Bird, Joseph Blenkinsopp, Dmytro Bondarenko, Paulo Bonfatti, Riet en Pim Bons-Storm, Jessica A. Boon, Marcus J. Borg, Mark Bosco, Peter C. Bouteneff, François Bovon, William D. Bowman, Paul S. Boyer, David Brakke, Richard E. Brantley, Marcus Braybrooke, Ian Breward, Ênio José da Costa Brito, Jewel Spears Brooker, Johannes Brosseder, Nicholas Canfield Read Brown, Robert F. Brown, Pamela K. Brubaker, Walter Brueggemann, Bishop Colin O. Buchanan, Stanley M. Burgess, Amy Nelson Burnett, J. Patout Burns, David B. Burrell, David Buttrick, James P. Byrd, Lavinia Byrne, Gerado Caetano, Marcos Caldas, Alkiviadis Calivas, William J. Callahan, Salvatore Calomino, Euan K. Cameron, William S. Campbell, Marcelo Ayres Camurça, Daniel F. Caner, Paul E. Capetz, Carlos F. Cardoza-Orlandi, Patrick W. Carey, Barbara Carvill, Hal Cauthron, Subhadra Mitra Channa, Mark D. Chapman, James H. Charlesworth, Kenneth R. Chase, Chen Zemin, Luciano Chianeque, Philip Chia Phin Yin, Francisca H. Chimhanda, Daniel Chiquete, John T. Chirban, Soobin Choi, Robert Choquette, Mita Choudhury, Gerald Christianson, John Chryssavgis, Sejong Chun, Esther Chung-Kim, Charles M. A. Clark, Elizabeth A. Clark, Sathianathan Clarke, Fred Cloud, John B. Cobb, W. Owen Cole, John A Coleman, John J. Collins, Sylvia Collins-Mayo, Paul K. Conkin, Beth A. Conklin, Sean Connolly, Demetrios J. Constantelos, Michael A. Conway, Paula M. Cooey, Austin Cooper, Michael L. Cooper-White, Pamela Cooper-White, L. William Countryman, Sérgio Coutinho, Pamela Couture, Shannon Craigo-Snell, James L. Crenshaw, David Crowner, Humberto Horacio Cucchetti, Lawrence S. Cunningham, Elizabeth Mason Currier, Emmanuel Cutrone, Mary L. Daniel, David D. Daniels, Robert Darden, Rolf Darge, Isaiah Dau, Jeffry C. Davis, Jane Dawson, Valentin Dedji, John W. de Gruchy, Paul DeHart, Wendy J. Deichmann Edwards, Miguel A. De La Torre, George E. Demacopoulos, Thomas de Mayo, Leah DeVun, Beatriz de Vasconcellos Dias, Dennis C. Dickerson, John M. Dillon, Luis Miguel Donatello, Igor Dorfmann-Lazarev, Susanna Drake, Jonathan A. Draper, N. Dreher Martin, Otto Dreydoppel, Angelyn Dries, A. J. Droge, Francis X. D'Sa, Marilyn Dunn, Nicole Wilkinson Duran, Rifaat Ebied, Mark J. Edwards, William H. Edwards, Leonard H. Ehrlich, Nancy L. Eiesland, Martin Elbel, J. Harold Ellens, Stephen Ellingson, Marvin M. Ellison, Robert Ellsberg, Jean Bethke Elshtain, Eldon Jay Epp, Peter C. Erb, Tassilo Erhardt, Maria Erling, Noel Leo Erskine, Gillian R. Evans, Virginia Fabella, Michael A. Fahey, Edward Farley, Margaret A. Farley, Wendy Farley, Robert Fastiggi, Seena Fazel, Duncan S. Ferguson, Helwar Figueroa, Paul Corby Finney, Kyriaki Karidoyanes FitzGerald, Thomas E. FitzGerald, John R. Fitzmier, Marie Therese Flanagan, Sabina Flanagan, Claude Flipo, Ronald B. Flowers, Carole Fontaine, David Ford, Mary Ford, Stephanie A. Ford, Jim Forest, William Franke, Robert M. Franklin, Ruth Franzén, Edward H. Friedman, Samuel Frouisou, Lorelei F. Fuchs, Jojo M. Fung, Inger Furseth, Richard R. Gaillardetz, Brandon Gallaher, China Galland, Mark Galli, Ismael