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Freezing FreeBSD systems - NCQ on SSDs - a short troubleshooting journey
5 mins
This article solves the mystery behind some of my FreeBSD systems that had appeared to be randomly freezing and provides a solution to this single specific problem.
Nuclear magnetic resonance and electron paramagnetic resonance: Basics
44 mins
Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) are pivotal techniques used to explore molecular structures and dynamics through the magnetic properties of atomic nuclei and unpaired electrons. This article provides an introductory level examination of NMR, integrating both classical and quantum mechanical descriptions. Key topics include the Zeeman effect, Bloch equations, relaxation processes, and the quantum mechanical framework involving spin operators, Eigenstates, and the density matrix formalism. The discussion delves into the effects of RF driving fields, Rabi oscillations, and the incorporation of relaxation processes using the Lindblad master equation. The article concludes by demonstrating how these quantum mechanical models align with the phenomenological Bloch equations, providing a comprehensive understanding of the dynamics of spin systems under resonance conditions. While the primary focus is on NMR, the article also offers insights into EPR, broadening the perspective on magnetic resonance techniques.
Language negotiation for static website using Apache httpd
9 mins
Discover how to implement language negotiation on a static website using Apaches mod_rewrite. This article provides a step-by-step guide to serving translated content based on users browser preferences, enabling a seamless multilingual experience without the need for complex server-side scripts or content management systems. Whether you are looking to add multilingual support to your Jekyll-generated site or simply explore the powerful features of Apache, this guide offers clear explanations and practical examples to help you get started.
Towards in-situ nanoscale spatially resolved electron spin resonance in scanning electron microscopes
1 min
Presented at the 14th ASEM (Austrian Society for Electron Microscopy) workshop Electron spin resonance is a widely used analytical tool in medicine, biology and material sciences. Traditionally, electron spin systems are driven by microwaves, which offers only limited spatial resolution due to the long wavelength of microwaves, which can be optimized by sophisticated techniques such as the use of magnetic field gradients. We propose a different way of driving spin systems using the non-radiative near-field of a modulated electron beam in a scanning electron microscope by tuning the microscopes to higher beam currents and using additional beam modulation mechanisms. Driving systems with higher harmonics of the modulated beam opens up future possibilities to perform in-situ electron spin resonance analysis with high spatial resolution down to the nanoscale. To perform our experiments we modified an Philips XL30 ESEM to allow for high frequency beam modulation, cryogenic cooling of our samples and microwave frequency readout of our spin systems.
The MLX90640 on the RaspberryPi with FreeBSD
51 mins
This article explores the integration of the MLX90640 far infrared thermal sensor with a RaspberryPi using FreeBSD. It delves into the technicalities of interfacing the sensor, the intricacies of its data processing and compensation algorithms, and demonstrates these concepts with Python code examples.
Using RaspberryPis I2C from Python
7 mins
This article gives a short summary on the way to interface with the I2C bus on RaspberryPi using Python by using a thin wrapper around the ioctl calls supported by FreeBSD. In addition it introduces a small PyPi package that supplies this thin wrapper.
Electric dipole interaction of atoms with radiated electromagnetic waves
22 mins
A short summary on the interaction of alkali atoms with electromagnetic radiation
A first quick look on different sentence embedding methods - playing with word and sentence embeddings
45 mins
A quick overview on how one can generate word and sentence embeddings using BERT, mpnet and OpenAIs sentence embedding API in Python. The second part also includes a mini semantic search engine (with linear index that only serves demonstration purpose). This article does not offer and in depth explanation but only a quick overview glance on the APIs to play around.
Another quick glance on the OpenAI API to ChatGPT using function calling
59 mins
This is a very short overview on how to use the tooling/function API of ChatGPT to call external functions to perform actions or retrieve some simple information. In addition a simple iterative problem solving process of GPTs is shown as an example in Python. It makes use of an external commercial API though.
Towards coherently driven spatially resolved electron spin resonance in a scanning electron microscope
1 min
Presented at the seminar at Atominstitut der Technischen Universität Wien. Electron spin resonance is a widely used analytical tool in medicine, biology and material sciences. Spin systems have many applications in quantum physics - for example in quantum computing and sensing. Traditionally such spin systems are driven with microwaves which offer only limited spatial resolution. We are currently in the process of developing and building experiments with the aim to coherently drive electron spin systems with high spatial resolution using the collective effect of the non radiative near field of modulated electron beams. Since electron microscopes offer a well established and highly capable platform for electron beam experiments we want to integrate our experimental setup in a scanning electron microscope. This also opens up future possibilities to perform in-situ electron spin analysis in scanning electron microscopes. In this talk I'm going to give a quick introduction to electron spin resonance and it's applications, our approach and our existing experimental setups as well as our current efforts and characterization measurements that have been performed to introduce this novel approach to interact with spin systems into an scanning electron
