Magnetic and electric response of gold nanoparticles for low frequency applications in biological cells

In the context of biomedicine, electromagnetic fields are utilized in a variety of applications, such as cellular reprogramming. At frequencies below the microwave spectrum, electric and magnetic fields can often be considered as decoupled. Controlled reprogramming is an example in which biological cells (and gold nanoparticles) are exposed to an external magnetic field. In contrast, tumor treating fields (TTFields) subject tumor cells to an external electric field. The controlled reprogramming of cells is an important part of regenerative medicine and a promising treatment strategy for degenerative diseases like Parkinson’s. In biological in vitro experiments with cell cultures and in some in vivo studies, it has been shown that exposure of cells in combination with gold nanoparticles (AuNPs) to magnetic fields can lead to a significant improvement in cell conversion rates. However, the initial interaction between magnetic fields and cells involving physical laws is still not fully understood. TTFields have been approved for clinical use in Germany for the treatment of glioblastoma since 2015, resulting in a relatively new treatment method for these highly malignant tumors. The effects of TTFields on tumor cells have been extensively studied in association with physical laws, but are not yet fully resolved. In this thesis, I contribute to the understanding of the initial effect of electric and magnetic fields on cells and cells with gold nanoparticles. In particular, electromagnetic parameters are examined that are typical for TTFields and cellular reprogramming. I evaluate and apply analytical and numerical methods to calculate electromagnetic field distributions. These calculations serve as the basis for the assessment of possible mechanisms of action. Furthermore, an electric lumped element model for a cell is developed which compared to other models, analytical calculations and numerical electromagnetic simulations, implifies the approximation of the relative electric field distribution in different cell layers. Additionally, to allow future consideration of electrical properties of nutrient media in calculations a capacitive measurement setup with platinum black electrodes is tested and proposed. This setup allows the determination of ion solution conductivity reliably even at relatively low frequencies around one kilohertz. In vitro cell experiments are important for the validation of theoretical results. In this regard, an improved setup for the in vitro exposure of cells to electric fields is presented, which allows the exposure of cells to more electric field polarization directions by simultaneously allowing higher electric field homogeneity. In conclusion, this thesis makes an important contribution to the field of bioelectromagnetics

Building on piles in floodplains

Last year in the Netherlands 15 locations were allocated along the Rhine branches where – under strong restrictions - it was allowed to build in floodplains. Building in floodplains may lead to a water level rise during floods and moreover, the river bed morphology may be disturbed (erosion/sedimentation). A potential building location on a floodplain of the river IJssel near Deventer (Wilpsche Klei) is used as a fictitious case to investigate these processes

A reality check : the expectations high school seniors have about their first year of college

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Reducing the number of templates for aligned-spin compact binary coalescence gravitational wave searches using metric-agnostic template nudging

Efficient multi-dimensional template placement is crucial in computationally intensive matched-filtering searches for Gravitational Waves (GWs). Here, we implement the Neighboring Cell Algorithm (NCA) to improve the detection volume of an existing Compact Binary Coalescence (CBC) template bank. This algorithm has already been successfully applied for a binary millisecond pulsar search in data from the Fermi satellite. It repositions templates from over-dense regions to under-dense regions and reduces the number of templates that would have been required by a stochastic method to achieve the same detection volume. Our method is readily generalizable to other CBC parameter spaces. Here we apply this method to the aligned--single-spin neutron-star--black-hole binary coalescence inspiral-merger-ringdown gravitational wave parameter space. We show that the template nudging algorithm can attain the equivalent effectualness of the stochastic method with 12% fewer templates

A quality certificate increases trust and donations to a charity

When donating to charities, people expect their money to be spent wisely. However, since donors are not the recipients of final goods and services, they cannot easily assess their quality. Given that large scandals involving charities are covered in press again and again (for example, Kids Company in UK in 2015, or Unicef in Germany in 2006), the reported trust in charities remains low in many countries

COVID-19 and Pro-Sociality: How Do Donors Respond to Local Pandemic Severity, Increased Salience, and Media Coverage?

Has the COVID-19 pandemic affected pro-sociality among individuals? After the onset of the pandemic, many charitable appeals were updated to include a reference to COVID-19. Did donors increase their giving in response to such changes? In order to answer these questions, we conducted a real-donation online experiment with more than 4,200 participants from 149 local areas in England and over 21 weeks. First, we varied the fundraising appeal to either include or exclude a reference to COVID-19. We found that including the reference to COVID-19 in the appeal increased donations. Second, in a natural experiment-like approach, we studied how the relative local severity of the pandemic and media coverage about local COVID-19 severity affected giving in our experiment. We found that both higher local severity and more related articles increased giving of participants in the respective areas. This holds for different specifications, including specifications with location fixed effects, time fixed effects, a broad set of individual characteristics to account for a potentially changing composition of the sample over time and to account for health- and work-related experiences with and expectations regarding the pandemic. While negative experiences with COVID-19 correlate negatively with giving, both approaches led us to conclude that the pure effect of increased salience of the pandemic on pro-sociality is positive. Despite the shift in public attention toward the domestic fight against the pandemic and away from developing countries’ challenges, we found that preferences did not shift toward giving more to a national project and less to developing countries

Solar Self-Sufficient Households as a Driving Factor for Sustainability Transformation

We present a model to estimate the technical requirements, including the photovoltaic area and battery capacity, along with the costs, for a four-person household to be 100% electrically self-sufficient in Germany. We model the hourly electricity consumption of private households with quasi-Fourier series and an autoregressive statistical model based on data from Berlin in 2010. Combining the consumption model and remote-sensed hourly solar irradiance data from the ERA5 data set, we find the optimal photovoltaic area and battery capacity that would have been necessary to be self-sufficient in electricity from July 2002 to June 2022. We show that it is possible to build a self-sufficient household with today’s storage technology for private households and estimate the costs expected to do so

A rare case report of neurolymphomatosis with NK-T-cell lymphoma

Neurolymphomatosis (NL) is a rare entity. It is usually a manifestation of B-cell lymphoma. Here we describe a case of neurolymphomatosis in a 72 year old man who was in remission for Nasal T-cell lymphoma and presented to us with subacute onset painful mononeuritis like weakness involving all 4 limbs sequentially over a period of 4 months. he was initially treated as CIDP with steroids but later in view of progression he was evaluated further. His FDG PET-CT showed increased uptake in left brachial plexus which was confirmed by subsequent MRI neurography. He underwent biopsy of left brachial plexus and diagnosis of neurolymphomatosis was confirmed. He was treated with intravenous immunoglobulins (2 gm/kg) over 5 days with minimal improvement in his neurological symptoms, his shoulder pain improved and he could feed himself with right hand. He was offered palliative treatment in view of poor prognosis seen in neurolymphomatosis. He succumbed to the illness 3 months later

Non-invasive detection of charge-rearrangement in a quantum dot in high magnetic fields

We demonstrate electron redistribution caused by magnetic field on a single quantum dot measured by means of a quantum point contact as non-invasive detector. Our device which is fabricated by local anodic oxidation allows to control independently the quantum point contact and all tunnelling barriers of the quantum dot. Thus we are able to measure both the change of the quantum dot charge and also changes of the electron configuration at constant number of electrons on the quantum dot. We use these features to exploit the quantum dot in a high magnetic field where transport through the quantum dot displays the effects of Landau shells and spin blockade. We confirm the internal rearrangement of electrons as function of the magnetic field for a fixed number of electrons on the quantum dot.Comment: 4 pages, 5 figure