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  1. Article ; Online: Multi-GeV wakefield acceleration in a plasma-modulated plasma accelerator.

    van de Wetering, J J / Hooker, S M / Walczak, R

    Physical review. E

    2024  Volume 109, Issue 2-2, Page(s) 25206

    Abstract: We investigate the accelerator stage of a plasma-modulated plasma accelerator (P-MoPA) [Jakobsson et al., Phys. Rev. Lett. 127, 184801 (2021)0031-900710.1103/PhysRevLett.127.184801] using both the paraxial wave equation and particle-in-cell (PIC) ... ...

    Abstract We investigate the accelerator stage of a plasma-modulated plasma accelerator (P-MoPA) [Jakobsson et al., Phys. Rev. Lett. 127, 184801 (2021)0031-900710.1103/PhysRevLett.127.184801] using both the paraxial wave equation and particle-in-cell (PIC) simulations. We show that adjusting the laser and plasma parameters of the modulator stage of a P-MoPA allows the temporal profile of pulses within the pulse train to be controlled, which in turn allows the wake amplitude in the accelerator stage to be as much as 72% larger than that generated by a plasma beat-wave accelerator with the same total drive laser energy. Our analysis shows that Rosenbluth-Liu detuning is unimportant in a P-MoPA if the number of pulses in the train is less than ∼30, and that this detuning is also partially counteracted by increased red-shifting, and hence increased pulse spacing, towards the back of the train. An analysis of transverse mode oscillations of the driving pulse train is found to be in good agreement with 2D (Cartesian) PIC simulations. PIC simulations demonstrating energy gains of ∼1.5GeV (∼2.5GeV) for drive pulse energies of 2.4J (5.0J) are presented. Our results suggest that P-MoPAs driven by few-joule, picosecond pulses, such as those provided by high-repetition-rate thin-disk lasers, could accelerate electron bunches to multi-GeV energies at pulse repetition rates in the kilohertz range.
    Language English
    Publishing date 2024-03-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2844562-4
    ISSN 2470-0053 ; 2470-0045
    ISSN (online) 2470-0053
    ISSN 2470-0045
    DOI 10.1103/PhysRevE.109.025206
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Modulational instability in large-amplitude linear laser wakefields.

    von Boetticher, A / Walczak, R / Hooker, S M

    Physical review. E

    2023  Volume 107, Issue 2, Page(s) L023201

    Abstract: We investigate the growth of ion density perturbations in large-amplitude linear laser wakefields via two-dimensional particle-in-cell simulations. Growth rates and wave numbers are found to be consistent with a longitudinal strong-field modulational ... ...

    Abstract We investigate the growth of ion density perturbations in large-amplitude linear laser wakefields via two-dimensional particle-in-cell simulations. Growth rates and wave numbers are found to be consistent with a longitudinal strong-field modulational instability. We examine the transverse dependence of the instability for a Gaussian wakefield envelope and show that growth rates and wave numbers can be maximized off axis. On-axis growth rates are found to decrease with increasing ion mass or electron temperature. These results are in close agreement with the dispersion relation of a Langmuir wave with an energy density that is large compared to the plasma thermal energy density. The implications for wakefield accelerators, in particular multipulse schemes, are discussed.
    Language English
    Publishing date 2023-03-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2844562-4
    ISSN 2470-0053 ; 2470-0045
    ISSN (online) 2470-0053
    ISSN 2470-0045
    DOI 10.1103/PhysRevE.107.L023201
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Book ; Online: Particle Physics in the LHC era

    Barr, Giles / Devenish, R. / Walczak, R. / Weidberg, T.

    (Oxford Master Series In Physics)

    2016  

    Series title Oxford Master Series In Physics
    Keywords Particle & high-energy physics ; Nuclear physics ; Astrophysics ; Cosmology & the universe ; Atomic & molecular physics ; Particle physics, nuclear physics, astrophysics, cosmology, accelerator physics, detector physics, quarks and leptons, Dirac equation, electroweak theory, quantum chromodynamics, flavour oscillations, CP violation, Higgs boson, Beyond the Standard Model physics
    Language 0|e
    Size 1 electronic resource (422 pages)
    Publisher Oxford University Press
    Document type Book ; Online
    Note English ; Open Access
    HBZ-ID HT021621224
    ISBN 9780198748557 ; 0198748558
    Database ZB MED Catalogue: Medicine, Health, Nutrition, Environment, Agriculture

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  4. Article ; Online: Stability of the modulator in a plasma-modulated plasma accelerator.

    van de Wetering, J J / Hooker, S M / Walczak, R

    Physical review. E

    2023  Volume 108, Issue 1-2, Page(s) 15204

    Abstract: We explore the regime of operation of the modulator stage of a recently proposed laser-plasma accelerator scheme [Phys. Rev. Lett. 127, 184801 (2021)0031-900710.1103/PhysRevLett.127.184801], dubbed the plasma-modulated plasma accelerator (P-MoPA). The P- ... ...

