| 1. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Bouyoucef, S E, et al.
(författare)
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Poster Session 2 : Monday 4 May 2015, 08
- 2015
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Ingår i: European Heart Journal Cardiovascular Imaging. - : Oxford University Press (OUP). - 2047-2404 .- 2047-2412. ; 16 Suppl 1
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Abbott, R., et al.
(författare)
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Hybridization and speciation
- 2013
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26:2, s. 229-246
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Forskningsöversikt (refereegranskat)abstract
- Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near-instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky-Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock-on effects on speciation both within and outside regions of hybridization.
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| 4. |
- Beyer, J., et al.
(författare)
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Maintaining success, reducing treatment burden, focusing on survivorship: highlights from the third European consensus conference on diagnosis and treatment of germ-cell cancer
- 2013
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Ingår i: Annals of Oncology. - : Elsevier BV. - 1569-8041 .- 0923-7534. ; 24:4, s. 878-888
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Forskningsöversikt (refereegranskat)abstract
- In November 2011, the Third European Consensus Conference on Diagnosis and Treatment of Germ-Cell Cancer (GCC) was held in Berlin, Germany. This third conference followed similar meetings in 2003 (Essen, Germany) and 2006 (Amsterdam, The Netherlands) [Schmoll H-J, Souchon R, Krege S et al. European consensus on diagnosis and treatment of germ-cell cancer: a report of the European Germ-Cell Cancer Consensus Group (EGCCCG). Ann Oncol 2004; 15: 1377-1399; Krege S, Beyer J, Souchon R et al. European consensus conference on diagnosis and treatment of germ-cell cancer: a report of the second meeting of the European Germ-Cell Cancer Consensus group (EGCCCG): part I. Eur Urol 2008; 53: 478-496; Krege S, Beyer J, Souchon R et al. European consensus conference on diagnosis and treatment of germ-cell cancer: a report of the second meeting of the European Germ-Cell Cancer Consensus group (EGCCCG): part II. Eur Urol 2008; 53: 497-513]. A panel of 56 of 60 invited GCC experts from all across Europe discussed all aspects on diagnosis and treatment of GCC, with a particular focus on acute and late toxic effects as well as on survivorship issues. The panel consisted of oncologists, urologic surgeons, radiooncologists, pathologists and basic scientists, who are all actively involved in care of GCC patients. Panelists were chosen based on the publication activity in recent years. Before the meeting, panelists were asked to review the literature published since 2006 in 20 major areas concerning all aspects of diagnosis, treatment and follow-up of GCC patients, and to prepare an updated version of the previous recommendations to be discussed at the conference. In addition, similar to 50 E-vote questions were drafted and presented at the conference to address the most controversial areas for a poll of expert opinions. Here, we present the main recommendations and controversies of this meeting. The votes of the panelists are added as online supplements.
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| 5. |
- Alcorn, Sara R., et al.
(författare)
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Low-Dose Image-Guided Pediatric CNS Radiation Therapy : Final Analysis From a Prospective Low-Dose Cone-Beam CT Protocol From a Multinational Pediatrics Consortium
- 2020
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Ingår i: Technology in Cancer Research & Treatment. - : SAGE PUBLICATIONS INC. - 1533-0346 .- 1533-0338. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lower-dose cone-beam computed tomography protocols for image-guided radiotherapy may permit target localization while minimizing radiation exposure. We prospectively evaluated a lower-dose cone-beam protocol for central nervous system image-guided radiotherapy across a multinational pediatrics consortium.Methods: Seven institutions prospectively employed a lower-dose cone-beam computed tomography central nervous system protocol (weighted average dose 0.7 mGy) for patients <= 21 years. Treatment table shifts between setup with surface lasers versus cone-beam computed tomography were used to approximate setup accuracy, and vector magnitudes for these shifts were calculated. Setup group mean, interpatient, interinstitution, and random error were estimated, and clinical factors were compared by mixed linear modeling.Results: Among 96 patients, with 2179 pretreatment cone-beam computed tomography acquisitions, median age was 9 years (1-20). Setup parameters were 3.13, 3.02, 1.64, and 1.48 mm for vector magnitude group mean, interpatient, interinstitution, and random error, respectively. On multivariable analysis, there were no significant differences in mean vector magnitude by age, gender, performance status, target location, extent of resection, chemotherapy, or steroid or anesthesia use. Providers rated >99% of images as adequate or better for target localization.Conclusions: A lower-dose cone-beam computed tomography protocol demonstrated table shift vector magnitude that approximate clinical target volume/planning target volume expansions used in central nervous system radiotherapy. There were no significant clinical predictors of setup accuracy identified, supporting use of this lower-dose cone-beam computed tomography protocol across a diverse pediatric population with brain tumors.
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| 6. |
- Alcorn, Sara R, et al.
