The Intrinsic Magnetization of Antiferromagnetic Textures

Antiferromagnets (AFMs) exhibit intrinsic magnetization when the order parameter spatially varies. This intrinsic spin is present even at equilibrium and can be interpreted as a twisting of the homogeneous AFM into a state with a finite spin. Because magnetic moments couple directly to external magnetic fields, the intrinsic magnetization can alter the dynamics of antiferromagnetic textures under such influence. Starting from the discrete Heisenberg model, we derive the continuum limit of the free energy of AFMs in the exchange approximation and explicitly rederive that the spatial variation of the antiferromagnetic order parameter is associated with an intrinsic magnetization density. We calculate the magnetization profile of a domain wall and discuss how the intrinsic magnetization reacts to external forces. We show conclusively, both analytically and numerically, that a spatially inhomogeneous magnetic field can move and control the position of domain walls in AFMs. By comparing our model to a commonly used alternative parametrization procedure for the continuum fields, we show that the physical interpretations of these fields depend critically on the choice of parametrization procedure for the discrete-to-continuous transition. This can explain why a significant amount of recent studies of the dynamics of AFMs, including effective models that describe the motion of antiferromagnetic domain walls, have neglected the intrinsic spin of the textured order parameter.Comment: 12 pages, 7 figure

Spatially detailed analysis of drill core samples with Laser-Induced Breakdown Spectroscopy: Detection, classification, and quantification of rare earth elements and lithium

In the transformation towards climate neutral consumption, electric alternatives rise in favour of fossil energy sources in a variety of different fields. Lithium and several elements from the group of Rare Earth Elements (REEs) are of particular importance for modern battery production and the supply of green energy, and therefore play a crucial role for this transformation. Their demand has increased constantly over the last years and an ongoing trend is expected for the future. New instruments and analytical methods for the geochemical investigation of drill cores can support mineral exploration and active mining and thereby help to cope with the growing demand. Laser-Induced Breakdown Spectroscopy (LIBS) is an analytical technique with many advantages for the analysis of drill core material. It has a high measurement speed, no sample preparation is needed, and major, minor as well as trace elements can be detected in a single spectrum under atmospheric conditions. Nevertheless, physical and chemical matrix effects prevent a straightforward analysis of heterogeneous material, which is especially relevant for spatially resolved investigations of drill core samples. This work displays novel methods that enable the analysis of LIBS mappings of large REE- and Li-bearing drill core samples by overcoming the problematic matrix effects with different un- semi- and supervised machine learning algorithms. In the first application, drill core samples of brecciated carbonatites were spatially investigated with LIBS to establish an intensity limit for La using the k-means clustering algorithm. Based on this intensity limit, REE enrichments were detected in the investigated sample. Afterwards, the REE content of the sample was estimated with mass balance calculations. For the second application, different Li-bearing drill core samples were mapped in high resolution with LIBS and a new classification model was developed. It combines Linear Discriminant Analysis (LDA) and One-Class Support Vector Machines (OC-SVM) to enable the classification of minerals that were covered by a train set, while also identifying LIBS matrices that are unknown to the model. The third application combined Laser Ablation – Inductively Coupled Plasma – Time of Flight Mass Spectrometry (LA-ICP-TOFMS) with LIBS measurements of the same sample. After image registration, this reference sample was used to create a Least-Square Support Vector Machine (LS-SVM) quantification model, which can be employed to convert LIBS intensities of similar material into element concentrations. The model allows a pixel-specific, spatially resolved quantification of multiple minerals with a single model. Each application displays possible solutions to minimize the influence of physical and chemical matrix effects on the spatial analysis of LIBS mappings of large drill core samples, which enables different kinds of analysis. Thereby, the great potential but also the challenges of LIBS as an analytical tool in geology and mining are highlighted

Economic Impact of the Mid-Term Review on Agricultural Production, Farm Income and Farm Survival: A Quantitative Analysis for Local Sub-Regions of Schleswig-Holstein in Germany

This study analyzes the impact of the Mid-Term Review (MTR) on the agricultural sector in Schleswig-Holstein, a federal state in Germany. First, a very detailed farm group linear programming model is built to quantify the effects on agricultural production and farm incomes. The production adjustment to the MTR and its impact on farm profit vary significantly between individual farms. These results depend mainly on the farm type and the resource endowments of the farms. Second, the impact on structural change is examined with a farm survival model. Although the MTR clearly reduces the incomes of several farm types, it accelerates the structural change only gradually.policy reform; modeling production adjustment; farm income; structural change

Phosphor-induzierte Kieferknochennekrose, eine "alte" aktuelle Berufserkrankung

Vor dem Hintergrund der kürzlich publizierten Fälle von Kieferknochennekrose in Verbindung mit einer Bisphosphonat-Therapie (sehr häufig angewandte medikamentöse Therapieform bei Osteoporose und in der Onkologie) soll ein historischer und medizinischer Überblick über die "alte" Berufserkrankung "Kieferknochennekrose durch Phosphor" gegeben werden. Die klinische Ausprägung der Berufserkrankung Phosphor-Kieferknochennekrose ähnelt dem Bild der Kieferknochennekrosen, die präsumptiv im Rahmen der Bisphosphonat-Therapie entstanden sind. Da diese Berufserkrankung in den letzten Jahrzehnten infolge industrieller Umstellungen selten geworden ist — lt. Auskunft des HVBG im Zeitraum 1998 bis 2002 keine Anzeige von Kieferknochennekrosen (BKZiffer 1109) —, soll hier ein Review zur Wissensauffrischung erfolgen. Vielleicht kann das arbeitsmedizinische Wissen zur Klärung dieser neu beobachteten Krankheitsentität in Verbindung mit Bisphosphonaten beitragen. Die ersten Beobachtungen einer Kieferknochennekrose bei Arbeitern in der Zündholzindustrie stammen aus den Jahren 1839 und 1843, die erste Publikation erfolgte in 1844, der ursächliche Zusammenhang wurde 1845 erkannt. Die phosphorinduzierte Kieferknochennekrose entsteht infolge Endothelschädigungen durch elementaren Phosphor. Gerade im Kieferknochenbereich können Bakterien via Zahnpathologien und anderen Umständen leicht in die ossären Strukturen vordringen, so dass schließlich eine Periostitis oder gar Osteomyelitis resultieren kann. Folgende Punkte werden behandelt: chemische Charakterisierung des Phosphor, historischer Abriss der Berufserkrankung Kieferknochennekrose, aktuelle Expositionsmöglichkeiten, Wirkungen des Phosphor, das klinische Bild der Kieferknochennekrose, Therapie und Prophylaxe

