Polarized phonons carry angular momentum in ultrafast demagnetization.

Magnetic phenomena are ubiquitous in nature and indispensable for modern science and technology, but it is notoriously difficult to change the magnetic order of a material in a rapid way. However, if a thin nickel film is subjected to ultrashort laser pulses, it loses its magnetic order almost completely within femtosecond timescales1. This phenomenon is widespread2-7 and offers opportunities for rapid information processing8-11 or ultrafast spintronics at frequencies approaching those of light8,9,12. Consequently, the physics of ultrafast demagnetization is central to modern materials research1-7,13-28, but a crucial question has remained elusive: if a material loses its magnetization within mere femtoseconds, where is the missing angular momentum in such a short time? Here we use ultrafast electron diffraction to reveal in nickel an almost instantaneous, long-lasting, non-equilibrium population of anisotropic high-frequency phonons that appear within 150-750 fs. The anisotropy plane is perpendicular to the direction of the initial magnetization and the atomic oscillation amplitude is 2 pm. We explain these observations by means of circularly polarized phonons that quickly absorb the angular momentum of the spin system before macroscopic sample rotation. The time that is needed for demagnetization is related to the time it takes to accelerate the atoms. These results provide an atomistic picture of the Einstein-de Haas effect and signify the general importance of polarized phonons for non-equilibrium dynamics and phase transitions.

Field-Induced Rocking-Curve Effects in Attosecond Electron Diffraction.

Recent advances in electron microscopy trigger the question of whether attosecond electron diffraction can resolve atomic-scale electron dynamics in crystalline materials in space and time. Here, we explore the ultrafast dynamics of the relevant electron-lattice scattering process. We drive a single-crystalline silicon membrane with the optical cycles of near-infrared laser light and use phase-locked attosecond electron pulses to produce electron diffraction patterns as a function of delay. For all Bragg spots, we observe time-dependent intensity changes and position shifts that are correlated with a time shift of 0.5-1.2 fs. For single-cycle excitation pulses with strong peak intensity, the correlations become nonlinear. The origins of these effects are local and integrated beam deflections by the optical electric and magnetic fields at the crystal membrane. Those deflections modify the diffraction intensities in addition to the atomic structure factor dynamics by time-dependent rocking-curve effects. However, the measured time delays and symmetries allow one to disentangle both effects. Future attosecond electron diffraction and microscopy experiments need to be based on these results.

Jitter-free terahertz pulses from LiNbO3.

Intense terahertz pulses are indispensable for modern science and technology, but time-critical applications require ultimate stability of the field cycles with respect to a reference clock. Here we report the nonlinear optical generation of terahertz single-cycle fields by femtosecond laser pulses under passive compensation of timing jitter. The converter is based on optical rectification in a LiNbO3 slab with two silicon prisms for extracting and combining the emitted Cherenkov radiation from both sides into a single beam. In this way, we achieve suppression of timing jitter to <200 as/µm of beam displacement, a factor of >70 better than in conventional non-collinear geometries.

Measurement of Temporal Coherence of Free Electrons by Time-Domain Electron Interferometry.

The temporal properties of an electron beam are decisive for modern ultrafast electron microscopy and for the quantum optics of the free electron in laser fields. Here, we report a time-domain interferometer that measures and distinguishes the pure and ensemble coherences of a free-electron beam in a transmission electron microscope via symmetry-breaking shifts of photon-order sideband peaks. This result is a free-electron analog to the reconstruction of attosecond busts and photoemission delays in optical attosecond spectroscopy. We find a substantial pure electron coherence that is connected to the thermodynamics of the emitter material and a lower ensemble coherence that is governed by space-charge effects. Pure temporal coherences above 5 fs are measured at >10^{9} electrons per second in a high-brightness beam.

Hospital volume following major surgery for gastric cancer determines in-hospital mortality rate and failure to rescue: a nation-wide study based on German billing data (2009-2017).

