Ultrastable, high-repetition-rate attosecond beamline for time-resolved XUV-IR coincidence spectroscopy.

The implementation of attosecond photoelectron-photoion coincidence spectroscopy for the investigation of atomic and molecular dynamics calls for a high-repetition-rate driving source combined with experimental setups characterized by excellent stability for data acquisition over time intervals ranging from a few hours up to a few days. This requirement is crucial for the investigation of processes characterized by low cross sections and for the characterization of fully differential photoelectron(s) and photoion(s) angular and energy distributions. We demonstrate that the implementation of industrial-grade lasers, combined with a careful design of the delay line implemented in the pump-probe setup, allows one to reach ultrastable experimental conditions leading to an error in the estimation of the time delays of only 12 as over an acquisition time of 6.5 h. This result opens up new possibilities for the investigation of attosecond dynamics in simple quantum systems.

Attosecond photoionisation time delays reveal the anisotropy of the molecular potential in the recoil frame.

Photoionisation time delays carry structural and dynamical information on the target system, including electronic correlation effects in atoms and molecules and electron transport properties at interfaces. In molecules, the electrostatic potential experienced by an outgoing electron depends on the emission direction, which should thus lead to anisotropic time delays. To isolate this effect, information on the orientation of the molecule at the photoionisation instant is required. Here we show how attosecond time delays reflect the anisotropic molecular potential landscape in CF4 molecules. The variations in the measured delays can be directly related to the different heights of the potential barriers that the outgoing electrons see in the vicinity of shape resonances. Our results indicate the possibility to investigate the spatial characteristics of the molecular potential by mapping attosecond photoionisation time delays in the recoil-frame.

Shape-controlling effects of hydrohalic and carboxylic acids in TiO2 nanoparticle synthesis.

The ability to synthesize nanoparticles (NPs), here TiO2, of different shapes in a controlled and reproducible way is of high significance for a wide range of fields including catalysis and materials design. Different NP shapes exhibit variations of emerging facets, and processes such as adsorption, diffusion, and catalytic activity are, in general, facet sensitive. Therefore, NP properties, e.g., the reactivity of NPs or the stability of assembled NPs, depend on their shape. We combine computational modeling based on density functional theory with experimental techniques such as transmission electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray powder diffraction to investigate the ability of various adsorbates, including hydrohalic and carboxylic acids, to influence NP shape. This approach allows us to identify mechanisms stabilizing specific surface facets and thus to predict NP shapes using computational model systems and to experimentally characterize the synthesized NPs in detail. Shape-controlled anatase TiO2 NPs are synthesized here in agreement with the calculations in platelet and bi-pyramidal shapes by employing different precursors. The importance of the physical conditions and chemical environment during synthesis, e.g., via competitive adsorption or changes in the chemical potentials, is studied via ab initio thermodynamics, which allows us to set previous and new results in a broader context and to highlight potentials for additional synthesis routes and NP shapes.

Injury severity in polytrauma patients is underestimated using the injury severity score: a single-center correlation study in air rescue.

PURPOSE: Prehospital estimation of injury severity is essential for prehospital therapy, deciding on the destination hospital and the associated emergency room care. The aim of this study was to compare prehospital estimates of the abbreviated injury scale (AIS) and the Injury Severity Score (ISS) by emergency physicians with the values of AIS and ISS of injury severity determined at the conclusion of diagnostics. METHODS: In this prospective study, the ISS was determined prehospital by emergency physicians. The validated AIS and ISS were analyzed based on final diagnoses. A Bland-Altman plot was used in analyzing the agreement between two different assays as well as sensitivity and specificity were determined. Confidence intervals were calculated for a Wilson score. Significance level was set at p ≤ 0.05. RESULTS: The prehospital ISS was estimated at 26.0 ± 13.0 and was 34.7 ± 16.3 (p < 0.001) after in-hospital validation. In addition, most of the AIS subgroups were significantly higher in the final calculation than preclinically estimated (p < 0.05). When analyzing subgroups of trauma patients (ISS < 16 vs. ISS ≥ 16), we were able to demonstrate a sensitivity of > 90% to identify a multiple-trauma patient. Diagnosing a higher injury severity group (ISS ≥ 25), sensitivity dropped to 61.1%. The Bland-Altman plot demonstrates that injury severity is underestimated in higher injury levels. CONCLUSION: Multiple-trauma patients can be identified using the ISS. Anatomic scores might be used for transport decisions; however, an accurate estimation of the injury severity should also be based on other criteria such as patient status, mechanism of injury, and other triage criteria.