    Abstract We explore the regime of operation of the modulator stage of a recently proposed laser-plasma accelerator scheme [Phys. Rev. Lett. 127, 184801 (2021)0031-900710.1103/PhysRevLett.127.184801], dubbed the plasma-modulated plasma accelerator (P-MoPA). The P-MoPA scheme offers a potential route to high-repetition-rate, GeV-scale plasma accelerators driven by picosecond-duration laser pulses from, for example, kilohertz thin-disk lasers. The first stage of the P-MoPA scheme is a plasma modulator in which a long, high-energy "drive" pulse is spectrally modulated by copropagating in a plasma channel with the low-amplitude plasma wave driven by a short, low-energy "seed" pulse. The spectrally modulated drive pulse is converted to a train of short pulses, by introducing dispersion, which can resonantly drive a large wakefield in a subsequent accelerator stage with the same on-axis plasma density as the modulator. In this paper we derive the 3D analytic theory for the evolution of the drive pulse in the plasma modulator and show that the spectral modulation is independent of transverse coordinate, which is ideal for compression into a pulse train. We then identify a transverse mode instability (TMI), similar to the TMI observed in optical fiber lasers, which sets limits on the energy of the drive pulse for a given set of laser-plasma parameters. We compare this analytic theory with particle-in-cell (PIC) simulations and find that even higher energy drive pulses can be modulated than those demonstrated in the original proposal.
    Language English
    Publishing date 2023-07-27
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2844562-4
    ISSN 2470-0053 ; 2470-0045
    ISSN (online) 2470-0053
    ISSN 2470-0045
    DOI 10.1103/PhysRevE.108.015204
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Fluorine‐18 fluorodeoxyglucose positron emission tomography‐computed tomography for staging of canine insulinoma: 3 cases (2019–2020)

    Walczak, R. / Kawalilak, L. / Griffin, L.

    journal of small animal practice. 2022 Mar., v. 63, no. 3

    2022  

    Abstract: OBJECTIVES: Canine insulinomas are uncommon malignant functional pancreatic neuroendocrine tumours with a high metastatic rate. Diagnostic imaging aids with staging and surgical planning of these tumours; however, identification is unpredictable across ... ...

    Abstract OBJECTIVES: Canine insulinomas are uncommon malignant functional pancreatic neuroendocrine tumours with a high metastatic rate. Diagnostic imaging aids with staging and surgical planning of these tumours; however, identification is unpredictable across modalities. High‐grade human pancreatic neuroendocrine tumours display increased avidity on ¹⁸F‐fluorodeoxyglucose positron emission tomography‐CT. MATERIALS AND METHODS: Dogs with clinicopathologic findings consistent with pancreatic insulinoma were prospectively enrolled. Patients underwent ¹⁸F‐fluorodeoxyglucose positron emission tomography‐CT and CT angiography, followed by exploratory laparotomy. RESULTS: Three patients met the inclusion criteria and had histologically confirmed insulinomas. Both metastatic lesions in patient 1 were mildly avid (SUVₘₐₓ 2.79 and 3.01). In patient 2, the primary pancreatic insulinoma was minimally avid (SUVₘₐₓ 2.16). The primary pancreatic lesion in patient 3 had similar avidity to normal pancreatic parenchyma (SUVₘₐₓ 1.54) and was undetected on ¹⁸F‐fluorodeoxyglucose positron emission tomography‐CT. Insulinomas demonstrated variable attenuation and contrast enhancement patterns on CT angiography and certain lesions were more conspicuous than on ¹⁸F‐fluorodeoxyglucose positron emission tomography‐CT. Two metastatic lesions not visible on either imaging modality were discovered in patient 2 at surgery. CLINICAL SIGNIFICANCE: Canine insulinomas were inconsistently avid on ¹⁸F‐fluorodeoxyglucose positron emission tomography‐CT. This finding is likely attributable to the confounding clinicopathological features and multifaceted transformation of these tumours, in addition to the influence of variable tumour size, composition and vascularity. Unpredictable tumoural avidity limits the value of ¹⁸F‐fluorodeoxyglucose positron emission tomography‐CT for staging canine insulinomas.
    Keywords angiography ; dogs ; electrons ; humans ; laparotomy ; metastasis ; neoplasms ; patients ; small animal practice ; tomography
    Language English
    Dates of publication 2022-03
    Size p. 227-233.
    Publishing place Blackwell Publishing Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 410743-3
    ISSN 1748-5827 ; 0022-4510 ; 1748-5827
    ISSN (online) 1748-5827
    ISSN 0022-4510 ; 1748-5827
    DOI 10.1111/jsap.13446
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Cologne/Königswinter