García, Tharscisse Gatwa, Jean-Marie Gaudeul, Luis María Gavilanes del Castillo, Pavel L. Gavrilyuk, Volney P. Gay, Metropolitan Athanasios Geevargis, Kondothra M. George, Mary Gerhart, Simon Gikandi, Maurice Gilbert, Michael J. Gillgannon, Verónica Giménez Beliveau, Terryl Givens, Beth Glazier-McDonald, Philip Gleason, Menghun Goh, Brian Golding, Bishop Hilario M. Gomez, Michelle A. Gonzalez, Donald K. Gorrell, Roy Gottfried, Tamara Grdzelidze, Joel B. Green, Niels Henrik Gregersen, Cristina Grenholm, Herbert Griffiths, Eric W. Gritsch, Erich S. Gruen, Christoffer H. Grundmann, Paul H. Gundani, Jon P. Gunnemann, Petre Guran, Vidar L. Haanes, Jeremiah M. Hackett, Getatchew Haile, Douglas John Hall, Nicholas Hammond, Daphne Hampson, Jehu J. Hanciles, Barry Hankins, Jennifer Haraguchi, Stanley S. Harakas, Anthony John Harding, Conrad L. Harkins, J. William Harmless, Marjory Harper, Amir Harrak, Joel F. Harrington, Mark W. Harris, Susan Ashbrook Harvey, Van A. Harvey, R. Chris Hassel, Jione Havea, Daniel Hawk, Diana L. Hayes, Leslie Hayes, Priscilla Hayner, S. Mark Heim, Simo Heininen, Richard P. Heitzenrater, Eila Helander, David Hempton, Scott H. Hendrix, Jan-Olav Henriksen, Gina Hens-Piazza, Carter Heyward, Nicholas J. Higham, David Hilliard, Norman A. Hjelm, Peter C. Hodgson, Arthur Holder, M. Jan Holton, Dwight N. Hopkins, Ronnie Po-chia Hsia, Po-Ho Huang, James Hudnut-Beumler, Jennifer S. Hughes, Leonard M. Hummel, Mary E. Hunt, Laennec Hurbon, Mark Hutchinson, Susan E. Hylen, Mary Beth Ingham, H. Larry Ingle, Dale T. Irvin, Jon Isaak, Paul John Isaak, Ada María Isasi-Díaz, Hans Raun Iversen, Margaret C. Jacob, Arthur James, Maria Jansdotter-Samuelsson, David Jasper, Werner G. Jeanrond, Renée Jeffery, David Lyle Jeffrey, Theodore W. Jennings, David H. Jensen, Robin Margaret Jensen, David Jobling, Dale A. Johnson, Elizabeth A. Johnson, Maxwell E. Johnson, Sarah Johnson, Mark D. Johnston, F. Stanley Jones, James William Jones, John R. Jones, Alissa Jones Nelson, Inge Jonsson, Jan Joosten, Elizabeth Judd, Mulambya Peggy Kabonde, Robert Kaggwa, Sylvester Kahakwa, Isaac Kalimi, Ogbu U. Kalu, Eunice Kamaara, Wayne C. Kannaday, Musimbi Kanyoro, Veli-Matti Kärkkäinen, Frank Kaufmann, Léon Nguapitshi Kayongo, Richard Kearney, Alice A. Keefe, Ralph Keen, Catherine Keller, Anthony J. Kelly, Karen Kennelly, Kathi Lynn Kern, Fergus Kerr, Edward Kessler, George Kilcourse, Heup Young Kim, Kim Sung-Hae, Kim Yong-Bock, Kim Yung Suk, Richard King, Thomas M. King, Robert M. Kingdon, Ross Kinsler, Hans G. Kippenberg, Cheryl A. Kirk-Duggan, Clifton Kirkpatrick, Leonid Kishkovsky, Nadieszda Kizenko, Jeffrey Klaiber, Hans-Josef Klauck, Sidney Knight, Samuel Kobia, Robert Kolb, Karla Ann Koll, Heikki Kotila, Donald Kraybill, Philip D. W. Krey, Yves Krumenacker, Jeffrey Kah-Jin Kuan, Simanga R. Kumalo, Peter Kuzmic, Simon Shui-Man Kwan, Kwok Pui-lan, André LaCocque, Stephen E. Lahey, John Tsz Pang Lai, Emiel Lamberts, Armando Lampe, Craig Lampe, Beverly J. Lanzetta, Eve LaPlante, Lizette Larson-Miller, Ariel Bybee Laughton, Leonard Lawlor, Bentley