Two-spinon and orbital excitations of the spin-Peierls system TiOCl

We combine high-resolution resonant inelastic x-ray scattering with cluster calculations utilizing a recently derived effective magnetic scattering operator to analyze the polarization, excitation energy, and momentum-dependent excitation spectrum of the low-dimensional quantum magnet TiOCl in the range expected for orbital and magnetic excitations (0-2.5 eV). Ti 3d orbital excitations yield complete information on the temperature-dependent crystal-field splitting. In the spin-Peierls phase we observe a dispersive two-spinon excitation and estimate the inter- and intradimer magnetic exchange coupling from a comparison to cluster calculations.

Elevated stricture rate following the use of fully covered self-expandable metal biliary stents for biliary leaks following liver transplantation

BACKGROUND

Biliary leaks and strictures are common complications after liver transplantation and can be managed surgically or endoscopically. Endoscopic management using fully covered self-expandable metal stents (FCSEMS) might provide some advantages over the commonly used plastic stents in the management of bile leaks after liver transplantation.

METHODS

Between December 2006 and January 2009, 17 liver transplant recipients underwent placement of a FCSEMS for treatment of biliary leaks.

RESULTS

FCSEMS were deployed at median of 18 days (range: 6 - 160) after liver transplantation and left in place for a median of 102 days (range: 35 - 427), with a median follow-up after FCSEMS removal of 407 days (range: 27 - 972). Long-term leak control was obtained in all but one patient. Complications included 6 clinically significant biliary strictures (35 %), which were treated with repeat stent placement, and two clinically insignificant strictures (12 %) which required no intervention. Additionally, three patients (18 %) had biliary ulcerations after stent removal, confirmed by choledochoscopy, and were managed conservatively. Two patients required repeat liver transplantation due to hepatic artery thrombosis, and one patient died from sepsis unrelated to FCSEMS stenting.

CONCLUSIONS

FCSEMS treat biliary leaks effectively, but carry a relatively high stricture risk in patients who have received liver transplants. FCSEMS cannot be recommended for management of biliary leaks following liver transplantation at this point.

Spatial quantum beats in vibrational resonant inelastic soft x-ray scattering at dissociating states in oxygen

Resonant inelastic soft x-ray scattering (RIXS) spectra excited at the 1σ(g) → 3σ(u) resonance in gas-phase O2 show excitations due to the nuclear degrees of freedom with up to 35 well-resolved discrete vibronic states and a continuum due to the kinetic energy distribution of the separated atoms. The RIXS profile demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the atoms separate. Thomson scattering strongly affects both the spectral profile and the scattering anisotropy.

[Benefit of a prolonged adjuvant treatment with temozolomide for the management of patients with glioblastoma]

PURPOSE

Temozolomide has significantly improved the outcome of patients with glioblastoma. However, the optimal duration of continuation treatment after chemoradiation remains uncertain. This retrospective analysis aims at assessing the feasibility, the tolerance, and the potential benefit of prolonging adjuvant temozolomide more than six months, which is the reference protocol.

PATIENTS AND METHODS

Forty-six patients were included in the analysis. Median age at diagnosis was 61 years old (range 40 to 77). Forty-five patients received a conformal external beam radiation with concurrent temozolomide-based chemotherapy. Then, 37 patients received adjuvant chemotherapy with temozolomide. The treatment was continued until progression or toxicity.

RESULTS

During the adjuvant phase, no treatment discontinuation for toxicity was necessary. Eight patients required dose adaptation because of toxicity. Thirty-two patients presented tumor progression during the adjuvant phase. Overall median survival was 12.3 months (range 11-13.2 months) and progression-free survival (PFS) was 7.6 months (range 5.6-9.6 months).

CONCLUSION

These results suggest feasibility of delivering temozolomide beyond the six months of the standard protocol, with mild toxicity and survival data at least comparable to those from literature. Prospective assessments are ongoing.