(författare)
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Practice patterns of photon and proton pediatric image guided radiation treatment : results from an International Pediatric Research consortium
- 2014
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Ingår i: Practical radiation oncology. - : Elsevier BV. - 1879-8500. ; 4:5, s. 336-341
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Image guided radiation therapy (IGRT) has become common practice for both photon and proton radiation therapy, but there is little consensus regarding its application in the pediatric population. We evaluated clinical patterns of pediatric IGRT practice through an international pediatrics consortium comprised of institutions using either photon or proton radiation therapy.METHODS AND MATERIALS: Seven international institutions with dedicated pediatric expertise completed a 53-item survey evaluating patterns of IGRT use in definitive radiation therapy for patients ≤21 years old. Two institutions use proton therapy for children and all others use IG photon therapy. Descriptive statistics including frequencies of IGRT use and means and standard deviations for planning target volume (PTV) margins by institution and treatment site were calculated.RESULTS: Approximately 750 pediatric patients were treated annually across the 7 institutions. IGRT was used in tumors of the central nervous system (98%), abdomen or pelvis (73%), head and neck (100%), lung (83%), and liver (69%). Photon institutions used kV cone beam computed tomography and kV- and MV-based planar imaging for IGRT, and all proton institutions used kV-based planar imaging; 57% of photon institutions used a specialized pediatric protocol for IGRT that delivers lower dose than standard adult protocols. Immobilization techniques varied by treatment site and institution. IGRT was utilized daily in 45% and weekly in 35% of cases. The PTV margin with use of IGRT ranged from 2 cm to 1 cm across treatment sites and institution.CONCLUSIONS: Use of IGRT in children was prevalent at all consortium institutions. There was treatment site-specific variability in IGRT use and technique across institutions, although practices varied less at proton facilities. Despite use of IGRT, there was no consensus of optimum PTV margin by treatment site. Given the desire to restrict any additional radiation exposure in children to instances where the exposure is associated with measureable benefit, prospective studies are warranted to optimize IGRT protocols by modality and treatment site.
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| 7. |
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| 8. |
- Borghesi, M., et al.
(författare)
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Progress in proton radiography for diagnosis of ICF-relevant plasmas
- 2010
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Ingår i: Laser and particle beams (Print). - 0263-0346 .- 1469-803X. ; 28:2, s. 277-284
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Tidskriftsartikel (refereegranskat)abstract
- Proton radiography using laser-driven sources has been developed as a diagnostic since the beginning of the decade, and applied successfully to a range of experimental situations. Multi-MeV protons driven from thin foils via the Target Normal Sheath Acceleration mechanism, offer, under optimal conditions, the possibility of probing laser-plasma interactions, and detecting electric and magnetic fields as well as plasma density gradients with similar to ps temporal resolution and similar to 5-10 mu m spatial resolution. In view of these advantages, the use of proton radiography as a diagnostic in experiments of relevance to Inertial Confinement Fusion is currently considered in the main fusion laboratories. This paper will discuss recent advances in the application of laser-driven radiography to experiments of relevance to Inertial Confinement Fusion. In particular we will discuss radiography of hohlraum and gasbag targets following the interaction of intense ns pulses. These experiments were carried out at the HELEN laser facility at AWE (UK), and proved the suitability of this diagnostic for studying, with unprecedented detail, laser-plasma interaction mechanisms of high relevance to Inertial Confinement Fusion. Non-linear solitary structures of relevance to space physics, namely phase space electron holes, have also been highlighted by the measurements. These measurements are discussed and compared to existing models.
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| 9. |
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| 10. |
- Rao, Avani Dholakia, et al.
(författare)
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Practice patterns of palliative radiation therapy in pediatric oncology patients in an international pediatric research consortium
- 2017
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Ingår i: Pediatric Blood & Cancer. - : Wiley. - 1545-5009 .- 1545-5017. ; 64:11
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Tidskriftsartikel (refereegranskat)abstract
- Background/Objectives:The practice of palliative radiation therapy (RT) is based on extrapolation from adult literature. We evaluated patterns of pediatric palliative RT to describe regimens used to identify opportunity for future pediatric-specific clinical trials.Design/Methods:Six international institutions with pediatric expertise completed a 122-item survey evaluating patterns of palliative RT for patients 21 years old from 2010 to 2015. Two institutions use proton RT. Palliative RT was defined as treatment with the goal of symptom control or prevention of immediate life-threatening progression.Results:Of 3,225 pediatric patients, 365 (11%) were treated with palliative intent to a total of 427 disease sites. Anesthesia was required in 10% of patients. Treatment was delivered to metastatic disease in 54% of patients. Histologies included neuroblastoma (30%), osteosarcoma (18%), leukemia/lymphoma (12%), rhabdomyosarcoma (12%), medulloblastoma/ependymoma (12%), Ewing sarcoma (8%), and other (8%). Indications included pain (43%), intracranial symptoms (23%), respiratory compromise (14%), cord compression (8%), and abdominal distention (6%). Sites included nonspine bone (35%), brain (16% primary tumors, 6% metastases), abdomen/pelvis (15%), spine (12%), head/neck (9%), and lung/mediastinum (5%). Re-irradiation comprised 16% of cases. Techniques employed three-dimensional conformal RT (41%), intensity-modulated RT (23%), conventional RT (26%), stereotactic body RT (6%), protons (1%), electrons (1%), and other (2%). The most common physician-reported barrier to consideration of palliative RT was the concern about treatment toxicity (83%).Conclusion:There is significant diversity of practice in pediatric palliative RT. Combined with ongoing research characterizing treatment response and toxicity, these data will inform the design of forthcoming clinical trials to establish effective regimens and minimize treatment toxicity for this patient population.
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| 11. |
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| 12. |
- Rao, Avani D., et al.
