71 results on '"Jack Chan"'
Search Results
2. Temporal quality assessment for mobile videos.
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An (Jack) Chan, Amit Pande, Eilwoo Baik, and Prasant Mohapatra
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- 2012
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3. Video-Aware Rate Adaptation for MIMO WLANs.
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An (Jack) Chan, Henrik Lundgren, and Theodoros Salonidis
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- 2011
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4. Comparing simulation tools and experimental testbeds for wireless mesh networks.
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Kefeng Tan, Daniel Wu, An (Jack) Chan, and Prasant Mohapatra
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- 2010
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5. Metrics for Evaluating Video Streaming Quality in Lossy IEEE 802.11 Wireless Networks.
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An (Jack) Chan, Kai Zeng 0001, Prasant Mohapatra, Sung-Ju Lee, and Sujata Banerjee
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- 2010
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6. Exploiting Multiple-Antenna Diversity for Shared Secret Key Generation in Wireless Networks.
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Kai Zeng 0001, Daniel Wu, An (Jack) Chan, and Prasant Mohapatra
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- 2010
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7. What Are the Preferences of Patients With Rheumatoid Arthritis for Treatment Modification? A Scoping Review
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Hui Yee Yeo, Carlo A. Marra, Lisa K. Stamp, Suz Jack Chan, and Gareth J. Treharne
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medicine.medical_specialty ,Health economics ,business.industry ,030503 health policy & services ,General Medicine ,Treatment goals ,medicine.disease ,Health administration ,Clinical Practice ,03 medical and health sciences ,0302 clinical medicine ,Patient satisfaction ,Rheumatoid arthritis ,medicine ,030212 general & internal medicine ,skin and connective tissue diseases ,0305 other medical science ,Intensive care medicine ,business ,Antirheumatic drugs ,Treatment modification - Abstract
Optimal care of rheumatoid arthritis (RA) patients entails regular assessment of disease activity and appropriate adjustment of disease-modifying antirheumatic drugs (DMARDs) until a predefined treatment goal is achieved. This raises questions about the approach to treatment decision making among RA patients and their preference for associated treatment changes. We aimed to systematically identify and synthesize the available evidence of RA patients’ preferences regarding DMARD modification with an emphasis on escalating, tapering, stopping, or switching of DMARDs. A scoping review was undertaken to gauge the breadth of evidence from the range of studies relating to RA patients’ preferences for DMARD modification. Pertinent databases were searched for relevant studies published between 1988 and 2019. Conventional content analysis was applied to generate themes about how patients perceive changes to their RA treatment. Of the 1730 distinct articles identified, 32 were included for review. Eight studies investigated RA patients’ perceptions of switching to other DMARDs, 18 studies reported RA patients’ preferences for escalating treatment, and six studies explored the possibility of tapering or stopping of biologic DMARDs. Four overarching themes relating to RA patients’ preferences for treatment modification were identified: (i) patient satisfaction, (ii) patients’ beliefs, (iii) information needs, and (iv) patient–clinician relationships. Uptake of treatment changes in clinical practice can be improved by understanding how RA patients approach the decision to modify their treatment and how this relates to their satisfaction, beliefs, information needs, and relationships with clinicians. Future work is needed to systematically determine the significance of these factors in RA patients’ decision-making processes.
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- 2020
8. Integrating immunotherapy in the (neo)adjuvant setting of early breast cancer
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Jack Chan, Rebecca Dent, and Tira Jing Ying Tan
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0301 basic medicine ,Oncology ,Cancer Research ,medicine.medical_specialty ,business.industry ,medicine.medical_treatment ,Immunotherapy ,Malignancy ,medicine.disease ,Immune checkpoint ,Clinical trial ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Breast cancer ,030220 oncology & carcinogenesis ,Internal medicine ,medicine ,business ,Adjuvant ,Neoadjuvant therapy ,Early breast cancer - Abstract
Purpose of review Breast cancer is a relative latecomer in the success story of immuno-oncology. In this review, we focus on the preclinical and clinical lines of evidence to justify the evaluation of immune checkpoint inhibition (ICI) for the curative-intent treatment of breast cancer, the latest and ongoing trials of (neo)adjuvant immunotherapy, and practical considerations in clinical practice associated with this new treatment paradigm. Recent findings Insights from the immunobiology of breast cancer have paved the way for the new frontier of immunotherapy in this malignancy, starting from advanced stages and moving onto curable cases. Tumor-infiltrating lymphocyte quantification and PD-L1 immunohistochemistry are forerunners of predictive biomarkers for sensitivity to ICI in breast cancers. Preliminary results from phase III trials of combinatorial immunochemotherapy to treat early high-risk or locally advanced triple-negative breast cancer are encouraging for pathological complete response. Additional efficacy and patient-reported outcomes of (neo)adjuvant immunochemotherapy trials are awaited. Summary The prospect of integrating ICI in the treatment of early-stage breast cancer is promising. Questions regarding patient selection, the choice of ICI agent and combination partner in escalation strategies, sequencing and duration of treatments, cost-effectiveness and mechanisms of resistance remain to be answered by future research.
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- 2020
9. Differences in Practitioner Experience, Practice Type, and Profession in Attitudes Toward Growing Contact Lens Practice
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Nilesh Thite, Alfredo Desiato, Lakshmi Shinde, James S Wolffsohm, Shehzad A. Naroo, Jacinto Santodomingo Rubido, Pauline Cho, Debbie Jones, Cesar Villa-Collar, Guillermo Carrillo, Osbert Chan, Haiying Wang, Elena Iomdina, Elena Tarutta, Olga Proskurina, Chi Shing Fan, Fabrizio Zeri, May M. Bakkar, Fakhruddin Barodawala, Neeraj Dabral, Edouard Lafosse, Cheni Lee, Jason Nichols, Jack Chan, Kyounghee Park, Vishakh Nair, Eef van der Worp, Gopi Vankudre, Vinod Maseedupally, Yashaswee Bhattarai, Dimple Nagzarkar, Peter Brauer, Raquel Gil-Cazorla, Thite, N, Desiato, A, Shinde, L, Wolffsohm, J, Naroo, S, Santodomingo Rubido, J, Cho, P, Jones, D, Villa-Collar, C, Carrillo, G, Chan, O, Wang, H, Iomdina, E, Tarutta, E, Proskurina, O, Fan, C, Zeri, F, Bakkar, M, Barodawala, F, Dabral, N, Lafosse, E, Lee, C, Nichols, J, Chan, J, Park, K, Nair, V, van der Worp, E, Vankudre, G, Maseedupally, V, Bhattarai, Y, Nagzarkar, D, Brauer, P, and Gil-Cazorla, R
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Male ,Health Knowledge, Attitudes, Practice ,Ophthalmology ,Universities ,Attitude ,Contact Lenses ,Surveys and Questionnaires ,Contact lens practitioner ,Humans ,Contact lens practice ,Female ,Intervention - Abstract
Objective:To investigate eye care practitioners' attitudes and perceptions toward potential interventions that can enhance contact lens (CL) practice across the world, and how this is influenced by their practice setting.Methods:A self-administered, anonymized survey was constructed in English and then forward and backward translated into six more languages. The survey was distributed online via social media platforms and mailing lists involving reputed international professional bodies.Results:In total, 2,222 responses from 27 countries with sufficient responses were analyzed (53% females, median age- 37 years). Most of the respondents were optometrists (81.9%) and 47.6% were from stand-alone/independent practices. Median working experience in CL prescribing was 11.0 years (IQR: 18.0, 4-22 years). Over two-third of them declared themselves to be very hopeful (22.9%) or hopeful (45.1%) about the future of their CL practice. Among the potential interventions proposed, continuous update of knowledge and skills and competently managing CL-related complications were rated the most important (median score: 9/10 for each). Practitioners working in national/regional retail chains expressed higher proactivity in recommending CLs (9/10) than those in local chains, hospitals, and universities (for all 8/10, P
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- 2022
10. Analysis of efficacy of intervention strategies for COVID-19 transmission: A case study of Hong Kong
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Zhang, Nan, primary, Jack Chan, Pak-To, additional, Jia, Wei, additional, Dung, Chung-Hin, additional, Zhao, Pengcheng, additional, Lei, Hao, additional, Su, Boni, additional, Xue, Peng, additional, Zhang, Weirong, additional, Xie, Jingchao, additional, and Li, Yuguo, additional
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- 2021
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11. Tapering biologic therapy for people with rheumatoid arthritis in remission: A review of patient perspectives and associated clinical evidence
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Lisa K. Stamp, Gareth J. Treharne, Caitlin Helme, Suz Jack Chan, and Carlo A. Marra
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medicine.medical_specialty ,Nursing (miscellaneous) ,Physical Therapy, Sports Therapy and Rehabilitation ,Tapering ,Disease ,Arthritis, Rheumatoid ,Biological Factors ,03 medical and health sciences ,0302 clinical medicine ,Rheumatology ,medicine ,Decision aids ,Humans ,Orthopedics and Sports Medicine ,030212 general & internal medicine ,Intensive care medicine ,030203 arthritis & rheumatology ,business.industry ,Rehabilitation ,medicine.disease ,Clinical research ,Clinical evidence ,Antirheumatic Agents ,Rheumatoid arthritis ,Dose reduction ,Chiropractics ,business ,Qualitative research - Abstract
Objectives Biologic therapies have increased the control of disease activity in rheumatoid arthritis (RA). Questions remain about tapering biologics when remission is achieved in RA. The patient perspective has to be incorporated in pragmatic applications of tapering but is rarely accounted for in clinical studies of tapering. The aim of the present review was to summarize the evidence about RA patient perspectives on biologic tapering. Methods We provided a narrative summary of the currently small body of research on patient perspectives retrieved through systematic searches with an emphasis on seeking qualitative research. In addition, we provided an update on relevant clinical research and financial considerations that frame the findings on patient perspectives. Results Financial considerations around commencing/continuing on biologic therapies in RA vary internationally and have implications for patient perspectives. Recent clinical studies indicate that the benefit of tapering biologic therapy when in remission are predicted by drug concentration and aspects of disease activity, severity and duration. Three major concerns have been identified from studies of patient perspectives on biologic tapering: (a) disease relapse; (b) access to treatment in the case of disease flare when tapering; and (c) local motivation for dose reduction (i.e., driven by funding or health benefit). Conclusions More research is needed on tapering biologics, and should include studies of patient perspectives as well as health economic evaluations. Patient decision aids are a potential way of applying clinical and patient-focused evidence to help all parties come to a decision, but require developmental research and pragmatic evaluation.
