A simplc formulation Io compute thc envelope correlation of an
antenna divemiry system is dcrired. 11 is shown how to compute the
envelope correlation hom the S-parameter descnplian of the antenna
...system. This approach has the advantage that i t does not require the
computation nor the measurement of the radiation panem of the
antenna system. It also offers the advantage of providing a clca
understanding ofthe effects ofmutual coupling and input match on the
diversity performance of the antcnnii system.
Dermatomal analgesia achieved with quadratus lumborum blocks is site-dependent and inconsistent. Cadaveric and clinical studies reveal multiple mechanisms of action. We dissected six fresh human ...cadavers bilaterally and thoroughly studied their neurological linkages to the quadratus lumborum muscle (QLM) to identify neural structures and block targets. At the end of the investigation, only the subcostal nerve (anterolateral) and the ilioinguinal nerves were found near the QLM in all specimens. The iliohypogastric nerve was found in only two specimens. No further neural targets were found in the fascial planes before and posterior to the QLM.
We studied the effects of phosphorus fertilisation on foliar terpene concentrations and foliar volatile terpene emission rates in six half‐sib families of Pinus pinaster Ait. seedlings. Half of the ...seedlings were resistant to attack of the pine weevil Hylobius abietis L., a generalist phloem feeder, and the remaining seedlings were susceptible to this insect. We hypothesised that P stress could modify the terpene concentration in the needles and thus lead to altered terpene emission patterns relevant to plant–insect signalling. The total concentration and emission rate ranged between 5732 and 13,995 μg·g−1 DW and between 2 and 22 μg·g−1 DW·h−1, respectively. Storage and emission were dominated by the isomers α‐ and β‐pinene (77.2% and 84.2% of the total terpene amount amassed and released, respectively). In both resistant and susceptible families, P stress caused an increase of 31% in foliar terpene concentration with an associated 5‐fold decrease in terpene emission rates. A higher terpene content in the leaves implies that the ‘excess carbon’, available under limiting growth conditions (P scarcity), is allocated to terpene production. Sensitive families showed a greater increase in terpene emission rates with increasing P concentrations, which could explain their susceptibility to H. abietis.
This paper reports an online reciprocal peer tutoring project for improving language competence in Spanish and English. Students aged 9–12 years from Scotland and Catalonia were matched to act as ...tutors in their own language and as tutees in a modern foreign language. Students were intended to improve both their first language (through helping the tutee) and a modern language (with their tutor's help). The methodology combined a quasi-experimental design and a qualitative analysis of texts. For Catalan students, pre-post test results indicated statistically significant improvements in reading comprehension (while acting as tutors) and writing (while acting as tutees). Scottish students improved only their writing (acting as tutees). Analysis of the texts showed that when more support was given, the tutor had more learning opportunities, but then there were fewer opportunities for the tutee, and vice versa. Thus the tutee learned more with less elaborated feedback, leading to fewer opportunities for tutor improvement. This paradox could be resolved by adjusting the scaffolding support given by tutors, to create a balanced interactive learning context for both members of the pair.
► An online reciprocal peer tutoring project for Spanish and English improvement. ► Involving students aged 9–12 years from Scotland and Catalonia. ► When more tutor support was given, the tutor had more learning opportunities. ► Tutees learned more with less elaborated feedback. ► This paradox could be resolved by adjusting the scaffolding support.
In this paper, the capability of ultra-wide-band (UWB) sensor arrays for tomographic radar of electrically large objects is presented. The major concern when imaging is extended to real objects is to ...achieve a correct reconstruction of the object shape and its electric properties. A general framework based on a UWB bifocusing operator (UWB-BF) with good tomographic imaging capabilities is presented. This general approach provides a comprehensive understanding of the basic tradeoffs with regard to sensing geometry and image quality parameters. Through numerical simulations and measurements applied to canonical as well as to complex objects, basic design criteria are assessed and the potential of UWB tomographic radar imaging is presented.
Frequency-selective surfaces (FSS), that have been designed using fractal iterative techniques, have been fabricated and measured. Fractals contain many scaled copies of the starting geometry, each ...of which acts as a scaled version of the original. A multiband FSS can be designed that uses several iterations of the geometry to form a prefractal that resonates corresponding to each of the scales present in the geometry. Minkowski and Sierpinski carpet fractals have been utilized in the design of three surfaces which exhibit two or three stopbands depending on how many iterations are used to generate the geometry of the cell. These surfaces are dual polarized due to the symmetry of the geometry. Simulation capabilities have been developed to analyze these periodic structures, including periodic method of moments (MOM) and finite-difference time-domain (FDTD) techniques which show good correlation to the measured results.
Soil Moisture and Ocean Salinity (SMOS) is an Earth Explorer Opportunity Mission from the European Space Agency with a launch date in 2007. Its goal is to produce global maps of soil moisture and ...ocean salinity variables for climatic studies using a new dual-polarization L-band (1400-1427 MHz) radiometer Microwave Imaging Radiometer by Aperture Synthesis (MIRAS). SMOS will have multiangular observation capability and can be optionally operated in full-polarimetric mode. At this frequency the sensitivity of the brightness temperature (T/sub B/) to the sea surface salinity (SSS) is low: 0.5 K/psu for a sea surface temperature (SST) of 20/spl deg/C, decreasing to 0.25 K/psu for a SST of 0/spl deg/C. Since other variables than SSS influence the T/sub B/ signal (sea surface temperature, surface roughness and foam), the accuracy of the SSS measurement will degrade unless these effects are properly accounted for. The main objective of the ESA-sponsored Wind and Salinity Experiment (WISE) field experiments has been the improvement of our understanding of the sea state effects on T/sub B/ at different incidence angles and polarizations. This understanding will help to develop and improve sea surface emissivity models to be used in the SMOS SSS retrieval algorithms. This paper summarizes the main results of the WISE field experiments on sea surface emissivity at L-band and its application to a performance study of multiangular sea surface salinity retrieval algorithms. The processing of the data reveals a sensitivity of T/sub B/ to wind speed extrapolated at nadir of /spl sim/0.23-0.25 K/(m/s), increasing at horizontal (H) polarization up to /spl sim/0.5 K/(m/s), and decreasing at vertical (V) polarization down to /spl sim/-0.2 K/(m/s) at 65/spl deg/ incidence angle. The sensitivity of T/sub B/ to significant wave height extrapolated to nadir is /spl sim/1 K/m, increasing at H-polarization up to /spl sim/1.5 K/m, and decreasing at V-polarization down to -0.5 K/m at 65/spl deg/. A modulation of the instantaneous brightness temperature T/sub B/(t) is found to be correlated with the measured sea surface slope spectra. Peaks in T/sub B/(t) are due to foam, which has allowed estimates of the foam brightness temperature and, taking into account the fractional foam coverage, the foam impact on the sea surface brightness temperature. It is suspected that a small azimuthal modulation /spl sim/0.2-0.3 K exists for low to moderate wind speeds. However, much larger values (4-5 K peak-to-peak) were registered during a strong storm, which could be due to increased foam. These sensitivities are satisfactorily compared to numerical models, and multiangular T/sub B/ data have been successfully used to retrieve sea surface salinity.
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