A Microwave Fourier Transform Spectrometer in the Range from 18 to 26.4 GHz Increased Sensitivity Using Circular Waveguides. Measurements of Isotopomeres of Carbonylsulfide and of Methane

We present a microwave Fourier transform spectrometer in the region of 18 to 26.4 GHz with an increase in sensitivity roughly by a factor of ten in comparison to a former set up. Measurements of rotational transitions of isotopomers of carbonylsulfide, OCS, in natural abundance and of rovibrational transitions of methane, CH4, illustrate the improvement

Automatic model-based semantic registration of multimodal MRI knee data

PURPOSE

To propose a robust and automated model-based semantic registration for the multimodal alignment of the knee bone and cartilage from three-dimensional (3D) MR image data.

MATERIALS AND METHODS

The movement of the knee joint can be semantically interpreted as a combination of movements of each bone. A semantic registration of the knee joint was implemented by separately reconstructing the rigid movements of the three bones. The proposed method was validated by registering 3D morphological MR datasets of 25 subjects into the corresponding T2 map datasets, and was compared with rigid and elastic methods using two criteria: the spatial overlap of the manually segmented cartilage and the distance between the same landmarks in the reference and target datasets.

RESULTS

The mean Dice Similarity Coefficient (DSC) of the overlapped cartilage segmentation was increased to 0.68 ± 0.1 (mean ± SD) and the landmark distance was reduced to 1.3 ± 0.3 mm after the proposed registration method. Both metrics were statistically superior to using rigid (DSC: 0.59 ± 0.12; landmark distance: 2.1 ± 0.4 mm) and elastic (DSC: 0.64 ± 0.11; landmark distance: 1.5 ± 0.5 mm) registrations.

CONCLUSION

The proposed method is an efficient and robust approach for the automated registration between morphological knee datasets and T2 MRI relaxation maps.

[Serious sepsis treatment in intensive care departments in the Czech Republic - EPOSS Project pilot results]

INTRODUCTION

Severe sepsis is still associated with significant morbidity and mortality, which is however different, as well as its management, depending on the region. What is the situation in the Czech Republic and what is the character of patients with severe sepsis is currently not known. The aim of the project is to describe the processes of care, outcome and characteristics of patients with severe sepsis admitted to the intensive care department of the Czech Republic.

METHODS

This is a multicentre and observational project with retrospective enrollment of patients who meet the criteria for severe sepsis before or within 24 hours after admission to selected intensive care units (ICU EPOSS).

RESULTS

394 patients were analyzed. Median age at admission was 66 (56- 76) years, males predominated (58.9%) and the median APACHE II score on admission was 25 (19- 32). Patients were predominantly medical (56.9%) and most were secondary admitted from other ICU (53.6%). Meeting the criteria of severe sepsis was most frequently within the period (± 4 hours) of admission the EPOSS ICU (77.6%). Median total fluid intake during the first 24 hours was 6,680 (4,840- 9,450) ml. Most patients required mechanical ventilation (58.4%). Compliance with the resuscitation bundle of severe sepsis in our group was very good and was associated with lower mortality of patients. Most frequently, the EPOSS ICU length of stay (LOS) was 7 (3- 15) days and median hospital LOS was 13 (8- 28) days. Hospital mortality in our cohort was 35.8%.

CONCLUSION

Introducing the project, which in its first stage obtained valuable and internationally comparable data about patients with severe sepsis admitted to the involved ICU in the Czech Republic.

Three-dimensional morphological and signal intensity features for detection of intervertebral disc degeneration from magnetic resonance images

BACKGROUND AND OBJECTIVES

Advances in MRI hardware and sequences are continually increasing the amount and complexity of data such as those generated in high-resolution three-dimensional (3D) scanning of the spine. Efficient informatics tools offer considerable opportunities for research and clinically based analyses of magnetic resonance studies. In this work, we present and validate a suite of informatics tools for automated detection of degenerative changes in lumbar intervertebral discs (IVD) from both 3D isotropic and routine two-dimensional (2D) clinical T2-weighted MRI.