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- 2019
12. Towards an improved understanding of nitrogen dioxide emissions from forest fires
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Paul A. Makar, John Liggio, Enrico Dammers, Adam Bourassa, Katherine Hayden, Lukas Fehr, Chris A. McLinden, Cristen Adams, Debora Griffin, Ayodeji Akingunola, Sumi N. Wren, Doug Degenstein, and Jack Chan
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chemistry.chemical_compound ,chemistry ,Environmental chemistry ,Environmental science ,Nitrogen dioxide - Abstract
Smoke from wildfires are a significant source of air pollution, which can adversely impact ecosystems and the air quality in downwind populated areas. With increasing severity of wildfires over the years, these are a significant threat to air quality in densely populated areas. Emissions from wildfires are most commonly estimated by a bottom-up approach, using proxies such fuel type, burn area, and emission factors. Emissions are also commonly derived with a top-down approach, using satellite observed Fire Radiative Power. Furthermore, wildfire emissions can also be estimated directly from satellite-borne measurements.Here, we present advancements and improvements of direct emission estimates of forest fire NOx emissions by using TROPOMI (Tropospheric Monitoring Instrument) high-resolution satellite datasets, including NO2 vertical column densities (VCDs) and information on plume height and aerosol scattering. The effect of smoke aerosols on the sensitivity of TROPOMI to NO2 (via air mass factors) is estimated with recalculated VCDs, and validated with aircraft observations. Different top-down emission estimation methods are tested on synthetic data to determine the accuracy, and the sensitivity to parameters, such as wind fields, satellite sampling, instrument noise, NO2:NOx conversion ratio, species atmosphere lifetime and plume spread. Lastly, the top-down, bottom-up and direct emission estimates of fire emissions are quantitatively compared.
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- 2021
13. Early Outcomes of a National Cancer Center's Strategy Against COVID-19 Executed Through a Disease Outbreak Response Taskforce
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Rebecca Dent, Chee Kian Tham, Jack Chan, Patricia Soek Hui Neo, Lita S T Chew, Ravindran Kanesvaran, Swee Peng Yap, Soon Thye Lim, Jin Wei Kwek, Michael L.C. Wang, Claramae Shulyn Chia, William Hwang, and Hiang Khoon Tan
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Health Personnel ,Advisory Committees ,MEDLINE ,Disease ,Cancer Care Facilities ,Health care rationing ,03 medical and health sciences ,0302 clinical medicine ,Pandemic ,Ambulatory Care ,Medicine ,Humans ,Mass Screening ,Center (algebra and category theory) ,030212 general & internal medicine ,Personal Protective Equipment ,Mass screening ,Cross Infection ,Infection Control ,Singapore ,Health Care Rationing ,Oncology (nursing) ,business.industry ,SARS-CoV-2 ,Health Policy ,Cancer ,Outbreak ,COVID-19 ,Continuity of Patient Care ,medicine.disease ,Community-Acquired Infections ,Hospitalization ,Oncology ,030220 oncology & carcinogenesis ,COVID-19 Nucleic Acid Testing ,Medical emergency ,business - Abstract
PURPOSE:We present the strategy of a comprehensive cancer center organized to make operations pandemic proof and achieve continuity of cancer care during the COVID-19 pandemic.METHODS:Disease Outbreak Response (DORS) measures implemented at our center and its satellite clinics included strict infection prevention, manpower preservation, prudent resource allocation, and adaptation of standard-of-care treatments. Critical day-to-day clinical operations, number of persons screened before entry, staff temperature monitoring, and personal protection equipment stockpile were reviewed as a dashboard at daily DORS taskforce huddles. Polymerase chain reaction swab tests performed for patients and staff who met defined criteria for testing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were tracked. Descriptive statistics of outpatient attendances and treatment caseloads from February 3 to May 23, 2020, were compared with the corresponding period in 2019.RESULTS:We performed COVID-19 swabs for 80 patients and 93 staff, detecting three cancer patients with community-acquired COVID-19 infections with no nosocomial transmission. Patients who required chemotherapy, radiotherapy, or surgery and patients who are on maintenance treatment continued to receive timely treatment without disruption. The number of intravenous chemotherapy treatments was maintained at 97.8% compared with 2019, whereas that of weekly radiotherapy treatments remained stable since December 2019. All cancer-related surgeries proceeded without delay, with a 0.3% increase in workload. Surveillance follow-ups were conducted via teleconsultation, accounting for a 30.7% decrease in total face-to-face clinic consultations.CONCLUSION:Through the coordinated efforts of a DORS taskforce, it is possible to avoid nosocomial SARS-CoV-2 transmissions among patients and staff without compromising on care delivery at a national cancer center.
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- 2021
14. Immunotherapy as maintenance treatment in metastatic triple negative breast cancer
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Jack Chan, Rebecca Dent, and Tira Jing Ying Tan
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Oncology ,medicine.medical_specialty ,Maintenance therapy ,business.industry ,Internal medicine ,medicine.medical_treatment ,medicine ,Immunotherapy ,business ,Triple-negative breast cancer - Published
- 2021
15. Fatty acid oxidation is a druggable gateway regulating cellular plasticity for driving metastasis in breast cancer
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May Yin Lee, S. Shatishwaran, Roger Foo, Magendran Muniandy, Benita Tan, Joanna Zhen Zhen Yeo, Soo-Chin Lee, Chow Yin Wong, Elina Pathak, Preetha Madhukumar, Li Ping Toh, William Haowei Xie, Wai Leong Tam, Esther Kai Lay Peh, Ju Yuan, Yirong Sim, Veronique Kiak Mien Tan, Lih-Wen Deng, Wilson Wei Sheng Tan, Yin Ying Ho, Elaine Hsuen Lim, Rebecca Dent, Markus R. Wenk, Puay Hoon Tan, Ying Swan Ho, Jack Chan, Siming Ma, Federico Torta, Ser Yue Loo, Yoon Sim Yap, Tira Jing Ying Tan, Wei Sean Yong, Kong Wee Ong, School of Biological Sciences, Genome Institute of Singapore, A*STAR, and National University of Singapore
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Multidisciplinary ,Epithelial-Mesenchymal Transition ,Transition (genetics) ,Chemistry ,digestive, oral, and skin physiology ,Retinoic Acid ,Druggability ,SciAdv r-articles ,Cancer ,Biological sciences [Science] ,medicine.disease ,Metastasis ,Breast cancer ,Cellular plasticity ,Cancer cell ,Cancer research ,medicine ,Biomedicine and Life Sciences ,Beta oxidation ,Research Article - Abstract
Description, Fatty acid oxidation is a metabolic gateway that regulates cellular plasticity and supports metastasis in breast cancer., Cell state transitions control the functional behavior of cancer cells. Epithelial-to-mesenchymal transition (EMT) confers cancer stem cell-like properties, enhanced tumorigenicity and drug resistance to tumor cells, while mesenchymal-epithelial transition (MET) reverses these phenotypes. Using high-throughput chemical library screens, retinoids are found to be potent promoters of MET that inhibit tumorigenicity in basal-like breast cancer. Cell state transitions are defined by reprogramming of lipid metabolism. Retinoids bind cognate nuclear receptors, which target lipid metabolism genes, thereby redirecting fatty acids for β-oxidation in the mesenchymal cell state towards lipid storage in the epithelial cell state. Disruptions of key metabolic enzymes mediating this flux inhibit MET. Conversely, perturbations to fatty acid oxidation (FAO) rechannel fatty acid flux and promote a more epithelial cell phenotype, blocking EMT-driven breast cancer metastasis in animal models. FAO impinges on the epigenetic control of EMT through acetyl-CoA-dependent regulation of histone acetylation on EMT genes, thus determining cell states.