[An optimised assessment of "severely injured patients" for the documentation of road traffic accident black spots]

INTRODUCTION

The success of traffic safety improvement strategies is based on documentation. Analysis and remedy of accident black spots in addition to improvements in automobile production involve the work of traffic engineers, politicians, traffic regulations, police, and medical care. To create priorities, the traffic statistics differentiate accidents in a 3-class system in relation to severe accidents: slightly injured, severely injured and fatally injured (death). This study assesses the validity of the existing classification of "severely injured" compared with the actual injury severity.

MATERIAL AND METHOD

We analysed accidents resulting in 182 "severely injured" people in one year in a city model. A synchronisation of anonymous police documentation with the medical notes of admitted casualties which were validated by established trauma scores and medical classification was undertaken. A correlation analysis of length of stay should give indications of the actual injury severity.

RESULTS

The study group showed a ubiquitous range of age, sex and injuries despite a relatively low case number. The range of MAIS, ISS and NACA index scores shows the inhomogeneity of the people classified as "severely injured". 70 % of the study group revealed ISS < 16 which means that they are not polytraumatised patients. The correlation analysis according to Spearman certifies the validity of these scores (r MAIS/NACA = 0.645 and r ISS/NACA = 0.592). The further differentiation on the basis of MAIS, ISS and NACA showed that 51 % of the study group should be classified as slightly injured and 83 % of these were discharged in less than 5 days.

CONCLUSION

This study shows that the traffic safety classification of "severely injured" people is not sufficient and most severely injured people are not even approximately recorded. We propose that a new continuous link system between police and medical data will be inevitable for future improvements in traffic safety. The use of established trauma scores and a differentiated look at lengths of stay could be an option.

Numerical optimization of spherical variable-line-spacing grating X-ray spectrometers

Operation of an X-ray spectrometer based on a spherical variable-line-spacing (VLS) grating is analyzed using dedicated ray-tracing software allowing fast optimization of the grating parameters and spectrometer geometry. The analysis is illustrated with optical design of a model spectrometer to deliver a resolving power above 20400 at a photon energy of 930 eV (Cu L-edge). With this energy taken as reference, the VLS coefficients are optimized to cancel the lineshape asymmetry (mostly from the coma aberrations) as well as minimize the symmetric aberration broadening at large grating illuminations, dramatically increasing the aberration-limited vertical acceptance of the spectrometer. For any energy away from the reference, corrections to the entrance arm and light incidence angle on the grating are evaluated to maintain the exactly symmetric lineshape. Furthermore, operational modes when these corrections are coordinated are evaluated to maintain either energy-independent focal curve inclination or maximal aberration-limited spectrometer acceptance. The results are supported by analytical evaluation of the coma term of the optical path function. This analysis thus gives a recipe for designing a high-resolution spherical VLS grating spectrometer operating with negligible aberrations at large acceptance and over an extended energy range.

Measurement of magnetic excitations in the two-dimensional antiferromagnetic Sr₂CuO₂Cl₂ insulator using resonant x-ray scattering: evidence for extended interactions

We measured the momentum dependence of magnetic excitations in the model spin-1/2 2D antiferromagnetic insulator Sr2CuO2Cl2 (SCOC). We identify a single-spin-wave feature and a multimagnon continuum, with different polarization dependences. The spin waves display a large (70 meV) dispersion between the zone-boundary points (π, 0) and (π/2, π/2). Employing an extended t-t'-t''-U one-band Hubbard model, we find significant electronic hopping beyond nearest-neighbor Cu ions, indicative of extended magnetic interactions. The spectral line shape at (π, 0) indicates sizable quantum effects in SCOC and probably more generally in the cuprates.

