Phonon Dispersion and Proton Disorder of Ice VII and VIII

The phonon dispersion of ice VII and that of its proton-ordered analog ice VIII are investigated through a combination of inelastic x-ray scattering (IXS) measurements and first-principles calculations of the oxygen sublattice dynamic structure factor. Particular attention is devoted to hydrogen-disorder in ice VII, addressed theoretically through a statistical ensemble of fictitious ordered supercell configurations. Similar phonon densities of states are found in both phases but are significantly less structured in the case of ice VII. Our data further show that, despite a full proton disorder, the acoustic phonon branches in this phase clearly inherit the periodicity of its body-centered cubic oxygen lattice. The calculations predict, however, the presence of gap openings in the one-atom phonon dispersion. These predictions are supported by revisiting the analysis of previous single-crystal IXS measurements along the longitudinal [111] branch of ice VII.

Single-atom vibrational spectroscopy in the scanning transmission electron microscope

Single-atom impurities and other atomic-scale defects can notably alter the local vibrational responses of solids and, ultimately, their macroscopic properties. Using high-resolution electron energy-loss spectroscopy in the electron microscope, we show that a single substitutional silicon impurity in graphene induces a characteristic, localized modification of the vibrational response. Extensive ab initio calculations reveal that the measured spectroscopic signature arises from defect-induced pseudo-localized phonon modes-that is, resonant states resulting from the hybridization of the defect modes and the bulk continuum-with energies that can be directly matched to the experiments. This finding realizes the promise of vibrational spectroscopy in the electron microscope with single-atom sensitivity and has broad implications across the fields of physics, chemistry, and materials science.

Polarization Selectivity in Vibrational Electron-Energy-Loss Spectroscopy

Orientation-dependent aloof-beam vibrational electron-energy-loss spectroscopy is carried out on uniaxial icosahedral B_{12}P_{2} submicron crystals. We demonstrate that the high sensitivity of the signal to the crystal orientation allows for an unambiguous determination of the symmetry of normal modes occurring at the Brillouin zone center of this anisotropic compound. The experimental results are assessed using first-principles quantum mechanical calculations (density functional theory) of the dielectric response of the specimen. The high spatial resolution inherent to this technique when implemented in the transmission electron microscope thus opens the door to nanoscale orientation-dependent vibrational spectroscopy.

First-Principles Vibrational Electron Energy Loss Spectroscopy of β-Guanine

A general approach to model vibrational electron energy loss spectra obtained using an electron beam positioned away from the specimen is presented. The energy-loss probability of the fast electron is evaluated using first-principles quantum mechanical calculations (density functional theory) of the dielectric response of the specimen. The validity of the method is assessed using recently measured anhydrous β-guanine, an important molecular solid used by animals to produce structural colors. The good agreement between theory and experiments lays the basis for a quantitative interpretation of this spectroscopy in complex systems.

Inpatient treatment of patients with acute idiopathic peripheral facial palsy: A population-based healthcare research study

OBJECTIVES

To determine the inpatient management for patients with acute idiopathic facial palsy (IFP) in Thuringia, Germany.

DESIGN

Population-based study.

SETTING

All inpatients with IFP in all hospitals with departments of otolaryngology and neurology in 2012, in the German federal state, Thuringia.

MAIN OUTCOME MEASURES

Patients' characteristics and treatment were compared between departments, and the probability of recovery was tested.

RESULTS

A total of 291 patients were mainly treated in departments of otolaryngology (55%) and neurology (36%). Corticosteroid treatment was the predominant therapy (84.5%). The probability to receive a facial nerve grading (odds ratio [OR=12.939; 95% confidence interval [CI]=3.599 to 46.516), gustatory testing (OR=6.878; CI=1.064 to 44.474) and audiometry (OR=32.505; CI=1.485 to 711.257) was significantly higher in otolaryngology departments, but lower for cranial CT (OR=0.192; CI=0.061 to 0.602), cerebrospinal fluid examination (OR=0.024; CI=0.006 to 0.102). A total of 131 patients (45%) showed a recovery to House-Brackmann grade≤II. A pathological stapedial reflex test (Hazard ratio [HR]=0.416; CI=0.180 to 0.959) was the only independent diagnostic predictor of worse outcome. Prednisolone dose >500 mg (HR=0.579; CI 0.400 to 0.838) and no adjuvant physiotherapy (HR=0.568; CI=0.407 to 0.794) were treatment-related predictors of worse outcome.

