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Sex differences impact ergonomic endoscopic training for gastroenterology fellows. Gastrointest Endosc 2024; 99:146-154.e1. [PMID: 37793505 DOI: 10.1016/j.gie.2023.09.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 09/14/2023] [Accepted: 09/26/2023] [Indexed: 10/06/2023]
Abstract
BACKGROUND AND AIMS Endoscopic-related injuries (ERIs) for gastroenterologists are common and can impact longevity of an endoscopic career. This study examines sex differences in the prevalence of ERIs and ergonomic training during gastroenterology fellowship. METHODS A 56-item anonymous survey was sent to 709 general and advanced endoscopy gastroenterology fellows at 73 U.S. training programs between May and June 2022. Demographic information was collected along with questions related to endoscopic environment, ergonomic instruction, technique, equipment availability, and ergonomic knowledge. Responses of female and male gastroenterology fellows were compared using χ2 and Fisher exact tests. RESULTS Of the 236 respondents (response rate, 33.9%), 113 (44.5%) were women and 123 (52.1%) were men. Female fellows reported on average smaller hand sizes and shorter heights. More female fellows reported endoscopic equipment was not ergonomically optimized for their use. Additionally, more female fellows voiced preference for same-gender teachers and access to dial extenders and well-fitting lead aprons. High rates of postendoscopy pain were reported by both sexes, with significantly more women experiencing neck and shoulder pain. Trainees of both sexes demonstrated poor ergonomic awareness with an average score of 68% on a 5-point knowledge-based assessment. CONCLUSIONS Physical differences exist between male and female trainees, and current endoscopic equipment may not be optimized for smaller hand sizes. This study highlights the urgent need for formal ergonomic training for trainees and trainers with consideration of stature and hand size to enhance safety, comfort, and equity in the training and practice of endoscopy.
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Adverse Events of Endoscopic Clip Placement: A MAUDE Database Analysis. J Clin Gastroenterol 2024; 58:76-79. [PMID: 36728443 DOI: 10.1097/mcg.0000000000001822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 11/22/2022] [Indexed: 02/03/2023]
Abstract
BACKGROUND Clips are endoscopic mechanical devices with tensile and closure strength that can approximate tissue and provide hemostasis through a tamponade effect. Clips are ubiquitously used in endoscopic practice, and numerous studies have validated the clinical efficacy of clips, with recent guidelines recommending them as a first-line intervention for recurrent and persistent nonvariceal gastrointestinal bleeding. However, the safety profile for these devices has yet to be delineated, thus, we aim to investigate this feature by examining the adverse events reported to the Food and Drug Administration. METHODS Postmarketing surveillance data from the Food and Drug Administration Manufacturer And User Facility Device Experience database were analyzed from January 2012 to January 2021. The Manufacturer And User Facility Device Experience database is a reporting software and does not independently verify the details of complications. RESULTS Two thousand five hundred forty reports were issued, of which 287 were patient adverse events and 2766 were device problems. Activation, separation, and positioning issues were most common. No consequences or clinically significant impact on patients were seen in 1968 reports. Foreign bodies were seen in 97 cases, hemorrhage in 57 cases, tissue damage in 42 cases, embedded clips in tissues/plaques in 16 cases, perforation in 15 cases, lacerations in 6 cases, and infection in 3 cases. CONCLUSIONS While the most commonly reported device problems involved activation, separation, and positioning, most patients were clinically unaffected. Moreover, perforation and infection were exceedingly rare, further highlighting the safety profile of endoscopic clips.