Layton, Robin A. Leaver, Karen Lebacqz, Archie Chi Chung Lee, Marilyn J. Legge, Hervé LeGrand, D. L. LeMahieu, Raymond Lemieux, Bill J. Leonard, Ellen M. Leonard, Outi Leppä, Jean Lesaulnier, Nantawan Boonprasat Lewis, Henrietta Leyser, Alexei Lidov, Bernard Lightman, Paul Chang-Ha Lim, Carter Lindberg, Mark R. Lindsay, James R. Linville, James C. Livingston, Ann Loades, David Loades, Jean-Claude Loba-Mkole, Lo Lung Kwong, Wati Longchar, Eleazar López, David W. Lotz, Andrew Louth, Robin W. Lovin, William Luis, Frank D. Macchia, Diarmaid N. J. MacCulloch, Kirk R. MacGregor, Marjory A. MacLean, Donald MacLeod, Tomas S. Maddela, Inge Mager, Laurenti Magesa, David G. Maillu, Fortunato Mallimaci, Philip Mamalakis, Kä Mana, Ukachukwu Chris Manus, Herbert Robinson Marbury, Reuel Norman Marigza, Jacqueline Mariña, Antti Marjanen, Luiz C. L. Marques, Madipoane Masenya (ngwan'a Mphahlele), Caleb J. D. Maskell, Steve Mason, Thomas Massaro, Fernando Matamoros Ponce, András Máté-Tóth, Odair Pedroso Mateus, Dinis Matsolo, Fumitaka Matsuoka, John D'Arcy May, Yelena Mazour-Matusevich, Theodore Mbazumutima, John S. McClure, Christian McConnell, Lee Martin McDonald, Gary B. McGee, Thomas McGowan, Alister E. McGrath, Richard J. McGregor, John A. McGuckin, Maud Burnett McInerney, Elsie Anne McKee, Mary B. McKinley, James F. McMillan, Ernan McMullin, Kathleen E. McVey, M. Douglas Meeks, Monica Jyotsna Melanchthon, Ilie Melniciuc-Puica, Everett Mendoza, Raymond A. Mentzer, William W. Menzies, Ina Merdjanova, Franziska Metzger, Constant J. Mews, Marvin Meyer, Carol Meyers, Vasile Mihoc, Gunner Bjerg Mikkelsen, Maria Inêz de Castro Millen, Clyde Lee Miller, Bonnie J. Miller-McLemore, Alexander Mirkovic, Paul Misner, Nozomu Miyahira, R. W. L. Moberly, Gerald Moede, Aloo Osotsi Mojola, Sunanda Mongia, Rebeca Montemayor, James Moore, Roger E. Moore, Craig E. Morrison O.Carm, Jeffry H. Morrison, Keith Morrison, Wilson J. Moses, Tefetso Henry Mothibe, Mokgethi Motlhabi, Fulata Moyo, Henry Mugabe, Jesse Ndwiga Kanyua Mugambi, Peggy Mulambya-Kabonde, Robert Bruce Mullin, Pamela Mullins Reaves, Saskia Murk Jansen, Heleen L. Murre-Van den Berg, Augustine Musopole, Isaac M. T. Mwase, Philomena Mwaura, Cecilia Nahnfeldt, Anne Nasimiyu Wasike, Carmiña Navia Velasco, Thulani Ndlazi, Alexander Negrov, James B. Nelson, David G. Newcombe, Carol Newsom, Helen J. Nicholson, George W. E. Nickelsburg, Tatyana Nikolskaya, Damayanthi M. A. Niles, Bertil Nilsson, Nyambura Njoroge, Fidelis Nkomazana, Mary Beth Norton, Christian Nottmeier, Sonene Nyawo, Anthère Nzabatsinda, Edward T. Oakes, Gerald O'Collins, Daniel O'Connell, David W. Odell-Scott, Mercy Amba Oduyoye, Kathleen O'Grady, Oyeronke Olajubu, Thomas O'Loughlin, Dennis T. Olson, J. Steven O'Malley, Cephas N. Omenyo, Muriel Orevillo-Montenegro, César Augusto Ornellas Ramos, Agbonkhianmeghe E. Orobator, Kenan B. Osborne, Carolyn Osiek, Javier Otaola Montagne, Douglas F. Ottati, Anna May Say Pa, Irina Paert, Jerry G. Pankhurst, Aristotle Papanikolaou, Samuele F. Pardini, Stefano Parenti, Peter Paris, Sung Bae Park, Cristián