Increasing nitrogen deposition and more frequent drought events are likely to change plant interactions in natural grasslands. Both factors may also influence the interactions between hemiparasitic ...plants, regarded as keystone species in many grasslands, and their host species.
We grew a combination of three suitable hosts, a grass, a forb and a legume, with and without the hemiparasite Rhinanthus alectorolophus at three levels of nitrogen (N) and two levels of water availability in a factorial design.
Biomass of the hemiparasite and host community increased with N level and was reduced by drought to a similar degree. Larger plants in fertilised pots started to wilt earlier, and the presence of a hemiparasite further increased drought sensitivity. The hemiparasite strongly reduced biomass of the host community and overall productivity, and affected the competitive balance among host plants because it particularly reduced biomass of the dominant grass. These effects were the opposite of those of high N. The hemiparasite increased the root mass fraction of the hosts at all levels of N and water availability, indicating that the effect of the hemiparasite on the hosts was mainly due to loss of belowground resources.
Our results indicate that hemiparasites will not always respond more strongly to increased N availability and drought than autotrophic plants, and that hemiparasites can have similarly strong effects on grassland communities as soil fertility and drought. By preferentially attacking dominant species the hemiparasites might alleviate the negative effects of nutrient enrichment on grassland diversity.
The environment experienced by plants can influence the phenotype of their offspring. Such transgenerational plasticity can be adaptive when it results in higher fitness of the offspring under ...conditions correlated with those experienced by the mother plant. However, it has rarely been tested if such anticipatory parental effects may be induced by different environments. We grew clonal replicates of Silene vulgaris under control conditions and three types of stress (nutrient deficiency, copper addition, and drought) which are known from natural populations of the species. We then subjected offspring from differently treated mother plants to each of the different stress treatments to analyze the influence of maternal and offspring environment on performance and several functional traits. Current stress treatments strongly influenced biomass and functional traits of the plants, mostly in line with responses predicted by the theory of functional equilibrium. Plant performance was also influenced by maternal stress treatments, and some effects independent of initial size differences remained until harvest. In particular, stressed mothers produced offspring of higher fitness than control plants. However, there was no evidence for treatment-specific adaptive transgenerational plasticity, as offspring from a mother plant that had grown in a specific environment did not grow better in that environment than other plants. Our results indicate that the maternal environment may affect offspring traits and performance, but also that this transgenerational plasticity is not necessarily adaptive. This article is protected by copyright. All rights reserved.
Assuring stable resonant oscillation with well controlled amplitude under varying environmental conditions is a major challenge for electrostatically driven MOEMS mirrors. For this reason, we ...developed a compact device comprising a resonant MOEMS micro-mirror, optical position sensing, and driver electronics with closed loop control, which ensures operation close to the mirror resonance. Closed loop control is realised by adjusting the driving frequency to minimize the phase offset of the mirror oscillation, which is notably applicable for high frequency devices. Here we present our position encoding and feedback scheme, and show first experimental results, which demonstrate the capability of our device.
Purpose
To evaluate feasibility of automatic software-based path proposals for CT-guided percutaneous biopsies.
Methods
Thirty-three patients (60
±
12 years) referred for CT-guided biopsy of focal ...liver lesions were consecutively included. Pre-interventional CT and dedicated software (FraunhoferMeVis Pathfinder) were used for (semi)automatic segmentation of relevant structures. The software subsequently generated three path proposals in downward quality for CT-guided biopsy. Proposed needle paths were compared with consensus proposal of two experts (comparable, less suitable, not feasible). In case of comparable results, equivalent approach to software-based path proposal was used. Quality of segmentation process was evaluated (Likert scale, 1
=
best, 6
=
worst), and time for processing was registered.
Results
All biopsies were performed successfully without complications. In 91 % one of the three automatic path proposals was rated comparable to experts’ proposal. None of the first proposals was rated not feasible, and 76 % were rated comparable to the experts’ proposal. 7 % automatic path proposals were rated not feasible, all being second choice (
n
=
1
) or third choice (
n
=
6
). In 79 %, segmentation at least was good. Average total time for establishing automatic path proposal was 42
±
9 s.
Conclusion
Automatic software-based path proposal for CT-guided liver biopsies in the majority provides path proposals that are easy to establish and comparable to experts’ insertion trajectories.
Recently, we have realized a novel, very compact position sensing device for MOEMS mirrors, which is based on the measurement of a reflected light beam with a quadrant diode. This scheme is ...applicable to arbitrary trajectories and in this work we present the characteristics of this device, showing experimental results obtained with a test set-up, but also theoretical considerations and optical ray-tracing simulations.
Objectives
To determine the diagnostic value of magnetic resonance (MR) first pass perfusion in the differentiation of benign and malignant cardiac tumours.