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Involvement in National Gastroenterological Societies for Professional Development and Career Advancement: Tips for Trainees. Dig Dis Sci 2023; 68:4073-4080. [PMID: 37713036 DOI: 10.1007/s10620-023-08103-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 08/28/2023] [Indexed: 09/16/2023]
Abstract
Engaging with national gastroenterological (GI) societies offers a plethora of pathways for professional development at every career stage. While each society has a mission with distinct aims, which provides a different spectrum of opportunities, almost all societies share several common goals. Involvement in national GI organizations can not only help in professional advancement but can be a rewarding and meaningful way to contribute to our field. There are several benefits of engagement with national GI organizations and trainees should see what aligns with their goals to make the best of the opportunities offered by these organizations. These include education, scholarship, and research opportunities, establishing mentorship, developing leadership skills, and involvement in advocacy among many others. In this article, we aim to provide a trainee and early career gastroenterologist's perspective of various benefits of involvement in national GI societies and how it can help in professional development and career advancement.Please verify if the provided city name in Affiliation 2 is correct and amend if necessary.The city is correctPlease confirm the corresponding author is correctly identified and amend if necessary.Information for the corresponding author is correct.
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Public health infection prevention: An analysis of existing training during the COVID-19 pandemic. Public Health 2023; 222:7-12. [PMID: 37494870 DOI: 10.1016/j.puhe.2023.06.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 06/12/2023] [Accepted: 06/19/2023] [Indexed: 07/28/2023]
Abstract
OBJECTIVES In response to the COVID-19 pandemic, agencies and organizations required trainings to support the needs of the public health workforce. To better understand the training resources available, this study identified, organized, and classified infection prevention and control (IPC) training and educational opportunities. STUDY DESIGN Environmental scan. METHODS A total of 306 IPC training resources were compiled between January and April 2021. Key themes and topics were identified and compared to the Healthcare Infection Control Practices Advisory Committee's (HICPAC) core IPC practices. RESULTS Three hundred and six training resources, including webinars, fact sheets, module-based learning activities, infographics, and professional practice guidance materials, were identified. Common themes included proper use of personal protective equipment (e.g., masks, gloves), community reopening guidance, and mass vaccination resources. A large proportion (74.9%) of trainings were under 60 min. Using the HICPAC framework, the most frequently addressed content included standard precautions (40%), leadership support (31.6%), and transmission-based precautions (25.8%). Few trainings addressed performance monitoring and feedback (17.1%). CONCLUSIONS A wide range of organizations developed IPC-specific content during the pandemic. However, these resources did not address the breadth of knowledge required to implement IPC concepts effectively. The creation of universally applicable IPC core competencies and the development of high-quality IPC education and trainings for public health and the overall responder workforces should be prioritized. Accessible high-quality online and just-in-time trainings are critical for future pandemic and disaster preparedness.
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Beam power scale-up in micro-electromechanical systems based multi-beam ion accelerators. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:103301. [PMID: 34717413 DOI: 10.1063/5.0058175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/12/2021] [Indexed: 06/13/2023]
Abstract
We report on the development of multi-beam radio frequency (RF) linear ion accelerators that are formed from stacks of low cost wafers and describe the status of beam power scale-up using an array of 112 beams. The total argon ion current extracted from the 112-beamlet extraction column was 0.5 mA. The measured energy gain in each RF gap reached as high as 7.25 keV. We present a path toward using this technology to achieve ion currents >1 mA and ion energies >100 keV for applications in material processing.
