Publications by authors named "Jongjin Lee"

17 Publications

  • Page 1 of 1

Radiological assessment schedule for 1p/19q-codeleted gliomas during the surveillance period using parametric modeling.

Neurooncol Adv 2021 Jan-Dec;3(1):vdab069. Epub 2021 May 20.

Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.

Background: There have been no evidence-based guidelines on the optimal schedule for the radiological assessment of 1p/19q-codeleted glioma. This study aimed to recommend an appropriate radiological evaluation schedule for 1p/19q-codeleted glioma during the surveillance period through parametric modeling of the progression-free survival (PFS) curve.

Methods: A total of 234 patients with 1p/19q-codeleted glioma (137 grade II and 97 grade III) who completed regular treatment were retrospectively reviewed. The patients were stratified into each layered progression risk group by recursive partitioning analysis. A piecewise exponential model was used to standardize the PFS curves. The cutoff value of the progression rate among the remaining progression-free patients was set to 10% at each scan.

Results: Progression risk stratification resulted in 3 groups. The optimal magnetic resonance imaging (MRI) interval for patients without a residual tumor was every 91.2 weeks until 720 weeks after the end of regular treatment following the latent period for 15 weeks. For patients with a residual tumor after the completion of adjuvant radiotherapy followed by chemotherapy, the optimal MRI interval was every 37.5 weeks until week 90 and every 132.8 weeks until week 361, while it was every 33.6 weeks until week 210 and every 14.4 weeks until week 495 for patients with a residual tumor after surgery only or surgery followed by radiotherapy only.

Conclusions: The optimal radiological follow-up schedule for each progression risk stratification of 1p/19q-codeleted glioma can be established from the parametric modeling of PFS.
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http://dx.doi.org/10.1093/noajnl/vdab069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8284622PMC
May 2021

The Characteristics of Women with Subsequent Distal Radius Fracture after Initial Distal Radius Fracture.

J Bone Metab 2021 May 31;28(2):123-129. Epub 2021 May 31.

Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Background: The purpose of this study was to investigate the characteristics of women with subsequent distal radius fracture (DRF) and to compare bone fragility variables in women with initial and subsequent DRF.

Methods: We enrolled 227 women who experienced DRF (203 women with initial DRF and 24 women with subsequent DRF) between September 2016 and April 2019. We compared demographic characteristics and bone fragility variables, including bone mineral density, trabecular bone score, hip geometry, bicortical thickness of the distal radius, and fracture risk assessment tool (FRAX) scores between the 2 groups. To reduce bias, patients with subsequent DRF were propensity score-matched in a 1:2 manner with patients affected by initial DRF, and additional comparisons were performed.

Results: Patients in the subsequent DRF group were older than those in the initial DRF group, but this difference was not significant (P=0.091). The proportion of patients receiving treatment with osteoporosis medication was significantly higher in the subsequent DRF group (41.7% vs. 19.2%, P=0.011). Bone fragility variables did not differ significantly between the 2 groups. However, the ten-year probability of major osteoporotic fractures based on FRAX scores was significantly higher in patients with subsequent DRF (7.5% vs. 10.8%, P<0.001). Similar results were observed when comparing the propensity score-matched initial and subsequent DRF groups.

Conclusions: These findings suggest that the occurrence of subsequent DRF after initial DRF can be attributed to multiple factors rather than bone fragility alone. Systematic and multidisciplinary management would be helpful in preventing the occurrence of subsequent DRF after the initial DRF.
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http://dx.doi.org/10.11005/jbm.2021.28.2.123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8206611PMC
May 2021

Radiological assessment schedule for high-grade glioma patients during the surveillance period using parametric modeling.

Neuro Oncol 2021 05;23(5):837-847

Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine.

Background: An optimal radiological surveillance plan is crucial for high-grade glioma (HGG) patients, which is determined arbitrarily in daily clinical practice. We propose the radiological assessment schedule using a parametric model of standardized progression-free survival (PFS) curves.