Methods
24 patients with cardiac tumours ...(11 malignant, histopathological correlation present in all cases) were examined using MRI. In addition to morphological sequences a saturation-recovery T1w-GRE technique was implemented for tumour perfusion. The maximum relative signal enhancement (RSE%) and the slope of the RSE
t
-curve (slopeRSE%/s) of tumour tissue were assessed. A
t
-test was used to identify significant differences between benign and malignant tumours. Sensitivities and specificities were calculated for detection of malignant lesions and were compared with the sensitivity and specificity based on solely morphological image assessment.
Results
The RSE and slopeRSE of malignant cardiac tumours were significantly higher compared with benign lesions (
p
< 0.001 and
p
< 0.001). The calculated sensitivities and specificities of RSE and slopeRSE for identification of malignant lesions were 100% and 84.6% and 100% and 92.3%, respectively with cut-off values of 80% and 6%/s. The sensitivity and specificity for identification of malignant lesions on the basis of morphological imaging alone were 90.9% and 69.2%.
Conclusions
With first pass perfusion, malignant cardiac masses can be identified with higher sensitivity and specificity compared with morphological image assessment alone.
Key Points
Malignant cardiac tumours can usually be differentiated from benign masses by MRI.
Combining morphologic imaging with dynamic first pass perfusion assists this differentiation.
MR first pass perfusion contributes useful diagnostic information about cardiac tumours.
A compact, robust grating spectrometer based on an optimised micro-electro-mechanical grating mirror component has been developed, built, and characterised. The application of an oscillating ...reflection grating micro-mirror component as scanning dispersive element in a modified Czerny-Turner monochromator layout enables the design of compact grating spectrometers capable of acquiring full spectra using a single detector element. Designed for a wavelength range between 1200 and 1900 nm, the spectrometer features a spectral resolution of 10 nm with wavelength stability better than ±0.5 nm. One-hundred scan spectra can be acquired in less than one second, or spectral changes can be monitored at time a resolution of less than 10 ms. In combination with a fibre-optic interface and a typical weight of less than 1 kg, this makes this novel type of fully portable micro-electro-mechanical near-IR scanning spectrometer an interesting alternative to existing spectrometers and opens a range of new applications, in particular the detection of major and minor components in the near-IR. graphic removed
Abstract Purpose To show that the use of an early and delayed contrast enhanced multislice inversion recovery steady state free precession (SS-IR-SSFP) is a valuable substitute for conventional ...post-contrast fat saturated turbo spin-echo (TSE) T1-weighted images in the assessment of cardiac tumors. Materials and methods 34 consecutive patients referred for MRI in order to assess cardiac tumors were examined. Shortly after administration of gadopenetate dimeglumine (Gd-DTPA) images were obtained using a SS-IR-SSFP sequence. The inversion time (TI) was set at 350 ms to achieve a good demarcation of intracavitary tumor spread. Hereafter 9 slices of a T1w TSE sequence were obtained. Finally a SS-IR-SSFP sequence with an optimized TI to null normal myocardium was employed. Quantitative comparisons were performed by calculating contrast to noise ratios of tumor/myocardium (CNRtumor/myo ) and CNR of tumor/left ventricular cavity (CNRtumor/LVC ). Image quality was assessed regarding overall image quality, artifacts and tumor conspicuity. Results Neither calculation of CNRtumor/LVC when comparing the early IR-SSFP and T1w TSE, nor calculation of CNRtumor/myo when comparing the late IR-SSFP and T1w TSE sequence resulted in statistically significant differences. However, qualitative assessments revealed significant superior results for the early and the late IR-SSFP images compared to the T1-weighted TSE images ( p < 0.001). Conclusions Image quality and tumor conspicuity were superior and image degradation by artifacts was less on IR-SSFP images compared to TSE images without loss of CNR. Thus the use of IR-SSFP sequences is an attractive alternative imaging method compared to post-contrast T1w TSE imaging in the assessment of cardiac tumors.
Recent developments in optical micro-electro-mechanical systems (MEMS) have produced rapidly oscillating translatory micro-mirrors with out-of-plane mirror displacements exceeding ±100 μm, which have ...a great potential for various applications requiring high-speed optical path difference modulation. A key factor affecting their practical applicability is a reliable operation control of the MEMS element. Presented here is a pro-active solution combining a laser reference interferometer with a novel position detection scheme and a dedicated control circuitry. By demodulating and processing the laser reference signal, the zero-crossing point of the moving MEMS device can be detected with an accuracy of one interference fringe only. This allows generating a highly accurate mirror control signal in real-time, enabling the implementation of a unique closed-loop control of such MEMS devices and thus ensuring optimally stable MEMS operation and maximal mechanical amplitudes even under varying environmental conditions. The presented solution so provides a vital step forward in the real-world deployment of optical systems using translatory micro-devices.