BACKGROUND: For many cancer resections, a hospital volume-outcome relationship exists. The data regarding gastric cancer resection-especially in the western hemisphere-are ambiguous. This study analyzes the impact of gastric cancer surgery caseload per hospital on postoperative mortality and failure to rescue in Germany. METHODS: All patients diagnosed with gastric cancer from 2009 to 2017 who underwent gastric resection were identified from nation-wide administrative data. Hospitals were grouped into five equal caseload quintiles (I-V in ascending caseload order). Postoperative deaths and failure to rescue were determined. RESULTS: Forty-six thousand one hundred eighty-seven patients were identified. There was a significant shift from partial resections in low-volume hospitals to more extended resections in high-volume centers. The overall in-house mortality rate was 6.2%. The crude in-hospital mortality rate ranged from 7.9% in quintile I to 4.4% in quintile V, with a significant trend between volume categories (p < 0.001). In the multivariable logistic regression analysis, quintile V hospitals (average of 29 interventions/year) had a risk-adjusted odds ratio of 0.50 (95% CI 0.39-0.65), compared to the baseline in-house mortality rate in quintile I (on average 1.5 interventions/year) (p < 0.001). In an analysis only evaluating hospitals with more than 30 resections per year mortality dropped below 4%. The overall postoperative complication rate was comparable between different volume quintiles, but failure to rescue (FtR) decreased significantly with increasing caseload. CONCLUSION: Patients who had gastric cancer surgery in hospitals with higher volume had better outcomes and a reduced failure to rescue rates for severe complications.

Efficient middle-infrared generation in LiGaS2by simultaneous spectral broadening and difference-frequency generation: erratum.

In this erratum, we correct the abstract and introduction of Opt. Lett.43, 1742 (2018)OPLEDP0146-959210.1364/OL.43.001742 to not include a wrong name for the crystal.

Efficient middle-infrared generation in LiGaS2 by simultaneous spectral broadening and difference-frequency generation.

We report a surprisingly broadband and efficient midinfrared pulse generation in LiGaS2 (Langasite, LGS) by invoking a simultaneous interplay of intrapulse difference-frequency generation, self-phase modulation, and dispersion. This cascaded mechanism expands the output bandwidth and output power at the same time. With 30-fs driving pulses centered at 1030-nm wavelength we obtain a broadband middle-infrared spectrum of 8-11 µm with an LGS crystal as thick as 4 mm, which is eight times longer than the walk-off length.

800-fs, 330-µJ pulses from a 100-W regenerative Yb:YAG thin-disk amplifier at 300 kHz and THz generation in LiNbO3.

Yb:YAG thin-disk lasers offer extraordinary output power, but systems delivering femtosecond pulses at a repetition rate of hundreds of kilohertz are scarce, even though this regime is ideal for ultrafast electron diffraction, coincidence imaging, attosecond science, and terahertz (THz) spectroscopy. Here we describe a regenerative Yb:YAG amplifier based on thin-disk technology, producing 800-fs pulses at a repetition rate adjustable between 50 and 400 kHz. The key design elements are a short regenerative cavity and fast-switching Pockels cell. The average output power is 130 W before the compressor and 100 W after compression, which at 300 kHz corresponds to pulse energies of 430 and 330 µJ, respectively. This is sufficient for a wide range of nonlinear conversions and broadening/compression schemes. As a first application, we use optical rectification in LiNbO3 to produce 30-nJ single-cycle THz pulses with 6 W pump power. The electric field exceeds 10 kV/cm at a central frequency of 0.3 THz, suitable for driving structural dynamics or controlling electron beams.

Single-electron pulses for ultrafast diffraction.

Visualization of atomic-scale structural motion by ultrafast electron diffraction and microscopy requires electron packets of shortest duration and highest coherence. We report on the generation and application of single-electron pulses for this purpose. Photoelectric emission from metal surfaces is studied with tunable ultraviolet pulses in the femtosecond regime. The bandwidth, efficiency, coherence, and electron pulse duration are investigated in dependence on excitation wavelength, intensity, and laser bandwidth. At photon energies close to the cathode's work function, the electron pulse duration shortens significantly and approaches a threshold that is determined by interplay of the optical pulse width and the acceleration field. An optimized choice of laser wavelength and bandwidth results in sub-100-fs electron pulses. We demonstrate single-electron diffraction from polycrystalline diamond films and reveal the favorable influences of matched photon energies on the coherence volume of single-electron wave packets. We discuss the consequences of our findings for the physics of the photoelectric effect and for applications of single-electron pulses in ultrafast 4D imaging of structural dynamics.

[Multilocular Paget's disease in IBMPFD syndrome. A case report with 14-year follow-up]. / Multilokulärer Morbus Paget bei IBMPFD-Syndrom. Darstellung eines Krankheitsverlaufes über 14 Jahre.

Paget's osteodystrophia deformans is a monoostotic or polyostotic disease of the skeletal system with increased bone remodelling, structural modifications and skeletal deformation, typically arranged like a chessboard. The unusual case of a patient is described who had suffered from generalized Paget's disease of the bone for 14 years and also developed progressive myopathy and a behavioural variant frontotemporal dementia. Further cytogenetic diagnostics revealed a point mutation in the valosin-containing protein (VCP, p97) gene on chromosome 9p13-p12 consistent with the finding of inclusion body myopathy with early onset Paget's disease and frontotemporal dementia (IBMPFD syndrome). A causal therapy of this disease is not known. Conservative treatment with bisphosphonate therapy, intensive physiotherapeutic exercise and psychotherapeutic treatment was performed to retard the progression of the disease.