Methods: A total of 277 HGG patients (178 glioblastoma [GBM] and 99 anaplastic astrocytoma [AA]) from a single institute who completed the standard treatment protocol were enrolled in this cohort study and retrospectively analyzed. The patients were stratified into each layered risk group by genetic signatures and residual mass or through recursive partitioning analysis. PFS curves were estimated using the piecewise exponential survival model. The criterion of a 10% progression rate among the remaining patients at each observation period was used to determine the optimal radiological assessment time point.

Results: The optimal follow-up intervals for MRI evaluations of isocitrate dehydrogenase (IDH) wild-type GBM was every 7.4 weeks until 120 weeks after the end of standard treatment, followed by a 22-week inflection period and every 27.6 weeks thereafter. For the IDH mutated GBM, scans every 13.2 weeks until 151 weeks are recommended. The optimal follow-up intervals were every 22.8 weeks for IDH wild-type AA, and 41.2 weeks for IDH mutated AA until 241 weeks. Tailored radiological assessment schedules were suggested for each layered risk group of the GBM and the AA patients.

Conclusions: The optimal schedule of radiological assessments for each layered risk group of patients with HGG could be determined from the parametric model of PFS.
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http://dx.doi.org/10.1093/neuonc/noaa250DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8099465PMC
May 2021

Medial and Lateral Meniscus Allograft Transplantation Showed No Difference With Respect to Graft Survivorship and Clinical Outcomes: A Comparative Analysis With a Minimum 2-Year Follow-Up.

Arthroscopy 2020 12 25;36(12):3061-3068. Epub 2020 Jul 25.

Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Purpose: To compare the differences with respect to clinical and graft survivorship and patient-reported outcomes (PROs) between lateral (LMAT) and medial (MMAT) meniscus allograft transplantation.

Methods: Patients having a primary MAT between 1998 and 2016 were enrolled. The inclusion criteria were (1) patients who had a minimum 2-year follow-up and (2) patients who had magnetic resonance imaging (MRI) >2 years after surgery. Knees with localized grade 4 articular cartilage lesions >3 cm at the time of MAT were excluded. Clinical failure was defined as follows: modified Lysholm score <65, meniscectomy >50% of the graft, meniscectomy to the meniscocapsular junction zone, conversion to revision MAT, or realignment osteotomy or arthroplasty. Graft failure was defined as follows: tears involving >50% of the graft or unhealed peripheral rim observed on MRI. Kaplan-Meier survival analysis with log-rank test was used to compare survivorship between LMAT and MMAT. Patient-reported outcomes were compared based on the Hospital for Special Surgery, modified Lysholm, and International Knee Documentation Committee subjective scores collected preoperatively and at the final follow-up.

Results: A total of 299 knees (249 LMAT, 50 MMAT, mean age 33.0 ± 9.8 years) were included. Twenty clinical [2 MMAT (4.0%), 18 LMAT (7.2%)] and 24 graft [2 MMAT (4.0%), 22 LMAT (8.8%)] failures were identified. The mean clinical follow-up period was 63.1 ± 43.1 months (range 2 to 248), and MRI follow-up period was 62.6 ± 43.8 months (range 2 to 248). No significant differences in clinical and graft survivorship were found between the LMAT and MMAT groups (P = .481, P = .271, respectively). PROs preoperatively and at last follow-up also showed no significant difference between the groups.

Conclusion: No significant differences in clinical survivorship, graft survivorship, and PROs were found between the LMAT and MMAT groups.

Level Of Evidence: Level III, retrospective comparative study.
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http://dx.doi.org/10.1016/j.arthro.2020.07.025DOI Listing
December 2020

Accelerated FRET-PAINT microscopy.

Mol Brain 2018 11 22;11(1):70. Epub 2018 Nov 22.

Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea.