(författare)
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Reirradiation for Recurrent Pediatric Central Nervous System Malignancies : A Multi-institutional Review
- 2017
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - : ELSEVIER SCIENCE INC. - 0360-3016 .- 1879-355X. ; 99:3, s. 634-641
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Reirradiation has been proposed as an effective modality for recurrent central nervous system (CNS) malignancies in adults. We evaluated the toxicity and outcomes of CNS reirradiation in pediatric patients.Methods and Materials: The data from pediatric patients <21 years of age at the initial diagnosis who developed a recurrent CNS malignancy that received repeat radiation therapy (RT) across 5 facilities in an international pediatric research consortium were retrospectively reviewed.Results: Sixty-seven pediatric patients underwent CNS reirradiation. The primary diagnoses included medulloblastoma/primitive neuroectodermal tumor (n = 20; 30%), ependymoma (n = 19; 28%), germ cell tumor (n = 8; 12%), high-grade glioma (n = 9; 13%), low-grade glioma (n = 5; 7%), and other (n = 6; 9%). The median age at the first course of RT was 8.5 years (range 0.5-19.5) and was 12.3 years (range 3.3-30.2) at reirradiation. The median interval between RT courses was 2.0 years (range 0.3-16.5). The median radiation dose and fractionation in equivalent 2-Gy fractions was 63.7 Gy (range 27.6-74.8) for initial RT and 53.1 Gy (range 18.6-70.1) for repeat RT. The relapse location was infield in 52 patients (78%) and surrounding the initial RT field in 15 patients (22%). Thirty-seven patients (58%) underwent gross or subtotal resection at recurrence. The techniques used for reirradiation were intensity modulated RT (n = 46), 3-dimensional conformal RT (n = 9), stereotactic radiosurgery (n = 4; 1213 Gy x 1 or 5 Gy x 5), protons (n = 4), combined modality (n = 3), 2-dimensional RT (n = 1), and brachytherapy (n = 1). Radiation necrosis was detected in 2 patients after the first RT course and 1 additional patient after reirradiation. Six patients (9%) developed secondary neoplasms after initial RT (1 hematologic, 5 intracranial). One patient developed a secondary neoplasm identified shortly after repeat RT. The median overall survival after completion of repeat RT was 12.8 months for the entire cohort and 20.5 and 8.4 months for patients with recurrent ependymoma and medulloblastoma after reirradiation, respectively.Conclusions: CNS reirradiation in pediatric patients could be a reasonable treatment option, with moderate survival noted after repeat RT. However, prospective data characterizing the rates of local control and toxicity are needed.
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| 13. |
- Sarri, G, et al.
(författare)
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The application of laser-driven proton beams to the radiography of intense laser–hohlraum interactions
- 2010
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Ingår i: New Journal of Physics. - : IOP Publishing Ltd. - 1367-2630. ; 12:4, s. 045006-
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Tidskriftsartikel (refereegranskat)abstract
- Plasma expansion following the interaction of an intense laser beam with the inner surface of gold hohlraums, emulating conditions relevant to indirect drive inertial confinement fusion (ICF), has been investigated by a radiographic technique which employs a beam of laser-accelerated protons. This probing technique has made it possible to measure the electric field distribution associated with the plasma front and its propagation throughout the interior of the hohlraum with a temporal and spatial resolution of the order of a few ps and μm, respectively. The data indicate that the expanding plasma slows down approaching the opposite walls, possibly due to the interaction with x-ray heated plasma from the non-irradiated walls. The electric field at the plasma front shows a bipolar structure, suggesting the presence of ion-acoustic soliton-like structures cotraveling with the front. Data obtained using enclosed hohlraums suggest the feasibility of this type of diagnosis in gas-filled hohlraums, as currently employed in ICF experiments.
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| 14. |
- Tjondro, Harry C., et al.
(författare)
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Hyper-truncated Asn355- And Asn391-glycans modulate the activity of neutrophil granule myeloperoxidase
- 2021
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 296
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Tidskriftsartikel (refereegranskat)abstract
- Myeloperoxidase (MPO) plays essential roles in neutrophil-mediated immunity via the generation of reactive oxidation products. Complex carbohydrates decorate MPO at discrete sites, but their functional relevance remains elusive. To this end, we have characterised the structure–biosynthesis–activity relationship of neutrophil MPO (nMPO). Mass spectrometry demonstrated that nMPO carries both characteristic under-processed and hyper-truncated glycans. Occlusion of the Asn355/Asn391-glycosylation sites and the Asn323-/Asn483-glycans, located in the MPO dimerisation zone, was found to affect the local glycan processing, thereby providing a molecular basis of the site-specific nMPO glycosylation. Native mass spectrometry, mass photometry and glycopeptide profiling revealed significant molecular complexity of diprotomeric nMPO arising from heterogeneous glycosylation, oxidation, chlorination and polypeptide truncation variants and a previously unreported low-abundance monoprotomer. Longitudinal profiling of maturing, mature, granule-separated and pathogen-stimulated neutrophils demonstrated that nMPO is dynamically expressed during granulopoiesis, unevenly distributed across granules and degranulated upon activation. We also show that proMPO-to-MPO maturation occurs during early/mid-stage granulopoiesis. While similar global MPO glycosylation was observed across conditions, the conserved Asn355-/Asn391-sites displayed elevated glycan hyper-truncation, which correlated with higher enzyme activities of MPO in distinct granule populations. Enzymatic trimming of the Asn355-/Asn391-glycans recapitulated the activity gain and showed that nMPO carrying hyper-truncated glycans at these positions exhibits increased thermal stability, polypeptide accessibility and ceruloplasmin-mediated inhibition potential relative to native nMPO. Finally, molecular modelling revealed that hyper-truncated Asn355-glycans positioned in the MPO-ceruloplasmin interface are critical for uninterrupted inhibition. Here, through an innovative and comprehensive approach, we report novel functional roles of MPO glycans, providing new insight into neutrophil-mediated immunity.