16 fs, 350 nJ pulses at 5 MHz repetition rate delivered by chirped pulse compression in fibers.

We demonstrate a simple approach for broadening and compression of intense pulses at megahertz repetition rates by self-phase modulation in nonlinear photonic crystal fibers. In order to avoid damage by self-focusing, we positively chirp the input pulses, which allows coupling of significantly more energy into the fiber, while maintaining the same spectral bandwidth and compression as compared to the Fourier-limited case at lower energy. Using a commercial long-cavity Ti:sapphire oscillator with 55 fs, 400 nJ pulses at 5 MHz, we generate 16 fs, 350 nJ pulses, which is a factor of 4 more energy than possible with unchirped input pulses. Self-phase-modulated spectra supporting 11 fs duration are also shown with 350 nJ pulse energy. Excellent stability is recorded over at least 1 h.

[Critical illness myopathy and neuropathy (CRIMYN). Electroneurographic classification]. / Critical-illness-Myopathie und -Neuropathie (CRIMYN). Elektroneurographische Klassifikation.

BACKGROUND: Critical Illness Myopathy and Neuropathy (CRIMYN) frequently coexist with severe sepsis and is associated with prolonged weaning from mechanical ventilation and prolonged ICU length of stay. We aimed to classify different levels as well as patterns of impairment with regard to electrophysiological disturbances in CRIMYN patients by cluster analysis. METHODS: A total of 30 patients with sepsis/SIRS were studied prospectively. Motor and sensory conduction studies were performed from six motor and four sensory nerves on a weekly basis from admission until discharge and finally after 6 months. A control group of 63 healthy persons was examined simultaneously using the same criteria. Different patterns of electrophysiological disturbances were classified by cluster analysis based on differences to reference values of 20 parameters, compound muscle action potential (CMAP), sensory nerve action potential (SNAP) and motor and sensor conduction velocity (NCV). RESULTS: Four different clusters were identified: cluster 1 showing normal values for CMAP, SNAP and NCV in all nerves (3 patients and all test persons), cluster 2 showing pathological values for CMAP in the lower extremities and the other parameters were normal (5 patients), cluster 3 showing moderately pathological values for CMAP, SNAP and sensory NCV in upper and lower extremities and motor NCV in lower extremities (12 patients) and cluster 4 showing severe disturbances of CMAP, SNAP and NCV in upper and lower extremities (10 patients). CONCLUSION: A total of four different clusters of electrophysiological impairment can be identified in patients with sepsis/SIRS, which enables further differentiation of the severity of neuromuscular disturbances in sepsis-associated organ failure. This might be useful as a prognostic parameter and can be correlated with additional clinical and paraclinical parameters related to sepsis.

[Wilson's disease and multiple sclerosis. Co-occurrence]. / Morbus Wilson und Multiple Sklerose. Eine Koinzidenz.

Wilson's disease is a rare autosomal recessive disorder of hepatic copper transport leading to hepatic but also to highly variable neurological symptoms with basal ganglia and cerebellar manifestation. Symptoms, signs and results of investigations can overlap with those of other central nervous system disorders such as multiple sclerosis and sometimes delay diagnosis.We report on a 38-year-old male patient who was diagnosed with a hepatic form of Wilson's disease at age 12 and with multiple sclerosis at age 38. Intravenous radio copper test confirmed the diagnosis of Wilson's disease. Multiple sclerosis was diagnosed after occurrence of transient sensory disturbances in both legs, based on typical changes on MRI over the course of 2 years, in the cerebrospinal fluid and in multimodal evoked potentials.Although Wilson's disease and multiple sclerosis are known as distinct diseases with a completely different pathophysiology, symptoms and results of evoked potentials overlap, and they share a common historic background. Similarities and differences of both disorders are discussed.

Attosecond metrology in a continuous-beam transmission electron microscope.

Electron microscopy can visualize the structure of complex materials with atomic and subatomic resolution, but investigations of reaction dynamics and light-matter interaction call for time resolution as well, ideally on a level below the oscillation period of light. Here, we report the use of the optical cycles of a continuous-wave laser to bunch the electron beam inside a transmission electron microscope into electron pulses that are shorter than half a cycle of light. The pulses arrive at the target at almost the full average brightness of the electron source and in synchrony to the optical cycles, providing attosecond time resolution of spectroscopic features. The necessary modifications are simple and can turn almost any electron microscope into an attosecond instrument that may be useful for visualizing the inner workings of light-matter interaction on the basis of the atoms and the cycles of light.