Recent development of FRET-PAINT microscopy significantly improved the imaging speed of DNA-PAINT, the previously reported super-resolution fluorescence microscopy with no photobleaching problem. Here we try to achieve the ultimate speed limit of FRET-PAINT by optimizing the camera speed, dissociation rate of DNA probes, and bleed-through of the donor signal to the acceptor channel, and further increase the imaging speed of FRET-PAINT by 8-fold. Super-resolution imaging of COS-7 microtubules shows that high-quality 40-nm resolution images can be obtained in just tens of seconds.
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http://dx.doi.org/10.1186/s13041-018-0414-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6249777PMC
November 2018

Potential Dip in Organic Photovoltaics Probed by Cross-sectional Kelvin Probe Force Microscopy.

Nanoscale Res Lett 2018 Aug 1;13(1):228. Epub 2018 Aug 1.

Department of Chemical and Biomolecular Engineering, NYU Tandon School of Engineering, 6 MetroTech Center, Brooklyn, NY, 11201, USA.

Cross-sectional potential distribution of high open-circuit voltage bulk heterojunction photovoltaic device was measured using Kelvin probe force microscopy. Potential drop confined at cathode interface implies that photo-active layer is an effective p-type semiconductor. Potential values in field-free region show wide variation according to log-normal distribution. This potential dip prone to have holes captured during the diffusive motion, which can increase bimolecular recombination, while potential gradient in depletion region makes this potential dip smaller and the captured holes easily escape from dip region by Schottky barrier lowering.
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http://dx.doi.org/10.1186/s11671-018-2639-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070447PMC
August 2018

Accelerated super-resolution imaging with FRET-PAINT.

Mol Brain 2017 12 28;10(1):63. Epub 2017 Dec 28.

Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea.

Super-resolution fluorescence microscopy in the current form is hard to be used to image the neural connectivity of thick tissue samples due to problems such as slow imaging speed, severe photobleaching of fluorescent probes, and high background noise. Recently developed DNA-PAINT solved the photobleaching problem, but its imaging speed is extremely low. We report accelerated super-resolution fluorescence microscopy named FRET-PAINT. Compared to conventional DNA-PAINT, the imaging speed of the microscopy increases up to ~30-fold. As demonstrations, we show that 25-50 second imaging time is long enough to provide super-resolution reconstruction of microtubules and mitochondria of COS-7 cells.
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http://dx.doi.org/10.1186/s13041-017-0344-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5747120PMC
December 2017

Diagnostic yield of stool culture and predictive factors for positive culture in patients with diarrheal illness.

Medicine (Baltimore) 2017 Jul;96(30):e7641

Department of Internal Medicine, Chung-Ang University College of Medicine Division of Infectious Diseases, Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.

We aimed to investigate the diagnostic yield of stool cultures and identify predictive factors for positive cultures in patients with diarrheal illness.A total of 13,327 patients who underwent stool cultures due to diarrheal illness were reviewed. Stool cultures were performed for enteric pathogens, including Salmonella, Shigella, Vibrio, Klebsiella oxytoca, and Yersinia. The culture-positive group was compared with the culture-negative group who were randomly selected from culture negative patients.A total of 196 patients (1.47%) were diagnosed with positive stool culture. In 196 culture positive patients, Salmonella spp. (75.0%) was detected most commonly, followed by Vibrio (19.4%). Univariate analyses showed fever (>37.8°C), vomiting, duration and frequency of diarrhea, and high C-reactive protein (CRP) were significantly associated with positive stool culture. Multivariate analysis showed fever (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.25-4.35; P = .008), ≥5/day of diarrhea (OR, 3.52; 95% CI, 1.93-6.44; P < .001) and >50 mg/L of CRP (OR, 2.27; 95% CI, 1.18-4.36; P = .014) were independent predictors for positive stool culture. OR in patients with all 3 factors was 6.55 (95% CI, 2.56-16.75; P < .001). Vomiting (OR, 0.32; 95% CI, 0.17-0.57; P < .001) was a negative predictive factor.Diagnostic yield of stool culture in patients with diarrheal illness is very low. Fever, frequency of diarrhea, and high CRP are predictors for positive stool cultures. These findings may lead to more discerning and cost-effective utilization of stool culture by clinicians.
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http://dx.doi.org/10.1097/MD.0000000000007641DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5627853PMC
July 2017

[A Case of Tenofovir-associated Fanconi Syndrome in Patient with Chronic Hepatitis B].