G. Parker, Raquel Pastor, Joseph Pathrapankal, Daniel Patte, W. Brown Patterson, Clive Pearson, Keith F. Pecklers, Nancy Cardoso Pereira, David Horace Perkins, Pheme Perkins, Edward N. Peters, Rebecca Todd Peters, Bishop Yeznik Petrossian, Raymond Pfister, Peter C. Phan, Isabel Apawo Phiri, William S. F. Pickering, Derrick G. Pitard, William Elvis Plata, Zlatko Plese, John Plummer, James Newton Poling, Ronald Popivchak, Andrew Porter, Ute Possekel, James M. Powell, Enos Das Pradhan, Devadasan Premnath, Jaime Adrían Prieto Valladares, Anne Primavesi, Randall Prior, María Alicia Puente Lutteroth, Eduardo Guzmão Quadros, Albert Rabil, Laurent William Ramambason, Apolonio M. Ranche, Vololona Randriamanantena Andriamitandrina, Lawrence R. Rast, Paul L. Redditt, Adele Reinhartz, Rolf Rendtorff, Pål Repstad, James N. Rhodes, John K. Riches, Joerg Rieger, Sharon H. Ringe, Sandra Rios, Tyler Roberts, David M. Robinson, James M. Robinson, Joanne Maguire Robinson, Richard A. H. Robinson, Roy R. Robson, Jack B. Rogers, Maria Roginska, Sidney Rooy, Rev. Garnett Roper, Maria José Fontelas Rosado-Nunes, Andrew C. Ross, Stefan Rossbach, François Rossier, John D. Roth, John K. Roth, Phillip Rothwell, Richard E. Rubenstein, Rosemary Radford Ruether, Markku Ruotsila, John E. Rybolt, Risto Saarinen, John Saillant, Juan Sanchez, Wagner Lopes Sanchez, Hugo N. Santos, Gerhard Sauter, Gloria L. Schaab, Sandra M. Schneiders, Quentin J. Schultze, Fernando F. Segovia, Turid Karlsen Seim, Carsten Selch Jensen, Alan P. F. Sell, Frank C. Senn, Kent Davis Sensenig, Damían Setton, Bal Krishna Sharma, Carolyn J. Sharp, Thomas Sheehan, N. Gerald Shenk, Christian Sheppard, Charles Sherlock, Tabona Shoko, Walter B. Shurden, Marguerite Shuster, B. Mark Sietsema, Batara Sihombing, Neil Silberman, Clodomiro Siller, Samuel Silva-Gotay, Heikki Silvet, John K. Simmons, Hagith Sivan, James C. Skedros, Abraham Smith, Ashley A. Smith, Ted A. Smith, Daud Soesilo, Pia Søltoft, Choan-Seng (C. S.) Song, Kathryn Spink, Bryan Spinks, Eric O. Springsted, Nicolas Standaert, Brian Stanley, Glen H. Stassen, Karel Steenbrink, Stephen J. Stein, Andrea Sterk, Gregory E. Sterling, Columba Stewart, Jacques Stewart, Robert B. Stewart, Cynthia Stokes Brown, Ken Stone, Anne Stott, Elizabeth Stuart, Monya Stubbs, Marjorie Hewitt Suchocki, David Kwang-sun Suh, Scott W. Sunquist, Keith Suter, Douglas Sweeney, Charles H. Talbert, Shawqi N. Talia, Elsa Tamez, Joseph B. Tamney, Jonathan Y. Tan, Yak-Hwee Tan, Kathryn Tanner, Feiya Tao, Elizabeth S. Tapia, Aquiline Tarimo, Claire Taylor, Mark Lewis Taylor, Bishop Abba Samuel Wolde Tekestebirhan, Eugene TeSelle, M. Thomas Thangaraj, David R. Thomas, Andrew Thornley, Scott Thumma, Marcelo Timotheo da Costa, George E. “Tink” Tinker, Ola Tjørhom, Karen Jo Torjesen, Iain R. Torrance, Fernando Torres-Londoño, Archbishop Demetrios [Trakatellis], Marit Trelstad, Christine Trevett, Phyllis Trible, Johannes Tromp, Paul Turner, Robert G. Tuttle, Archbishop Desmond Tutu, Peter Tyler, Anders Tyrberg, Justin Ukpong, Javier Ulloa, Camillus Umoh, Kristi