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Management and Treatment of Hepatocellular Carcinoma with Immunotherapy: A Review of Current and Future Options. J Clin Transl Hepatol 2020; 8:168-176. [PMID: 32832397 PMCID: PMC7438354 DOI: 10.14218/jcth.2020.00001] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 05/13/2020] [Accepted: 05/16/2020] [Indexed: 02/06/2023] Open
Abstract
With mortality rates of liver cancer doubling in the last 20 years, this disease is on the rise and has become the fifth most common cancer in men and the seventh most common cancer in women. Hepatocellular carcinoma (HCC) represents approximately 90% of all primary liver cancers and is a major global health concern. Patients with HCC can be managed curatively with surgical resection or with liver transplantation, if they are diagnosed at an early stage. Unfortunately, most patients with HCC present with advanced stages of the disease and have underlying liver dysfunction, which allows only 15% of patients to be eligible for curative treatment. Several different treatment modalities are available, including locoregional therapy radiofrequency ablation, microwave ablation, percutaneous ethanol injection, trans-arterial chemoembolization, transarterial radio-embolization, cryoablation, radiation therapy, stereotactic radiotherapy, systemic chemotherapy, molecularly targeted therapies, and immunotherapy. Immunotherapy has recently become a promising method for inhibiting HCC tumor progression, recurrence, and metastasis. The term "Immunotherapy" is a catch-all, encompassing a wide range of applications and targets, including HCC vaccines, adoptive cell therapy, immune checkpoint inhibitors, and use of oncolytic viruses to treat HCC. Immunotherapy in HCC is a relatively safe option for treating patients with advanced disease in the USA who are either unable to receive or failed sorafenib/lenvatinib therapy and thus may offer an additional survival benefit for these patients. The purpose of this review is to elaborate on some of the most recent advancements in immunotherapy.
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The weekend effect does not influence management of inflammatory bowel disease. JGH Open 2020; 4:44-48. [PMID: 32055696 PMCID: PMC7008161 DOI: 10.1002/jgh3.12205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 03/11/2019] [Accepted: 05/04/2019] [Indexed: 11/12/2022]
Abstract
Background The weekend effect describes worsened outcomes due to perceived inefficiency occurring over the weekend. This effect has not been studied in inflammatory bowel disease (IBD) despite increasing prevalence in the community. Therefore, our aim is to assess differences in the outcomes of weekend versus weekday management of IBD exacerbations. Methods The National Inpatient Sample database comprises approximately 20% of admissions to nonfederal hospitals in the United States. Complications requiring hospitalization (“flares”) were the criteria upon which patient selection was based. A total of 193, 848 flares were identified from 2008 to 2014 using the International Classification of Diseases 9th edition codes. Differences in time to first procedure, length of stay (LOS), and cost were evaluated for patients with flares between weekend and weekday admissions. Results The time to first procedure was 3.33 days on weekends versus 3.19 days on weekdays (P < 0.001). The mean LOS was shorter when admissions occurred on weekends versus weekdays (8.01 days vs 8.22 days, P < 0.001). Finally, the cost of hospitalization was higher for weekday admissions versus weekend admissions ($18 072 vs $17 495, P < 0.001). Conclusion Our results showed a similar LOS and cost associated with the management of exacerbations on the weekend compared to weekdays. While many high‐risk conditions exhibit increased mortality and prolonged hospital course over the weekend, this phenomenon does not appear to affect IBD. These findings indicate efficient patient care on the weekend and can be utilized for logistical purposes such as resource allocation and procedure scheduling in the endoscopy suite.
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A comparison of diverticulitis in Crohn's disease versusulcerative colitis. JGH Open 2019; 3:508-512. [PMID: 31832551 PMCID: PMC6891016 DOI: 10.1002/jgh3.12192] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/10/2019] [Accepted: 04/17/2019] [Indexed: 11/15/2022]
Abstract
Background and Aim Inflammatory bowel disease (IBD) and diverticulitis both increase morbidity, especially when associated with in‐patient hospitalization. This study aimed to evaluate whether hospitalization burden differs for diverticulitis in patients with a history of Crohn's disease (CD) compared to ulcerative colitis (UC). Method All patients hospitalized for acute diverticulitis with pre‐existing UC or CD in 2014 were selected using the national in‐patient sample. Cases were identified using the International Classification of Diseases, Ninth Edition codes. Primary outcomes were mortality, cost of admission, length of stay (LOS), and colectomy. Results A total of 1815 patients were admitted with diverticulitis, and those with CD had a hospitalization associated with decreased cost (aOR −14 537, 95% CI −27 316 to −1758; P = 0.026) and LOS (aOR −1.31, 95% CI −2.41 to −0.208; P = 0.02) compared to UC. A second analysis comparing diverticulitis hospitalization between those with CD and those with the absence of IBD showed no significant difference in mortality (aOR 2.47, 95% CI 0.59 to 10.36; P = 0.22), LOS (aOR 0.03, 95% CI −0.47 to 0.54; P = 0.92), or cost of admission (aOR −2196, 95% CI −6933 to 2539; P = 0.36) between the cohorts. Conclusion Patients with UC have worsened hospitalization outcomes when being treated for diverticulitis compared to CD. While the findings may be a result of a difference in colectomy rates, the etiology may also be multifactorial. These conclusions have not been previously described, and further investigations would better characterize these associations.