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- 2021
16. MAIT cells regulate NK cell mediated tumor immunity
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Emma Petley, Hui-Fern Koay, Melissa Henderson, Kevin Sek, Kirsten Todd, Simon Keam, Junyun Lai, Imran House, Magnus Zethoven, Amanda Chen, Amanda Oliver, Jessica Michie, Andrew Freeman, Lauren Giuffrida, Jack Chan, Angela Pizzolla, Jeffrey Mak, Fernando Souza-Fonseca-Guimaraes, Conor Kearney, Rosemary Millen, Rob Ramsay, Nicholas Huntington, James McCluskey, Jane Oliaro, David Fairlie, Paul Neeson, Dale Godfrey, Paul (A.) Beavis, and Phillip Darcy
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MR1-restricted mucosal-associated invariant T (MAIT) cells recognize microbial metabolites and play an important role in immunity to infection, however, the role they play in tumor immunity is unclear. Here we show that MAIT cell-deficient mice are more resistant to subcutaneous and lung metastasis B16F10 tumor growth compared to control mice, an effect that was associated with enhanced NK cell numbers and was NK cell-dependent. Analysis of this interplay in cancer patients also revealed that a high expression of a novel MAIT gene signature negatively impacted the prognostic significance of NK cells. Paradoxically, pre-pulsing tumors with MAIT cell antigens, or antigen-mediated MAIT cell activation in vivo, enhanced immunity against B16F10 and E0771 lung tumor metastasis. Furthermore, MAIT cell activation effectively reduced metastatic burden in a more stringent model of established lung metastases in mice. These effects were associated with enhanced NK cell responses and increased expression of both IFNγ-dependent and inflammatory genes in NK cells, which was neutralized by IFNγ blockade. Importantly, activated human MAIT cells also enhanced the function of NK cells isolated from patient tumor samples. These findings provide insight into the contrasting roles that MAIT cells can play in controlling anti-tumor immune responses depending on their activation status, in both mice and humans, and suggest potential therapeutic avenues for exploiting their potential anti-tumor properties for cancer treatment.
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- 2020
17. The impact of COVID-19 on and recommendations for breast cancer care: the Singapore experience
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Joline Si Jing Lim, Fuh Yong Wong, Veronique Kiak Mien Tan, Tira Jing Ying Tan, Qingyuan Zhuang, Samuel Guan Wei Ow, Ru Xin Wong, Jack Chan, Yirong Sim, and Grace Kusumawidjaja
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0301 basic medicine ,Cancer Research ,medicine.medical_specialty ,Palliative care ,Coronavirus disease 2019 (COVID-19) ,Endocrinology, Diabetes and Metabolism ,Pneumonia, Viral ,Context (language use) ,Breast Neoplasms ,03 medical and health sciences ,Betacoronavirus ,0302 clinical medicine ,Endocrinology ,Resource (project management) ,Breast cancer ,Health care ,Pandemic ,medicine ,Humans ,Pandemics ,Clinical Trials as Topic ,Singapore ,business.industry ,SARS-CoV-2 ,Public health ,COVID-19 ,medicine.disease ,030104 developmental biology ,Oncology ,030220 oncology & carcinogenesis ,Family medicine ,Practice Guidelines as Topic ,Female ,business ,Coronavirus Infections - Abstract
The ensuing COVID-19 pandemic poses unprecedented and daunting challenges to the routine delivery of oncological and supportive care to patients with breast cancer. Considerations include the infective risk of patients who are inherently immunosuppressed from their malignancy and therapies, long-term oncological outcomes from the treatment decisions undertaken during this extraordinary period, and diverted healthcare resources to support a coordinated whole-of-society outbreak response. In this review, we chronicle the repercussions of the COVID-19 outbreak on breast cancer management in Singapore and describe our approach to triaging and prioritising care of breast tumours. We further propose adaptations to established clinical processes and practices across the different specialties involved in breast oncology, with references to the relevant evidence base or expert consensus guidelines. These recommendations have been developed within the unique context of Singapore’s public healthcare sector. They can serve as a resource to guide breast cancer management for future contingencies in this city-state, while certain elements therein may be extrapolatable to other medical systems during this global public health emergency.
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- 2020
18. Abstract TP138: Chronic Kidney Disease in Heart Failure Patients is Associated with Increased Prevalence of Atrial Fibrillation or Atrial Flutter as well as CVA/TIA
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Christopher Lu, Jack Chan, Mikhail Torosoff, Paula Anzenberg, and Zejia Yu
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Advanced and Specialized Nursing ,medicine.medical_specialty ,Kidney ,business.industry ,Atrial fibrillation ,medicine.disease ,Stroke risk ,medicine.anatomical_structure ,Internal medicine ,Heart failure ,Cardiology ,medicine ,In patient ,cardiovascular diseases ,Neurology (clinical) ,Cardiology and Cardiovascular Medicine ,business ,Stroke ,Atrial flutter ,Kidney disease - Abstract
Background: The CHADS-VASC score does not incorporate renal dysfunction in stroke risk assessment in patients with atrial fibrillation and the prevalence of atrial fibrillation, atrial flutter, and cerebrovascular accidents (CVA) in patients with concurrent CHF and CKD is not well investigated. Objective: Evaluate the prevalence of history of stroke, atrial fibrillation, atrial flutter in patients with CHF and CKD. Methods: Data from the single institution Get With The Guidelines- Heart Failure (GWG-HF) cohort of 2938 consecutive inpatients with known GFR was utilized. CHADS-VASC score was calculated from the GWG-HF variables. Chronic kidney disease (CKD) was defined as GFR Results: An overwhelming majority (95%) of GWG-HF patients had elevated >1 CHADS-VASC score, which was also significantly more common in patients with CKD (97.6% vs. 91.7% in patients without CKD, p Conclusions: In patients admitted with heart failure, CKD is associated with increased prevalence of atrial fibrillation or atrial flutter as well as increased prevalence of CVA/TIA. Further prospective studies are warranted to examine whether CKD history should be included in stroke risk assessment in patients with atrial fibrillation or atrial flutter, in conjunction with existing risk assessment frameworks.
- Published
- 2020
19. Tapering Biologic Therapy for Rheumatoid Arthritis: A Qualitative Study of Patient Perspectives
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Nicola Liebergreen, Suz Jack Chan, Carlo A. Marra, Lisa K. Stamp, Gareth J. Treharne, and Henry C. Ndukwe
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Adult ,Male ,medicine.medical_specialty ,Tapering ,Health administration ,Arthritis, Rheumatoid ,03 medical and health sciences ,0302 clinical medicine ,Quality of life (healthcare) ,medicine ,Humans ,030212 general & internal medicine ,Intensive care medicine ,Adverse effect ,Qualitative Research ,Aged ,Aged, 80 and over ,Biological Products ,Health economics ,business.industry ,030503 health policy & services ,Focus Groups ,Middle Aged ,medicine.disease ,Clinical trial ,Rheumatoid arthritis ,Antirheumatic Agents ,Quality of Life ,Female ,Thematic analysis ,0305 other medical science ,business ,New Zealand - Abstract
Biologic therapies are cost effective for active rheumatoid arthritis but have adverse effects and are costly. Tapering of biologics is emerging as an important consideration when sustained remission is achieved. Recent trials have highlighted the clinical feasibility of tapering, but there is little evidence on how proposed tapering would be received by patients. The aim of this study was to explore factors influencing hypothetical decisions of patients with rheumatoid arthritis on tapering their biologics and their perspectives on remission and flare when considering the possibility of tapering. Patients with rheumatoid arthritis with diverse experiences of biologics with different modes of administration were purposively sampled to participate in one of six focus groups (n = 43) or an individual interview (n = 2). Transcripts were analyzed using inductive thematic analysis. Five overarching themes on what influences a participant’s decision to taper their biologic were identified. First, participants were fearful of uncertain outcomes of tapering, especially flare and joint damage. Second, participants prioritized quality of life from continuing biologics over the risk of adverse effects. Third, tapering biologics was seen as providing relief from the inconvenience of taking biologics regularly. Fourth, participants wanted assurance of prompt access to healthcare if their rheumatoid arthritis were to flare when tapering. Fifth, preferences for involvement in decision making varied, but fulfilling information needs was desired to aid a patient’s preferred role in decision making on tapering. This study provides novel insight into the perspectives of patients with rheumatoid arthritis on tapering biologics when sustained remission is achieved at a crucial juncture in global affordability for healthcare systems. These patient perspectives can inform the planning of decision aids and clinical trials of decision-making processes when tapering is proposed.
- Published
- 2019
20. Are There Any Clinically Relevant Subgroups of Triple-Negative Breast Cancer in 2018?
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Tira Jing Ying Tan, Rebecca Dent, and Jack Chan
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0301 basic medicine ,Oncology ,medicine.medical_specialty ,Oncology (nursing) ,business.industry ,Gene Expression Profiling ,Health Policy ,Triple Negative Breast Neoplasms ,medicine.disease ,Clinical trial ,Clinical Practice ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Breast cancer ,030220 oncology & carcinogenesis ,Internal medicine ,medicine ,Molecular targets ,Humans ,Treatment strategy ,Molecular Targeted Therapy ,business ,Triple-negative breast cancer - Abstract
The working immunohistochemical definition of triple-negative breast cancer (TNBC) is admittedly reductionist and has only limited usefulness for informing oncologists about therapeutic decisions beyond chemotherapy. Early molecular taxonomies of TNBC based heavily on gene expression profiling, which is not readily available in the clinic today, do not necessarily encompass other molecular targets already incorporated into rationally designed clinical trials. We state that it is possible to delineate five subgroups of TNBC relevant to present-day clinical practice and cover the evidence that lends credence to emerging biomarker-directed treatment strategies for each subgroup.