High-resolution soft X-ray beamline ADRESS at the Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies

The concepts and technical realisation of the high-resolution soft X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV and intended for resonant inelastic X-ray scattering (RIXS) and angle-resolved photoelectron spectroscopy (ARPES) are described. The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0-180 degrees rotatable linear polarizations) but also the energy without changing the gap. The beamline optics is based on the well established scheme of plane-grating monochromator operating in collimated light. The ultimate resolving power E/DeltaE is above 33000 at 1 keV photon energy. The choice of blazed versus lamellar gratings and optimization of their profile parameters is described. Owing to glancing angles on the mirrors as well as optimized groove densities and profiles of the gratings, the beamline is capable of delivering high photon flux up to 1 x 10(13) photons s(-1) (0.01% BW)(-1) at 1 keV. Ellipsoidal refocusing optics used for the RIXS endstation demagnifies the vertical spot size down to 4 microm, which allows slitless operation and thus maximal transmission of the high-resolution RIXS spectrometer delivering E/DeltaE > 11000 at 1 keV photon energy. Apart from the beamline optics, an overview of the control system is given, the diagnostics and software tools are described, and strategies used for the optical alignment are discussed. An introduction to the concepts and instrumental realisation of the ARPES and RIXS endstations is given.

Genetic poverty of an extremely specialized wetland species, Nehalennia speciosa: implications for conservation (Odonata: Coenagrionidae)

Oligo- and mesotrophic wetlands, such as bogs, fens and swamps, have become more and more restricted in Europe, and wetland species related to them have increasingly been threatened. Due to increasing habitat fragmentation, the exchange of individuals of these species among sites and, as a consequence, gene flow has been reduced or even eliminated. Therefore, we analysed the genetic structure of 11 populations of an endangered stenotopic damselfly, Nehalennia speciosa (Odonata: Coenagrionidae), in Poland and Lithuania by means of allozyme electrophoresis of 14 gene loci. The overall genetic diversity of all populations was low (A: 1.32; H: 2.6%; Ptot: 29.2%), and no significant differences were observed among the different groupings of populations (degree of fragmentation, habitat type and size, population size). The genetic differentiation among populations was also low (FST: 2.0%) and no regional groups were detected. A low degree of isolation by distance was observed for genetic distances. Taking into account these results, the conservation effort for this species should be focused on large local populations and not necessarily on metapopulation structures. Furthermore, N. speciosa could be (re-)introduced in extinct patches and seemingly suitable localities. Genetically, such relocations should be feasible due to the generally high genetic homogeneity of populations.

Deep intra-uterine artificial inseminations using cryopreserved spermatozoa in beluga (Delphinapterus leucas)

Artificial insemination (AI) with liquid-stored spermatozoa and sperm cryopreservation using directional freezing (DF) have been successful in the beluga. This study built on this foundation to develop a deep intra-uterine AI technique with frozen-thawed semen in beluga. Forty-two ejaculates from one male were cryopreserved using DF technology and subsequently used for 10 insemination attempts with seven females. Percentage pre- and post-thaw progressive motility and viability were (mean +/- SD) 73.0 +/- 12.2, 38.4 +/- 8.8, 88.0 +/- 0.1, and 59.3 +/- 15.7%, respectively. A series of GnRH injections (3 x 250 microg, IV, 1.5 to 2 h apart) were used to induce ovulation, once a growing follicle >2.5 cm in diameter was visualized via trans-abdominal ultrasonography. Artificial insemination was performed at 30.1 +/- 3.8 h post-initial GnRH injection with semen deposited in the uterine horn, 92.6 +/- 16.2 cm beyond the genital opening using a flexible endoscope. The external cervical os (cEOS) was located beyond a series of 5 to 10 vaginal rings, 44.8 +/- 9.3 cm from the external genital opening. The internal bifurcation of the uterus was 27 +/- 6.8 cm beyond the cEOS. Ovulation occurred at 8.5 +/- 7.6 h post-AI. Two of 10 inseminations (20%) resulted in pregnancy. The first pregnancy resulted in twins; both calves were born 442 d after AI, with one surviving. The second pregnancy is ongoing. These findings represent the first successful application of AI using frozen-thawed semen in beluga, and are important examples of how assisted reproductive technologies can provide tools for the global management of threatened species.