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Association of Autoimmune Hepatitis and Cardiovascular Disease. Dig Liver Dis 2019; 51:1604-1609. [PMID: 31171486 DOI: 10.1016/j.dld.2019.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 05/01/2019] [Accepted: 05/03/2019] [Indexed: 02/09/2023]
Abstract
BACKGROUND Autoimmune Hepatitis is a chronic liver disease while Cardiovascular Disease is seen in inflammatory states. This study sought to determine if Cardiovascular Disease was associated with Autoimmune Hepatitis. METHODS The National Inpatient Sample selected patients with a primary diagnosis of Autoimmune Hepatitis and secondary diagnosis of Cardiovascular Disease in 2014. The primary outcome was the association of Autoimmune Hepatitis with Cardiovascular Disease. Secondary outcomes evaluated the hospital burden with Cardiovascular Disease. RESULTS 16,375 patients with Autoimmune Hepatitis were included in the study. There was a decreased association between Autoimmune Hepatitis and Cardiovascular Disease (aOR 0.77, 95% CI 0.69-0.85, p < 0.00), Coronary Artery Disease, (aOR 0.75, 95% CI 0.67-0.85, p < 0.00), and Peripheral Vascular Disease (aOR 0.75, 95% CI 0.60-0.93, p = 0.01). Moreover, Coronary Artery Disease comprises 84% of the overall Cardiovascular Disease cohort and did not demonstrate significantly increased length of stay (aOR -0.53, 95% CI -1.16 to 0.12, p = 0.11) or hospitalization cost (aOR -6711, 95% CI -14336 to 912, p = 0.08). DISCUSSION The decreased association between Autoimmune Hepatitis and Cardiovascular Disease is likely multifactorial in etiology. Consequently, this observation requires further examination with prospective trials.
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Absolute calibration of GafChromic film for very high flux laser driven ion beams. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:053301. [PMID: 31153260 DOI: 10.1063/1.5086822] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 04/13/2019] [Indexed: 06/09/2023]
Abstract
We report on the calibration of GafChromic HD-v2 radiochromic film in the extremely high dose regime up to 100 kGy together with very high dose rates up to 7 × 1011 Gy/s. The absolute calibration was done with nanosecond ion bunches at the Neutralized Drift Compression Experiment II particle accelerator at Lawrence Berkeley National Laboratory (LBNL) and covers a broad dose dynamic range over three orders of magnitude. We then applied the resulting calibration curve to calibrate a laser driven ion experiment performed on the BELLA petawatt laser facility at LBNL. Here, we reconstructed the spatial and energy resolved distributions of the laser-accelerated proton beams. The resulting proton distribution is in fair agreement with the spectrum that was measured with a Thomson spectrometer in combination with a microchannel plate detector.