[Injury to the upper limbs and prevention in equestrian sports]. / Verletzungen der oberen Extremität und Prävention im Reitsport.

The upper limb is one of the most frequently injured body regions in equestrian sports, but it is unclear which injuries are involved, and there are no data on the associated accident mechanism. The present study is aimed at evaluating the accident mechanisms, injuries of the upper limbs, and the circumstances of the accident in equestrian sports. We included 218 patients who were all treated between 2006 and 2014 at the level I trauma center at the Medical University in Hannover because of equestrian-related accidents. The most frequent injuries were fractures and bruising in the shoulder area, fingers and hands, and the distal area of the lower arm, which were mostly caused by the horse kicking. To prevent hand injuries it is recommended that gloves are worn; the potential introduction of strengthened materials could protect the bones from severe bumping. Training in falling techniques to prevent serious injury to the upper limb would be useful. In general, primary prevention in equestrian sports should be extended to counteract the increasing neglect of protective equipment.

Limited influence of blunt aortic injuries on the outcome of polytraumatized patients: a matched pair analysis.

INTRODUCTION: Traumatic lesions of great vessels such as the aorta are life-threatening injuries. There is limited evidence about the influence of traumatic aortic injuries in multiple trauma patients in particular with regard to posttraumatic complications. The aim of this study was to evaluate the influence of blunt thoracic aortic injuries in multiple trauma patients compared to a multiple trauma cohort without this specific injury. In addition, the safety of Thoracic Endovascular Aortic Repair (TEVAR) in multiple trauma patients was analyzed. MATERIALS AND METHODS: A retrospective study was performed. We included all multiple trauma patients (ISS ≥ 16, age > 14 years) between 2005 and 2014 with (group BTAI) and without (group nBTAI) blunt traumatic aortic injuries who were treated at our level-1 trauma center. Demographic as well as clinical parameters were analyzed including injury pattern, mechanism of injury, posttraumatic complications such as ARDS, multiple organ dysfunction syndrome (MODS) and others. A matched pair analysis was performed by propensity score matching. RESULTS: In total, 721 patients were enrolled (group BTAI: n = 45; nBTAI: n = 676). In the initial study population, surgical intervention was done in n = 32 (71.1%) patients (TEVAR: n = 25; 78.1%), there was an increased AISChest and overall injury severity in group BTAI with associated significantly more posttraumatic complications in group BTAI. The matched pair analysis consisted of 42 patients per group. Beside an increased ventilation time, no significant differences were evident after the matching process. There was a trend to increased risk for SIRS using binary logistic regression analysis. CONCLUSIONS: Multiple trauma patients with blunt thoracic aortic injuries who are treated at a level-1 trauma center show a comparable outcome matched to their counterparts without aortic injuries. Our study confirms that using TEVAR in polytraumatized patients is a safe procedure. In all patients treated with TEVAR, there were no procedure-related complications, especially no neurological deficit.

[Accidents in equestrian sports : Analysis of injury mechanisms and patterns]. / Unfälle im Reitsport : Analyse von Verletzungsmechanismen und -mustern.

BACKGROUND: Equestrian sports are one of the most popular forms of sport in Germany, while also being one of the most accident-prone sports. Furthermore, riding accidents are frequently associated with a high degree of severity of injuries and mortality. Nevertheless, there are insufficient data regarding incidences, demographics, mechanisms of accidents, injury severity and patterns and outcome of injured persons in amateur equestrian sports. Accordingly, it was the aim of the present study to retrospectively analyze these aspects. METHODS: A total of 503 patients were treated in the emergency room of the Hannover Medical School because of an accident during recreational horse riding between 2006 and 2011. The female gender was predominantly affected with 89.5 %. The mean age of the patients was 26.2 ± 14.9 years and women (24.5 ± 12.5 years) were on average younger than men (40.2 ± 23.9 years). A special risk group was girls and young women aged between 10 and 39 years. The overall injury severity was measured using the injury severity score (ISS). RESULTS: Based on the total population, head injuries were the most common location of injuries with 17.3 % followed by injuries to the upper extremities with 15.2 % and the thoracic and lumbar spine with 10.9 %. The three most common injury locations after falling from a horse were the head (17.5 %), the upper extremities (17.4 %), the thoracic and lumbar spine (12.9 %). The most frequent injuries while handling horses were foot injuries (17.2 %), followed by head (16.6 %) and mid-facial injuries (15.0 %). With respect to the mechanism of injury accidents while riding were predominant (74 %), while accidents when handling horses accounted for only 26 %. The median ISS was 9.8 points. The proportion of multiple trauma patients (ISS > 16) was 18.1 %. Based on the total sample, the average in-hospital patient stay was 5.3 ± 5.4 days with a significantly higher proportion of hospitalized patients in the group of riding accidents. Fatal cases were not found in this study but the danger of riding is not to be underestimated. The large number of sometimes severe injuries with ISS values up to 62 points can be interpreted as an indication that recreational riding can easily result in life-threatening situations. CONCLUSION: Girls and young women could be identified as a group at particular risk. It has been demonstrated in this study that the three most common injury locations after falling from a horse were the head, the upper extremities, the thoracic and lumbar spine. The most frequent injury locations while handling horses were foot injuries, followed by head and mid-facial injuries.

