Phase-stabilized UV light at 267 nm through twofold second harmonic generation.

Providing phase stable laser light is important to extend the interrogation time of optical clocks towards many seconds and thus achieve small statistical uncertainties. We report a laser system providing more than 50 µW phase-stabilized UV light at 267.4 nm for an aluminium ion optical clock. The light is generated by frequency-quadrupling a fibre laser at 1069.6 nm in two cascaded non-linear crystals, both in single-pass configuration. In the first stage, a 10 mm long PPLN waveguide crystal converts 1 W fundamental light to more than 0.2 W at 534.8 nm. In the following 50 mm long DKDP crystal, more than 50 µW of light at 267.4 nm are generated. An upper limit for the passive short-term phase stability has been measured by a beat-node measurement with an existing phase-stabilized quadrupling system employing the same source laser. The resulting fractional frequency instability of less than 5×10-17 after 1 s supports lifetime-limited probing of the 27Al+ clock transition, given a sufficiently stable laser source. A further improved stability of the fourth harmonic light is expected through interferometric path length stabilisation of the pump light by back-reflecting it through the entire setup and correcting for frequency deviations. The in-loop error signal indicates an electronically limited instability of 1 × 10-18 at 1 s.

Ablating Ion Velocity Distributions in Short-Pulse-Heated Solids via X-Ray Doppler Shifts.

Solids ablate under laser irradiation, but experiments have not previously characterized the initiation of this process at ultrarelativistic laser intensities. We present first measurements of bulk ion velocity distributions as ablation begins, captured as a function of depth via Doppler-shifted x-ray line emission from two viewing angles. Bayesian analysis indicates that bulk ions are either nearly stationary or flowing outward at the plasma sound speed. The measurements quantitatively constrain the laser-plasma ablation mechanism, suggesting that a steplike electrostatic potential structure drives solid disassembly.

Hot Spot Evolution Measured by High-Resolution X-Ray Spectroscopy at the National Ignition Facility.

Evolution of the hot spot plasma conditions was measured using high-resolution x-ray spectroscopy at the National Ignition Facility. The capsules were filled with DD gas with trace levels of Kr and had either a high-density-carbon (HDC) ablator or a tungsten (W)-doped HDC ablator. Time-resolved measurement of the Kr Heß spectra, absolutely calibrated by a simultaneous time-integrated measurement, allows inference of the electron density and temperature through observing Stark broadening and the relative intensities of dielectronic satellites. By matching the calculated hot spot emission using a collisional-radiative code to experimental observations, the hot spot size and areal density are determined. These advanced spectroscopy techniques further reveal the effect of W dopant in the ablator on the hot spot parameters for their improved implosion performance.

Solid-Density Ion Temperature from Redshifted and Double-Peaked Stark Line Shapes.

Heß spectral line shapes are important for diagnosing temperature and density in many dense plasmas. This work presents Heß line shapes measured with high spectral resolution from solid-density plasmas with minimized gradients. The line shapes show hallmark features of Stark broadening, including quantifiable redshifts and double-peaked structure with a significant dip between the peaks; these features are compared to models through a Markov chain Monte Carlo framework. Line shape theory using the dipole approximation can fit the width and peak separation of measured line shapes, but it cannot resolve an ambiguity between electron density n_{e} and ion temperature T_{i}, since both parameters influence the strength of quasistatic ion microfields. Here a line shape model employing a full Coulomb interaction for the electron broadening computes self-consistent line widths and redshifts through the monopole term; redshifts have different dependence on plasma parameters and thus resolve the n_{e}-T_{i} ambiguity. The measured line shapes indicate densities that are 80-100% of solid, identifying a regime of highly ionized but well-tamped plasma. This analysis also provides the first strong evidence that dense ions and electrons are not in thermal equilibrium, despite equilibration times much shorter than the duration of x-ray emission; cooler ions may arise from nonclassical thermalization rates or anomalous energy transport. The experimental platform and diagnostic technique constitute a promising new approach for studying ion-electron equilibration in dense plasmas.

All Pure Fermionic Non-Gaussian States Are Magic States for Matchgate Computations.