Upson-Saia, Martina Urban, Monica Uribe, Elochukwu Eugene Uzukwu, Richard Vaggione, Gabriel Vahanian, Paul Valliere, T. J. Van Bavel, Steven Vanderputten, Peter Van der Veer, Huub Van de Sandt, Louis Van Tongeren, Luke A. Veronis, Noel Villalba, Ramón Vinke, Tim Vivian, David Voas, Elena Volkova, Katharina von Kellenbach, Elina Vuola, Timothy Wadkins, Elaine M. Wainwright, Randi Jones Walker, Dewey D. Wallace, Jerry Walls, Michael J. Walsh, Philip Walters, Janet Walton, Jonathan L. Walton, Wang Xiaochao, Patricia A. Ward, David Harrington Watt, Herold D. Weiss, Laurence L. Welborn, Sharon D. Welch, Timothy Wengert, Traci C. West, Merold Westphal, David Wetherell, Barbara Wheeler, Carolinne White, Jean-Paul Wiest, Frans Wijsen, Terry L. Wilder, Felix Wilfred, Rebecca Wilkin, Daniel H. Williams, D. Newell Williams, Michael A. Williams, Vincent L. Wimbush, Gabriele Winkler, Anders Winroth, Lauri Emílio Wirth, James A. Wiseman, Ebba Witt-Brattström, Teofil Wojciechowski, John Wolffe, Kenman L. Wong, Wong Wai Ching, Linda Woodhead, Wendy M. Wright, Rose Wu, Keith E. Yandell, Gale A. Yee, Viktor Yelensky, Yeo Khiok-Khng, Gustav K. K. Yeung, Angela Yiu, Amos Yong, Yong Ting Jin, You Bin, Youhanna Nessim Youssef, Eliana Yunes, Robert Michael Zaller, Valarie H. Ziegler, Barbara Brown Zikmund, Joyce Ann Zimmerman, Aurora Zlotnik, Zhuo Xinping
- Edited by Daniel Patte, Vanderbilt University, Tennessee
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- The Cambridge Dictionary of Christianity
- Published online:
- 05 August 2012
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- 20 September 2010, pp xi-xliv
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Contributors
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- By Isabella Aboderin, W. Andrew Achenbaum, Katherine R. Allen, Toni C. Antonucci, Sara Arber, Claudine Attias‐Donfut, Paul B. Baltes, Sandhi Maria Barreto, Vern L. Bengtson, Simon Biggs, Joanna Bornat, Julie B. Boron, Mike Boulton, Clive E. Bowman, Marjolein Broese van Groenou, Edna Brown, Robert N. Butler, Bill Bytheway, Neena L. Chappell, Neil Charness, Kaare Christensen, Peter G. Coleman, Ingrid Arnet Connidis, Neal E. Cutler, Sara J. Czaja, Svein Olav Daatland, Lia Susana Daichman, Adam Davey, Bleddyn Davies, Freya Dittmann‐Kohli, Glen H. Elder, Carroll L. Estes, Mike Featherstone, Amy Fiske, Alexandra Freund, Daphna Gans, Linda K. George, Roseann Giarrusso, Chris Gilleard, Jay Ginn, Edlira Gjonça, Elena L. Grigorenko, Jaber F. Gubrium, Sarah Harper, Jutta Heckhausen, Akiko Hashimoto, Jon Hendricks, Mike Hepworth, Charlotte Ikels, James S. Jackson, Yuri Jang, Bernard Jeune, Malcolm L. Johnson, Randi S. Jones, Alexandre Kalache, Robert L. Kane, Rosalie A. Kane, Ingrid Keller, Rose Anne Kenny, Thomas B. L. Kirkwood, Kees Knipscheer, Martin Kohli, Gisela Labouvie‐Vief, Kristina Larsson, Shu‐Chen Li, Charles F. Longino, Ariela Lowenstein, Erick McCarthy, Gerald E. McClearn, Brendan McCormack, Elizabeth MacKinlay, Alfons Marcoen, Michael Marmot, Tom Margrain, Victor W. Marshall, Elizabeth A. Maylor, Ruud ter