Resonant inelastic scattering spectra of free molecules with vibrational resolution

Inelastic x-ray scattering spectra excited at the 1s(-1)π* resonance of gas phase O2 have been recorded with an overall energy resolution that allows for well-resolved vibrational progressions. The nuclear wave packet dynamics in the intermediate state is reflected in vibrational excitations of the electronic ground state, and by fine-tuning the excitation energy the dissociation dynamics in the predissociative B'(3)Πg final state is controlled.

Behavioral and genetic characteristics of a new species of Nasonia

Nasonia (Hymenoptera: Pteromalidae) is a genus of parasitoid wasps, which is fast emerging as a model system for evolutionary, genetic, developmental and host-endosymbiont interaction studies. In this study, we report a new species, Nasonia oneida, distinguish its behavioral, genetic and morphological features, and characterize its pre-mating and post-mating isolation with the other Nasonia species. Phylogenetic analyses indicate that N. oneida is the sister species to Nasonia giraulti with its own uniquely distinct cuticular hydrocarbon profiles, behavioral characteristics and subtle morphological differences. An important characteristic of N. oneida is the strong mate discrimination shown by the females against all the other Nasonia species. A genetic analysis of this phenotype by interspecies hybridization indicates that this strong discriminating phenotype is recessive. A formal species description of N. oneida Raychoudhury & Desjardins is also provided.

Magnetic excitations and phase separation in the underdoped La2-xSrxCuO4 superconductor measured by resonant inelastic X-ray scattering

We probe the collective magnetic modes of La2CuO4 and underdoped La2-xSrxCuO4 (LSCO) by momentum resolved resonant inelastic x-ray scattering (RIXS) at the Cu L3 edge. For the undoped antiferromagnetic sample, we show that the single magnon dispersion measured with RIXS coincides with the one determined by inelastic neutron scattering, thus demonstrating that x rays are an alternative to neutrons in this field. In the spin dynamics of LSCO, we find a branch dispersing up to approximately 400 meV coexisting with one at lower energy. The high-energy branch has never been seen before. It indicates that underdoped LSCO is in a dynamic inhomogeneous spin state.

The genetic consequences of different dispersal behaviours in lycaenid butterfly species

Many studies in population ecology have shown that related species have different dispersal behaviours. Species with sedentary and migratory behaviour exist in butterflies. While the genetic responses to population isolation are well studied, the effects of different dispersal behaviours of species are widely unknown. Therefore, we analysed 19 allozyme loci of two lycaenid butterflies, Cupido minimus as a sedentary butterfly and Aricia agestis as a mobile and expansive species. We collected 594 individuals (280 of C. minimus and 314 of A. agestis) in a western German study region with adjacent areas in Luxembourg and northeastern France. The genetic differentiation among populations of A. agestis (FST=3.9%) was lower than in C. minimus (FST=5.6%). Both species built up an isolation-by-distance system, which is more pronounced in A. agestis than in C. minimus. The genetic diversity in C. minumus populations (e.g. Ptot=73.5%) is higher for all analysed parameters than in A. agestis (e.g. Ptot=52.1%). Both species show specific genetic characteristics fitting with their different dispersal behaviours and respective ecological strategies. In the light of conservation genetics, we deduce that highly fragmented populations do not necessarily have a high extinction probability, but this risk depending much more on specific population genetic structures. In the studied species, C. minimus preserves a complex genetic constitution by high population densities. The patchily distributed A. agestis represents less rare alleles, present only in some populations, and holds up genetic diversity by high mobility.

Momentum dependence of orbital excitations in Mott-insulating titanates

High-resolution resonant inelastic x-ray scattering has been used to determine the momentum dependence of orbital excitations in Mott-insulating LaTiO(3) and YTiO(3) over a wide range of the Brillouin zone. The data are compared to calculations in the framework of lattice-driven and superexchange-driven orbital ordering models. A superexchange model in which the experimentally observed modes are attributed to two-orbiton excitations yields the best description of the data.