Magic states were introduced in the context of Clifford circuits as a resource that elevates classically simulatable computations to quantum universal capability, while maintaining the same gate set. Here we study magic states in the context of matchgate (MG) circuits, where the notion becomes more subtle, as MGs are subject to locality constraints. Nevertheless a similar picture of gate-gadget constructions applies, and we show that every pure fermionic state which is non-Gaussian, i.e., which cannot be generated by MGs from a computational basis state, is a magic state for MG computations. This result has significance for prospective quantum computing implementation in view of the fact that MG circuit evolutions coincide with the quantum physical evolution of noninteracting fermions.

A comparison of the effects of carbon dioxide and medical air for abdominal insufflation on respiratory parameters in xylazine-sedated sheep undergoing laparoscopic artificial insemination.

AIMS: To determine if abdominal insufflation with medical air will improve oxygenation and ventilation parameters when compared to insufflation with CO2 in xylazine-sedated sheep undergoing laparoscopic artificial insemination (AI). METHODS: Forty-seven sheep underwent oestrus synchronisation and were fasted for 24 hours prior to laparoscopic AI. Each animal was randomised to receive either CO2 or medical air for abdominal insufflation. An auricular arterial catheter was placed and utilised for serial blood sampling. Respiratory rates (RR) and arterial blood samples were collected at baseline, after xylazine (0.1 mg/kg I/V) sedation, 2 minutes after Trendelenburg positioning, 5 minutes after abdominal insufflation, and 10 minutes after being returned to a standing position. Blood samples were collected in heparinised syringes, stored on ice, and analysed for arterial pH, partial pressure of arterial O2 (PaO2), and CO2 (PaCO2). The number of ewes conceiving to AI was also determined. RESULTS: Repeated measures ANOVA demonstrated temporal effects on RR, PaO2, PaCO2 and arterial pH during the laparoscopic AI procedure (p<0.001), but no difference between insufflation groups (p>0.01). No sheep experienced hypercapnia (PaCO2>50 mmHg) or acidaemia (pH<7.35). Hypoxaemia (PaO2<70 mmHg) was diagnosed during the procedure in 14/22 (64%) ewes in the CO2 group compared with 8/23 (35%) ewes in the medical air group (p=0.053). Overall, 15/20 (75%) ewes in the CO2 group conceived to AI compared with 16/22 (72.7%) in the medical air group (p=0.867). CONCLUSIONS AND CLINICAL RELEVANCE: There were no statistical or clinical differences in RR, PaO2, PaCO2, pH, or conception to AI when comparing the effects of CO2 and medical air as abdominal insufflation gases. None of the sheep experienced hypercapnia or acidaemic, yet 42% (19/45) of sheep developed clinical hypoxaemia, with a higher percentage of ewes in the CO2 group developing hypoxaemia than in the medical air group. Based on the overall analysis, medical air could be utilised as a comparable alternative for abdominal insufflation during laparoscopic AI procedures.

[Complications of anterior skull base surgery]. / Komplikationen bei Operationen an der Rhinobasis.

Anterior skull base operations are complex surgical procedures that are performed to treat serious and complicated diseases. Despite significant advances in surgical techniques, complications are relatively frequent and can be serious. Endoscopic skull base surgery seems to be associated with less complications than open techniques. Different classifications aimed at categorizing these complications have been suggested, the use of which can be recommended when reporting complication rates. The most relevant and frequent complications of anterior skull base surgery are hemorrhage, cerebrospinal fluid (CSF) leak, meningitis, and cranial nerve injury. Careful planning, close interdisciplinary cooperation, the competence of the skull base center and its members, and rigorous quality management are decisive for the avoidance of complications. With respect to the frequency and the seriousness of the complications, their meticulous and complete discussion with the patient before obtaining informed consent plays a central role.

Entangled Pure State Transformations via Local Operations Assisted by Finitely Many Rounds of Classical Communication.

We consider generic pure n-qubit states and a general class of pure states of arbitrary dimensions and arbitrarily many subsystems. We characterize those states which can be reached from some other state via local operations assisted by finitely many rounds of classical communication (LOCC_{N}). For n qubits with n>3, we show that this set of states is of measure zero, which implies that the maximally entangled set is generically of full measure if restricted to the practical scenario of LOCC_{N}. Moreover, we identify a class of states for which any LOCC_{N} protocol can be realized via a concatenation of deterministic steps. We show, however, that in general there exist state transformations which require a probabilistic step within the protocol, which highlights the difference between bipartite and multipartite LOCC.

Operational Multipartite Entanglement Measures.