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| 15. |
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| 16. |
- Alcorn, Sara, et al.
(författare)
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Practice Patterns of Stereotactic Radiotherapy in Pediatrics : Results From an International Pediatric Research Consortium
- 2018
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Ingår i: Journal of pediatric hematology/oncology (Print). - : Lippincott Williams & Wilkins. - 1077-4114 .- 1536-3678. ; 40:7, s. 522-526
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Tidskriftsartikel (refereegranskat)abstract
- Purpose/Objectives: There is little consensus regarding the application of stereotactic radiotherapy (SRT) in pediatrics. We evaluated patterns of pediatric SRT practice through an international research consortium. Materials and Methods: Eight international institutions with pediatric expertise completed a 124-item survey evaluating patterns of SRT use for patients 21 years old and younger. Frequencies of SRT use and median margins applied with and without SRT were evaluated. Results: Across institutions, 75% reported utilizing SRT in pediatrics. SRT was used in 22% of brain, 18% of spine, 16% of other bone, 16% of head and neck, and <1% of abdomen/pelvis, lung, and liver cases across sites. Of the hypofractionated SRT cases, 42% were delivered with definitive intent. Median gross tumor volume to planning target volume margins for SRT versus non-SRT plans were 0.2 versus 1.4 cm for brain, 0.3 versus 1.5 cm for spine/other bone, 0.3 versus 2.0 cm for abdomen/pelvis, 0.7 versus 1.5 cm for head and neck, 0.5 versus 1.7 cm for lung, and 0.5 versus 2.0 cm for liver sites. Conclusions: SRT is commonly utilized in pediatrics across a range of treatment sites. Margins used for SRT were substantially smaller than for non-SRT planning, highlighting the utility of this approach in reducing treatment volumes.
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| 17. |
- Czamara, D, et al.
(författare)
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Genome-Wide Copy Number Variant and High-Throughput Transcriptomics Analyses of Placental Tissues Underscore Persisting Child Susceptibility in At-Risk Pregnancies Cleared in Standard Genetic Testing
- 2022
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Ingår i: International journal of molecular sciences. - : MDPI AG. - 1422-0067. ; 23:19
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have shown that children from pregnancies with estimated first-trimester risk based on fetal nuchal translucency thickness and abnormal maternal serum pregnancy protein and hormone levels maintain a higher likelihood of adverse outcomes, even if initial testing for known genetic conditions is negative. We used the Finnish InTraUterine cohort (ITU), which is a comprehensively characterized perinatal cohort consisting of 943 mothers and their babies followed throughout pregnancy and 18 months postnatally, including mothers shortlisted for prenatal genetic testing but cleared for major aneuploidies (cases: n = 544, 57.7%) and control pregnancies (n = 399, 42.3%). Using genome-wide genotyping and RNA sequencing of first-trimester and term placental tissue, combined with medical information from registry data and maternal self-report data, we investigated potential negative medical outcomes and genetic susceptibility to disease and their correlates in placenta gene expression. Case mothers did not present with higher levels of depression, perceived stress, or anxiety during pregnancy. Case children were significantly diagnosed more often with congenital malformations of the circulatory system (4.12 (95% CI [1.22–13.93]) higher hazard) and presented with significantly more copy number duplications as compared to controls (burden analysis, based on all copy number variants (CNVs) with at most 10% frequency, 823 called duplications in 297 cases versus 626 called duplications in 277 controls, p = 0.01). Fifteen genes showed differential gene expression (FDR < 0.1) in association with congenital malformations in first-trimester but not term placenta. These were significantly enriched for genes associated with placental dysfunction. In spite of normal routine follow-up prenatal testing results in early pregnancy, case children presented with an increased likelihood of negative outcomes, which should prompt vigilance in follow-up during pregnancy and after birth.
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| 18. |
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| 19. |
- Dendy, R.O., et al.
(författare)
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Energetic particles in magnetic confinement systems : Synergies beyond fusion
- 2002
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Magnetic confinement fusion science leads many other branches of plasma physics in its capacity to predict, interpret and understand the behaviour of energetic particle populations. The range of applications of this capability should be extended, for the mutual benefit of fusion research and of other branches of science. In this paper we review progress in applying fusion-derived techniques to one of the central questions of astrophysics: the origin of the cosmic ray population that is magnetically confined within our Galaxy. While it is widely believed that supernova remnant shocks provide the main acceleration sites for cosmic ray electrons and protons, the fundamental 'injection' problem remains. Namely, how particles are initially accelerated from ambient thermal to mildly relativistic energies, beyond which Fermi-type processes take over. The cosmic ray injection environment is magnetized and has many other physical resemblances to beam-heated and deuterium-tritium tokamak plasmas, in consequence, many of the same physical processes come into play. These include, for example, collective beam-plasma instability, resonant wave-particle coupling, and the stochasticization of particle orbits. A broad range of analytical and numerical techniques familiar in the fusion context has been successfully applied to the injection problem (see, for example, Dieckmann M.E. et al 2000 Astron. Astrophys. 356 377). Ideas from magnetic fusion have also been used to help design and interpret recent magnetized plasma experiments (Woolsey N.C. et al 2001 Phys. Plasmas 8 2439) using the high-power VULCAN laser, which address the cosmic ray injection problem from a new perspective.