CONCLUSIONS

Inpatient treatment of IFP seems to be highly variable in daily practice, partly depending on the treating discipline and despite the availability of evidence-based guidelines. The population-based recovery rate was worse than reported in clinical trials.

Long-range antiferromagnetic order in malonate-based compounds Na2M(H2C3O4)2·2H2O (M = Mn, Fe, Co, Ni)

Newly synthetized metal malonates of formulae Na₂M(H₂C₃O₄)₂·2H₂O (M = Mn, Fe, Co, Ni) exhibit distinct long-range antiferromagnetic orders despite their similar structure and chemistry.

Parotidectomy and submandibulectomy for benign diseases in Thuringia, Germany: a population-based study on epidemiology and outcome

Although salivary gland surgery for benign diseases is an integral part of clinical routine of head and neck surgeons, there is not many population-based data published on incidence and efficiency of this surgery. Parotidectomy was performed in 180 patients and submandibulectomy in 97 patients for benign diseases in eight otorhinolaryngology and two maxillofacial surgery departments in Thuringia, Germany, in 2005. All patients were analysed regarding patients' characteristics, therapy, complications and further course of disease. Predominant indications were epithelial tumours for parotidectomy (79 %) and sialolithiasis for submandibulectomy (50 %). The most frequent tumour types were pleomorphic adenoma (46 %) and Warthin tumours (29 %). Pleomorphic adenoma was significantly more frequent in female patients and Warthin tumours in male patients and smokers. The incidence of parotidectomy, i.e. the surgical rate, was 7.8/100,000 habitants and of submandibulectomy 4.1/100,000 habitants. One hundred and seventy-eight tumours including 154 epithelial tumours resulted in an incidence of 7.6/100,000 habitants for all treated tumours and of 6.6/100,000 for epithelial tumours, respectively. The majority of parotid cases were treated by lateral parotidectomy (79 %). Relevant complications were observed in 22 % of patients. After parotidectomy and submandibulectomy a postoperative facial palsy was observed in 28 and 2 % of cases, respectively. Only 1 % was permanent. During a mean follow-up time of 9.6 months, 3 % of parotidectomy patients developed a Frey's syndrome needing treatment and 0.8 % developed a tumour recurrence. This population-based analysis shows that salivary gland surgery is performed in higher incidence than expected, effectively and with low-risk in daily routine of head and neck surgeons.

[Health services research on paranasal sinus surgery in Thuringia: epidemiologic key data and outcome]

BACKGROUND

Although modern minimal-invasive paranasal sinus surgery is an integral part of clinical routine of otorhinolaryngologic surgeons, there are no population-based data on incidence and efficiency of this surgery published.

MATERIAL AND METHODS

1,582 patients underwent paranasal sinus surgery in the 8 Thuringian departments of otorhinolaryngology in 2005. All patients were analysed regarding patients' characteristics, therapy, complications and further course of disease.

RESULTS

The incidence of paranasal sinus surgery was 46/100,000 for women and higher for men with 72/100,000. Median age was 48 years. Chronic sinusitis was the main reason for surgery (94%; including 33% with nasal polyps) and was performed dominantly as endoscopic sinus surgery (96%). Surgery was performed bilaterally in 75% of the cases and as primary surgery. In most cases at least 2 paranasal sinuses per side were approached. Relevant complications were observed in 4% of patients. During the follow-up time of 45-51 months a recurrence was observed in 9% of cases. Using a multivariate regression analysis, revision surgery, allergic subject and diagnosis of a malignant tumor were significant independent risk factors to predict a recurrence. Older age and longer time of surgery were significant independent risk factors for a complication.

CONCLUSION

This population based analysis is showing that modern paranasal sinus surgery is performed in high incidence, effectively and with low-risk on a large scale in daily routine of rhinologic surgeons.

