Persisting correlations of a central spin coupled to large spin baths

The decohering environment of a quantum bit is often described by the coupling to a large bath of spins. The quantum bit itself can be seen as a spin $S=1/2$ which is commonly called the central spin. The resulting central spin model describes an important mechanism of decoherence. We provide mathematically rigorous bounds for a persisting magnetization of the central spin in this model with and without magnetic field. In particular, we show that there is a well defined limit of infinite number of bath spins. Only if the fraction of very weakly coupled bath spins tends to 100\% does no magnetization persist.Comment: 19 pages, 15 figures, rigorous bounds for the central spin mode

MEASURING REGRET: EMOTIONAL ASPECTS OF AUCTION DESIGN

Recent research strengthens the conjecture that human decision-making stems from a complex interaction of rational judgment and emotional processes. A prominent example of the impact of emotions in economic decision-making is the effect of regret-related information feedback on bidding behaviour in first-price sealed-bid auctions. Revealing the information “missed opportunity to win” upon losing an auction, results in higher bids. Revealing the information “money left on the table” upon winning an auction, results in lower bids. The common explanation for this pattern is winner and loser regret. However, this explanation is still hypothetical and little is known about the actual emotional processes that underlie this phenomenon. This paper investigates actual emotional processes in auctions with varying feedback information. Thereby, we provide an approach that combines an auction experiment with psychophysiological measures which indicate emotional involvement. Our economic results are in line with those of previous studies. Moreover, we can show that loser regret results in a stronger emotional response than winner regret. Remarkably, loser regret is strong for high values of “missed opportunity.” However, the pattern for different amounts of “money left on the table” is diametric to what winner regret theory suggests

HemoCue®, an Accurate Bedside Method of Hemoglobin Measurement?

Objective. Evaluate the accuracy of this bedside method to determinehemoglobin (Hb) concentration in general surgery over a wide range of Hbvalues and to determine potential sources of error. Methods. Accuracy of Hbmeasurement using HemoCue® (AB Leo Diagnostics, Helsinborg, Sweden) wasassessed in 140 surgical blood samples using 7 HemoCue® devices incomparison with a CO-Oximeter (IL 482, Instrumentation Laboratory,Lexington, MA). To analyze potential sources of error, packed red cells andfresh frozen plasma were reconstituted to randomized Hb levels of 2-18g/dL. Results. In the surgical blood samples, the Hb concentrationdetermined by the CO-Oximeter (HbCOOX) ranged from 5.1 to 16.7 g/dL and theHb concentration measured by HemoCue® (HbHC) from 4.7 to 16.0 g/dL. Bias(HbCOOX - HbHC) between HbCOOX and HbHC was 0.6 ± 0.6 g/dL(mean ± SD) or 5.4 ± 5.0% (p < 0.001). Also in thereconstituted blood, the bias between HbCOOX and HbHC was significant (0.2± 0.3 g/dL or 2.1 ± 3.2%; p < 0.001). Themicrocuvette explained 68% of the variability between HbCOOX andHbHC. HemoCue® thus underestimates the Hb concentration by2-5% and exhibits a 8-10 times higher variability withonly 86.4% of HbHC being within ± 10% of HbCOOX.Conclusion. Although the mean bias between HbCOOX and HbHC was relativelylow, Hb measurement by HemoCue® exhibited a significant variability.Loading multiple microcuvettes and averaging the results may increase theaccuracy of Hb measurement by HemoCue

PSMA-PET/CT in Patients with Recurrent Clear Cell Renal Cell Carcinoma: Histopathological Correlations of Imaging Findings