[Cervical spine injury in equestrian sports]. / Halswirbelsäulenverletzungen im Breitenreitsport.

The cervical spine is considered fragile and vulnerable to injuries in equestrian sport. This retrospective study investigates the injury pattern and severity. Patients of the medical university in Hannover from the years 2006-2011, who had an equestrian accident, were identified. Patients who had been injured in the course of their work were excluded. Results counted with a p-value < 0.05 were considered significant. In 13.1% of patients, there were 71 cervical spine injuries (92.4% female; 7.6% male). The mean age was 27.1 ± 13.2 years. Of these, 86.4% associated the injury to the riding accident. In 56 cases, it concerned falls from the horse. In 13.6% of the cases, the injury was caused while handling the horse. Sprains were most common (70.4%). Fractures of the neck vertebrae were found in 22.5% of the cases. The mean ISS was 7.0 ± 5.8 pts. Polytrauma was identified in 6.1% of patients (ISS ≥ 16 Pkt). The most common accompanying injury presented was an injury to the head (29.2%; p = 0.003). Of the 30 hospitalized patients, 13.3% were admitted to intensive medical care for 2.3 ± 15.4 d. The mortality was 0%. Injuries of the cervical spine are not to be underestimated in their frequency and severity. It is shown that, especially with injuries of the head and thoracic and lumbar spine area, patients are at increased risk of concurrent cervical lesions. The prevention of neck injuries is currently done in the form of riding helmets, airbag jackets, riding behavior and education. Further study of the prevention of neck injuries is required.

Ultrafast electron diffraction imaging of bond breaking in di-ionized acetylene.

Visualizing chemical reactions as they occur requires atomic spatial and femtosecond temporal resolution. Here, we report imaging of the molecular structure of acetylene (C2H2) 9 femtoseconds after ionization. Using mid-infrared laser-induced electron diffraction (LIED), we obtained snapshots as a proton departs the [C2H2]2+ ion. By introducing an additional laser field, we also demonstrate control over the ultrafast dissociation process and resolve different bond dynamics for molecules oriented parallel versus perpendicular to the LIED field. These measurements are in excellent agreement with a quantum chemical description of field-dressed molecular dynamics.

The cryogenic storage ring CSR.

An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm(-3) is derived, equivalent to a room-temperature pressure below 10(-14) mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams.

Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets.

The ability to directly follow and time-resolve the rearrangement of the nuclei within molecules is a frontier of science that requires atomic spatial and few-femtosecond temporal resolutions. While laser-induced electron diffraction can meet these requirements, it was recently concluded that molecules with particular orbital symmetries (such as πg) cannot be imaged using purely backscattering electron wave packets without molecular alignment. Here, we demonstrate, in direct contradiction to these findings, that the orientation and shape of molecular orbitals presents no impediment for retrieving molecular structure with adequate sampling of the momentum transfer space. We overcome previous issues by showcasing retrieval of the structure of randomly oriented O2 and C2H2 molecules, with πg and πu symmetries, respectively, and where their ionization probabilities do not maximize along their molecular axes. While this removes a serious bottleneck for laser-induced diffraction imaging, we find unexpectedly strong backscattering contributions from low-Z atoms.

Is there a benefit for health care workers in testing HIV, HCV and HBV in routine before elective arthroplasty?