Meulen, Harry R. Moody, Robert A. Neimeyer, Demi Patsios, Margaret J. Penning, Stephen A. Petrill, Chris Phillipson, Leonard W. Poon, Norella M. Putney, Jill Quadagno, Pat Rabbitt, Jennifer Reid Keene, Sandra G. Reynolds, Steven R. Sabat, Clive Seale, Merril Silverstein, Hannes B. Staehelin, Ursula M. Staudinger, Robert J. Sternberg, Debra Street, Philip Taylor, Fleur Thomése, Mats Thorslund, Jinzhou Tian, Theo van Tilburg, Fernando M. Torres‐Gil, Josy Ubachs‐Moust, Christina Victor, K. Warner Shaie, Anthony M. Warnes, James L. Werth, Sherry L. Willis, François‐Charles Wolff, Bob Woods
- Edited by Malcolm L. Johnson, University of Bristol
- Edited in association with Vern L. Bengtson, University of Southern California, Peter G. Coleman, University of Southampton, Thomas B. L. Kirkwood, University of Newcastle upon Tyne
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- The Cambridge Handbook of Age and Ageing
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- 05 June 2016
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- 01 December 2005, pp xii-xvi
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Collagen-Inspired Nano-fibrous Poly(L-lactic acid) Scaffolds for Bone Tissue Engineering Created from Reverse Solid Freeform Fabrication
- Victor J. Chen, Laura A. Smith, Peter X. Ma
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- MRS Online Proceedings Library Archive / Volume 823 / 2004
- Published online by Cambridge University Press:
- 17 March 2011, W11.13
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- 2004
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Reverse solid freeform (SFF) fabrication was used to create highly-controlled macroporous structures in nano-fibrous poly (L-lactic acid) (PLLA) scaffolds. By using a computer-aided design (CAD) program to create a negative template for the scaffold, the three-dimensional (3-D) mold was created on a 3-D printer using a wax. After the template was printed, a solution of PLLA in tetrahydrofuran (THF) was cast into the mold, and was subsequently phase separated at -70°C which gives the nano-fibrous morphology. This resulted in a 3-D nano-fibrous scaffold with a uniform fiber mesh throughout the entire matrix, and greatly increased the surface area within the scaffold. Fiber diameters in these scaffolds were 50-500 nm, similar to type I collagen, and the densities of the fiber meshes can be altered by changing the polymer concentration. To examine the scaffold's potential for tissue regeneration, MC3T3-E1 osteoblasts were seeded and cultured on the scaffolds. Results show that the osteoblasts attached and proliferated on the scaffolds. After 6 weeks in culture, bone-like tissue was evident within the nano-fibrous scaffolds. By having the ability to control the macroporous architecture, interconnectivity, orientation, and external shape of the scaffold, as well as the nanometer-scaled fibrous features in the pore walls, this SFF fabrication/phase separation technique has great potential to design and create ideal scaffolds for bone tissue engineering.