PET/CT with prostate-specific membrane antigen (PSMA)-targeted tracers has been used in the diagnosis and staging of patients with clear cell renal cell carcinoma (ccRCC). For ccRCC primary tumors, PET parameters were shown to predict histologic grade and features. The aim of this study was to correlate PSMA PET/CT with histopathological findings in patients with metastatic recurrence of ccRCC. Patients with ccRCC who underwent PSMA-targeted PET/CT and subsequent histopathological evaluation of suspicious lesions were included. Specimens underwent immunohistochemical marking. Lesion diameter, volume and tracer uptake were correlated with the extent and intensity of molecular PSMA expression and with clinical findings. Twelve PET-positive lesions of nine patients were evaluated. Eleven ccRCC metastases and one prostate carcinoma were detected histopathologically. Molecular PSMA expression was detected in all lesions, which intensity and distribution did not correlate with PET parameters. PSMA-targeted PET/CT is a feasible tool for the evaluation of patients with ccRCC but cannot reliably predict histologic features of metastases. PSMA may also be expressed in malignant lesions other than ccRCC, leading to incidental detection of these tumors

Diagnostic performance of different thyroid imaging reporting and data systems (Kwak-TIRADS, EU-TIRADS and ACR TI-RADS) for risk stratification of small thyroid nodules (≤10 mm)

Due to the widespread use of ultrasound, small thyroid nodules (TNs) ≤ 10 mm are common findings. Standardized approaches for the risk stratification of TNs with Thyroid Imaging Reporting and Data Systems (TIRADS) were evaluated for the clinical routine. With TIRADS, the risk of malignancy in TNs is calculated by scoring the number or combination of suspicious ultrasound features, leading to recommendations for further diagnostic steps. However, there are only scarce data on the performance of TIRADS for small TNs. The aim was to compare three different TIRADS for risk stratification of small TNs in routine clinical practice. We conducted a retrospective cohort analysis of TNs ≤ 10 mm and their available histology. Nodules were classified according to three different TIRADS. In the study, 140 patients (n = 113 female) with 145 thyroid nodules (n = 76 malignant) were included. Most of the malignant nodules were papillary carcinoma (97%), and the remaining 3% were medullary carcinoma. For all tested TIRADS, the prevalence of malignancy rose with increasing category levels. The highest negative predictive value was found for ACR TI-RADS and the highest positive predictive value for Kwak-TIRADS. All tested variants of TIRADS showed comparable diagnostic performance for the risk stratification of small TNs. TIRADS seems to be a promising tool to reliably assess the risk of malignancy of small TNs

PET/CT of the Spleen with Gallium-Oxine-Labeled, Heat-Damaged Red Blood Cells: Clinical Experience and Technical Aspects

Several scintigraphic techniques have been supplemented or replaced by PET/CT methods because of their superior sensitivity, high resolution, and absolute activity quantification capability. The purpose of this project was the development of a PET tracer for splenic imaging, its radiopharmaceutical validation, and its application in selected patients in whom unclear constellations of findings could not be resolved with established imaging methods. Heat-damaged red blood cells (RBCs) were labeled with [ 68 Ga]gallium-oxine, which was produced from [ 68 Ga]gallium and 8-Hydroxyquinoline (oxine) on an automated synthesizer. Ten patients underwent [ 68 Ga]gallium-oxine-RBC-PET/CT for the classification of eleven unclear lesions (3 intra-, 8 extrapancreatic). [ 68 Ga]gallium-oxine and [68Ga]gallium-oxine-labeled RBCs could be synthesized reproducibly and reliably. The products met GMP quality standards. The tracer showed high accumulation in splenic tissue. Of the 11 lesions evaluated by PET/CT, 3 were correctly classified as non-splenic, 6 as splenic, 1 as equivocal, and 1 lesion as a splenic hypoplasia. All lesions classified as non-splenic were malignant, and all lesions classified as splenic did not show malignant features during follow-up. PET/CT imaging of the spleen with [ 68 Ga]gallium-oxine-labeled, heat-damaged RBCs is feasible and allowed differentiation of splenic from non-splenic tissues, and the diagnosis of splenic anomalies

Interplay of itinerant magnetism and reentrant spin-glass behavior in Fex_{x}Cr1−x_{1-x}