INTRODUCTION: Occupational infection of clinical health care workers with blood-borne viruses (BBVs) like human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV) is a current and often emotionally discussed issue. HCV and especially HIV are still stigmatized. The consequence is a broad and maybe irrational fear of professional health care workers being infected occupationally. Therefore, we assessed preoperative screening to: (1) answer whether this can detect not previously diagnosed blood-borne virus infections to a great extent, (2) calculate a cost-benefit ratio to find out, if the screening's potential ability to prevent occupational transmission of BBVs to health care workers faces unjustifiable high costs. HYPOTHESIS: Preoperative routine screening is limited suitable for enhancement of detecting fomites compared to interview the patient. MATERIALS AND METHODS: Retrospective cohort study of preoperative screening for HIV, HBV and HCV (HBsAg, anti-HCV and HIV-Ab/Ag-Combination) for every patient who was admitted to the traumatologic department for elective arthroplasty between 01/01/1997 and 31/12/2008. RESULTS: Among the 1534 patients who underwent elective prosthetic surgery [total hip (879) and knee arthroplasty (508), followed by shoulder, elbow and upper ankle joint], 693 (45.2%) patients were male and 841 (54.8) female. Mean age was 64.2±13.8 years. Screening tests were available for 1373 patients (89.5%). Among all screened patients, we found 21 HCV, 10 HBV and 1 HIV infections. 5 HBV (0.5%) and 7 HCV infections (0.7%) were unknown before. Every newly detected infectious patient occasions screening costs about 7250€. Considering this data, the risk of HCV transmission from an index patient with unknown status of infectiousness to health care worker after percutaneous contact to blood is 0.08 ‰ and of HIV transmission is 0.00054 ‰ in our study population. DISCUSSION: Routine preoperative screening for BBVs of patients undergoing elective arthroplasty, who were asked for HBV, HCV and HIV, should be reconsidered and is, in times of sparse funds, overpriced. LEVEL OF EVIDENCE: IV.

Multiple ionization and fragmentation dynamics of molecular iodine studied in IR-XUV pump-probe experiments.

The ionization and fragmentation dynamics of iodine molecules (I(2)) are traced using very intense (∼10(14) W cm(-2)) ultra-short (∼60 fs) light pulses with 87 eV photons of the Free-electron LASer at Hamburg (FLASH) in combination with a synchronized femtosecond optical laser. Within a pump-probe scheme the IR pulse initiates a molecular fragmentation and then, after an adjustable time delay, the system is exposed to an intense FEL pulse. This way we follow the creation of highly-charged molecular fragments as a function of time, and probe the dynamics of multi-photon absorption during the transition from a molecule to individual atoms.

Electron rearrangement dynamics in dissociating I(2)

The charge rearrangement in dissociating I_{2}^{n+} molecules is measured as a function of the internuclear distance R using extreme ultraviolet pulses delivered by the free-electron laser in Hamburg. Within an extreme ultraviolet pump-probe scheme, the first pulse initiates dissociation by multiply ionizing I_{2}, and the delayed probe pulse further ionizes one of the two fragments at a given time, thus triggering charge rearrangement at a well-defined R. The electron transfer between the fragments is monitored by analyzing the delay-dependent ion kinetic energies and charge states. The experimental results are in very good agreement with predictions of the classical over-the-barrier model demonstrating its validity in a thus far unexplored quasimolecular regime relevant for free-electron laser, plasma, and chemistry applications.

[Challenges in the context of medical care during a naval research expedition. A case report]. / Herausforderungen im Rahmen der ärztlichen Begleitung einer Forschungsseereise. Ein Erfahrungsbericht.

Exploration for natural resources in the seabed of the Indian Ocean was undertaken by the German government institution of earth sciences and resources ("Bundesanstalt für Geowissenschaften und Rohstoffe", BGR) in November 2012. To provide for the medical safety of crew and scientists, a cooperation between the BGR and the trauma department of the Hannover Medical School was established. Research by physicians accompanying the naval expedition revealed that medical consultations mainly occur because of respiratory infections, abdominal discomfort, genitourinary discomfort and seasickness, with the rate of traumas being between 31% and 41%. Di Giovanna et al. stated that 97% of all emergencies on cruise ships are not critical and only 3% need an immediate emergency medical intervention. Consultations were already performed on the mainland prior to departure and included minor traumas due to non-appropriate footwear, otitis and respiratory infections. Seasickness was the main reason for consultation during the first days at sea. Strong seas resulted in some bruises. Minor injuries and foreign body injuries to the hands and feet also required consultation. First-degree sunburns resulted from exposure to the sun, while air-conditioning caused rhinosinusitis and conjunctivitis. A special consultation was a buccal splitting of tooth 36. An immediate emergency medical intervention was not necessary due to the relative low level of pain for the patient; however, due to the risk of further damage caused by nocturnal bruxism, a protective splint was formed using a small syringe. Other reasons for consultation were similar to those reported in the general literature. Medical activities at exotic locations may create the vision of a holiday character at first; however, intensive planning and preparation are needed. We recommend contacting police, customs, the federal institute for drugs and medical devices as well as the labour inspectorate, preferably in both the originating country and the destination, to prepare custom formalities and to obtain formal documents and approvals beforehand. It is advisable to be prepared not only for emergency situations, but also for general medical and dental problems. Improvisation in the treatment of special health problems is an unavoidable requisite.