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Hospitalization Burden of Biliary Strictures and Cholangitis After Pancreaticoduodenectomy. J Surg Res 2019; 241:95-102. [PMID: 31018171 DOI: 10.1016/j.jss.2019.03.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 02/25/2019] [Accepted: 03/22/2019] [Indexed: 01/04/2023]
Abstract
BACKGROUND Postsurgical biliary disease in Roux-en-y and cholecystectomies has been investigated, but less literature exists regarding biliary complications after Whipple procedure (pancreaticoduodenectomy [PD]). Moreover, the hospital burden incurred after this complication has not been previously examined. The aim of this study is to assess the trends in hospitalization for biliary strictures and cholangitis after PD. MATERIALS AND METHODS The National Inpatient Sample identified all cases with a PD and a primary diagnosis of biliary complication in 2014. Cases were identified using the International Classification of Diseases, Clinical Modification codes. Primary outcomes were association of biliary complications with mortality, cost of admission, and length of stay. RESULTS A total of 10,145 patients in 2014 were documented with a previous PD. Mortality was 50-fold greater without biliary complications (2.7% versus 0.05%), but a 95% increased length of stay (25.8 d versus 13.2 d, P = 0.014) and 70% increased cost of admission ($293,894 versus $165,862, P = 0.092) occurred with biliary complications. Regression analysis revealed increased length of stay in all cohorts (adjusted odds ratio: 14.3, P = 0.007) and increased cost of admission with cholangitis (adjusted odds: 458283, P = 0.00). Finally, there was increased biliary strictures, cost of hospitalization, and length of stay from 2011 to 2014. CONCLUSIONS Biliary disease due to the PD appears to longitudinally increase length of stay and cost of hospitalization. Compared with gastrointestinal bleed and delayed gastric emptying, biliary strictures and cholangitis are still very high acuity, requiring more extensive medical resources. Minimally invasive surgeries and robotics could play a vital role in minimizing biliary complications and the ensuing hospitalization burden.
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Design and implementation of a Thomson parabola for fluence dependent energy-loss measurements at the Neutralized Drift Compression eXperiment. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:103302. [PMID: 30399880 DOI: 10.1063/1.5030541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 09/29/2018] [Indexed: 06/08/2023]
Abstract
The interaction of ion beams with matter includes the investigation of the basic principles of ion stopping in heated materials. An unsolved question is the effect of different, especially higher, ion beam fluences on ion stopping in solid targets. This is relevant in applications such as in fusion sciences. To address this question, a Thomson parabola was built for the Neutralized Drift Compression eXperiment (NDCX-II) for ion energy-loss measurements at different ion beam fluences. The linear induction accelerator NDCX-II delivers 2 ns short, intense ion pulses, up to several tens of nC/pulse, or 1010-1011 ions, with a peak kinetic energy of ∼1.1 MeV and a minimal spot size of 2 mm FWHM. For this particular accelerator, the energy determination with conventional beam diagnostics, for example, time of flight measurements, is imprecise due to the non-trivial longitudinal phase space of the beam. In contrast, a Thomson parabola is well suited to reliably determine the beam energy distribution. The Thomson parabola differentiates charged particles by energy and charge-to-mass ratio, through deflection of charged particles by electric and magnetic fields. During first proof-of-principle experiments, we achieved to reproduce the average initial helium beam energy as predicted by computer simulations with a deviation of only 1.4%. Successful energy-loss measurements with 1 μm thick silicon nitride foils show the suitability of the accelerator for such experiments. The initial ion energy was determined during a primary measurement without a target, while a second measurement, incorporating the target, was used to determine the transmitted energy. The energy-loss was then determined as the difference between the two energies.