MATERIALS AND METHODS

An automated segmentation approach was used to extract morphological (traditional 2D radiological measures and novel 3D shape descriptors) and signal appearance (extracted from signal intensity histograms) features. The features were validated against manual reference, compared between 2D and 3D MRI scans and used for quantification and classification of IVD degeneration across magnetic resonance datasets containing IVD with early and advanced stages of degeneration.

RESULTS AND CONCLUSIONS

Combination of the novel 3D-based shape and signal intensity features on 3D (area under receiver operating curve (AUC) 0.984) and 2D (AUC 0.988) magnetic resonance data deliver a significant improvement in automated classification of IVD degeneration, compared to the combination of previously used 2D radiological measurement and signal intensity features (AUC 0.976 and 0.983, respectively). Further work is required regarding the usefulness of 2D and 3D shape data in relation to clinical scores of lower back pain. The results reveal the potential of the proposed informatics system for computer-aided IVD diagnosis from MRI in large-scale research studies and as a possible adjunct for clinical diagnosis.

Controversies in childhood osteosarcoma

Osteosarcoma, the most frequent bone cancer of children and adolescents, will almost always result in death due to pulmonary metastatic disease unless treated by surgery and effective multidrug chemotherapy. Imaging of the primary tumor is by X-ray and magnetic resonance imaging. Imaging of the chest is by computed tomography, but many questions regarding the interpretation of small, nonspecific findings and how to deal with them remain. The diagnosis must be confirmed by a well-placed biopsy. Chemotherapy is usually initiated prior to definitive surgery. Treatment generally includes high-dose methotrexate, doxorubicin, and cisplatin, with some regimens also incorporating ifosfamide. While limb-saving resections have become standard after completion of skeletal growth, reconstruction in the growing child poses much greater challenges. The use of modern, expandable endoprostheses, but also rotation-plasties and even amputation may all be valid options in selected cases. Histologic response of the primary to preoperative chemotherapy has been identified as an important prognostic factor. Various imaging methods can help to predict tumor response to preoperative chemotherapy, yet all have their limitations. Results of a randomized trial assessing if modifying postoperative treatment based on the extent of response will improve results, EURAMOS-1, are pending. The debate about whether biologic agents or targeted therapies added to chemotherapy might improve outcomes is ongoing. Follow-up to detect late-effects of treatment and recurrences of osteosarcoma must be continued for several decades.

Automated detection, 3D segmentation and analysis of high resolution spine MR images using statistical shape models

Recent advances in high resolution magnetic resonance (MR) imaging of the spine provide a basis for the automated assessment of intervertebral disc (IVD) and vertebral body (VB) anatomy. High resolution three-dimensional (3D) morphological information contained in these images may be useful for early detection and monitoring of common spine disorders, such as disc degeneration. This work proposes an automated approach to extract the 3D segmentations of lumbar and thoracic IVDs and VBs from MR images using statistical shape analysis and registration of grey level intensity profiles. The algorithm was validated on a dataset of volumetric scans of the thoracolumbar spine of asymptomatic volunteers obtained on a 3T scanner using the relatively new 3D T2-weighted SPACE pulse sequence. Manual segmentations and expert radiological findings of early signs of disc degeneration were used in the validation. There was good agreement between manual and automated segmentation of the IVD and VB volumes with the mean Dice scores of 0.89 ± 0.04 and 0.91 ± 0.02 and mean absolute surface distances of 0.55 ± 0.18 mm and 0.67 ± 0.17 mm respectively. The method compares favourably to existing 3D MR segmentation techniques for VBs. This is the first time IVDs have been automatically segmented from 3D volumetric scans and shape parameters obtained were used in preliminary analyses to accurately classify (100% sensitivity, 98.3% specificity) disc abnormalities associated with early degenerative changes.

[Laboratory survey on the incidence of Pneumocystis jirovecii - obviously a peculiar fungus, but also a rare pathogen?]

Pneumocystsis jirovecii is a peculiar fungus for a variety of reasons. This opportunistic pathogen multiplies in humans only under certain conditions; a defect in the T-cell defense system creates a predisposition to this infection. In 2010 a data survey (IFT as well as PCR) from a few laboratories in Germany revealed 412 positive individuals. Even if only a few patients test positive for the colonization stage of this pathogen, the sheer number of individuals testing positive for other stages of infection indicate that the incidence of pneumocystosis in immunocompromised patients in Germany is underestimated.

