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  • Publication
    Glass Molding Tools Fabricated with Selective Laser-induced Etching for Sustainable Treatment of Solid-State Electrolytes
    ( 2024)
    Peters, Christian
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    Geppert, Benjamin
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    Dashjav, Enkhtsetseg
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    Kratz, Martin Thomas
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    Tietz, Frank
    Selective laser-induced etching enables the high-precision fabrication of three-dimensional com ponents from transparent materials. First, ultrashort pulsed, tightly focused laser radiation is used to create a modification within the bulk of the transparent material. By selectively moving the focus, entire contiguous surfaces and volumes can be modified. Subsequently, the modified areas are etched free using an etching liquid. Thus, the desired three-dimensional component is exposed and separated from the surrounding material. Using the SLE process, molding tools made of fused silica are fabri cated with functional structures of less than 150 µm in size. By molding the solid-state electrolyte foil of a sodium-based battery cell, the contact areas between the chemical components are increased to enhance the power density. Different structural geometries and dimensions are compared to increase this effect
  • Publication
    An ultra-stable high-power optical frequency comb
    ( 2024)
    Schmidt, Fabian
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    Moreno, Jorge O.
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    Russbueldt, Peter
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    Hänsch, Theodor W.
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    Udem, Thomas
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    Ozawa, Akira
    Optical frequency combs are typically generated in the near-infrared wavelength range, where many mode-locked lasers operate. Nonlinear frequency conversion can then be used to extend optical frequency metrology to other spectral regions, such as the extreme ultraviolet (XUV). High-power frequency combs at the fundamental wavelength can efficiently drive nonlinear frequency conversions. Low phase noise is an important requirement because the frequency conversion process not only multiplies the carrier frequency but also the phase fluctuations. In this work, we have developed a low-noise frequency comb centered at 1030 nm with an average power of 230 W, a temporal pulse duration of 59 fs, and a peak power of 32 MW. One of the modes of the seed laser is phase-locked to a continuous wave reference laser stabilized to an ultra-stable high-finesse cavity. The residual integrated phase noise from 10 Hz to 10 MHz is 41 mrad, which is sufficiently low to address narrow transitions with kHz-level linewidths after the frequency conversion to XUV wavelengths.
  • Publication
    Ripple-locked coactivity of stimulus-specific neurons and human associative memory
    ( 2024)
    Kunz, Lukas
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    Staresina, Bernhard P.
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    Brandt, Armin
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    Guth, Tim A.
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    Schulze-Bonhage, Andreas
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    Jacobs, Joshua
    Associative memory enables the encoding and retrieval of relations between different stimuli. To better understand its neural basis, we investigated whether associative memory involves temporally correlated spiking of medial temporal lobe (MTL) neurons that exhibit stimulus-specific tuning. Using single-neuron recordings from patients with epilepsy performing an associative object-location memory task, we identified the object-specific and place-specific neurons that represented the separate elements of each memory. When patients encoded and retrieved particular memories, the relevant object-specific and place-specific neurons activated together during hippocampal ripples. This ripple-locked coactivity of stimulus-specific neurons emerged over time as the patients’ associative learning progressed. Between encoding and retrieval, the ripple-locked timing of coactivity shifted, suggesting flexibility in the interaction between MTL neurons and hippocampal ripples according to behavioral demands. Our results are consistent with a cellular account of associative memory, in which hippocampal ripples coordinate the activity of specialized cellular populations to facilitate links between stimuli.
  • Publication
    Alternative printing technologies
    With respect to the solar cell application, homogeneous, fine-line printed front contacts allowed for efficiency increases of around Δη/η = 1% compared to respective screen-printed reference over the years and the absence of mesh marks reduced the silver (Ag) laydown by 20% without reducing grid conductivity with commercially available screen-printing pastes.
  • Publication
    Disbalanced recruitment of crossed and uncrossed cerebello-thalamic pathways during deep brain stimulation is predictive of delayed therapy escape in essential tremor
    ( 2024)
    Sajonz, Bastian E.A.
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    Frommer, Marvin L
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    Reisert, Marco
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    Blazhenets, Ganna
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    Schröter, Nils
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    Rau, Alexander
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    Prokop, Thomas
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    Rijntjes, Michel
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    Urbach, Horst
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    Meyer, Philipp T.
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    Coenen, Volker A.
    Background: Thalamic deep brain stimulation (DBS) is an efficacious treatment for drug-resistant essential tremor (ET) and the dentato-rubro-thalamic tract (DRT) constitutes an important target structure. However, up to 40% of patients habituate and lose treatment efficacy over time, frequently accompanied by a stimulation-induced cerebellar syndrome. The phenomenon termed delayed therapy escape (DTE) is insufficiently understood. Our previous work showed that DTE clinically is pronounced on the non-dominant side and suggested that differential involvement of crossed versus uncrossed DRT (DRTx/DRTu) might play a role in DTE development. Methods: We retrospectively enrolled right-handed patients under bilateral thalamic DBS >12 months for ET from a cross-sectional study. They were characterized with the Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS) and Scale for the Assessment and Rating of Ataxia (SARA) scores at different timepoints. Normative fiber tractographic evaluations of crossed and uncrossed cerebellothalamic pathways and volume of activated tissue (VAT) studies together with [18F]Fluorodeoxyglucose positron emission tomography were applied. Results: A total of 29 patients met the inclusion criteria. Favoring DRTu over DRTx in the non-dominant VAT was associated with DTE (R2 = 0.4463, p < 0.01) and ataxia (R2 = 0.2319, p < 0.01). Moreover, increasing VAT size on the right (non-dominant) side was associated at trend level with more asymmetric glucose metabolism shifting towards the right (dominant) dentate nucleus. Conclusion: Our results suggest that a disbalanced recruitment of DRTu in the non-dominant VAT induces detrimental stimulation effects on the dominant cerebellar outflow (together with contralateral stimulation) leading to DTE and thus hampering the overall treatment efficacy.