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The Association of leptin with severity of non-alcoholic fatty liver disease: A population-based study. Clin Mol Hepatol 2018; 24:392-401. [PMID: 30068065 PMCID: PMC6313023 DOI: 10.3350/cmh.2018.0011] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 06/10/2018] [Indexed: 02/06/2023] Open
Abstract
Background/Aims Leptin is associated with metabolic disorders, which predispose one to non-alcoholic fatty liver disease (NAFLD). The role of leptin in NAFLD pathogenesis is not fully understood. We aim to investigate the association between serum leptin level and severity of NAFLD using U.S. nationally representative data. Methods Data were obtained from the United States Third National Health and Nutrition Examination Survey. NAFLD was defined by ultrasound detection and severity of hepatic steatosis in the absence of other liver diseases. The severity of hepatic fibrosis was determined by NAFLD fibrosis score (NFS). We used multivariate survey-weighted generalized logistic regression to evaluate the association between leptin level and the degree of NAFLD. We also performed subgroup analyses by body mass index (lean vs. classic NAFLD). Results Among 4,571 people, 1,610 (35%) had NAFLD. By ultrasound findings, there were 621 people with mild, 664 with moderate, and 325 with severe steatosis. There were 885 people with low NFS (<-1.455, no significant fibrosis), 596 with intermediate NFS, and 129 with high NFS (>0.676, advanced fibrosis). Leptin levels for normal, mild, moderate and severe steatosis were 10.7±0.3 ng/mL, 12.1±0.7 ng/mL, 15.6±0.8 ng/mL, 16±1.0 ng/mL, respectively (trend P-value<0.001). Leptin levels for low, intermediate, and high NFS were 11.8±0.5 ng/mL, 15.6±0.8 ng/mL, 28.5±3.5ng/mL, respectively (trend P-value<0.001). This association remained significant even after adjusting for known demographic and metabolic risk factors. In the subgroup analysis, this association was only prominent in classic NAFLD, but not in lean NAFLD. Conclusions Serum leptin level is associated with the severity of NAFLD, especially in classic NAFLD patients.
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Source-to-accelerator quadrupole matching section for a compact linear accelerator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:053302. [PMID: 29864834 DOI: 10.1063/1.5023415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing elements. In this paper, we combine these units to form a working accelerator structure: a matching section between the ion source extraction grids and the RF-acceleration unit and electrostatic focusing quadrupoles between successive acceleration units. The matching section consists of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture more beam current and to match the beam envelope to conditions for stable transport in an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.
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A compact linear accelerator based on a scalable microelectromechanical-system RF-structure. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:063304. [PMID: 28667999 DOI: 10.1063/1.4984969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number of parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further reducing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.
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Development and testing of a pulsed helium ion source for probing materials and warm dense matter studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:02B707. [PMID: 26932070 DOI: 10.1063/1.4932569] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The neutralized drift compression experiment was designed and commissioned as a pulsed, linear induction accelerator to drive thin targets to warm dense matter (WDM) states with peak temperatures of ∼1 eV using intense, short pulses (∼1 ns) of 1.2 MeV lithium ions. At that kinetic energy, heating a thin target foil near the Bragg peak energy using He(+) ions leads to more uniform energy deposition of the target material than Li(+) ions. Experiments show that a higher current density of helium ions can be delivered from a plasma source compared to Li(+) ions from a hot plate type ion source. He(+) beam pulses as high as 200 mA at the peak and 4 μs long were measured from a multi-aperture 7-cm-diameter emission area. Within ±5% variation, the uniform beam area is approximately 6 cm across. The accelerated and compressed pulsed ion beams can be used for materials studies and isochoric heating of target materials for high energy density physics experiments and WDM studies.
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Teaching anatomy and research skills. Assoc Med J 2014. [DOI: 10.1136/sbmj.g4001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Novel methods for improvement of a Penning ion source for neutron generator applications. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:02B309. [PMID: 22380288 DOI: 10.1063/1.3670744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Penning ion source performance for neutron generator applications is characterized by the atomic ion fraction and beam current density, providing two paths by which source performance can be improved for increased neutron yields. We have fabricated a Penning ion source to investigate novel methods for improving source performance, including optimization of wall materials and electrode geometry, advanced magnetic confinement, and integration of field emitter arrays for electron injection. Effects of several electrode geometries on discharge characteristics and extracted ion current were studied. Additional magnetic confinement resulted in a factor of two increase in beam current density. First results indicate unchanged proton fraction and increased beam current density due to electron injection from carbon nanofiber arrays.