Pathways to Earth-like atmospheres. Extreme ultraviolet (EUV)-powered escape of hydrogen-rich protoatmospheres

We discuss the evolution of the atmosphere of early Earth and of terrestrial exoplanets which may be capable of sustaining liquid water oceans and continents where life may originate. The formation age of a terrestrial planet, its mass and size, as well as the lifetime in the EUV-saturated early phase of its host star play a significant role in its atmosphere evolution. We show that planets even in orbits within the habitable zone of their host stars might not lose nebular- or catastrophically outgassed initial protoatmospheres completely and could end up as water worlds with CO2 and hydrogen- or oxygen-rich upper atmospheres. If an atmosphere of a terrestrial planet evolves to an N2-rich atmosphere too early in its lifetime, the atmosphere may be lost. We show that the initial conditions set up by the formation of a terrestrial planet and by the evolution of the host star's EUV and plasma environment are very important factors owing to which a planet may evolve to a habitable world. Finally we present a method for studying the discussed atmosphere evolution hypotheses by future UV transit observations of terrestrial exoplanets.

Substitute voice production: quantification of PE segment vibrations using a biomechanical model

After total larynx excision due to laryngeal cancer, the tracheoesophageal substitute tissue vibrations at the intersection between the pharynx and the esophagus [pharyngoesophageal segment (PE segment)] serve as voice generator. The quality of the substitute voice significantly depends on the vibratory characteristics of the PE segment. For improving voice rehabilitation, the relationship between the PE dynamics and the resulting substitute voice quality is a matter of particular interest. Precondition for a comprehensive analysis of this relationship is an objective quantification of the PE vibrations. For quantification purposes, a method is proposed, which is based on the reproduction of the tissue vibrations by means of a biomechanical model of the PE segment. An optimization procedure for an automatic determination of appropriate model parameters is suggested to adapt the model dynamics to tissue movements extracted from high-speed (HS) videos. The applicability of the optimization procedure is evaluated with ten synthetic data sets. A mean error of 8.2% for the determination of previously defined model parameters was achieved as well as an overall stability of 7.1%. The application of the model to six HS recordings presented a mean correlation of the vibration patterns of 82%.

Transient Photoresponse from Co Schottky Barriers on AlGaN

Co on AlGaN is expected to form a large barrier Schottky contact due to its high work function. We have used this material combination with 18 % of Al in AlxGaN for the study of transient photoresponse in the photovoltaic mode and in secondary photocurrent measurements after pulsed laser excitation. In reverse bias and in short- circuit mode a fast decay with a characteristic time of a few microseconds is dominant at room temperature. This mode is appropriate for UV detector operation. At elevated temperature, a much slower tail extending to several milliseconds is also observed. In forward bias operation the slow tail is dominating at any temperature. We discuss this asymmetry with respect to fast minority carrier collection within the space charge region for primary photocurrents and the slower majority carrier transport in forward bias.

Carrier Transport Through Grain Boundaries in Hydrogenated Microcrystalline Silicon

To analyse the influence of the grain boundaries (gb) on the transport of carriers in hydrogenated microcrystalline silicon (μC-Si:H) the ambipolar diffusion length (LLMB) was measured by SSPG. In addition, the films were characterised by photo-conductivity, dark conductivity activation energy, Urbach energy (determined by CPM), hydrogen effusion, Raman spectroscopy, X-ray scattering and optical transmission.

The sample series was prepared by PECVD of SiH4 diluted with increasing H2 content. Taking the structural information by Raman spectra and X-ray into account, we explain our optical and activation energy measurements within a three-phase-model (amorphous phase, crystalline phase, gb) and a Fermi level pinning in μc-Si:H.

Preparation of α-(Si.Ge):H Alloys by D.C. Glow Discharge Deposition

We report the preparation of α-(Si.Ge):H alloy films by decomposition of SiF4, GeF4, and H2 in a d.c. glow discharge. Germanium is incorporated very efficiently from GeF4. The germanium content and optical gap canbe controlled by varying the GeF4 flow while keeping the SiF4 and H2 flows constant. The films, all prepared at 300 ºC substrate temperature, exhibit high photo- to dark-conductivity ratios for compositions of up to -25% germanium.