Radio-frequency magnetometry using a single electron spin

We experimentally demonstrate a simple and robust protocol for the detection of weak radio-frequency magnetic fields using a single electron spin in diamond. Our method relies on spin locking, where the Rabi frequency of the spin is adjusted to match the MHz signal frequency. In a proof-of-principle experiment we detect a 7.5 MHz magnetic probe field of 40 nT amplitude with <10 kHz spectral resolution over a T_1-limited noise floor of 0.3 nT/rtHz. Rotating-frame magnetometry may provide a direct and sensitive route to high-resolution spectroscopy of nanoscale nuclear spin signals

Investor-State Dispute Settlement (ISDS), Germany and the Transatlantic Relationship

The European Union (EU) has negotiated a comprehensive trade and investment agreement with Canada, and is currently negotiating one with the United States (US). Investor-State Dispute Settlement (ISDS), a provision in most Bilateral Investment Treaties (BITs) and other International Investment Agreements (IIAs), gives investors the right to pursue arbitration with a state. The inclusion of this mechanism in both the Transatlantic Trade and Investment Partnership (TTIP) between the EU and the US, and the Comprehensive Economic and Trade Agreement (CETA) between the EU and Canada has caused considerable public concern. Germany, as one of the most vocal opponents to ISDS in these trade agreements, is making headlines arguing in favor of removing ISDS provisions from the agreements, threatening the continuation of the TTIP negotiations and the ratification of the CETA. Germany has a longstanding history of negotiating BITs containing ISDS. As one of the originators of the concept, it seems surprising for many viewers to see Germany now opposing investment protection. This essay will argue that Germany is seen as opposing the inclusion of ISDS in both the CETA and the TTIP primarily because it does not want it included in the TTIP with the US. Germany’s perceived opposition to ISDS in the CETA is thereby tied to the strategically more important TTIP. This essay is aimed to be part of a larger research effort designed to look at the transatlantic investment protection and ISDS debate. What are the pros and cons of investment protection? Is it a necessary component of transatlantic trade and investment agreements? Could the CETA and the TTIP play a role in setting global, more modern investment protection standards? Examining these possible factors of why the US, Canada and the EU behave the way they do with respect to this debate and casting them against some of the facts of how ISDS works and some of the rulings that have been made with respect to ISDS in the past, future research as part of an PhD hopes to contribute to the larger scholarship on foreign direct investment and the direction thereof. Any suggestions, comments and feedback with respect to either this paper or the intended future research in terms of designing a research proposal for possible PhD applications are welcome

Regulation of peptidoglycan biosynthesis in Hyphomonas neptunium

Abstract The spatial and temporal regulation of peptidoglycan biosynthesis and its role in cell morphology has been studied intensively in well-characterized model organisms such as Escherichia coli, Bacillus subtilis, and Caulobacter crescentus, which divide either by symmetric or asymmetric binary fission. To broaden our knowledge of the mechanisms governing bacterial morphogenesis, we started to investigate the dimorphic marine α-proteobacterium Hyphomonas neptunium as a new model organism. This Gram-negative species is characterized by a unique mode of proliferation, whereby the new offspring is generated by the formation of a bud at the tip of a stalk that emanates from the mother cell body. The main focus of our previous studies was the identification of cell wall biosynthetic enzymes and regulatory factors that are critically involved in stalk and bud biogenesis. These studies revealed that peptidoglycan biosynthesis in H. neptunium is a complex process mediated by an intricate interplay of various factors. Among the open questions, it is still unknown how the generation of the daughter cell is regulated and how the mother cell orchestrates the localization of peptidoglycan remodeling enzymes at specific site of action during the cell cycle. Consequently, that includes the initial localization of enzymes at the stalked pole. At a certain point, they have to diffuse through the stalk into the growing bud. There, they center at the junction between the bud and the stalk to separate the mother cell from the bud. The main goal of the present study our current research is a deeper and more thorough characterization of previously investigated peptidoglycan remodeling enzymes, and especially the lytic enzymes, that cleave the peptidoglycan mesh. We particularly focused on two classes, the M23 metallopeptidases and the amidases. In doing so, we compre-hensively analyzed the six M23 endopeptidases of H. neptunium with localization studies and genetic approaches. Our results revealed a high degree of redundancy among these enzymes, which combined with the absence of a distinct localization pattern, indicated a generalized role in cell wall maintenance. We also investigated the role of the only amidase in H. neptunium in cell separation and bud formation. A deletion of the amidase gene led to an aberrant morphology and a mild chaining phenotype. Importantly, we showed that one of the M23 endopeptidases (LmdE) acts as a regulator of AmiC. Using biochemical approaches, we proved an interaction between AmiC and LmdE, where LmdE stimulates the catalytic activity of AmiC and thus regulates peptidoglycan hydrolysis. A further crucial player in this system is the inner membrane-embedded FtsEX complex. A deletion of the whole complex resulted in cells with very elongated and misshapen stalks. Probably, FtsEX plays a role in the regulation of amidase activity by interacting with LmdE. These results are similar between α- and γ-proteobacteria indicating that the mechanism of amidase regulation is conserved. A further goal of our work was the identification of novel factors that are specifically involved in the regulation of budding in H. neptunium. To this end, we started to establish a transposon mutagenesis system to identify all essential genes in this species. In the future, we will be able to investigate these novel factors and their contribution to cell morphology. Taken together, these results provide insight into the mechanisms of morphogenesis in stalked budding bacteria, thus setting the stage for an in-depth analysis of the regulatory mechanisms that control the spatiotemporal dynamics of the peptidoglycan biosynthetic machinery in these organisms