Ultrafast electron diffraction from nanophotonic waveforms via dynamical Aharonov-Bohm phases.

Electron interferometry via phase-contrast microscopy, holography, or picodiffraction can provide a direct visualization of the static electric and magnetic fields inside or around a material at subatomic precision, but understanding the electromagnetic origin of light-matter interaction requires time resolution as well. Here, we demonstrate that pump-probe electron diffraction with all-optically compressed electron pulses can capture dynamic electromagnetic potentials in a nanophotonic material with sub-light-cycle time resolution via centrosymmetry-violating Bragg spot dynamics. The origin of this effect is a sizable quantum mechanical phase shift that the electron de Broglie wave obtains from the oscillating electromagnetic potentials within less than 1 fs. Coherent electron imaging and scattering can therefore reveal the electromagnetic foundations of light-matter interaction on the level of the cycles of light.

Nationwide in-hospital mortality rate following rectal resection for rectal cancer according to annual hospital volume in Germany.

BACKGROUND: The impact of hospital volume after rectal cancer surgery is seldom investigated. This study aimed to analyse the impact of annual rectal cancer surgery cases per hospital on postoperative mortality and failure to rescue. METHODS: All patients diagnosed with rectal cancer and who had a rectal resection procedure code from 2012 to 2015 were identified from nationwide administrative hospital data. Hospitals were grouped into five quintiles according to caseload. The absolute number of patients, postoperative deaths and failure to rescue (defined as in-hospital mortality after a documented postoperative complication) for severe postoperative complications were determined. RESULTS: Some 64 349 patients were identified. The overall in-house mortality rate was 3·9 per cent. The crude in-hospital mortality rate ranged from 5·3 per cent in very low-volume hospitals to 2·6 per cent in very high-volume centres, with a distinct trend between volume categories (P < 0·001). In multivariable logistic regression analysis using hospital volume as random effect, very high-volume hospitals (53 interventions/year) had a risk-adjusted odds ratio of 0·58 (95 per cent c.i. 0·47 to 0·73), compared with the baseline in-house mortality rate in very low-volume hospitals (6 interventions per year) (P < 0·001). The overall postoperative complication rate was comparable between different volume quintiles, but failure to rescue decreased significantly with increasing caseload (15·6 per cent after pulmonary embolism in the highest volume quintile versus 38 per cent in the lowest quintile; P = 0·010). CONCLUSION: Patients who had rectal cancer surgery in high-volume hospitals showed better outcomes and reduced failure to rescue rates for severe complications than those treated in low-volume hospitals.

ANTECEDENTES: El impacto del volumen hospitalario en los resultados de la cirugía del cáncer de recto ha sido poco investigado. Este estudio tuvo como objetivo analizar el impacto de los casos anuales de cirugía de cáncer de recto por hospital en la mortalidad postoperatoria (postoperative mortality, POM) y el fracaso en el rescate (failure to rescue, FtR). MÉTODOS: Todos los casos de pacientes hospitalizados con un diagnóstico de cáncer de recto y un código de procedimiento de resección rectal, tratados de 2012 a 2015, se identificaron a partir de datos hospitalarios administrativos a nivel nacional. Los hospitales se agruparon en cinco quintiles según el volumen de casos. Se determinó el número absoluto de pacientes, la POM y el FtR por complicaciones postoperatorias graves. El FtR se definió como la mortalidad hospitalaria después de una complicación postoperatoria documentada. RESULTADOS: Se identificaron 64.349 casos entre 2012 y 2015. La tasa de mortalidad hospitalaria global fue del 3,89% (n = 2.506). Las tasas brutas de mortalidad hospitalaria variaron de 5,34% (n = 687) en hospitales de muy bajo volumen a 2,63% (n = 337) en centros de muy alto volumen, con una tendencia distinta entre las categorías de centros (P < 0,001). En el análisis de regresión logística multivariante utilizando el volumen hospitalario como efecto aleatorio, los hospitales de muy alto volumen (53 intervenciones/año) tenían una razón de oportunidades (odds ratio, OR) ajustada por riesgo de 0,58 (i.c. del 95%: 0,47-0,73) en comparación con la tasa basal de mortalidad hospitalaria en hospitales de muy bajo volumen (6 intervenciones/año) (P < 0,001). La tasa global de complicaciones postoperatorias fue comparable entre los diferentes quintiles de volumen, pero el FtR disminuyó significativamente con el aumento del volumen de casos (15,63% FtR tras una embolia pulmonar en el quintil más alto versus 38,4% en el hospital del quintil más bajo, P = 0,01). CONCLUSIÓN: Los pacientes sometidos a cirugía de cáncer de recto en hospitales de gran volumen presentaron mejores resultados y una disminución de las tasas de fracaso en el rescate por complicaciones graves en comparación con los pacientes tratados en hospitales de bajo volumen.

