Publications by authors named "Tim Vogel"

Ultrafast THz transients with large spectral bandwidths are commonly generated in the two-color air-plasma scheme, typically driven by high-pulse-energy laser sources, operating at low repetition rates up to a few kHz. The low repetition rate of these sources is a strong limiting factor to reaching high dynamic ranges in measurements involving long integration times or multi-dimensional scans. The advent of high-power Yb-based laser sources in combination with nonlinear temporal compression schemes opens the door to air-plasma THz sources at significantly higher repetition rates up to hundreds of kHz and beyond.

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Rhythmic Movement Disorder (RMD) is a parasomnia characterized by repetitive, rhythmic movements such as headbanging or body rocking. It typically occurs in infancy and early childhood, often disrupting sleep, and may occasionally persist into later childhood or, in rare cases, adulthood. Although its etiology remains poorly understood, RMD episodes may function as self-soothing behaviors to facilitate sleep.

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Emitters based on photoconductive materials excited by ultrafast lasers are well-established and popular devices for THz generation. However, so far, these emitters - both photoconductive antennas and large area emitters - were mostly explored using driving lasers with moderate average powers (either fiber lasers with up to hundreds of milliwatts or Ti:Sapphire systems up to few watts). In this paper, we explore the use of high-power, MHz repetition rate Ytterbium (Yb) based oscillator for THz emission using a microstructured large-area photoconductive emitter, consist of semi-insulating GaAs with a 10 × 10 mm active area.

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We present the highest, to the best of our knowledge, average power from a laser-driven single-cycle THz source demonstrated so far, using optical rectification in the tilted pulse front geometry in cryogenically cooled lithium niobate, pumped by a commercially available 500 W ultrafast thin-disk ytterbium (Yb) amplifier. We study repetition rate-dependent effects in our setup at 100 and 40 kHz at this high average power, revealing different optimal fluence conditions for efficient conversion. The demonstrated sources with multi-100 mW average power at these high repetition rates combine high THz pulse energies and high repetition rate and are thus ideally suited for nonlinear THz spectroscopy experiments with significantly reduced measurement times.

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As high-average power ultrafast lasers become increasingly available for nonlinear conversion, the temperature dependence of the material properties of nonlinear crystals becomes increasingly relevant. Here, we present temperature-dependent THz complex refractive index measurements of the organic crystal BNA over a wide range of temperatures from 300 K down to 80 K for THz frequencies up to 4 THz for the first time. Our measurements show that whereas the temperature-dependent refractive index has only minor deviation from room temperature values, the temperature-dependent absorption coefficient decreases at low temperature (-24% from 300 K to 80 K).

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Multi-pass cell (MPC) based temporal pulse compressors have emerged in recent years as a powerful and versatile solution to the intrinsic issue of long pulses from Yb-based high-power ultrafast lasers. The spectral broadening of high-energy (typically more than 100 µJ) pulses has only been realized in gas-filled MPCs due to the significantly lower nonlinear coefficient of gases compared with solid-state media. Whereas these systems reach impressive performance in terms of spectral broadening with very low spatiotemporal couplings, they are typically complex setups, i.

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Components of the growth hormone (GH) axis, such as insulin-like growth factor-1 (IGF-1), IGF-1 binding protein-3 (IGFBP-3), GH receptor (GHR) and GH-binding protein (GHBP), regulate growth and metabolic pathways. Here, we asked if serum levels of these factors are altered with overweight/obesity and if this is related to adipose tissue (AT) expression and/or increased fat mass. Furthermore, we hypothesized that expression of and is associated with AT function.

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Metallic spintronic terahertz (THz) emitters have become well-established for offering ultra-broadband, gapless THz emission in a variety of excitation regimes, in combination with reliable fabrication and excellent scalability. However, so far, their potential for high-average-power excitation to reach strong THz fields at high repetition rates has not been thoroughly investigated. In this article, we explore the power scaling behavior of tri-layer spintronic emitters using an Yb-fiber excitation source, delivering an average power of 18.

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We demonstrate a 13.3 MHz repetition rate, broadband THz source with milliwatt- average power, obtained by collinear optical rectification of a high-power Yb-doped thin-disk laser in the organic crystal BNA (N-benzyl-2-methyl-4-nitroaniline). Our source reaches a maximum THz average power of 0.

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Harvesting solar energy for vapor generation is an appealing technology that enables substantial eco-friendly applications to overcome the long-standing global challenge of water and energy crisis. Nonetheless, an undesirable low light utilization efficiency and large heat losses impede their practical use. Here, we demonstrate a typical design paradigm capable of achieving superb nonconvective flow assisted water collecting rates of 2.

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Background: Obesity can affect linear growth of children but there is uncertainty regarding the dynamics and potential causes.

Methods: In the population-based LIFE Child and the obesity-enriched Leipzig Obesity Childhood cohorts (8,629 children, 37,493 measurements), recruited from 1999 to 2018 in Germany, we compared height, growth, and endocrine parameters between normal-weight and children with obesity (0-20 years). Derived from the independent German CrescNet registry (12,703 children) we generated height reference values specific for children with obesity (data collected from 1999 to 2020).

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Primary cilia are microtubule-based organelles present on most cells that regulate many physiological processes, ranging from maintaining energy homeostasis to renal function. However, the role of these structures in the regulation of behavior remains unknown. To study the role of cilia in behavior, we employ mouse models of the human ciliopathy, Bardet-Biedl Syndrome (BBS).

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The current number of drugs available for the treatment of Alzheimer's disease (AD) is strongly limited and their benefit for therapy is given only in the early state of the disease. An effective therapy should affect those processes which mainly contribute to the neuronal decay. There have been many approaches for a reduction of toxic Aβ peptides which mostly failed to halt cognitive deterioration in patients.

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Bardet-Biedl Syndrome (BBS) is a pleiotropic and genetically heterozygous disorder caused independently by numerous genes (BBS1-BBS17). Seven highly conserved BBS proteins (BBS1, 2, 4, 5, 7, 8 and 9) form a complex known as the BBSome, which functions in ciliary membrane biogenesis. BBS7 is both a unique subunit of the BBSome and displays direct physical interaction with a second BBS complex, the BBS chaperonin complex.

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Bardet-Biedl syndrome (BBS) is a heterogeneous disorder characterized by obesity, retinopathy, polydactyly, and congenital anomalies. The incidence of hypertension and diabetes are also increased in BBS patients. Mutation of 16 genes independently causes BBS, and seven BBS proteins form the BBSome that promotes ciliary membrane elongation.

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