- Published
- 2018
21. The impact of link-layer retransmissions on video streaming in wireless mesh networks.
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An (Jack) Chan, Sung-Ju Lee, Xiaolin Cheng, Sujata Banerjee, and Prasant Mohapatra
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- 2008
- Full Text
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22. Novel therapeutic avenues in triple-negative breast cancer: PI3K/AKT inhibition, androgen receptor blockade, and beyond
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Jack Chan, Tira Jing Ying Tan, and Rebecca Dent
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business.industry ,TNBC in 2019: Promising Signals for the Treatment of a Formidable Disease ,Context (language use) ,Review ,lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,PI3K/AKT/PTEN altered ,lcsh:RC254-282 ,Ipatasertib ,AKT inhibitor ,Blockade ,Androgen receptor ,ipatasertib ,Oncology ,androgen receptor ,Cancer research ,triple-negative breast cancer ,Medicine ,Signal transduction ,business ,Protein kinase B ,PI3K/AKT/mTOR pathway ,Triple-negative breast cancer - Abstract
Multiomic analyses have shed light upon the molecular heterogeneity and complexity of triple-negative breast cancers (TNBCs). With increasing recognition that TNBC is not a single disease entity but encompasses different disease subtypes, a one-size-fits-all treatment paradigm has become obsolete. In this context, the inhibition of phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) and androgen receptor (AR) signaling pathways have emerged as potential therapeutic strategies against selected tumors. In this paper, we reviewed the preclinical rationale, predictive biomarkers, efficacy, and safety data from early phase trials, and the future directions for these two biomarker-directed treatment approaches in TNBC.
- Published
- 2019
23. Replication and Meta-analysis of the Association between BDNF Val66Met Polymorphism and Cognitive Impairment in Patients Receiving Chemotherapy
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Alexandre Chan, Mabel Wong, Raymond Ng, Koon Mian Foo, Guek Eng Lee, Sok Yuen Beh, Jack Chan, Wen Yee Chay, Maung Shwe, Pat Chu, Amit Jain, Yi Long Toh, Si-Lin Koo, Han Kiat Ho, Angie Yeo, Terence Ng, Rebecca Dent, Elaine Hsuen Lim, Sheree Wan Ting Lim, Tira Jing Ying Tan, Chia Jie Tan, Chiea Chuen Khor, Kiley Wei-Jen Loh, and Yoon Sim Yap
- Subjects
0301 basic medicine ,Oncology ,Anxiety ,Logistic regression ,0302 clinical medicine ,Breast cancer ,Gene Frequency ,Polymorphism (computer science) ,Prevalence ,Odds Ratio ,Psychology ,Fatigue ,Cancer ,Confounding ,Neuropsychology ,Single Nucleotide ,Middle Aged ,Neurology ,Meta-analysis ,Cohort ,Female ,Cognitive Sciences ,Cancer-related cognitive impairment ,medicine.medical_specialty ,Neuroscience (miscellaneous) ,Antineoplastic Agents ,Polymorphism, Single Nucleotide ,Article ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Clinical Research ,Internal medicine ,medicine ,Genetics ,Humans ,Chemotherapy ,Genetic Predisposition to Disease ,Cognitive Dysfunction ,Allele ,Polymorphism ,Alleles ,Genetic polymorphism ,Neurology & Neurosurgery ,business.industry ,Brain-Derived Neurotrophic Factor ,Human Genome ,Neurosciences ,Reproducibility of Results ,medicine.disease ,Brain Disorders ,030104 developmental biology ,BDNF ,business ,030217 neurology & neurosurgery - Abstract
Cancer-related cognitive impairment (CRCI) adversely affects cancer patients. We had previously demonstrated that the BDNF Val66Met genetic polymorphism is associated with lower odds of subjective CRCI in the multitasking and verbal ability domains among breast cancer patients receiving chemotherapy. To further assess our previous findings, we evaluated the association of BDNF Val66Met polymorphism with subjective and objective CRCI in a temporally separate cohort of patients and pooled findings from both the original (n = 145) and current (n = 193) cohorts in a meta-analysis. Subjective CRCI was assessed using FACT-Cog. Objective CRCI was evaluated using computerized neuropsychological tests. Genotyping was carried out using Sanger sequencing. The association of BDNF Val66Met genotypes and CRCI was examined with logistic regression. A fixed-effect meta-analysis was conducted using the inverse variance method. In the meta-analysis (n = 338), significantly lower odds of CRCI were associated with Met allele carriers based on the global FACT-Cog score (OR = 0.52, 95% CI 0.29–0.94). Furthermore, Met allele carriers were at lower odds of developing impairment in the domains of memory (OR = 0.34, 95% CI: 0.17–0.70), multitasking (OR = 0.33, 95% CI: 0.18–0.59), and verbal ability (OR = 0.46, 95% CI: 0.24–0.88). Consistent with the previous study, lower odds of subjective CRCI among patients with the BDNF Met allele was observed after adjusting for potential confounders in the multitasking (OR = 0.30, 95% CI: 0.14–0.67) domain. In conclusion, carriers of the BDNF Met allele were protected against global subjective CRCI, particularly in the domains of memory, multitasking, and verbal ability. Our findings further contribute to the understanding of CRCI pathophysiology. Electronic supplementary material The online version of this article (10.1007/s12035-018-1410-4) contains supplementary material, which is available to authorized users.
- Published
- 2019
24. Implementation of MyChart for recruitment at an academic medical center
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Carrie Dykes, Cody Gardner, Jack Chang, David Pinto, Karen Wilson, Martin S. Zand, and Ann Dozier
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Recruitment ,electronic health record ,electronic medical record ,patient portal ,response rate ,translational science barrier ,Medicine - Abstract
Abstract Introduction: Recruitment of participants into research studies remains a major concern for investigators. Using clinical teams to identify potentially eligible patients can present a significant barrier. To overcome this, we implemented a process for using our patient portal, called MyChart, as a new institutional recruitment option utilizing our electronic health record’s existing functionality. Methods: To streamline the institutional approval process, we established a working group comprised of representatives from human subject protection, information technology, and privacy and vetted our process with many stakeholder groups. Our specific process for study approval is described and started with a consultation with our recruitment and retention function funded through our Clinical and Translational Science Award. Results: The time from consultation to the first message(s) sent ranged from 84 to 442 days and declined slightly over time. The overall patient response rate to MyChart messages about available research studies was 23% with one third of those saying they were interested in learning more. The response rate for Black and Hispanic patients was about 50% that of White patients. Conclusions: Many different types of studies from any medical specialty successfully identified interested patients using this option. Study teams needed support in defining appropriate inclusion/exclusion criteria to identify the relevant population in the electronic health records and they needed assistance writing study descriptions in plain language. Using MyChart for recruitment addressed a critical barrier and opened up the opportunity to provide a full recruitment consultation to identify additional recruitment channels the study teams would not have considered otherwise.
- Published
- 2024
- Full Text
- View/download PDF
25. Python API Development Fundamentals : Develop a Full-stack Web Application with Python and Flask
- Author
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Jack Chan, Ray Chung, Jack Huang, Jack Chan, Ray Chung, and Jack Huang
- Subjects
- Python (Computer program language), Application program interfaces (Computer software), Web applications, Application software--Development
- Abstract
Learn all that's needed to build a fully functional web application from scratch.Key FeaturesDelve deep into the principle behind RESTful APILearn how to build a scalable web application with the RESTful API architecture and Flask frameworkKnow what are the exact tools and methodology to test your applications and how to use themBook DescriptionPython is a flexible language that can be used for much more than just script development. By knowing the Python RESTful APIs work, you can build a powerful backend for web applications and mobile applications using Python.You'll take your first steps by building a simple API and learning how the frontend web interface can communicate with the backend. You'll also learn how to serialize and deserialize objects using the marshmallow library. Then, you'll learn how to authenticate and authorize users using Flask-JWT. You'll also learn how to enhance your APIs by adding useful features, such as email, image upload, searching, and pagination. You'll wrap up the whole book by deploying your APIs to the cloud.By the end of this book, you'll have the confidence and skill to leverage the power of RESTful APIs and Python to build efficient web applications.What you will learnUnderstand the concept of a RESTful APIBuild a RESTful API using Flask and the Flask-Restful extensionManipulate a database using Flask-SQLAlchemy and Flask-MigrateSend out plaintext and HTML format emails using the Mailgun APIImplement a pagination function using Flask-SQLAlchemyUse caching to improve API performance and efficiently obtain the latest informationDeploy an application to Heroku and test it using PostmanWho this book is forThis book is ideal for aspiring software developers who have a basic-to-intermediate knowledge of Python programming and who want to develop web applications using Python. Knowledge of how web applications work will be beneficial but is not essential.