Korean J Gastroenterol 2016 Dec;68(6):317-320

Division of Gastroenterology and Hepatology, Department of Internal Medicine, Korea University Ansan Hospital, Ansan, Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea.

Tenofovir disoproxil fumarate (TDF) is one of the most widely used treatment options for human immunodeficiency virus (HIV) and HBV infections. Despite its efficacy and safety, some cases of nephrotoxicity have been reported in the treatment of HIV patients. Even more recently, very few cases of Fanconi syndrome associated with tenofovir therapy in HBV monoinfection have been reported. Herein, we report a case of a 47-year-old male with an HBV monoinfection, who developed Fanconi syndrome and a secondary osteomalacia with multiple bone pain. After TDF withdrawal and supplementation of calcitriol, his renal function was reverted. Although the overall risk of TDF-associated nephrotoxicity is very low, both glomerular and tubular function should be monitored in patients undergoing TDF treatment.
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http://dx.doi.org/10.4166/kjg.2016.68.6.317DOI Listing
December 2016

Fluoroscopically guided balloon dilation or temporary stent placement for patients with gastric conduit strictures after esophagectomy with esophagogastrostomy.

AJR Am J Roentgenol 2013 Jul;201(1):202-7

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul, 138-736, Republic of Korea.

Objective: The purpose of this study was to evaluate the clinical features of patients with gastric conduit strictures after esophagectomy and to report our initial experience in the management of these strictures with fluoroscopically guided balloon dilation, temporary stent placement, or both.

Materials And Methods: From January 1996 to January 2012, 12 patients with gastric conduit stricture after esophagectomy underwent fluoroscopic balloon dilation, temporary stent placement, or both. Stent placement was indicated in patients who had gastro-respiratory fistulas or recurrent symptoms within 2 weeks of balloon dilation. Technical and clinical success, complications, and length of strictures were retrospectively evaluated.

Results: The mean length of strictures in all patients was 49 mm (range, 21-76 mm). The strictures were accompanied by gastrorespiratory fistulas in four patients. Seven patients with gastric conduit strictures without fistulas underwent 23 balloon dilations. Five patients underwent stent placement owing to gastrorespiratory fistula formation (n = 4) and frequent recurrent symptoms after balloon dilation (n = 1). During a mean follow-up period of 8 months (range, 2-28 months), clinical success was achieved in 11 patients (91.6%) after a single balloon dilation (n = 1), multiple balloon dilations (n = 5), or stent placement (n = 5). Complications occurred in 3 of 10 patients (30%) after balloon dilation and in one of five patients (20%) after stent placement.

Conclusion: Gastric conduit strictures are characterized by their substantial length and tend to be accompanied by gastrorespiratory fistulas. Despite relatively high complication and recurrence rates, this study may offer a viable treatment of gastric conduit strictures by using fluoroscopically guided balloon dilation and stent placement.
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http://dx.doi.org/10.2214/AJR.12.9420DOI Listing
July 2013

How to design the optimal self-expandable oesophageal metallic stents: 22 years of experience in 645 patients with malignant strictures.

Eur Radiol 2013 Mar 27;23(3):786-96. Epub 2012 Sep 27.

Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.

Objectives: To evaluate the clinical efficacy and safety of self-expandable metallic stent (SEMS) placement for malignant oesophageal strictures and their relationship with stent designs.