Time-resolved measurement of interatomic coulombic decay in Ne2.

The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al., Phys. Rev. Lett. 79, 4778 (1997)] in Ne2 is determined via an extreme ultraviolet pump-probe experiment at the Free-Electron Laser in Hamburg. The pump pulse creates a 2s inner-shell vacancy in one of the two Ne atoms, whereupon the ionized dimer undergoes ICD resulting in a repulsive Ne+(2p(-1))-Ne+(2p(-1)) state, which is probed with a second pulse, removing a further electron. The yield of coincident Ne+-Ne2+ pairs is recorded as a function of the pump-probe delay, allowing us to deduce the ICD lifetime of the Ne2(+)(2s(-1)) state to be (150±50) fs, in agreement with quantum calculations.

Ionization with low-frequency fields in the tunneling regime.

Strong-field ionisation surprises with richness beyond current understanding despite decade long investigations. Ionisation with mid-IR light has promptly revealed unexpected kinetic energy structures that seem related to unanticipated quantum trajectories of the electrons. We measure first 3D momentum distributions in the deep tunneling regime (γ = 0.3) and observe surprising new electron dynamics of near-zero momentum electrons and extremely low momentum structures, below the eV, despite very high quiver energies of 95 eV. Such level of high-precision measurements at only 1 meV above the threshold, despite 5 orders higher ponderomotive energies, has now become possible with a specifically developed ultrafast mid-IR light source in combination with a reaction microscope, thereby permitting a new level of investigations into mid-IR recollision physics.

Ultrafast charge rearrangement and nuclear dynamics upon inner-shell multiple ionization of small polyatomic molecules.

Ionization and fragmentation of methylselenol (CH(3)SeH) molecules by intense (>10(17) W/cm(2)) 5 fs x-ray pulses (hω=2 keV) are studied by coincident ion momentum spectroscopy. We contrast the measured charge state distribution with data on atomic Kr, determine kinetic energies of resulting ionic fragments, and compare them to the outcome of a Coulomb explosion model. We find signatures of ultrafast charge redistribution from the inner-shell ionized Se atom to its molecular partners, and observe significant displacement of the atomic constituents in the course of multiple ionization.

Nanoplasma dynamics of single large xenon clusters irradiated with superintense x-ray pulses from the linac coherent light source free-electron laser.

The plasma dynamics of single mesoscopic Xe particles irradiated with intense femtosecond x-ray pulses exceeding 10(16) W/cm2 from the Linac Coherent Light Source free-electron laser are investigated. Simultaneous recording of diffraction patterns and ion spectra allows eliminating the influence of the laser focal volume intensity and particle size distribution. The data show that for clusters illuminated with intense x-ray pulses, highly charged ionization fragments in a narrow distribution are created and that the nanoplasma recombination is efficiently suppressed.

Wavelength dependence of the suppressed ionization of molecules in strong laser fields.

We study ionization of molecules by an intense laser field over a broad wavelength regime, ranging from 0.8 to 1.5 µm experimentally and from 0.6 to 10 µm theoretically. A reaction microscope is combined with an optical parametric amplifier to achieve ionization yields in the near-infrared wavelength regime. Calculations are done using the strong-field S-matrix theory and agreement is found between experiment and theory, showing that ionization of many molecules is suppressed compared to the ionization of atoms with identical ionization potentials at near-infrared wavelengths at around 0.8 µm, but not at longest wavelengths (10 µm). This is due to interference effects in the electron emission that are effective at low photoelectron energies but tend to average out at higher energies. We observe the transition between suppression and nonsuppression of molecular ionization in the near-infrared wavelength regime (1-5 µm).