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| 20. |
- Dieckmann, Mark E, 1969-, et al.
(författare)
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Aspects of self-similarity of the filamentation instability
- 2007
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Ingår i: 34th European Physical Society Conference on Plasma Physics,2007. - Warsaw : European Physical Society. ; , s. P2.080-
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Konferensbidrag (refereegranskat)abstract
- The filamentation instability (FI) is an aperiodically growing instability driven by counterpropagating electron beams. Its ability to generate magnetic fields is important for the energetic plasmas in gamma ray burst jets and inertial confinement fusion plasmas. The FI has been examined both analytically and with particle-in-cell (PIC) simulations. We perform PIC simulations and follow the FI through its nonlinear saturation. The power spectrum of the flow-aligned current component is self-similar during the linear phase. We show that the perpendicular current distribution is self-similar during the nonlinear evolution and that the filament size increases linearly with time. We demonstrate that, at least for warm plasmas, the current filaments can't be described by simple flux tubes. Instead, the filaments merge by magnetic reconnection to form larger, partially overlapping current sheets. In the filament overlap region the electrons are accelerated.
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| 21. |
- Dieckmann, Mark E, 1969-, et al.
(författare)
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Simulating thermal noise
- 2004
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; 69:6, s. 456-460
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Tidskriftsartikel (refereegranskat)abstract
- Thermal noise measurements by space-borne antennas are commonly used to determine plasma parameters like the electron density and the plasma temperature from the noise spectra. It would be desirable to have a controlled experiment in which noise from a plasma with known properties is sampled in space and in time and which results can then be used to reproduce the satellite measurements. Here we examine the possibility to use particle-in-cell (PIC) simulations as such an experiment. In this work we present a statistically averaged noise spectrum computed with a PIC code for a simple single-Maxwellian and unmagnetized electron plasma and we compare it to both, the thermal noise spectrum for the corresponding real plasma and the noise spectrum we would anticipate from our numerical scheme. We find that we can produce noise fields with sufficiently low amplitudes to keep the plasma in a linear regime. We show that the simulation noise at low and at large wave numbers differs not only from thermal noise of a physical plasma but also from the numerical noise we would expect from our numerical scheme. We explain the drop of the noise power at low wave numbers by our initial conditions. We find experimentally the relation that connects the theoretical noise spectrum for our simulation code with that we actually measure, provided that the phase velocity of the noise is less than the maximum velocity of the computational particles.
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| 22. |
- Dieckmann, Mark E, 1969-, et al.
(författare)
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The formation of a relativistic planar plasma shock
- 2008
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Ingår i: 35th EPS Conference on Plasma Physics,2008. - Switzerland : Europhysics Conference Abstracts. ; , s. O5.067-
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Konferensbidrag (refereegranskat)abstract
- The shock is considered that develops, when two plasma clouds collide at the speed 0.9 c. Initially, an almost flow-aligned magnetic field is introduced, which decreases the growth rates of the oblique mixed mode instability and of the filamentation instability. A 2D PIC simulation demonstrates that a planar, electromagnetic wave structure is growing that amplifies the magnetic field component orthogonal to the flow velocity vector. The formation of the forward and reverse shocks is followed with a 1D PIC simulation and it is shown that an energy equi-partition is established downstream between the ions, the electrons and the magnetic field.
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| 23. |
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| 24. |
- Eliasson, Bengt, et al.
(författare)
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Role of spontaneous thermal emissionsin inflationary laser Raman instability
- 2024
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 31
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Tidskriftsartikel (refereegranskat)abstract
- The role of thermal fluctuations on the stimulated Raman backscattering instability is investigated by means of Vlasov and particle-in-cell (PIC) simulations in a regime of strong linear Landau damping of the Langmuir wave. The instability is initially convective and amplifies thermal noise, leading to a low-amplitude back-scattered laser sideband. Linear Landau damping of the Langmuir sideband modifies and flattens the electron velocity distribution function at the resonant velocity, leading to a gradual decrease in the Landau damping rate and an increase in the convective amplification. The Langmuir wave traps electrons resulting in a rapid nonlinear absolute instability and large amplitude flashes of backscattered light off large amplitude Langmuir waves with trapped electrons, leading to the production of hot electrons. Conditions for simulating realistic thermal noise with Vlasov and PIC simulations are discussed and defined.
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| 25. |
- Franklin, Oskar, et al.