    Zs.B 590: Show issues Location:
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  6. Article ; Online: Gev-Scale Accelerators Driven by Plasma-Modulated Pulses from Kilohertz Lasers.

    Jakobsson, O / Hooker, S M / Walczak, R

    Physical review letters

    2021  Volume 127, Issue 18, Page(s) 184801

    Abstract: We describe a new approach for driving GeV-scale plasma accelerators with long laser pulses. We show that the temporal phase of a long, high-energy driving laser pulse can be modulated periodically by copropagating it with a low-amplitude plasma wave ... ...

    Abstract We describe a new approach for driving GeV-scale plasma accelerators with long laser pulses. We show that the temporal phase of a long, high-energy driving laser pulse can be modulated periodically by copropagating it with a low-amplitude plasma wave driven by a short, low-energy seed pulse. Compression of the modulated driver by a dispersive optic generates a train of short pulses suitable for resonantly driving a plasma accelerator. Modulation of the driver occurs via well-controlled linear processes, as confirmed by good agreement between particle-in-cell (PIC) simulations and an analytic model. PIC simulations demonstrate that a 1.7 J, 1 ps driver, and a 140 mJ, 40 fs seed pulse can accelerate electrons to energies of 0.65 GeV in a plasma channel with an axial density of 2.5×10^{17}  cm^{-3}. This work opens a route to high repetition-rate, GeV-scale plasma accelerators driven by thin-disk lasers, which can provide joule-scale, picosecond-duration laser pulses at multikilohertz repetition rates and high wall-plug efficiencies.
    Language English
    Publishing date 2021-11-12
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.127.184801
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    In stock of ZB MED Bonn / Germany

    Z 4' 58/153: Show issues

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  7. Article ; Online: Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography for staging of canine insulinoma: 3 cases (2019-2020).

    Walczak, R / Kawalilak, L / Griffin, L

    The Journal of small animal practice

    2021  Volume 63, Issue 3, Page(s) 227–233

    Abstract: Objectives: Canine insulinomas are uncommon malignant functional pancreatic neuroendocrine tumours with a high metastatic rate. Diagnostic imaging aids with staging and surgical planning of these tumours; however, identification is unpredictable across ... ...

    Abstract Objectives: Canine insulinomas are uncommon malignant functional pancreatic neuroendocrine tumours with a high metastatic rate. Diagnostic imaging aids with staging and surgical planning of these tumours; however, identification is unpredictable across modalities. High-grade human pancreatic neuroendocrine tumours display increased avidity on
    Materials and methods: Dogs with clinicopathologic findings consistent with pancreatic insulinoma were prospectively enrolled. Patients underwent
    Results: Three patients met the inclusion criteria and had histologically confirmed insulinomas. Both metastatic lesions in patient 1 were mildly avid (SUV
    Clinical significance: Canine insulinomas were inconsistently avid on
    MeSH term(s) Animals ; Dog Diseases/diagnostic imaging ; Dog Diseases/pathology ; Dogs ; Fluorine Radioisotopes ; Fluorodeoxyglucose F18 ; Humans ; Insulinoma/diagnostic imaging ; Insulinoma/pathology ; Insulinoma/veterinary ; Neoplasm Staging ; Pancreatic Neoplasms/diagnostic imaging ; Pancreatic Neoplasms/pathology ; Pancreatic Neoplasms/veterinary ; Positron Emission Tomography Computed Tomography/methods ; Positron Emission Tomography Computed Tomography/veterinary ; Positron-Emission Tomography/methods ; Radiopharmaceuticals
    Chemical Substances Fluorine Radioisotopes ; Radiopharmaceuticals ; Fluorodeoxyglucose F18 (0Z5B2CJX4D) ; Fluorine-18 (GZ5I74KB8G)
    Language English
    Publishing date 2021-11-22
    Publishing country England
    Document type Journal Article
    ZDB-ID 410743-3
    ISSN 1748-5827 ; 0022-4510 ; 1748-5827
    ISSN (online) 1748-5827
    ISSN 0022-4510 ; 1748-5827
    DOI 10.1111/jsap.13446
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Nanosatellite Payload for Research on Seed Germination in a 3D Printed Micropot.