- Published
- 2019
26. Impact of Various Estimated Glomerular Filtration Rate Equations on the Pharmacokinetics of Meropenem in Critically Ill Adults
- Author
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Erin F. Barreto, PharmD, MSc, Jack Chang, PharmD, MSc, Andrew D. Rule, MD, Kristin C. Mara, MSc, Laurie A. Meade, RN, Johar Paul, RRT, Paul J. Jannetto, PhD, Arjun P. Athreya, PhD, Marc H. Scheetz, PharmD, MSc, and For the BLOOM Study Group
- Subjects
Medical emergencies. Critical care. Intensive care. First aid ,RC86-88.9 - Abstract
IMPORTANCE:. Meropenem dosing is typically guided by creatinine-based estimated glomerular filtration rate (eGFR), but creatinine is a suboptimal GFR marker in the critically ill. OBJECTIVES:. This study aimed to develop and qualify a population pharmacokinetic model for meropenem in critically ill adults and to determine which eGFR equation based on creatinine, cystatin C, or both biomarkers best improves model performance. DESIGN, SETTING, AND PARTICIPANTS:. This single-center study evaluated adults hospitalized in an ICU who received IV meropenem from 2018 to 2022. Patients were excluded if they had acute kidney injury, were on kidney replacement therapy, or were treated with extracorporeal membrane oxygenation. Two cohorts were used for population pharmacokinetic modeling: a richly sampled development cohort (n = 19) and an opportunistically sampled qualification cohort (n = 32). MAIN OUTCOMES AND MEASURES:. A nonlinear mixed-effects model was developed using parametric methods to estimate meropenem serum concentrations. RESULTS:. The best-fit structural model in the richly sampled development cohort was a two-compartment model with first-order elimination. The final model included time-dependent weight normalized to a 70-kg adult as a covariate for volume of distribution (Vd) and time-dependent eGFR for clearance. Among the eGFR equations evaluated, eGFR based on creatinine and cystatin C expressed in mL/min best-predicted meropenem clearance. The mean (se) Vd in the final model was 18.2 (3.5) liters and clearance was 11.5 (1.3) L/hr. Using the development cohort as the Bayesian prior, the opportunistically sampled cohort demonstrated good accuracy and low bias. CONCLUSIONS AND RELEVANCE:. Contemporary eGFR equations that use both creatinine and cystatin C improved meropenem population pharmacokinetic model performance compared with creatinine-only or cystatin C-only eGFR equations in adult critically ill patients.
- Published
- 2023
- Full Text
- View/download PDF
27. Clinical Development of c-MET Inhibition in Hepatocellular Carcinoma
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Joycelyn Lee, Jack Chan, and Su Pin Choo
- Subjects
Sorafenib ,Oncology ,medicine.medical_specialty ,C-Met ,Cabozantinib ,hepatocyte growth factor (HGF) ,lcsh:Medicine ,tivantinib ,Review ,c-Met inhibitor ,chemistry.chemical_compound ,hepatocellular carcinoma (HCC) ,cabozantinib ,Internal medicine ,medicine ,Tivantinib ,neoplasms ,c-MET ,business.industry ,lcsh:R ,medicine.disease ,digestive system diseases ,Clinical trial ,Drug development ,chemistry ,Hepatocellular carcinoma ,c-MET inhibitor ,business ,medicine.drug - Abstract
Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death. In patients with advanced or unresectable HCC, there are few treatment options. Conventional chemotherapy has limited benefits. Sorafenib, a multi-kinase inhibitor, improves survival, but options for patients intolerant of or progressing on sorafenib are limited. There has been much interest in recent years in molecular therapeutic targets and drug development for HCC. One of the more promising molecular targets in HCC is the cellular-mesenchymal-epithelial transition (c-MET) factor receptor. Encouraging phase II data on two c-MET inhibitors, tivantinib and cabozantinib, has led to phase III trials. This review describes the c-MET/hepatocyte growth factor (HGF) signalling pathway and its relevance to HCC, and discusses the preclinical and clinical trial data for inhibitors of this pathway in HCC.
- Published
- 2015
28. Formation of pre-silicide layers below Ni1−xPtxSi/Si interfaces
- Author
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Christopher L. Hinkle, K. van Benthem, James Walter Blatchford, Eric M. Vogel, Timothy J. Pennycook, Weidong Luo, J. B. Shaw, Amitabh Jain, Andrew M. Thron, Deborah J. Riley, and Jack Chan
- Subjects
Materials science ,Polymers and Plastics ,Physics ,Diffusion ,Schottky barrier ,Metals and Alloys ,Substrate (electronics) ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Crystallography ,chemistry ,Chemical physics ,Metastability ,Silicide ,Scanning transmission electron microscopy ,Ceramics and Composites ,Engineering sciences. Technology ,Layer (electronics) ,Stoichiometry - Abstract
The formation of a pre-silicide layer below Ni1-xPtxSi films is reported with structure and composition distinctly different from previously observed diffusion layers. It was found that during two-step rapid thermal annealing Ni interstitial diffusion can kinetically dominate over the formation of Ni silicide, which results in a metastable pre-silicide layer. Aberration corrected scanning transmission electron microscopy experiments have revealed Ni to occupy interstitial and substitutional sites in the pre-silicide layer. Rapid thermal annealing and Pt alloying determines the stoichiometry and thickness of the layer, while the point defect configurations give rise to lowering of the associated Schottky barrier heights. The pre-silicide layer effectively limits diffusion of Ni into the substrate and therefore allows for the low-temperature growth of Ni2Si and NiSi. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
- Published
- 2013
29. Large Area Mapping of Graphene Grain Structure and Orientation
- Author
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Moon J. Kim, Ning Lu, Herman C. Floresca, J Wang, Robert M. Wallace, Jack Chan, Luigi Colombo, David Hinojos, and Jiyoung Kim
- Subjects
Materials science ,Condensed matter physics ,Graphene ,law ,Orientation (graph theory) ,Grain structure ,law.invention - Abstract
Chemical vapor deposited (CVD) graphene grows as a polycrystalline sheet with grains that are oriented in many directions. There is a push to increase the size of these grains until a large single-crystal graphene sheet can be achieved. With the increase in grain size comes the need to be able to determine the lattice orientation of larger areas. Here we present a method using a simple well-known transmission electron microscopy (TEM) technique that allows us to map the orientation of a 50µm by 50µm area of graphene. This method created the largest graphene orientation map to date and has the ability to scale with the increasing grain sizes. From the map, statistics and interpretations were drawn, giving details about the graphene grown through the CVD recipe.
- Published
- 2012
30. Reducing Extrinsic Performance-Limiting Factors in Graphene Grown by Chemical Vapor Deposition
- Author
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Luigi Colombo, Eric M. Vogel, David Hinojos, Archana Venugopal, Jack Chan, Rodney S. Ruoff, Carl W. Magnuson, Robert M. Wallace, Adam Pirkle, and Stephen McDonnell
- Subjects
Fabrication ,Materials science ,Graphene ,business.industry ,General Engineering ,General Physics and Astronomy ,Nanotechnology ,Substrate (electronics) ,Chemical vapor deposition ,Conductivity ,law.invention ,Resist ,law ,Impurity ,Optoelectronics ,General Materials Science ,business ,Graphene nanoribbons - Abstract
Field-effect transistors fabricated on graphene grown by chemical vapor deposition (CVD) often exhibit large hysteresis accompanied by low mobility, high positive backgate voltage corresponding to the minimum conductivity point (V(min)), and high intrinsic carrier concentration (n(0)). In this report, we show that the mobility reported to date for CVD graphene devices on SiO(2) is limited by trapped water between the graphene and SiO(2) substrate, impurities introduced during the transfer process and adsorbates acquired from the ambient. We systematically study the origin of the scattering impurities and report on a process which achieves the highest mobility (μ) reported to date on large-area devices for CVD graphene on SiO(2): maximum mobility (μ(max)) of 7800 cm(2)/(V·s) measured at room temperature and 12,700 cm(2)/(V·s) at 77 K. These mobility values are close to those reported for exfoliated graphene on SiO(2) and can be obtained through the careful control of device fabrication steps including minimizing resist residue and non-aqueous transfer combined with annealing. It is also observed that CVD graphene is prone to adsorption of atmospheric species, and annealing at elevated temperature in vacuum helps remove these species.