(författare)
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Modeling carbon allocation in trees : a search for principles
- 2012
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Ingår i: Tree Physiology. - : Oxford University Press (OUP). - 0829-318X .- 1758-4469. ; 32:6, s. 648-666
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Forskningsöversikt (refereegranskat)abstract
- We review approaches to predicting carbon and nitrogen allocation in forest models in terms of their underlying assumptions and their resulting strengths and limitations. Empirical and allometric methods are easily developed and computationally efficient, but lack the power of evolution-based approaches to explain and predict multifaceted effects of environmental variability and climate change. In evolution-based methods, allocation is usually determined by maximization of a fitness proxy, either in a fixed environment, which we call optimal response (OR) models, or including the feedback of an individual's strategy on its environment (game-theoretical optimization, GTO). Optimal response models can predict allocation in single trees and stands when there is significant competition only for one resource. Game-theoretical optimization can be used to account for additional dimensions of competition, e.g., when strong root competition boosts root allocation at the expense of wood production. However, we demonstrate that an OR model predicts similar allocation to a GTO model under the root-competitive conditions reported in free-air carbon dioxide enrichment (FACE) experiments. The most evolutionarily realistic approach is adaptive dynamics (AD) where the allocation strategy arises from eco-evolutionary dynamics of populations instead of a fitness proxy. We also discuss emerging entropy-based approaches that offer an alternative thermodynamic perspective on allocation, in which fitness proxies are replaced by entropy or entropy production. To help develop allocation models further, the value of wide-ranging datasets, such as FLUXNET, could be greatly enhanced by ancillary measurements of driving variables, such as water and soil nitrogen availability.
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| 26. |
- Kawahara, Rebeca, et al.
(författare)
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Glycoproteome remodeling and organelle-specific N-glycosylation accompany neutrophil granulopoiesis
- 2023
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 120:36
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophils store microbicidal glycoproteins in cytosolic granules to fight intruding pathogens, but their granule distribution and formation mechanism(s) during granulopoiesis remain unmapped. Herein, we comprehensively profile the neutrophil N-glycoproteome with spatiotemporal resolution by analyzing four key types of intracellular organelles isolated from blood-derived neutrophils and during their maturation from bone marrow–derived progenitors using a glycomics-guided glycoproteomics approach. Interestingly, the organelles of resting neutrophils exhibited distinctive glycophenotypes including, most strikingly, highly truncated N-glycans low in α2,6-sialylation and Lewis fucosylation decorating a diverse set of microbicidal proteins (e.g., myeloperoxidase, azurocidin, neutrophil elastase) in the azurophilic granules. Excitingly, proteomics and transcriptomics data from discrete myeloid progenitor stages revealed that profound glycoproteome remodeling underpins the promyelocytic-to-metamyelocyte transition and that the glycophenotypic differences are driven primarily by dynamic changes in protein expression and less by changes within the glycosylation machinery. Notable exceptions were the oligosaccharyltransferase subunits responsible for initiation of N-glycoprotein biosynthesis that were strongly expressed in early myeloid progenitors correlating with relatively high levels of glycosylation of the microbicidal proteins in the azurophilic granules. Our study provides spatiotemporal insights into the complex neutrophil N-glycoproteome featuring intriguing organelle-specific N-glycosylation patterns formed by dynamic glycoproteome remodeling during the early maturation stages of the myeloid progenitors.
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| 27. |
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| 28. |
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| 29. |
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| 30. |
- Lütgendorf-Caucig, C, et al.
(författare)
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Multicenter evaluation of different target volume delineation concepts in pediatric Hodgkin's lymphoma : a case study
- 2012
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Ingår i: Strahlentherapie und Onkologie (Print). - : Springer Science and Business Media LLC. - 0179-7158 .- 1439-099X. ; 188:11, s. 1025-1030
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: In pediatric Hodgkin's lymphoma (PHL) improvements in imaging and multiagent chemotherapy have allowed for a reduction in target volume. The involved-node (IN) concept is being tested in several treatment regimens for adult Hodgkin's lymphoma. So far there is no consensus on the definition of the IN. To improve the reproducibility of the IN, we tested a new involved-node-level (INL) concept, using defined anatomical boundaries as basis for target delineation. The aim was to evaluate the feasibility of IN and INL concepts for PHL in terms of interobserver variability. PATIENTS AND METHODS: The INL concept was defined for the neck and mediastinum by the PHL Radiotherapy Group based on accepted concepts for solid tumors. Seven radiation oncologists from six European centers contoured neck and mediastinal clinical target volumes (CTVs) of 2 patients according to the IN and the new INL concepts. The median CTVs, coefficient of variation (COV), and general conformity index (CI) were assessed. The intraclass correlation coefficient (ICC) for reliability of delineations was calculated. RESULTS: All observers agreed that INL is a feasible and practicable delineation concept resulting in stronger interobserver concordance than the IN (mediastinum CI(INL) = 0.39 vs. CI(IN) = 0.28, neck left CI(INL) = 0.33; CI(IN) = 0.18; neck right CI(INL) = 0.24, CI(IN) = 0.14). The COV showed less dispersion and the ICC indicated higher reliability of contouring for INL (ICC(INL) = 0.62, p < 0.05) as for IN (ICC(IN) = 0.40, p < 0.05). CONCLUSION: INL is a practical and feasible alternative to IN resulting in more homogeneous target delineation, and it should be therefore considered as a future target volume concept in PHL.
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| 31. |
- McClements, K. G., et al.