We introduce two operational entanglement measures that are applicable for arbitrary multipartite (pure or mixed) states. One of them characterizes the potentiality of a state to generate other states via local operations assisted by classical communication and the other characterizes the simplicity of generating the state at hand. We show how these measures can be generalized to two classes of entanglement measures. Moreover, we compute the new measures for pure few-partite systems and use them to characterize the entanglement contained in a three-qubit state. We identify the Greenberger-Horne-Zeilinger and W state as the most powerful pure three-qubit states regarding state manipulation.

The accuracy of 3D fluoroscopy-navigated screw insertion in the upper and subaxial cervical spine.

PURPOSE: Due to better primary stability and repositioning options, pedicle screws are increasingly used during posterior stabilization of the cervical spine. However, the serious risks generally associated with the insertion of screws in the cervical spine remain. The purpose of this study is to examine the accuracy of pedicle screw insertion with the use of 3D fluoroscopy navigation systems, also accounting for various spine levels. METHODS: Data of 64 patients were collected during and after screw implantation (axial and subaxial) in the cervical spine. 207 screws were implanted from C1 to C7 and analyzed for placement accuracy according to postoperative CT scans and following the modified Gertzbein and Robbins classification. RESULTS: The accuracy of most of the inserted screws was assessed as grade 2 according to the modified Gertzbein and Robbins classification. 93.9% of the screws implanted at C1 or C2, and 78.51% of the screws implanted at levels C3-C7 showed placement accuracy grade 2 or better, indicating pedicle wall perforation of <2 mm. Overall, seven complications were observed. In three cases, the vertebral artery was affected, leading to one fatality. Surgical revision was necessary once because of Magerl screw misplacement and three times due to impaired wound healing. No radicular symptoms resulted from screw malposition. CONCLUSION: Axial and subaxial screws can be inserted with a high grade of accuracy using 3D fluoroscopy-based navigation systems. Nevertheless, while this useful innovation helps to minimize the risks of misplacement, the surgery is still a challenge, as arising complications remain severe.

Sonographers' perspectives on research - A worldwide online questionnaire study.

INTRODUCTION: Research has been performed by sonographers (also known as ultrasound reporting radiographers) for many years for improving diagnosis of disease, developing new imaging approaches, and enhancing patient outcomes. Despite this, sonographers' perspectives on research have not been well studied. To understand the views of sonographers is essential, as they have an important role in the successful implementation of research outcomes during their daily work. The study aimed to explore sonographers' perspectives on research. METHODS: This cross-sectional online questionnaire was developed, and pilot tested, before distribution on social media platforms by the research group to sonographers or reporting radiographers in ultrasound worldwide. The questionnaire included 21-items. The link was open for 8 weeks in the spring of 2023. A mix of closed, open and scale questions were used. Informed consent was mandatory, and information about the study and anonymity was presented. RESULTS: A total of 165 sonographers participated in the questionnaire of which 66.1 % were from Europe (n = 109), 6.1 % from North America (n = 10), 0.6 % from South America (n = 1), 2.4 % from Asia (n = 4), 13.3 % from Africa (n = 22) and 11.5 % from Oceania (n = 19). A total of 32 % of the participants had performed research. Also, 68.5 % would like to become more involved in research. CONCLUSION: Most sonographers work in large hospitals, and half of them have obtained academic level 7 education. A limited number of sonographers have published peer reviewed papers. Many sonographers expressed an interest in research. This suggests a potential for future development of the sonographers' role in research. IMPLICATIONS FOR PRACTICE: The findings for this study provide insight that could be used to improve research practice for sonographers.

Ultrasound education across European Federation of Radiographers Societies (EFRS) countries: Similarities and differences.

INTRODUCTION: Ultrasound education varies greatly across European healthcare systems. This paper focuses on ultrasound academic education as a part of wider suite of surveys on radiographers working in ultrasound. The aim was to investigate sonography educational levels, methods of training, course duration and other factors in European Federation of Radiographers Societies (EFRS) member countries. METHOD: In 2019 an online survey was sent to the 38 EFRS member societies to distribute to higher education institutions within their own country. The survey was in English and contained different types of questions such as closed questions, free text options, and scale responses, to investigate sonography education including academic course types and duration, curriculum content, learning and teaching methods. RESULTS: A total of 45 responses were received, showing wide variation in the duration of training between the respective countries. Academic level 7 (part-time) ultrasound education was most frequently reported (n = 13), followed by direct entry ultrasound courses (n = 9) and bachelor's degree programmes at EQF level 6 (n = 7). The duration of part-time courses ranged from nine months up to four years. CONCLUSION: Sonography training and education varies among EFRS member countries ranging from short focused courses to postgraduate awards. Few countries offer sonography education leading to an award. The majority of clinical teaching and learning takes place in the learner's workplace. IMPLICATIONS FOR PRACTICE: High quality academic and clinical education for radiographers extending their role into ultrasound is important to ensure safe, effective sonography practice and good patient care.