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A tandem-based compact dual-energy gamma generator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:02B904. [PMID: 20192470 DOI: 10.1063/1.3258028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.
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Abstract
We report the integration of a scanning force microscope with ion beams. The scanning probe images surface structures non-invasively and aligns the ion beam to regions of interest. The ion beam is transported through a hole in the scanning probe tip. Piezoresistive force sensors allow placement of micromachined cantilevers close to the ion beam lens. Scanning probe imaging and alignment is demonstrated in a vacuum chamber coupled to the ion beam line. Dot arrays are formed by ion implantation in resist layers on silicon samples with dot diameters limited by the hole size in the probe tips of a few hundred nm.
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Abstract
The introduction of the European Convention on Human Rights into UK law will have a direct effect on practice in mental health care. The authors discuss developments associated with the Convention, examine different articles and suggest the changes they could bring. They suggest that, rather than reacting to the development of convention rights, healthcare professionals should take the opportunity to influence new standards for psychiatric care.
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Abstract
To determine whether reduced Na+/K+-ATPase activity might be involved in acrylamide (ACR)-induced peripheral axon swelling and degeneration, rubidium (Rb+) transport was measured as an index of enzyme function. x-ray microanalysis was used to quantify elemental Rb uptake and accumulation in internodal myelinated axons, mitochondria, Schwann cells, and myelin of rat tibial nerve cryosections. Results demonstrated impairment of Rb uptake in tibial axons from orally intoxicated (2.8 mM ACR for 34 days), moderately affected rats. In severely affected oral rats (49 days), complete inhibition of Rb transport and frank axon degeneration were evident. However, in moderate-to-severely affected rats exposed to ACR via ip injection (50 mg/kg/day for 11 days), neither structural nor enzymatic changes were present in tibial fibers. These findings in nerve cryosections suggested inhibition of axolemmal Na+ pump activity and degeneration were dependent upon route of ACR administration. This possibility was substantiated by a quantitative longitudinal morphometric study of conventionally fixed tibial nerve. Oral ACR treatment (2.8 mM ACR for 15-49 days) was associated with progressive axon degeneration, which was preceded by atrophy. Axonal swellings were rarely (<1%) observed. In contrast, ip ACR injection (50 mg/kg/day for 5-11 days) produced classic behavioral neurotoxicity but did not alter axon morphology in tibial nerve. Thus, fiber degeneration and decreased Na+ pump activity were consequences of subchronic oral ACR administration. This parallel expression suggests a mechanistic relationship. However, the corresponding general neurotoxicological significance is unclear since, behavioral toxicity induced by ip ACR develops without structural and enzymatic changes in tibial nerve.
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Cost-effectiveness analysis of extended conservative therapy versus surgical intervention in the management of herniated lumbar intervertebral disc. Spine (Phila Pa 1976) 1992; 17:176-82. [PMID: 1532460 DOI: 10.1097/00007632-199202000-00010] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The management of herniated lumbar intervertebral disc for patients not responding to an initial trial of conservative therapy is generally surgical. Little is known about the effect of continued conservative therapy on patients who have not improved or have deteriorated within the first 3 months. This study assessed which form of treatment, surgical or continued conservative therapy, is more cost-effective once an adequate trial of conservative therapy has failed. The study is a retrospective chart review of 55 white male truck drivers who presented with acutely herniated nucleus pulposus between 1985 and 1989. Twenty-five patients underwent surgery, and 30 underwent continued conservative therapy after initial rehabilitation. No significant difference was found in outcome (80% good or fair in both the surgical and conservative groups) or costs ($55,000 +/- $1,000/case during a 5-year period), hence no difference in the cost-effectiveness between the two treatment modalities (each $63,000 +/- $2,000/adjusted outcome). Conservatively treated patients, however, missed significantly more work. It was concluded that, for a patient not responding to the initial trial of conservative therapy, the option to undergo continued conservative treatment should be made available.
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