(författare)
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Surfatron and stochastic acceleration of electrons in astrophysical plasmas
- 2005
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Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 71:2, s. 127-141
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Tidskriftsartikel (refereegranskat)abstract
- Electron acceleration by large amplitude electrostatic waves in astro-physical plasmas is studied using particle-in-cell (PIC) simulations. The waves are excited initially at the electron plasma frequency ωpe by a Buneman instability driven by ion beams: the parameters of the ion beams are appropriate for high Mach number astrophysical shocks, such as those associated with supernova remnants (SNRs). If ωpe is much higher than the electron cyclotron frequency Ωe, the linear phase of the instability does not depend on the magnitude of the magnetic field. However, the subsequent time evolution of particles and waves depends on both ωpe/Ωeand the size of the simulation box L. If L is equal to one wavelength, λ0, of the Buneman-unstable mode, electrons trapped by the waves undergo acceleration via the surfatron mechanism across the wave front. This occurs most efficiently when ωpe/Ω ≃ 100: in this case electrons are accelerated to speeds of up c/2 where c is the speed of light. In a simulation with L = 4λ0 and ωpe/ Ωe = 100, it is found that sideband instabilities give rise to a broad spectrum of wavenumbers, with a power law tail. Some stochastic electron acceleration is observed in this case, but not the surfatron process. Direct integration of the electron equations of motion, using parameters approximating to those of the wave modes observed in the simulations, suggests that the surfatron is compatible with the presence of a broad wave spectrum if Ωpe/Ωe > 100. It is concluded that a combination of stochastic and surfatron acceleration could provide an efficient generator of mildly relativistic electrons at SNR shocks.
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| 32. |
- Murphy, G. C., et al.
(författare)
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Kinetic particle-in-cell simulations of asymmetric quasi-parallel mildly relativistic plasma collisions: Field and electron dynamics
- 2010
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Ingår i: International Journal of Modern Physics D. - 0218-2718. ; 19:6, s. 707-713
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Tidskriftsartikel (refereegranskat)abstract
- A gamma-ray burst (GRB) is triggered by a stellar implosion and the subsequent ejection of an ultrarelativistic jet. The prompt emissions are attributed to mildly relativistic collisions of plasma clouds within this jet. The resulting internal shocks are instrumental in the generation of the magnetic fields and the energetic electrons, which excite the observed electromagnetic emissions. We use particle-in-cell (PIC) simulations to examine such a shock. The colliding hot magnetized plasma clouds have densities that differ by a factor of 10. Current channels form rapidly in the 3D simulation, which resemble those in a Hammer–Rostoker equilibrium, are observed also in the 2D simulation. The 2D simulation also shows the formation of a shock, which is mediated by a strong electromagnetic wave, and the energy equipartition between electrons and ions.
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| 33. |
- Peters, Ellen, et al.
(författare)
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Bringing meaning to numbers: The impact of evaluative categories on decisions.
- 2009
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Ingår i: Journal of Experimental Psychology: Applied. - 1076-898X. ; 15:3, s. 213-227
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Tidskriftsartikel (refereegranskat)abstract
- Decision makers are often quite poor at using numeric information in decisions. The results of 4 experimentsdemonstrate that a manipulation of evaluative meaning (i.e., the extent to which an attribute can be mappedonto a good/bad scale; this manipulation is accomplished through the addition of visual boundary lines andevaluative labels to a graphical format) has a robust influence in health judgments and choices and acrossdiverse adult populations. The manipulation resulted in greater use of numeric quality-of-care information injudgments and less reliance on an irrelevant affective state among the less numerate. Recall results forprovided quality-of-care numbers suggested that the manipulation did not influence depth of number processingwith the exception of cost information that was not remembered as well. Results of a reaction-timeparadigm revealed that feelings were more accessible than thoughts in the presence of the manipulation,suggesting that the effect may be due, at least in part, to an affective mechanism. Numeric information is oftenprovided in decisions, but may not be usable by consumers without assistance from information providers.Implications for consumer decision making and the functions of affect are discussed.
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| 34. |
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| 35. |
- Sarri, Gianluca, et al.
(författare)
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A table-top laser-based source of short, collimated, ultra-relativistic positron beams
- 2013
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Ingår i: Laser Acceleration of Electrons, Protons, and Ions II; and Medical Applications of Laser-Generated Beams of Particles II; and Harnessing Relativistic Plasma Waves III. - : SPIE - International Society for Optical Engineering. - 9780819495815 - 0819495816 ; , s. 87790Z-1-87790Z-7
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Konferensbidrag (refereegranskat)abstract
- An ultra-relativistic electron beam passing through a thick, high-Z solid target triggers an electromagnetic cascade, whereby a large number of high energy photons and electron-positron pairs are produced. By exploiting this physical process, we present here the first experimental evidence of the generation of ultra-short, highly collimated and ultra-relativistic positron beams following the interaction of a laser-wakefield accelerated electron beam with high-Z solid targets. Clear evidence has also been obtained of the generation of GeV electron-positron jets with variable composition depending on the solid target material and thickness. The percentage of positrons in the overall leptonic beam has been observed to vary from a few per cent up to almost fifty per cent, implying a quasi-neutral electron-positron beam. We anticipate that these beams will be of direct relevance to the laboratory study of astrophysical leptonic jets and their interaction with the interstellar medium
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| 36. |
- Sarri, Gianluca, et al.