Phossy jaws : an old occupational disease - up to date?

Recently a few reports of osteonecrosis of the jaws associated with a bisphosphonate therapy were published. There seemed to be some clinical commonalities with the old occupational disease "phossy jaws\u27;. We give an historical and medical overview of "phossy jaws\u27;. Because of many industrial changes that old disease has become rare; in Germany there are no cases reported in the years 1998 until 2002 — according to the German Hauptverband der gewerblichen Berufsgenossenschaften. Maybe the old knowledge about phossy jaws is able to clear up some secrets of the new drug-associated phenomenon. First observations of phossy jaws date back to the years 1839 and 1843, they are seen with workers in match stick factories. The causality between phosphorus and phossy jaws was re-cognized in 1845. Phossy jaws are a consequence of endothelium-damage by elemental phosphorus inhaled when working with it. Especially the jaws are exposed to a number of foreign substances, i.e. bacteria by tooth decay or other circumstances. Thus — decreased blood flow and bacteria lead to an Osteomyelitis, so called phossy jaws

Respiratory Syncytial Virus Infection in Children with Neuromuscular Impairment

Clinically obvious reasons why children with neurological impairment (NMI) may be more severely affected in case of a viral respiratory tract infection include reduced vital capacity due to muscular weakness or spastic scoliosis, disturbed clearance of respiratory excretions (weak coughing and dysphagia), inability to comply actively with physiotherapeutic interventions, recurrent micro-aspirations (gastroesophageal reflux disease, vomiting related to coughing), a history of frequent exposure to antibiotics and health care institutions, colonization with resistant pathogens, impaired immunologic defence mechanisms due to severe malnutrition and cachexia, and early clinical deterioration in case of high fever with metabolic acidosis and hypercapnia, and maybe associated seizures or febrile convulsions

The role of myeloid derived suppressor cells in musculoskeletal disorders

The immune system is closely linked to bone homeostasis and plays a pivotal role in several pathological and inflammatory conditions. Through various pathways it modulates various bone cells and subsequently sustains the physiological bone metabolism. Myeloid-derived suppressor cells (MDSCs) are a group of heterogeneous immature myeloid-derived cells that can exert an immunosuppressive function through a direct cell-to-cell contact, secretion of anti-inflammatory cytokines or specific exosomes. These cells mediate the innate immune response to chronic stress on the skeletal system. In chronic inflammation, MDSCs act as an inner offset to rebalance overactivation of the immune system. Moreover, they have been found to be involved in processes responsible for bone remodeling in different musculoskeletal disorders, autoimmune diseases, infection, and cancer. These cells can not only cause bone erosion by differentiating into osteoclasts, but also alleviate the immune reaction, subsequently leading to long-lastingly impacted bone remodeling. In this review, we discuss the impact of MDSCs on the bone metabolism under several pathological conditions, the involved modulatory pathways as well as potential therapeutic targets in MDSCs to improve bone health

The comfortable roller coaster -- on the shape of tracks with constant normal force

A particle that moves along a smooth track in a vertical plane is influenced by two forces: gravity and normal force. The force experienced by roller coaster riders is the normal force, so a natural question to ask is: what shape of the track gives a normal force of constant magnitude? Here we solve this problem. It turns out that the solution is related to the Kepler problem; the trajectories in velocity space are conic sections.Comment: 10 pages, 4 figure

A ToxR-based two-hybrid system for the detection of periplasmic and cytoplasmic protein-protein interactions in Escherichia coli: minimal requirements for specific DNA binding and transcriptional activation

The Vibrio cholerae transcriptional regulator ToxR is anchored in the cytoplasmic membrane by a single transmembrane segment, its C-terminal domain facing the periplasm. Most of its N-terminal cytoplasmic domain shares sequence similarity with the winged helix-turn-helix (wHTH) motif of OmpR-like transcriptional regulators. In the heterologous host Escherichia coli ToxR activates transcription at the V.cholerae ctx promoter in a dimerization-dependent manner, which has led to its employment as a genetic indicator for protein-protein interactions. However, although offering a broader potential application range than other prokaryotic two-hybrid systems described to date, ToxR has so far only been used to study interactions between heterologous transmembrane segments or to monitor homodimerization of C-terminal fusion partners in the periplasm and the cytoplasm of E.coli. Here we show that the ToxR-system also allows the detection of heterodimerization in both cellular compartments of E.coli. In addition, to better understand ToxR's mode of action at ctx in E.coli, we have investigated the minimal requirements for its function as a transcriptional activator. We show that the wHTH motif of ToxR's N-terminal domain constitutes the minimal structural element required to activate transcription at ctx in E.coli when fused to a dimerizing protein modul