MPS1 and MPS2: novel yeast genes defining distinct steps of spindle pole body duplication.

It is crucial to the eucaryotic cell cycle that the centrosome undergo precise duplication to generate the two poles of the mitotic spindle. In the budding yeast Saccharomyces cerevisiae, centrosomal functions are provided by the spindle pole body (SPB), which is duplicated at the time of bud emergence in G1 of the cell cycle. Genetic control of this process has previously been revealed by the characterization of mutants in CDC31 and KAR1, which prevent SPB duplication and lead to formation of a monopolar spindle. Newly isolated mutations described here (mps1 and mps2, for monopolar spindle) similarly cause monopolar mitosis but their underlying effects on SPB duplication are unique. The MPS1 gene is found by electron microscopy to be essential for proper formation of the site at which the new SPB normally arises adjacent to the existing one. By contrast, a mutation in MPS2 permits duplication to proceed, but the newly formed SPB is structurally defective and unable to serve as a functional spindle pole. Distinct temporal requirements for the CDC31, MPS1, and MPS2 gene functions during the SPB duplication cycle further demonstrate the individual roles of these genes in the morphogenetic pathway.

Nationwide in-hospital mortality following colonic cancer resection according to hospital volume in Germany.

Background: Colonic cancer is the most common cancer of the gastrointestinal tract. The aim of this study was to determine mortality rates following colonic cancer resection and the effect of hospital caseload on in-hospital mortality in Germany. Methods: Patients admitted with a diagnosis of colonic cancer undergoing colonic resection from 2012 to 2015 were identified from a nationwide registry using procedure codes. The outcome measure was in-hospital mortality. Hospitals were ranked according to their caseload for colonic cancer resection, and patients were categorized into five subgroups on the basis of hospital volume. Results: Some 129 196 colonic cancer resections were reviewed. The overall in-house mortality rate was 5·8 per cent, ranging from 6·9 per cent (1775 of 25 657 patients) in very low-volume hospitals to 4·8 per cent (1239 of 25 825) in very high-volume centres (P < 0·001). In multivariable logistic regression analysis the risk-adjusted odds ratio for in-house mortality was 0·75 (95 per cent c.i. 0·66 to 0·84) in very high-volume hospitals performing a mean of 85·0 interventions per year, compared with that in very low-volume hospitals performing a mean of only 12·7 interventions annually, after adjustment for sex, age, co-morbidity, emergency procedures, prolonged mechanical ventilation and transfusion. Conclusion: In Germany, patients undergoing colonic cancer resections in high-volume hospitals had with improved outcomes compared with patients treated in low-volume hospitals.

Neuronal migrations and axon fasciculation are disrupted in ina-1 integrin mutants.

Integrins are heterodimeric cell surface receptors implicated in cell adhesion and signaling. Our analysis of C. elegans ina-1 alpha integrin mutants provides the first genetic evidence that migrating neurons require integrins. Mosaic analysis and expression studies show that ina-1 acts autonomously in cells to promote their migrations. Although axons generally extend to their normal targets in ina-1 mutants, bundling of axons into fascicles is defective, defining a previously unrecognized role for integrins. In addition to these neuronal phenotypes, ina-1 mutants also display many morphogenetic defects. Finally, we show that the C. elegans INA-1 alpha integrin subunit associates with the PAT-3beta subunit in vivo, suggesting that these proteins function together in cell migration, axon fasciculation, and morphogenesis.

Octave wide tunable UV-pumped NOPA: pulses down to 20 fs at 0.5 MHz repetition rate.

Femtosecond laser pulses, which are tunable from 440 to 990 nm, are generated at MHz repetition rates by noncollinear parametric amplification (NOPA). The pulses have durations of 20 to 30 fs over the major part of the tuning range and a high energy stability of 1.3% (rms). The NOPA is pumped with ultraviolet pulses from the third harmonic of an ytterbium doped fiber laser system and seeded by a smooth continuum generated in bulk sapphire. The residual second harmonic is used to pump an additional NOPA, which is independently tunable from 620 to 990 nm. Interference experiments show that the two NOPA systems have a precisely locked relative phase, despite of being pumped by different harmonics with a random phase jitter. This demonstrates that the phase of pulses generated by optical parametric amplification does not depend on the pump phase.