A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center ...frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm.
All mammalian infants suckle, a fundamentally different process than drinking in adults. Infant mammal oropharyngeal anatomy is also anteroposteriorly compressed and becomes more elongate ...postnatally. While suckling and drinking require different patterns of muscle use and kinematics, little insight exists into how the neuromotor and anatomical systems change through the time that infants suckle. We measured the orientation, activity and contractile patterns of five muscles active during infant feeding from early infancy until weaning using a pig model. Muscles not aligned with the long axis of the body became less mediolaterally orientated with age. However, the timing of activation and the contractile patterns of those muscles exhibited little change, although variation was larger in younger infants than older infants. At both ages, there were differences in contractile patterns within muscles active during both sucking and swallowing, as well as variation among muscles during swallowing. The changes in anatomy, coupled with less variation closer to weaning and little change in muscle firing and shortening patterns suggest that the neuromotor system may be optimized to transition to solid foods. The lesser consequences of aspiration during feeding on an all-liquid diet may not necessitate the evolution of variation in neuromotor function through infancy.
Background
Preoperative immunonutrition has been proposed to reduce the duration of hospital stay and infective complications following major elective surgery in patients with gastrointestinal ...malignancy. A multicentre 2 × 2 factorial RCT was conducted to determine the impact of preoperative and postoperative immunonutrition versus standard nutrition in patients with oesophageal cancer.
Methods
Patients were randomized before oesophagectomy to immunonutrition (IMPACT®) versus standard isocaloric/isonitrogenous nutrition, then further randomized after operation to immunonutrition versus standard nutrition. Clinical and quality‐of‐life outcomes were assessed at 14 and 42 days after operation on an intention‐to‐treat basis. The primary outcome was the occurrence of infective complications. Secondary outcomes were other complications, duration of hospital stay, mortality, nutritional and quality‐of‐life outcomes (EuroQol EQ‐5D‐3 L™, European Organisation for Research and Treatment of Cancer (EORTC) QLQ‐C30 and EORTC QLQ‐OES18). Patients and investigators were blinded until the completion of data analysis.
Results
Some 278 patients from 11 Australian sites were randomized; two were excluded and data from 276 were analysed. The incidence of infective complications was similar for all groups (37 per cent in perioperative standard nutrition group, 51 per cent in perioperative immunonutrition group, 34 per cent in preoperative immunonutrition group and 40 per cent in postoperative immunonutrition group; P = 0·187). There were no significant differences in any other clinical or quality‐of‐life outcomes.
Conclusion
Use of immunonutrition before and/or after surgery provided no benefit over standard nutrition in patients undergoing oesophagectomy. Registration number: ACTRN12611000178943 (
https://www.anzctr.org.au).
No difference
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Three new classes of miniaturized Marchand balun are defined based on the synthesis of filter prototypes. They are suitable for mixed lumped-distributed planar realizations with small size resulting ...from transmission-line resonators being a quarter-wavelength long at frequencies higher than the passband center frequency. Each class corresponds to an S-plane bandpass prototype derived from the specification of transmission zero locations. A tunable 50:100-/spl Omega/ balun is realized at 1 GHz to demonstrate the advantages of the approach presented here.
A new class of parallel-coupled line filters with broad stopband response is introduced. The design is based on the synthesis of bandpass prototypes with pre-defined upper stopband characteristics. ...The new filters have uniform- and stepped-impedance resonators, some of which are loaded by open-circuited stubs at their open-circuited ends. A seventh-order filter implementation is presented with a fundamental passband centered at 1 GHz. The measured wide-band transmission characteristic of the filter demonstrated a broad upper stopband and was in agreement with simulations. The performance of the new filter is also compared with the characteristic of a conventionally designed filter to highlight the advantages of the proposed design method.
The history of RF and microwave computer-aided engineering is documented in the annals of the IEEE Microwave Theory and Techniques Society. The era began with elaborate analytically based models of ...microwave components and simple computer-aided techniques to cascade, cascode, and otherwise connect linear component models to obtain the responses of linear microwave circuits. Development has become rapid with computer-oriented microwave practices addressing complex geometries and with the ability to globally model and optimize large circuits. The pursuit of accurate models of active devices and of passive components continues to be a key activity.
The nonlinear characteristic of an RF front-end results in in-band distortion and spectral regrowth of digitally modulated signals with distortion being dependent on the statistical variation of the ...signal. In this paper, the interaction of the nonlinear response with the signal is explored using a time-averaged autocorrelation analysis applied to several limiter-amplifier models having characteristics ranging from soft-to-hard amplitude limiting. The analysis is verified by comparing measured and predicted adjacent channel power rejection for a code-division multiple-access amplifier.
Interdigitated capacitors containing the field-tunable ferroelectric Ba0DDT75Sr0DDT25TiO3, polycrystalline alumina substrates, and copper metallization have been fabricated. Dielectric layers were ...prepared by magnetron sputtering, while the Cu metallization was evaporated. The dielectric tunability of the Ba0DDT75Sr0DDT25TiO3 was 40% at an applied electric field of 12 V/D*mm. This corresponds to a 3-D*mm electrode gap width and a 35 V dc bias. Low-frequency (1 MHz) loss tangent measurements indicate a dielectric Q (quality factor) of ~100 while microwave measurements reveal a zero bias device Q of ~30 at 26 GHz. These values are comparable or superior to numerous reports of barium strontium titanate interdigitated capacitors prepared using single crystalline substrates and noble metallization. As such, this technology is significantly less expensive and more amenable to large-volume manufacturing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A network prototype suitable for reconfigurable filters with imaginary-axis transmission zeros is presented. The prototype is synthesized using classical cascade synthesis. Reconfiguration of the ...transmission zeros is implemented entirely by tunable capacitors. The measured performance of a narrow-band reconfigurable bandpass filter realized in a planar combline using varactor diodes demonstrates the principle.
The current generation of non-linear vector network analysers (NVNA) relies on a multi-harmonic generator to establish an absolute phase reference. Here a hybrid NVNA is proposed that combines a ...sampling oscilloscope, a four-port VNA and phase-locked signal generators. A signal generator, phase locked to generators that are combined as the multi-tone excitation, provides the relative phase reference during swept power measurements using the VNA. The high dynamic range VNA-based measurements are corrected in absolute phase, using the oscilloscope-based NVNA measurement at a specific power level. The hybrid NVNA has high dynamic range and the lower bound on tone spacing is determined by the memory depth of the oscilloscope, the windowing effect of the VNA receivers and the phase noise of the multi-tone sources. At 2 GHz, the hybrid NVNA has a dynamic range of 40 dB at 200 Hz tone spacing for a two-tone signal, increasing to more than 80 dB for tone spacings of 200 kHz and greater.
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