Statistical data analysis of x-ray spectroscopy data enabled by neural network accelerated Bayesian inference.

Bayesian inference applied to x-ray spectroscopy data analysis enables uncertainty quantification necessary to rigorously test theoretical models. However, when comparing to data, detailed atomic physics and radiation transfer calculations of x-ray emission from non-uniform plasma conditions are typically too slow to be performed in line with statistical sampling methods, such as Markov Chain Monte Carlo sampling. Furthermore, differences in transition energies and x-ray opacities often make direct comparisons between simulated and measured spectra unreliable. We present a spectral decomposition method that allows for corrections to line positions and bound-bound opacities to best fit experimental data, with the goal of providing quantitative feedback to improve the underlying theoretical models and guide future experiments. In this work, we use a neural network (NN) surrogate model to replace spectral calculations of isobaric hot-spots created in Kr-doped implosions at the National Ignition Facility. The NN was trained on calculations of x-ray spectra using an isobaric hot-spot model post-processed with Cretin, a multi-species atomic kinetics and radiation code. The speedup provided by the NN model to generate x-ray emission spectra enables statistical analysis of parameterized models with sufficient detail to accurately represent the physical system and extract the plasma parameters of interest.

Maximally entangled set of multipartite quantum states.

Entanglement is a resource in quantum information theory when state manipulation is restricted to local operations assisted by classical communication (LOCC). It is therefore of paramount importance to decide which LOCC transformations are possible and, particularly, which states are maximally useful under this restriction. While the bipartite maximally entangled state is well known (it is the only state that cannot be obtained from any other and, at the same time, it can be transformed to any other by LOCC), no such state exists in the multipartite case. In order to cope with this fact, we introduce here the notion of the maximally entangled set (MES) of n-partite states. This is the set of states which are maximally useful under LOCC manipulation; i.e., any state outside of this set can be obtained via LOCC from one of the states within the set and no state in the set can be obtained from any other state via LOCC. We determine the MES for states of three and four qubits and provide a simple characterization for them. In both cases, infinitely many states are required. However, while the MES is of measure zero for 3-qubit states, almost all 4-qubit states are in the MES. This is because, in contrast to the 3-qubit case, deterministic LOCC transformations are almost never possible among fully entangled four-partite states. We determine the measure-zero subset of the MES of LOCC convertible states. This is the only relevant class of states for entanglement manipulation.

Immediate effects of individualized heparin and protamine management on hemostatic activation and platelet function in adult patients undergoing cardiac surgery with tranexamic acid antifibrinolytic therapy.

OBJECTIVE: This randomized prospective study was initiated to clarify whether individualized heparin and protamine dosing has immediate effects on hemostatic activation and platelet function in adult cardiac surgery. METHODS: Sixty adults undergoing elective coronary artery bypass grafting (CABG) were assigned to receive individualized heparin and protamine (HMS group, n= 29) or a standard dose (ACT group, n=24). Measures of thrombin generation and Multiplate (Verum Diagnostica, Munich, Germany) platelet function tests were performed before and after cardiopulmonary bypass (CPB). RESULTS: HMS patients received higher heparin (p = 0.006) and lower protamine (p<0.001) doses. Post-CPB, HMS managed patients showed significantly lower thrombin generation (thrombin-antithrombin (TAT) p<0.02) than the ACT group. Moreover, HMS managed patients had a better preservation of platelet function (COL p = 0.013; ADP p = 0.04; TRAP p = 0.04). CONCLUSION: An individualized and stable heparin concentration and appropriate dosing of protamine can reduce thrombin generation and preserve platelet function, even in short-time CPB.

Complete set of operational measures for the characterization of three-qubit entanglement.