- Published
- 2012
31. Abstract B22: Inducing cell state transitions in triple-negative breast cancer (TNBC)
- Author
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Ju Yuan, Elina Pathak, Siming Ma, Roger Foo, Yirong Sim, Preetha Madhukumar, Elaine Lim, Wai Leong Tam, Markus R. Wenk, Jack Chan, Kong Wee Ong, Chow Yin Wong, Benita Tan, Wilson Lek Wen Tan, Giridharan Periyasamy, Liping Toh, Veronique Kiak Mien Tan, Federico Torta, Ser Yue Loo, Yoon Sim Yap, Tira Jing Ying Tan, and Wei Sean Yong
- Subjects
Cancer Research ,business.industry ,Cell ,Estrogen receptor ,Cancer ,medicine.disease ,medicine.anatomical_structure ,Breast cancer ,Oncology ,Cancer stem cell ,Cancer cell ,Progesterone receptor ,medicine ,Cancer research ,business ,Molecular Biology ,Triple-negative breast cancer - Abstract
Triple-negative breast cancer (TNBC), as immunohistochemically defined by its estrogen receptor (ER)-negative, progesterone receptor (PR)-negative and human epidermal growth factor receptor-2 (HER2)-negative status, is an important subtype due to its biologically aggressive behavior and limited treatment options available. TNBC is associated with an overall poorer prognosis, with higher risk of disease recurrence/progression and shorter duration of treatment response, i.e., treatment resistance. Treatment resistance may be largely attributed to cancer stem cells (CSCs), which are intrinsically treatment resistant and continually self-renew, proliferate, and differentiate into different phenotypes. Activation of the cell biologic program, epithelial-mesenchymal transition (EMT), has been demonstrated to promote the dedifferentiation of heterogeneous subpopulations of cancer cells towards CSC phenotypes. We hypothesized that induction of the mesenchymal-epithelial transition (MET) program might disrupt CSC function, drive differentiation, and render greater susceptibility to conventional chemotherapy. In this study, we utilized high-throughput chemical-genetic screens to uncover a potent class of MET mediators. With the use of in vitro and in vivo models of TNBC, we showed that changing the malignant cell state to a differentiated phenotype by inducing MET reduced mammosphere formation, increased chemosensitivity, and decreased the tumor burden in NSG mice. Delving into the mechanisms of tumor differentiation via ChIP-seq, RNA-seq, and Gene Ontology analysis revealed differences in metabolic status between cell states, which might be exploited in the treatment of TNBC. We also assessed combinations of MET mediators, in order to increase the potency and durability of differentiation. Hence, this study assessed the role of differentiation in the treatment of TNBC and the efficacy of various MET mediators, singly and in combination, in inducing differentiation. Citation Format: Ser Yue Loo, Liping Toh, Elina Pathak, Wilson Tan, Siming Ma, Ju Yuan, Giridharan Periyasamy, Federico Torta, Jack Chan, Tira Tan, Yi Rong Sim, Veronique Tan, Benita Tan, Preetha Madhukumar, Wei Sean Yong, Kong Wee Ong, Chow Yin Wong, Markus R. Wenk, Roger Foo, Yoon-Sim Yap, Elaine Lim, Wai Leong Tam. Inducing cell state transitions in triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the AACR Special Conference: Advances in Breast Cancer Research; 2017 Oct 7-10; Hollywood, CA. Philadelphia (PA): AACR; Mol Cancer Res 2018;16(8_Suppl):Abstract nr B22.
- Published
- 2018
32. What is the role of immunotherapy in breast cancer?
- Author
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Jack Chan, Sulastri Kamis, Tira Jing Ying Tan, and Rebecca Alexandra Dent
- Subjects
business.industry ,medicine.medical_treatment ,Immune checkpoint inhibitors ,Cancer ,Breast Neoplasms ,General Medicine ,Immunotherapy ,medicine.disease ,Clinical trial ,03 medical and health sciences ,0302 clinical medicine ,Breast cancer ,Immune system ,Oncology ,030220 oncology & carcinogenesis ,Cancer research ,Humans ,Medicine ,Female ,Chimeric Antigen Receptor T-Cell Therapy ,business ,Human Epidermal Growth Factor Receptor 2 ,030215 immunology - Abstract
The immune system plays a complex role in the recognition/prevention, early eradication as well as progression of cancer. Recently, we have witnessed great momentum in the field of immuno-oncology. Checkpoint inhibitors and chimeric antigen receptor T cell therapy have now entered the clinic, with impressive and durable clinical responses seen across a broad array of tumor types. There are several lines of evidence supporting the development of an immune targeted approach in breast cancer. Emerging data of early clinical trials evaluating monotherapy checkpoint inhibition have shown modest activity in breast cancer, in particular high grade and aggressive subtypes such as triple negative, human epidermal growth factor receptor 2 (HER2)-positive and luminal B breast cancers. A considerable amount of effort is currently underway in exploring the use of combinatory strategies where therapies with distinct and potentially complementary mechanisms of actions may further enhance the immune response broadening out the group of breast cancer patients who would benefit from this strategy of cancer treatment. In this review, we discuss approaches to targeting the immune system in breast cancer adopted through understanding why the host immune system has failed in natural tumor suppression as well as the processes evolved by the tumor to circumvent an active immune system.
- Published
- 2018
33. Raman study of Fano interference in p-type doped silicon
- Author
-
Brian Burke, Jack Chan, Alexander A. Puretzky, David B. Geohegan, Zili Wu, and Keith A. Williams
- Subjects
Condensed Matter - Materials Science ,Materials science ,Silicon ,Phonon ,business.industry ,Doping ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,chemistry.chemical_element ,Semimetal ,symbols.namesake ,chemistry ,Condensed Matter::Superconductivity ,symbols ,Optoelectronics ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,business ,Electronic band structure ,Spectroscopy ,Penetration depth ,Raman spectroscopy ,Physics - Optics ,Optics (physics.optics) - Abstract
As the silicon industry continues to push the limits of device dimensions, tools such as Raman spectroscopy are ideal to analyze and characterize the doped silicon channels. The effect of inter-valence band transitions on the zone center optical phonon in heavily p-type doped silicon is studied by Raman spectroscopy for a wide range of excitation wavelengths extending from the red (632.8 nm) into the ultra-violet (325 nm). The asymmetry in the one-phonon Raman lineshape is attributed to a Fano interference involving the overlap of a continuum of electronic excitations with a discrete phonon state. We identify a transition above and below the one-dimensional critical point (E = 3.4 eV) in the electronic excitation spectrum of silicon. The relationship between the anisotropic silicon band structure and the penetration depth is discussed in the context of possible device applications., Comment: 6 pages, 7 figures, paper
- Published
- 2010
34. Network-Level Performance Measures for Low-Volume Highways in Alberta, Canada
- Author
-
Jack Chan, Lynne Cowe Falls, and Roy Jurgens
- Subjects
Low volume ,Transport engineering ,Program evaluation ,Geography ,Operations research ,Kilometer ,Cost effectiveness ,Mechanical Engineering ,Network level ,Agency cost ,Alberta canada ,Performance measurement ,Civil and Structural Engineering - Abstract
The province of Alberta is responsible for 30,740 km of highway, of which 4,320 km is gravel surfaced. Approximately 8,750 km (28.5%) carries traffic volumes of fewer than 400 vehicles per day. The objectives of this study are to outline network-level performance measures for highways in Alberta and to ensure that they are effective for managing low-volume highways. The performance measures used relate primarily to physical condition and functional adequacy. In 2002 these measures were studied as part of a joint project with the University of Calgary in an attempt to make them more budget sensitive. Criteria were determined and subsequently adopted by Alberta Infrastructure and Transportation. Subsequent to that, a study was undertaken to determine optimal levels for these measures. These optimal measures would be used to set desired future performance targets. The results showed that on the order of 5% of the highways should remain in poor condition and should not be part of the backlog to be corrected. It was at first thought that the majority of these highways would be low-volume roads, but this did not prove to be true, primarily because of the younger age of these roads. The study also examines the cost-effectiveness of projects to pave low-volume gravel roads in comparison with other projects in the program. Cost-effectiveness is defined as agency cost per user per kilometer over a 20-year life-cycle. In conclusion, a future direction is suggested for the department to follow with respect to its low-volume highway improvements.
- Published
- 2007
35. Examining the broader psychosocial effects of mass conflict on PTSD symptoms and functional impairment amongst West Papuan refugees resettled in Papua New Guinea (PNG)
- Author
-
Alvin Kuowei Tay, Moses Kareth, Derrick Silove, Susan Rees, and Jack Chan
- Subjects
Adult ,Male ,medicine.medical_specialty ,Health (social science) ,Functional impairment ,Cross-sectional study ,Refugee ,Models, Psychological ,Structural equation modeling ,Stress Disorders, Post-Traumatic ,Papua New Guinea ,History and Philosophy of Science ,medicine ,Humans ,Psychiatry ,Refugees ,War Exposure ,New guinea ,Middle Aged ,Displacement (psychology) ,Mental health ,Cross-Sectional Studies ,Mental Health ,Female ,Psychology ,Psychosocial - Abstract
Mass conflict and displacement erode the core psychosocial foundations of society, but there is a dearth of quantitative data examining the long-term mental health effects of these macrocosmic changes, particularly in relation to posttraumatic stress disorder (PTSD) symptoms. In 2013, we conducted a cross-sectional community study (n = 230) of West Papuan refugees residing in Port Moresby, Papua New Guinea, testing a moderated-mediation structural equation model of PTSD symptoms in which we examined relationships involving the psychosocial effects of mass conflict and displacement based on the Adaptation and Development after Persecution and Trauma (ADAPT) model, a trauma count (TC) of traumatic events (TEs) related to mass conflict, and a count index of current adversity (AC). A direct and an indirect path via AC led to PTSD symptoms. The ADAPT index exerted two effects on PTSD symptoms, an indirect effect via AC, and a moderating effect on TC. PTSD symptoms were directly associated with functional impairment. Although based on cross-sectional data, our findings provide support for a core prediction of the ADAPT model, that is, that undermining of the core psychosocial foundations of society brought about by mass conflict and displacement exerts an indirect and moderating influence on PTSD symptoms. The path model supports the importance of repairing the psychosocial pillars of society as a foundation for addressing trauma-related symptoms and promoting the functioning of refugees.