Methods: Seven generations of SEMS were used to treat 645 consecutive patients with oesophageal strictures. Logistic regression models were constructed to identify predictive factors associated with complications.

Results: Stent placement was technically successful in 641 of 645 patients (99.4%). The clinical success rate was 95.5%. There were 260 (40.3%) complications after stent placement. Due to complications, 68 stents were removed; 66 of 68 stents (97.1%) were removed successfully. Stainless steel (SS) stents (odds ratio [OR] 4.18; 95% confidence interval [CI] 2.10, 8.32) and radiation therapy (RT) before stent placement (OR 4.23; CI 2.02, 8.83) were significantly associated with severe pain. Flared ends (OR 9.63; CI 3.38, 27.43), stricture length <6 cm (OR 2.01; CI 1.13, 3.60), and a stent diameter <18 mm (OR 3.00; CI 1.32, 6.84) were predictive factors of stent migration. Polyurethane membranes were associated with more frequent tumour ingrowth than polytetrafluoroethylene (PTFE) membranes (P = 0.002).

Conclusions: Despite the relatively high complication rate, retrievable self-expandable PTFE-covered nitinol stents equipped with a head and a tail appeared to be an effective treatment for malignant oesophageal strictures.
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http://dx.doi.org/10.1007/s00330-012-2661-5DOI Listing
March 2013

Role of interchain coupling in the metallic state of conducting polymers.

Phys Rev Lett 2012 Sep 7;109(10):106405. Epub 2012 Sep 7.

School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.

We investigated the charge dynamics of the conductivity enhancement from 2 to 1000 S/cm in poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) as induced by structural changes through the addition of a polar solvent and the following solvent bath treatment. Our results indicate that the addition of a polar solvent selectively enhanced the π-π coupling of the polymer chains, resulting in the reduction of disorder and tremendously increasing the charge carrier mobility, which yielded an insulator-to-metal transition. In contrast, the following solvent bath treatment selectively enhanced the intergrain coupling, which did not affect the disorder or the mobility but increased the charge carrier density. Therefore, we demonstrate that the conduction-character defining disorder in this conducting polymer system is determined by the extent of interchain coupling.
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http://dx.doi.org/10.1103/PhysRevLett.109.106405DOI Listing
September 2012

Building mechanism for a high open-circuit voltage in an all-solution-processed tandem polymer solar cell.

Phys Chem Chem Phys 2012 Aug 28;14(30):10547-55. Epub 2012 Jun 28.

School of Materials Science & Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712, South Korea.

Additional post-processing techniques, such as post-thermal annealing and UV illumination, were found to be required to obtain desirable values of the cell parameters in a tandem polymer solar cell incorporated with solution-processed basic n-type titanium sub-oxide (TiO(x))/acidic p-type poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) interlayers. Subsequent to the fabrication of the tandem polymer solar cells, the open-circuit voltage (V(OC)) of the cells exhibited half of the expected value. Only after the application of the post-treatments, the V(OC) of a tandem cell increased from the initial half-cell value (∼0.6 V) to its full-cell value (∼1.2 V). The selective light-biased incident photon-to-current efficiency (IPCE) measurements indicated that the initial V(OC) originated from the back subcell and that the application of the post-processing treatments revived the front subcell, such that the net photocurrent of the tandem cell was finally governed by a recombination process of holes from the back subcell and electrons from the front subcell. Based on our experimental results, we suggest that a V(OC) enhancement could be ascribed to two types of subsequent junction formations at the interface between the TiO(x) and PEDOT:PSS interlayers: an 'ion-mediated dipole junction', resulting from the electro-kinetic migration of cationic ions in the interlayers during post-thermal annealing in the presence of a low-work-function metal cathode, and a 'photoinduced Schottky junction', formed by increasing the charge carrier density in the n-type TiO(x) interlayer during UV illumination process. The two junctions separately contributed to the formation of a recombination junction through which the electrons in TiO(x) and the holes in PEDOT:PSS were able to recombine without substantial voltage drops.
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http://dx.doi.org/10.1039/c2cp41501aDOI Listing
August 2012

Electrostatically self-assembled nonconjugated polyelectrolytes as an ideal interfacial layer for inverted polymer solar cells.