An internationalization strategy: what is the best country for the further international expansion of trade republic

This work project aims to identify a target country and market entry strategy for the further expansion of Trade Republic. Therefore, a literature review on Fintech companies and internationalization strategies was conducted. The research method used in this paper was a quantitative analysis of primary and secondary data. First, a country ranking for 70 relevant countries was developed by using 20 variables to evaluate the market attractiveness. Thereafter, an online survey was sent to people that live in the three most suitable countries to gather primary data. Based on that data, Switzerland was identified as the target country

Spurious harmonic response of multipulse quantum sensing sequences

Multipulse sequences based on Carr-Purcell decoupling are frequently used for narrow-band signal detection in single spin magnetometry. We have analyzed the behavior of multipulse sensing sequences under real-world conditions, including finite pulse durations and the presence of detunings. We find that these non-idealities introduce harmonics to the filter function, allowing additional frequencies to pass the filter. In particular, we find that the XY family of sequences can generate signals at the 2fac, 4fac and 8fac harmonics and their odd subharmonics, where fac is the ac signal frequency. Consideration of the harmonic response is especially important for diamond-based nuclear spin sensing where the NMR frequency is used to identify the nuclear spin species, as it leads to ambiguities when several isotopes are present.Comment: 6 pages, 7 figure

Development of mechanical soil stability in an initial homogeneous loam and sand planted with two maize (Zea mays L.) genotypes with contrasting root hair attributes under in-situ field conditions

Purpose: Soil structure evolving from physical and biological processes is closely related to soil mechanical characteristics and texture. We studied the influence of substrate and genotype on the initial development of mechanical traits, differences between depths, and changes over the course of two years in the field. Methods: Plots were homogeneously filled with a loam and a sand and planted with two maize (Zea mays L.) genotypes (wild type (WT) and rth3 mutant) with contrasting root hair attributes. Undisturbed soil cores were taken in 2019 and 2020 at 14 and 34 cm depth. Confined uniaxial compression tests were performed to determine pre-compression stress (σpc), compressibility (Cc, Cs) and elasticity index (EI). Mechanical energy was calculated based on penetration resistance (PR) tests with a penetrometer needle resembling root geometries. Results: σpc, Cc and Cs were significantly higher in loam as compared to sand, whereas the factor genotype proved to be negligible. Over time, σpc increased and Cc decreased in loam from 2019 to 2020 and Cs declined in both substrates. Higher mechanical energies were observed in loam and partially in WT. Required energy was higher at 14 cm than at 34 cm depth and decreased from 2019 to 2020 in sand. Airdry sand samples required four times as much energy than those at matric potential (Ψm) of -50 kPa. Conclusion: For the development of the mechanical traits examined texture proved to be the dominating factor and changes in soil stability could be observed within a short period of time

Difference-differential operators for basic adaptive discretizations and their central function systems

The concept of inherited orthogonality is motivated and an optimality statement for it is derived. Basic adaptive discretizations are introduced. Various properties of difference operators which are directly related to basic adaptive discretizations are looked at. A Lie-algebraic concept for obtaining basic adaptive discretizations is explored. Some of the underlying moment problems of basic difference equations are investigated in greater detail