- Published
- 2015
36. A field study of the use of methoprene for West Nile virus mosquito control
- Author
-
Angelune Des Lauriers, James Li, Kevin Sze, Stacey L Baker, Jack Chan, and Greg Gris
- Subjects
Environmental Engineering ,West Nile virus ,Ecology ,fungi ,Methoprene ,Storm ,Biology ,medicine.disease_cause ,chemistry.chemical_compound ,Mosquito control ,chemistry ,medicine ,Environmental Chemistry ,Drainage ,General Environmental Science - Abstract
The occurrence of vector-borne West Nile virus in Canada has resulted in the use of larvicides for widespread urban mosquito control. To determine the fate of larvicides in storm drainage systems, three catch basins in Toronto, Ontario were treated with methoprene (Altosid) pellets three times over the summer of 2003, at the recommended mosquito control dose of 0.7 g per catch basin. Daily monitoring included: methoprene concentration analysis, precipitation in the area, the presence of mosquito larvae, and the chemical composition of catch basin sumps. A model catch basin in the laboratory was also dosed with methoprene pellets and sampled daily to observe concentration over time under quiescent conditions. It was found that (1) the methoprene concentration at the catch basins fell below the minimum lethal concentration after one or two weeks after treatment; (2) rainfall flushed methoprene from the catch basins to the storm sewer outfall at concentrations lower than the level that may cause ecosystem damage; and (3) the methoprene concentrations in the experiments exhibited a double peak decay pattern. Key words: methoprene, Altosid, West Nile virus, larvicide, catch basin, Toronto.
- Published
- 2006
37. Occurrence of Endocrine-Disrupting Chemicals in Sewage and Sludge Samples in Toronto, Canada
- Author
-
Jack Chan, Hing-Biu Lee, Thomas E. Peart, and Greg Gris
- Subjects
Bisphenol A ,Alkylphenol ,Bisphenol ,business.industry ,Supercritical fluid extraction ,Sewage ,Contamination ,Nonylphenol ,chemistry.chemical_compound ,Wastewater ,chemistry ,Environmental chemistry ,business ,Water Science and Technology - Abstract
In recent years, many anthropogenic chemicals occurring in the environment have been shown to mimic the action of endogenous hormones. These endocrine-disrupting chemicals (EDCs) can potentially lead to a host of adverse effects on wildlife, such as the feminization of fish, the lack of reproductive success of some species, birth defects, and the development of physical abnormality. In an attempt to establish the levels of contamination by EDCs in municipal sewage and sludge, we have collected samples in the Toronto area and analyzed them for alkylphenols, alkylphenol ethoxylates and carboxylates, 17ß-estradiol and its metabolites, testosterone, bisphenol A, as well as butyltin species. Previously developed methods using solvent extraction, solid-phase extraction, supercritical fluid extraction, GC/MS, and HPLC determination have been used for such samples. Levels of these chemicals varied from 500 µg/g for nonylphenol to
- Published
- 2004
38. Endocrine-Disrupting Chemicals in Industrial Wastewater Samples in Toronto, Ontario
- Author
-
Hing-Biu Lee, Thomas E. Peart, Jack Chan, and Greg Gris
- Subjects
Industrial wastewater treatment ,chemistry.chemical_compound ,chemistry ,Wastewater ,Chemical products ,Environmental chemistry ,Environmental science ,Water Science and Technology ,Nonylphenol - Abstract
The occurrence of endocrine-disrupting chemicals (EDCs) such as bisphenol A (BPA), 4-tert-octylphenol (OP), nonylphenol (NP) and its ethoxylates (NPEO) in wastewater generated in the Toronto area has been studied. In all, 97 samples from 40 facilities in ten different industry classes have been collected and analyzed. Widely divergent concentrations have been observed in these samples. They ranged from
- Published
- 2002
39. Concept for an ASRG hosted payload mission
- Author
-
Erich Schulze, Richard Quinn, Robert LeRoy, Jack Chan, and Dennis Connolly
- Subjects
Engineering ,business.industry ,Payload ,International Space Station ,General Purpose Heat Source ,Geosynchronous orbit ,Electric power ,Aerospace engineering ,business ,Advanced Stirling radioisotope generator ,Host (network) ,Space environment - Abstract
This paper describes a concept to demonstrate the operation of an advanced power supply (known as ASRG) in space for an extended period of time as a hosted payload. The demonstration unit will test the highest risk technologies associated with the Advanced Stirling Radioisotope Generator (ASRG) design while eliminating the complexities and cost associated with the already demonstrated General Purpose Heat Source (GPHS) by using electrical power from the host to drive heaters in place of the GPHS. The primary goal of this demonstration is to verify the system performance of these new technologies in the space environment for an extended period of time. A secondary goal is to operate through the launch environment. These goals could be accomplished aboard a host Geosynchronous Earth Orbiting (GEO) satellite or the International Space Station (ISS) as long as electrical power is available to the electric heat source. This paper also discusses the accommodation considerations for interfacing the demonstration unit on a host satellite. The overarching objective is to provide additional confidence in the suitability of the ASRG for use in deep space missions.
- Published
- 2014
40. Network Characterization and Perceptual Evaluation of Skype Mobile Videos
- Author
-
Amit Pande, Prasant Mohapatra, Shraboni Jana, and An Jack Chan
- Subjects
Voice over IP ,Computer science ,business.industry ,Quality of service ,Real-time computing ,Mobile computing ,Video processing ,Video quality ,Videotelephony ,Packet loss ,Video tracking ,Telephony ,business ,Computer network - Abstract
We characterize the performance of both video and network layer properties of Skype, the most popular video telephony application. The performance in both mobile and stationary scenarios is investigated; considering network characteristics such as packet loss, propagation delay, available bandwidth and their effects on the perceptual video quality, measured using spatial and temporal no-reference video metrics. Based on 200+ live traces, we study the performance of this mobile video telephony application. We model video quality as a function of input network parameters and derive a feed-forward Artificial-Neural-Network that accurately predicts video quality given network conditions (0.0206 ≤ MSE ≤ 0.570). The accuracy of this model improves significantly by incorporating end-user mobility as an input to the model.
- Published
- 2013
41. Reduced NiPtSi Schottky barriers by controlling interface composition and new materials incorporation
- Author
-
R. A. Chapman, Kwan-Yong Lim, Amitabh Jain, Christopher L. Hinkle, J. B. Shaw, Javier Mendez, Deborah J. Riley, Eric M. Vogel, Jack Chan, James Walter Blatchford, and Seung-Chul Song
- Subjects
Materials science ,Equivalent series resistance ,CMOS ,Annealing (metallurgy) ,business.industry ,Contact resistance ,Metallurgy ,Optoelectronics ,Schottky diode ,New materials ,Thermal stability ,Work function ,business - Abstract
Contact resistance (R c ) contributes over 65% of the total source to drain series resistance in < 32 nm CMOS technologies. In this work, reduction of R c is achieved by lowering the SBH through the incorporation of new materials into NiPtSi. The impact of implanted elemental species as well as alloyed low work function metals is discussed. As diffusion and subsequent interface composition is highly dependent on the incorporated material, these NiPtSi junctions with complex composition are often inhomogeneous, making SBH extraction a less trivial task. Advanced analysis for extracting the true SBH of these junctions will also be presented.
- Published
- 2012
42. The effect of field effect device channel dimensions on the effective mobility of graphene
- Author
-
Luigi Colombo, Eric M. Vogel, Archana Venugopal, Jack Chan, and Wiley P. Kirk
- Subjects
Electron mobility ,Materials science ,Phonon scattering ,Condensed matter physics ,Graphene ,law ,Scanning electron microscope ,Scattering ,Analytical chemistry ,Field effect ,Conductivity ,Well-defined ,law.invention - Abstract
Graphene is a possible candidate for post CMOS applications and mobility is a material characteristic that has been utilized to gauge the quality of the material[1]. Mobility of exfoliated graphene transferred on SiO 2 has been reported to range from 2,000 to 25,000 cm2/V·s [1, 2]. The large variation is typically attributed to factors such as scattering by defects in the underlying substrate, residue from processing, charged impurity scattering and phonon scattering [3]. In most previous studies one of the primary assumptions made is that the mobility is independent of channel dimensions. In this study, we performed room temperature effective mobility measurements as a function of channel dimensions. The mobility exhibits clear channel length (L ch ) and width (W ch ) dependence and varies from less than 1,000 cm2/V·s to 7,000 cm2/V·s. Theoretical analysis of the conductivity (σ) in graphene devices as a function of W ch performed by Vasko et al [4]. is in agreement with our experimental results. Mobility values for back gated devices with well defined channel dimensions in literature [5] are seen to be consistent with the trend that we report here.