    Kawa, Bartosz / Śniadek, Patrycja / Walczak, Rafał / Dziuban, Jan

    Sensors (Basel, Switzerland)

    2023  Volume 23, Issue 4

    Abstract: In this paper, an autonomous payload proposal for a nanosatellite mission allowing for the cultivation of grains in space was presented. For the first time, a micropot made with 3D printing technology, enabling the parametric determination of plant ... ...

    Abstract In this paper, an autonomous payload proposal for a nanosatellite mission allowing for the cultivation of grains in space was presented. For the first time, a micropot made with 3D printing technology, enabling the parametric determination of plant growth, both on Earth and in the simulated microgravity condition, was presented. A completed system for dosing the nutrient solution and observing the growth of a single grain, where the whole size did not exceed 70 × 50 × 40 mm
    MeSH term(s) Germination ; Seeds ; Edible Grain ; Nutrients ; Printing, Three-Dimensional
    Language English
    Publishing date 2023-02-10
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2052857-7
    ISSN 1424-8220 ; 1424-8220
    ISSN (online) 1424-8220
    ISSN 1424-8220
    DOI 10.3390/s23041974
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  9. Article ; Online: Vulvar Ulcers in a Non-Sexually Active Adolescent.

    Corrado, Alisa / Cheo, Savannah / Walczak, Rose

    Pediatrics in review

    2023  Volume 45, Issue 4, Page(s) e11–e13

    MeSH term(s) Female ; Adolescent ; Humans ; Ulcer/diagnosis ; Ulcer/etiology ; Ulcer/therapy ; Vulvar Diseases/diagnosis ; Vulvar Diseases/etiology ; Vulvar Diseases/therapy ; Diagnosis, Differential
    Language English
    Publishing date 2023-12-27
    Publishing country United States
    Document type Journal Article
    ZDB-ID 774515-1
    ISSN 1526-3347 ; 0191-9601
    ISSN (online) 1526-3347
    ISSN 0191-9601
    DOI 10.1542/pir.2022-005917
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    Zs.B 2595: Show issues Location:
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    Zs.MO 53: Show issues

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  10. Article: Possibilities of Increasing Effectiveness of RC Structure Strengthening with FRP Materials.

    Derkowski, Wit / Walczak, Rafał

    Materials (Basel, Switzerland)

    2021  Volume 14, Issue 6

    Abstract: Modern composite materials based on non-metallic continuous fibres are increasingly used in civil engineering to strengthen building structures. In the strengthening of reinforced concrete (RC) structures, the utilisation of externally bonded fibre- ... ...

    Abstract Modern composite materials based on non-metallic continuous fibres are increasingly used in civil engineering to strengthen building structures. In the strengthening of reinforced concrete (RC) structures, the utilisation of externally bonded fibre-reinforced polymer (FRP) composites is only up to 35% because of the pilling-off failure mechanism. This problem can be solved using pre-tensioned composite laminates. Due to more complex behaviour, the strengthening of structures by means of prestressing technology needs a careful design approach and a full understanding of the behaviour of both the materials and elements. The advantages and risks of the presented technology, which may determine the success of the entire project, will be highlighted in the paper. The possibility of using a flexible adhesive layer in carbon fibre reinforced polymer (CFRP) strengthening applications for flexural strengthening of RC elements, as an innovative solution in civil engineering, will also be presented. Parallel introduction of the flexible adhesive layer (made of polyurethane masses) and a traditional epoxy adhesive layer in one strengthening system was investigated in the laboratory tests. This solution was used for the repair and protection of a previously damaged RC beam against brittle failure.
    Language English
    Publishing date 2021-03-12
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2487261-1
    ISSN 1996-1944
    ISSN 1996-1944
    DOI 10.3390/ma14061387
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