Magnetic couplings in CsV(2)O(5): a new picture

Concerning its magnetic properties, the layered vanadate CsV(2)O(5) has long been considered as formed by isolated spin-1/2 dimers characterized by a large antiferromagnetic coupling of about 146 K. This interpretation was supported by both magnetic susceptibility measurements and the obvious presence of magnetically active strongly dimerized V(4+) ions. In this work we investigate the magnetic properties of this compound through an extensive use of the broken-symmetry formalism in the framework of density-functional theory. Our calculations demonstrate that the system is built from strongly dimerized alternating chains where the structural and magnetic dimers are distinct from each other.

Interplay between structural, electronic, and magnetic degrees of freedom in Sr(3)Cr(2)O(8)

We present a theoretical investigation of the orbital ordering occurring in Sr(3)Cr(2)O(8) based on density functional theory calculations. We demonstrate that the strong electron correlation arising within the Cr-3d shell can clearly explain both the phase transition leading to the stabilization of its monoclinic C2/c space-group symmetry and its spin-singlet magnetic ground state. The relevance of the electronic structure determined theoretically is further established by comparison to high-resolution electron energy loss spectroscopy measurements.

Electron inelastic scattering and anisotropy: The two-dimensional point of view

The measurement of the electronic structure of anisotropic materials using energy loss near edge structure (ELNES) spectroscopy is an important field of microanalysis in transmission electron microscopy. We present a novel method to study the angular dependence of electron inelastic scattering in anisotropic materials. This method has been applied to the study of 1s-->pi* and sigma* transitions on the carbon K edge in pyrolitic graphite. An excellent agreement between experimental and theoretical two-dimensional scattering patterns has been found. In particular, the need of a fully relativistic calculation of the inelastic scattering cross-section to explain the experimental results is demonstrated.

N-K ELNES study of anisotropy effects in hexagonal AlN

Anisotropic effects in hexagonal aluminium nitride have been studied by electron energy-loss spectroscopy (EELS) in the N-K energy loss near edge structure (ELNES). Experimental data acquired with different collection angles and with a nearly parallel incident electron beam aligned along the c-axis have been compared to simulations based on ab initio calculations. The extraction of intrinsic parallel I|| (with momentum transfer q || c axis) and perpendicular I perpendicular (with momentum transfer q perpendicular c axis) components has been performed directly from the experimental spectra. This has been done according to their description as linear combinations of I|| and I perpendicular, with adequate weights deduced from a geometrical model of anisotropic behaviour.

Electron spectroscopy imaging to study ELNES at a nanoscale

Series of energy-filtered TEM images have been acquired with very narrow energy slit using a post-column energy filter. This allowed us to reconstruct spectra with an energy resolution estimated to 2 eV, and a spatial resolution in the order of 0.5 nm. In that way, fine structures of the N-K edge in AlN/GaN heterostructures have been investigated and compared to EELS spectra. The fine structure in the two nitrides is very sensitive to the local environment. Very good agreement between ESI and EELS spectra was found. Moreover, this technique allowed analysis of the AlN/GaN interface at a nanoscale. The second example is an application of the technique to construct bonding maps. In this case, maps differentiating AlN nanoprecipitates with either the cubic or the hexagonal phase were created.

[Studies on the problem of a composite anchoring post and core]

The authors conclude from the results of preliminary model experiments that the composite resins Noracryl 100 and Evicrol are suited as materials for stump restoration after the loss of the natural tooth crown in case of primarily shortened root.

[Determination of the time of mineralization of the dental hard substances in rabbits]

On the basis of radiographic studies on animals (rabbits), the authors determined the beginning of bone and dental hard tissue calcification. First signs of ossification were observed on the 17th day after copulation, whereas the calcification of the incisors began only on the 19th day after copulation.

[Epidemiologic studies. I. Secondary caries in tooth areas restored by silver-tin-amalgam, silicate cement or inlays]

On the basis of epidemiologic studies on 10 106 sugjects from the population of the town of Rostock, the authors deal with the frequency of filled tooth areas and their affection by secondary caries with special regard to filling materials (silver-tin amalgam, silicate cement, inlay). The low frequency of secondary caries in tooth areas restored by means of inlays is noteworthy. Finally, the authors give recommendations for practice.