- Published
- 2011
43. Vibrational spectrum of the endohedralY2C2@C92fullerene by Raman spectroscopy: Evidence for tunneling of the diatomicC2molecule
- Author
-
Keith A. Williams, Jack Chan, Brian Burke, David B. Geohegan, Timothy J. Fuhrer, Alexander A. Puretzky, Harry C. Dorn, and Wujun J. Fu
- Subjects
Physics ,Fullerene ,Vibrational spectrum ,Condensed Matter Physics ,Molecular physics ,Diatomic molecule ,Electronic, Optical and Magnetic Materials ,symbols.namesake ,Physics::Atomic and Molecular Clusters ,Endohedral fullerene ,symbols ,Molecule ,Density functional theory ,Raman spectroscopy ,Quantum tunnelling - Abstract
The structure and vibrational spectrum of the novel endohedral fullerene ${\mathrm{Y}}_{2}$C${}_{2}$@C${}_{92}$ was studied by Raman spectroscopy, with particular emphasis on the rotational transitions of the diatomic ${\mathrm{C}}_{2}$ unit in the low-energy Raman spectrum. We report evidence for tunneling of this unit through the ${\mathrm{C}}_{2}$ rotation plane and observe anomalous narrowing in a hindered rotational mode. We also report complementary density functional theory calculations that support our conclusions and discuss potential applications to quantum computing and nonvolatile memory devices.
- Published
- 2011
44. Investigation ofGd3N@C2n (40≤n≤44)family by Raman and inelastic electron tunneling spectroscopy
- Author
-
Brian Burke, James G. Kushmerick, Jiechao C. Ge, Alexander A. Puretzky, Jack Chan, Chunying Shu, Harry C. Dorn, Wujun J. Fu, Keith A. Williams, and David B. Geohegan
- Subjects
Physics ,Icosahedral symmetry ,Inelastic electron tunneling spectroscopy ,Force field (physics) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Spectral line ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,symbols.namesake ,Crystallography ,Molecular vibration ,symbols ,Kondo effect ,Ideal (ring theory) ,Atomic physics ,0210 nano-technology ,Raman spectroscopy - Abstract
The structure and vibrational spectrum of ${\text{Gd}}_{3}{\text{N@C}}_{80}$ is studied through Raman and inelastic electron tunneling spectroscopy as well as density-functional theory and universal force field calculations. Hindered rotations, shown by both theory and experiment, indicate the formation of a ${\text{Gd}}_{3}\text{N-}{\text{C}}_{80}$ bond which reduces the ideal icosahedral symmetry of the ${\text{C}}_{80}$ cage. The vibrational modes involving the movement of the encapsulated species are a fingerprint of the interaction between the fullerene cage and the core complex. We present Raman data for the ${\text{Gd}}_{3}{\text{N@C}}_{2n}\text{ }(40\ensuremath{\le}n\ensuremath{\le}44)$ family as well as ${\text{Y}}_{3}{\text{N@C}}_{80}$, ${\text{Lu}}_{3}{\text{N@C}}_{80}$, and ${\text{Y}}_{3}{\text{N@C}}_{88}$ for comparison. Conductance measurements have been performed on ${\text{Gd}}_{3}{\text{N@C}}_{80}$ and reveal a Kondo effect similar to that observed in ${\text{C}}_{60}$.
- Published
- 2010
45. Reversal of current blockade in nanotube-based field effect transistors through multiple trap correlations
- Author
-
Brian Burke, Joe C. Campbell, Avik W. Ghosh, Jack Chan, Kenneth Evans, Keith A. Williams, Mingguo Liu, and Smitha Vasudevan
- Subjects
Trap (computing) ,Carbon nanotube quantum dot ,Nanotube ,Materials science ,Condensed matter physics ,Field-effect transistor ,Current (fluid) ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Carbon nanotube field-effect transistor - Published
- 2009
46. Electron Beam Induced Two-State Noise in Carbon Nanotubes
- Author
-
Joe C. Campbell, Brian Burke, Jack Chan, Keith A. Williams, Lloyd R. Harriott, and Chong Hu
- Subjects
Optical properties of carbon nanotubes ,Amplitude ,Materials science ,law ,Cathode ray ,Electron beam processing ,Biasing ,Carbon nanotube ,Electron beam-induced deposition ,Atomic physics ,Noise (electronics) ,law.invention - Abstract
Discrete current switching is induced in carbon nanotubes by electron beam irradiation. Switching amplitudes of 3% to 6% are observed at room temperature. Switching is created by electron beam exposure with dosage as low as 1000 pC/cm. Relative switching amplitude remains constant as the bias voltage varies, suggesting that current fluctuation is dominated by mobility fluctuation. Changes in the noise power spectral density following electron beam exposure will be discussed.
- Published
- 2009
47. Investigation of Gd2@C90, Gd2C2@C92, and Gd2@C79N by Raman Spectroscopy
- Author
-
Brian Burke, Harry C. Dorn, Chunying Shu, Keith A. Williams, Alexander A. Puretzky, Jack Chan, Jiechao Ge, David B. Geohegan, and Wujun Fu
- Subjects
symbols.namesake ,Materials science ,Force field (physics) ,Endohedral fullerene ,symbols ,Vibrational spectrum ,Raman spectroscopy ,Molecular physics ,Symmetry (physics) - Abstract
The structure and vibrational spectrum of Gd2 and Gd2C2 endofullerenes are studied through Raman spectroscopy and universal force field (UFF) calculations. Hindered rotations, shown by both theory and experiment, indicate the formation of a Gd–cage bond, which reduces the ideal symmetry of the cage. We have conducted Raman studies of Gd2@C90, Gd2@C79N, and Gd2C2@C92. We have also studied Y2C2@C92 for comparison. Several modes have been identified which provide information about the endohedral complex.
- Published
- 2009
48. Development of Advanced Stirling Radioisotope Generator for Planetary Surface and Deep Space Missions
- Author
-
Dennis Hill, Jack Chan, Lockheed Martin, Doug Leland, and Tim Hoye
- Subjects
Physics ,Deep space missions ,Development (topology) ,Planetary surface ,business.industry ,Multi-Mission Radioisotope Thermoelectric Generator ,Aerospace engineering ,business ,Nuclear power in space ,Advanced Stirling radioisotope generator - Published
- 2008
49. Development of Advanced Stirling Radioisotope Generator for Space Exploration
- Author
-
Jeffrey G. Schreiber, Jack Chan, and J. Gary Wood
- Subjects
Engineering ,Stirling engine ,business.industry ,General Purpose Heat Source ,Electrical engineering ,law.invention ,Thermoelectric generator ,law ,Stirling radioisotope generator ,Stirling cycle ,Multi-Mission Radioisotope Thermoelectric Generator ,Radioisotope thermoelectric generator ,Aerospace engineering ,business ,Advanced Stirling radioisotope generator - Abstract
Under the joint sponsorship of the Department of Energy and NASA, a radioisotope power system utilizing Stirling power conversion technology is being developed for potential future space missions. The higher conversion efficiency of the Stirling cycle compared with that of Radioisotope Thermoelectric Generators (RTGs) used in previous missions (Viking, Pioneer, Voyager, Galileo, Ulysses, Cassini, and New Horizons) offers the advantage of a four-fold reduction in PuO2 fuel, thereby saving cost and reducing radiation exposure to support personnel. With the advancement of state-of-the-art Stirling technology development under the NASA Research Announcement (NRA) project, the Stirling Radioisotope Generator program has evolved to incorporate the advanced Stirling convertor (ASC), provided by Sunpower, into an engineering unit. Due to the reduced envelope and lighter mass of the ASC compared to the previous Stirling convertor, the specific power of the flight generator is projected to increase from 3.5 to 7 We/kg, along with a 25 percent reduction in generator length. Modifications are being made to the ASC design to incorporate features for thermal, mechanical, and electrical integration with the engineering unit. These include the heat collector for hot end interface, cold-side flange for waste heat removal and structural attachment, and piston position sensor for ASC control and power factor correction. A single-fault tolerant, active power factor correction controller is used to synchronize the Stirling convertors, condition the electrical power from AC to DC, and to control the ASCs to maintain operation within temperature and piston stroke limits. Development activities at Sunpower and NASA Glenn Research Center (GRC) are also being conducted on the ASC to demonstrate the capability for long life, high reliability, and flight qualification needed for use in future missions.
- Published
- 2007
50. A Model Linking Store Attributes, Service Quality and Customer Experience: A Study Among Community Pharmacies.
- Author
-
SUZ JACK CHAN and CHENG LING TAN
- Subjects
DRUGSTORES ,QUALITY of service ,CUSTOMER satisfaction ,CONSUMER behavior ,EMOTIONS ,PUBLIC health - Abstract
Community pharmacies are one of the few healthcare premises in Malaysia that provide service and products concurrently. It is of essential importance to research into the factors that could enhance customer experience during their shopping trip. Based on this premise, a model linking service quality and store attributes and customer experience is tested. Data were collected from a survey of 194 customers from community pharmacies in Malaysia. Analysis using partial least square method revealed security and reliability and store attributes have direct effects on the specific dimensions of customer emotional experiences. This implies store attributes and reliability of community pharmacies are a significant predictor of customer emotional experience among community pharmacies customers. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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