Adv Mater 2012 Jun 2;24(22):3005-9, 2938. Epub 2012 May 2.

School of Materials Science and Engineering, Heeger Center for Advanced Materials, Research Institute for Solar and Sustainable Energies, Gwangju Institute of Science and Technology, Gwangju 500-712, South Korea.

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http://dx.doi.org/10.1002/adma.201200594DOI Listing
June 2012

Confining grains of textured Cu2O films to single-crystal nanowires and resultant change in resistive switching characteristics.

Nanoscale 2012 Mar 15;4(6):2029-33. Epub 2012 Feb 15.

Division of Quantum Phases & Devices, Department of Physics, Konkuk University, Seoul 143-701, South Korea.

By confining columnar grains of textured oxide film using anodized aluminum oxide template, we could obtain a grain-boundary-free (GB-free) cuprous oxide (Cu(2)O) nanowire arrays with a narrow diameter distribution and a high density under the same electrochemical deposition condition. A two-terminal device fabricated using an individual GB-free nanowire and Au/Cr electrodes exhibits bipolar resistive switching contrary to the unipolar one of a textured film, and Schottky-like conduction. On the other hand, a nanowire device with Pt electrodes reveals non-switching behavior and Ohmic conduction. Thus, we can propose that the bipolar switching of a nanowire device with Au/Cr electrodes may result from the modulation of Schottky barrier at the interface by migration of oxygen vacancies while the unipolar one of a textured film may be defined as the bulky filamentary switching along the GBs in the GB-embedded texture films.
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http://dx.doi.org/10.1039/c2nr12100jDOI Listing
March 2012

Field modulation in Na-incorporated Cu(In,Ga)Se2 (CIGS) polycrystalline films influenced by alloy-hardening and pair-annihilation probabilities.

Nanoscale Res Lett 2011 Nov 7;6(1):581. Epub 2011 Nov 7.

Research Institute for Solar and Sustainable Energies (RISE), Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea.

The influence of Na on Cu(In,Ga)Se2 (CIGS) solar cells was investigated. A gradient profile of the Na in the CIGS absorber layer can induce an electric field modulation and significantly strengthen the back surface field effect. This field modulation originates from a grain growth model introduced by a combination of alloy-hardening and pair-annihilation probabilities, wherein the Cu supply and Na diffusion together screen the driving force of the grain boundary motion (GBM) by alloy hardening, which indicates a specific GBM pinning by Cu and Na. The pair annihilation between the ubiquitously evolving GBMs has a coincident probability with the alloy-hardening event.PACS: 88. 40. H-, 81. 10. Aj, 81. 40. Cd.
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http://dx.doi.org/10.1186/1556-276X-6-581DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3339401PMC
November 2011

Multisoliton propagation in a linear granular chain.

Phys Rev E Stat Nonlin Soft Matter Phys 2003 Jun 25;67(6 Pt 2):066607. Epub 2003 Jun 25.

School of Physics and Condensed Matter Research Institute, Seoul National University, Seoul 151-742, Korea.

When m grains hit a linear Hertzian chain of identical grains, m solitons are generated. We studied the multisoliton propagation using a particle dynamic simulation. The speed of solitons depends not only on the number of colliding grains but also on the sequence of generation. We found the hierarchy and evolution of the solitons as well as the generation of secondary solitons. We also found the oscillation and beats in the kinetic energy of the chain, which come from the discreteness of the medium in comparison with the spatial spreading of the soliton.
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http://dx.doi.org/10.1103/PhysRevE.67.066607DOI Listing
June 2003
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