Nano-fibrous scaffolding architecture enhances protein adsorption and cell attachment
- Kyung Mi Woo, Victor J. Chen, Peter X. Ma
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- Journal:
- MRS Online Proceedings Library Archive / Volume 735 / 2002
- Published online by Cambridge University Press:
- 11 February 2011, C5.2
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- 2002
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Tissue engineering aims at resolving problems such as donor shortage and immune rejection faced in transplantation. Scaffolds (artificial extracellular matrices) play critical roles in tissue engineering. Recently, we developed nano-fibrous poly(L-lactic acid) (PLLA) scaffolds under the hypothesis that synthetic nano-fibrous scaffolding, mimicking the structure of natural collagen fibers, could create a more favorable microenvironment for cells. This is the first report that the nano-fibrous architecture built in three-dimensional scaffolds improved the features of protein adsorption, which mediates cell interactions with scaffolds. Scaffolds with nano-fibrous pore walls adsorbed 4 times more serum proteins than scaffolds with solid pore walls. More interestingly, the nano-fibrous architecture selectively enhanced protein adsorption including fibronectin and vitronectin, even though both scaffolds were made from the same PLLA material. Furthermore, nano-fibrous scaffolds also allowed more than 1.7 times of osteoblastic cell attachment than scaffolds with “solid” pore walls. These results demonstrate that the biomimetic nano-fibrous architecture serves as superior scaffolding for tissue engineering.
Biomimetic Poly(L-Lactic Acid) Scaffolds with Interconnected Macropores, Collagen-Like Nano-Scale Fibers, and Bone-Like Apatite
- Victor J. Chen, Peter X. Ma
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- Journal:
- MRS Online Proceedings Library Archive / Volume 735 / 2002
- Published online by Cambridge University Press:
- 11 February 2011, C6.5
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- 2002
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Highly porous nano-fibrous poly(L-lactic acid) (PLLA) scaffolds were prepared and incubated in a simulated body fluid which resulted in the in situ formation of partially carbonated bone-like apatite. The macroporous interconnected architecture was created with a three-dimensional mold of thermally-bonded paraffin microspheres. PLLA solution was cast over the paraffin mold and was thermally induced to phase separate to form nano-scale fibers that mimic the fibrous structures of type I collagen. To potentially improve the osteoconductivity of these scaffolds, they were incubated in a buffered simulated body fluid at 37°C for certain periods of time to allow for apatite formation. It was seen that over time, the apatite particles increased in size. In addition, the growth of apatite particles on the nano-fibrous scaffolds was compared with the growth of particles on similar porous PLLA scaffolds with a solid-walled (not nano-fibrous) morphology. It was seen that the initial number of particles per unit area and the overall increase in mass of the scaffolds were significantly higher in the nano-fibrous scaffolds than in the solid-walled scaffolds. These novel scaffolds have well-defined architectures at three different size scales: (i) interconnected spherical pores ∼250–400 m in diameter; (ii) fibrous collagen-like matrix with fibers 50–500 nm in diameter; and (iii) carbonated bone-like apatite particles at the nanometer to micrometer scales; the scaffolds may serve as superior support for bone tissue regeneration.
Design, Synthesis, and Characterization of Hydroxyapatite Particulates
- Chun-Wei Chen, Kullaiah Byrappa, Charles S. Oakes, Wojciech Sushanek, Richard E. Riman, Mamoru Senna, Kelly Brown, Kevor S. TenHuisen, Victor F. Janas
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- Journal:
- MRS Online Proceedings Library Archive / Volume 662 / 2000
- Published online by Cambridge University Press:
- 15 March 2011, LL6.2
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- 2000
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New hydrothermal technology for the preparation of hydroxyapatite designer particulates has been developed. Phase diagrams were constructed for the pH dependent equilibrium between monetite and HA from 50 to 200°C. Thermodynamic calculations were completed using temperature dependent functions for the relevant solution phase and solid-liquid equilibria and solute species activity coefficients. Model accuracy was evaluated through experiment at 50, 100, and 200°C and pHs between 2.2 and 8.9. The thermodynamic calculations and experimental results are in good agreement. Stoichiometric, crystalline HA has also been prepared by heterogeneous reaction of Ca(OH)2 powder and aqueous (NH4)2HPO4 at room temperature using mechanochemical-hydrothermal methods. This method appears to have very good reproducibility in terms of crystallinity and chemical composition.