When suppressing the itinerant antiferromagnetism in chromium by doping with the isostructual itinerant ferromagnet iron, a dome of spin-glass behavior emerges around a putative quantum critical point at an iron concentration $x \approx 0.15$. Here, we report a comprehensive investigation of polycrystalline samples of Fe$_{x}$Cr$_{1-x}$ in the range $0.05 \leq x \leq 0.30$ using x-ray powder diffraction, magnetization, ac susceptibility, and neutron depolarization measurements, complemented by specific heat and electrical resistivity data for $x = 0.15$. Besides antiferromagnetic ($x < 0.15$) and ferromagnetic regimes ($0.15 \leq x$), we identify a dome of reentrant spin-glass behavior at low temperatures for $0.10 \leq x \leq 0.25$ that is preceded by a precursor phenomenon. Neutron depolarization indicates an increase of the size of ferromagnetic clusters with increasing $x$ and the Mydosh parameter $\phi$, inferred from the ac susceptibility, implies a crossover from cluster-glass to superparamagnetic behavior. Taken together, these findings consistently identify Fe$_{x}$Cr$_{1-x}$ as an itinerant-electron system that permits to study the evolution of spin-glass behavior of gradually varying character in unchanged crystalline environment

Thermal and Mechanical Safety Assessment of Type 21700 Lithium-Ion Batteries with NMC, NCA and LFP Cathodes–Investigation of Cell Abuse by Means of Accelerating Rate Calorimetry (ARC)

In this experimental investigation, we studied the safety and thermal runaway behavior of commercial lithium-ion batteries of type 21700. The different cathode materials NMC, NCA and LFP were compared, as well as high power and high energy cells. After characterization of all relevant components of the batteries to assure comparability, two abuse methods were applied: thermal abuse by the heat-wait-seek test and mechanical abuse by nail penetration, both in an accelerating rate calorimeter. Several critical temperatures and temperature rates, as well as exothermal data, were determined. Furthermore, the grade of destruction, mass loss and, for the thermal abuse scenario, activation energy and enthalpy, were calculated for critical points. It was found that NMC cells reacted first, but NCA cells went into thermal runaway a little earlier than NMC cells. LFP cells reacted, as expected, more slowly and at significantly higher temperatures, making the cell chemistry considerably safer. For mechanical abuse, no thermal runaway was observed for LFP cells, as well as at state of charge (SOC) zero for the other chemistries tested. For thermal abuse, at SOC 0 and SOC 30 for LFP cells and at SOC 0 for the other cell chemistries, no thermal runaway occurred until 350 °C. In this study, the experimental data are provided for further simulation approaches and system safety design

Battery safety assessment using calorimetry, gas chromatography and mass spectrometry

For LIB, a holistic safety assessment is in the focus, because the thermal runaway can have multiple interacting causes and effects. A test in an Accelerating Rate Calorimeter (ARC) reveals the entire process of the thermal runaway with the different stages of exothermic reactions. As a result quantitative and system relevant data for temperature, heat and pressure development of materials and cells are provided. In addition it will be explained how calorimeters can be combined with gas chromatography and mass spectrometry to analyse the gases, which are occurring during abuse tests. There is still a lack of thermal and safety data of Li-ion cells that are publicly available. However, such data are urgently needed for a better understanding of the processes that could end up in thermal runaway. Even before the thermal runaway explosive or toxic gases can be released during venting of the cell that represent a potential hazard due to their rapid and widespread distribution. Therefore, it is important to get more insight into the volume of the released gases and their qualitative and quantitative composition. All these information will lead to an earlier prediction and prevention of events that can lead to thermal runaway and thus for improved thermal management and safety systems. The audience will get insights into the use of battery calorimetry to record thermal and safety data of cells of different sizes from coin cells to hardcase prismatic cells. It will be made clear how these data help to understand thermal behavior and the exothermic reactions triggering thermal runaway. In addition, delegates will be introduced to the use of gas chromatography and mass spectroscopy for analyzing venting gases