We characterize the entanglement contained in a pure three-qubit state via operational entanglement measures. To this end, we derive a new decomposition for arbitrary three-qubit states which is characterized by five parameters (up to local unitary operations). We show that these parameters are uniquely determined by bipartite entanglement measures. These quantities measure the entanglement required to generate the state following a particular preparation procedure and have a clear physical meaning. Moreover, we show that the classification of states obtained in this way is strongly related to the one obtained when considering general local operations and classical communication.

Pitfalls in cell culture work with xanthohumol.

Xanthohumol, the most abundant prenylated chalcone in hop (Humulus lupulus L.) cones, is well known to exert several promising pharmacological activities in vitro and in vivo. Among these, the chemopreventive, anti-inflammatory and anti-cancer effects are probably the most interesting. As xanthohumol is hardly soluble in water and able to undergo conversion to isoxanthohumol we determined several handling characteristics for cell culture work with this compound. Recovery experiments revealed that working with xanthohumol under cell culture conditions requires a minimal amount of 10% FCS to increase its solubility to reasonable concentrations (-50-75 micromol/l) for pharmacological in vitro tests. Additionally, more than 50% of xanthohumol can be absorbed to various plastic materials routinely used in the cell culture using FCS concentrations below 10%. In contrast, experiments using fluorescence microscopy in living cells revealed that detection of cellular intake of xanthohumol is hampered by concentrations above 1% FCS.

Radiographers' individual perspectives on sonography - A survey of European Federation of Radiographer Societies (EFRS).

INTRODUCTION: Radiographers can elect to work within many different modalities, one being ultrasound. Within Europe there are differing opinions about how much of a role radiographers should take in relation to the ultrasound examination, particularly report writing. This paper provides findings exploring the radiographer's views on working within sonography. METHODS: In 2019 an electronic survey was disseminated to radiographer members by European Federation of Radiographer Societies (EFRS) national radiographer societies, following a pilot study. A mix of closed questions, free text, and scale responses aimed to investigate radiographers' practice, legal responsibilities, report writing, educational level and experiences of support and mentoring. RESULTS: Of 561 radiographers participating, most (92%) reported performing ultrasound scans. Challenges with legislation, medical protectionism and lack of high-quality education restricted other radiographers. On average, the respondents have practiced ultrasound for 13.5 years. A total of 60% had postgraduate education and carried out a wide range of examinations. A full interpretative report, including advice on further investigations is performed by 52%, whilst 22% provide a checklist or descriptive report. Over 55% of radiographers took legal responsibility for the examination and the majority had clear protocols, good mentoring and support in the workplace. Peer review of their work was less common. CONCLUSION: The result shows that in 21 (n = 25) countries radiographers perform ultrasound, however not without challenges. Educational levels range from no formal education or short courses to an MSc in ultrasound. Report writing practice differs across the EFRS countries responding to the survey, as does peer review to enhance skills and clinical practice. IMPLICATIONS FOR PRACTICE: National Radiographer societies could review findings to support campaigning for a change in legislation and improvements to educational offerings in ultrasound.

Streaked sub-ps-resolution x-ray line shapes and implications for solid-density plasma dynamics (invited).

A high-resolution x-ray spectrometer was coupled with an ultrafast x-ray streak camera to produce time-resolved line shape spectra measured from hot, solid-density plasmas. A Bragg crystal was placed near laser-produced plasma to maximize throughput; alignment tolerances were established by ray tracing. The streak camera produced single-shot, time-resolved spectra, heavily sloped due to photon time-of-flight differences, with sufficient reproducibility to accumulate photon statistics. The images are time-calibrated by the slope of streaked spectra and dewarped to generate spectra emitted at different times defined at the source. The streaked spectra demonstrate the evolution of spectral shoulders and other features on ps timescales, showing the feasibility of plasma parameter measurements on the rapid timescales necessary to study high-energy-density plasmas.

Compressed quantum simulation of the Ising model.

Jozsa et al. [Proc. R. Soc. A 466, 809 2009)] have shown that a match gate circuit running on n qubits can be compressed to a universal quantum computation on log(n)+3 qubits. Here, we show how this compression can be employed to simulate the Ising interaction of a 1D chain consisting of n qubits using a universal quantum computer running on log(n) qubits. We demonstrate how the adiabatic evolution can be realized on this exponentially smaller system and how the magnetization, which displays a quantum phase transition, can be measured. This shows that the quantum phase transition of very large systems can be observed experimentally with current technology.