(författare)
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Dynamics of Self-Generated, Large Amplitude Magnetic Fields Following High-Intensity Laser Matter Interaction
- 2012
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 109:20, s. 205002-
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of magnetic fields with an amplitude of several tens of megagauss, generated at both sides of a solid target irradiated with a high-intensity (∼1019 W/cm2) picosecond laser pulse, has been spatially and temporally resolved using a proton imaging technique. The amplitude of the magnetic fields is sufficiently large to have a constraining effect on the radial expansion of the plasma sheath at the target surfaces. These results, supported by numerical simulations and simple analytical modeling, may have implications for ion acceleration driven by the plasma sheath at the rear side of the target as well as for the laboratory study of self-collimated high-energy plasma jets.
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| 37. |
- Sarri, Gianluca, et al.
(författare)
-
Reply to a comment
- 2020
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 124
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 38. |
- Sarri, Gianluca, et al.
(författare)
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Table-Top Laser-Based Source of Femtosecond, Collimated, Ultrarelativistic Positron Beams
- 2013
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 110:25, s. 255002-1-255002-5
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Tidskriftsartikel (refereegranskat)abstract
- The generation of ultrarelativistic positron beams with short duration (τe+≃30 fs), small divergence (θe+≃3 mrad), and high density (ne+≃1014–1015 cm-3) from a fully optical setup is reported. The detected positron beam propagates with a high-density electron beam and γ rays of similar spectral shape and peak energy, thus closely resembling the structure of an astrophysical leptonic jet. It is envisaged that this experimental evidence, besides the intrinsic relevance to laser-driven particle acceleration, may open the pathway for the small-scale study of astrophysical leptonic jets in the laboratory.
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| 39. |
- Slavc, I, et al.
(författare)
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Improved Long-Term Survival of Patients with Recurrent Medulloblastoma Treated with a "MEMMAT-like" Metronomic Antiangiogenic Approach
- 2022
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Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 14:20
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Tidskriftsartikel (refereegranskat)abstract
- Medulloblastoma (MB) recurrence is usually incurable despite intensive therapy including high-dose chemotherapy. An evolving alternative approach to conventional chemotherapy aims at interfering with tumor angiogenesis at different levels. We report on a novel combinatorial metronomic antiangiogenic approach. The study is a retrospective observational study of 29 consecutive patients with first or multiple recurrences prospectively treated according to the MEMMAT strategy (“MEMMAT-like”) before the formal protocol (MEMMAT; ClinicalTrials.gov Identifier: NCT01356290) started. The study period was 11/2006 to 06/2016. Treatment consisted of daily oral thalidomide, fenofibrate, celecoxib, and alternating 21-day cycles of low-dose oral etoposide and cyclophosphamide supplemented by IV bevacizumab and intraventricular therapy consisting of alternating etoposide and liposomal cytarabine. Median overall survival (OS) after recurrence for the whole group was 29.5 months, OS was 48.3 ± 9.3% at three years and 34.5 ± 8.8% at five years, and progression-free survival was 42.0 ± 9.5% at three years and 29.4 ± 9% at five years. As of 07/2022, 9/29 patients are alive 86 to 164 months after the recurrence that prompted the “MEMMAT-like” therapy. Treatment was primarily out-patient and generally well-tolerated. Toxicities did occur but were manageable. In conclusion, antiangiogenic therapy according to the MEMMAT strategy increased median OS of patients with recurrent MB and may lead to long-term survival. Adherence to the protocol, including intraventricular therapy, appears important.
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Venkatakrishnan, Vignesh, 1987, et al.
(författare)
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Glycan analysis of human neutrophil granules implicates a maturation-dependent glycosylation machinery
- 2020
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:36, s. 12648-12660
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Tidskriftsartikel (refereegranskat)abstract
- Protein glycosylation is essential to trafficking and immune functions of human neutrophils. During granulopoiesis in the bone marrow, distinct neutrophil granules are successively formed. Distinct receptors and effector proteins, many of which are glycosylated, are targeted to each type of granule according to their time of expression, a process called "targeting by timing." Therefore, these granules are time capsules reflecting different times of maturation that can be used to understand the glycosylation process during granulopoiesis. Herein, neutrophil subcellular granules were fractionated by Percoll density gradient centrifugation, andN- andO-glycans present in each compartment were analyzed by LC-MS. We found abundant paucimannosidicN-glycans and lack ofO-glycans in the early-formed azurophil granules, whereas the later-formed specific and gelatinase granules and secretory vesicles contained complexN-andO-glycans with remarkably elongatedN-acetyllactosamine repeats with Lewis epitopes. Immunoblotting and histochemical analysis confirmed the expression of Lewis X and sialyl-Lewis X in the intracellular granules and on the cell surface, respectively. Many glycans identified are unique to neutrophils, and their complexity increased progressively from azurophil granules to specific granules and then to gelatinase granules, suggesting temporal changes in the glycosylation machinery indicative of "glycosylation by timing" during granulopoiesis. In summary, this comprehensive neutrophil granule glycome map, the first of its kind, highlights novel granule-specific glycosylation features and is a crucial first step toward a better understanding of the mechanisms regulating protein glycosylation during neutrophil granulopoiesis and a more detailed understanding of neutrophil biology and function.
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