3,362 research outputs found
Millimeter-wave FET modeling based on a frequency extrapolation approach
An empirical distributed model, based on electromagnetic analysis and standard S-parameter measurements up to microwave frequencies, is shown to be capable of accurate small-signal predictions up to the millimeter-wave range. The frequency-extrapolation approach takes advantage from a physically-expected, smooth behavior of suitably defined elementary active devices connected to a passive distributed network. On this basis, small-signal millimeter-wave FET modeling becomes an affordable task in any laboratory equipped with a standard microwave vector network analyzer and electromagnetic simulation capabilities. In the paper, wide experimental validation of the proposed model up to 110GHz is presented for PHEMT devices with different sizes and bias conditions
High frequency of inadequate test requests for antiphospholipid antibodies in daily clinical practice
Abstract Background: We have empirically noted that many physicians routinely request anti-phospholipid antibodies (aPL) without a correct clinical indication. The aim of this study was to evaluate retrospectively whether aPL testing at our Thrombosis Centre was justified. Methods: Medical records from 520 subjects for aPL screening tests for various clinical conditions were reviewed. The aPL screening tests were: lupus anticoagulant (LA), anti-cardiolipin antibodies (aCL) and anti-β(2) glycoptotein I (aβ(2) GPI). Requests for aPL screening were divided into justified, potentially justified or not adequately justified. Results: aPL testing requests were considered justified in 358 (69%) patients, potentially justified in 66 (12.6%) and not adequately justified in 96 (18.4%). LA was positive in 65 (18%) of justified requests and in only one (1%) of the 96 potentially justified requests. None of the 66 not adequately justified for aPL testing was positive for LA. aβ(2) ..
Global modeling approach to the design of an MMIC amplifier using Ohmic Electrode-Sharing Technology
An innovative technique for high--density, high-frequency integrated circuit design is proposed.The procedure exploits the potentialities of a global modeling approach,previously applied only at device level,enabling the circuit designer to explore flexible layout solutions imed at important reduction in chip size and cost.The new circuit design technique is presented by means of an example consisting of a wide-band amplifier,implemented with the recently proposed Ohmic Electrode-Sharing Technology (OEST).The good agreement between experimental and simulated results confirms the validity of the proposed MMIC design approach
New tricks for an old dog: Brf2-dependent RNA Polymerase III transcription in oxidative stress and cancer
Here, we discuss the role of Brf2, an RNA Polymerase III core transcription factor, as a master switch of the oxidative stress response. We highlight the interplay of Brf2 with the Nrf2/Keap1 pathway, as well as the role of Brf2 in cancer and other possible regulations
Targeting of Regulators as a Promising Approach in the Search for Novel Antimicrobial Agents
Since the discovery of penicillin in the first half of the last century, antibiotics have become the pillars of modern medicine for fighting bacterial infections. However, pathogens resistant to antibiotic treatment have increased in recent decades, and efforts to discover new antibiotics have decreased. As a result, it is becoming increasingly difficult to treat bacterial infections successfully, and we look forward to more significant efforts from both governments and the scientific community to research new antibacterial drugs. This perspective article highlights the high potential of bacterial transcriptional and posttranscriptional regulators as targets for developing new drugs. We highlight some recent advances in the search for new compounds that inhibit their biological activity and, as such, appear very promising for treating bacterial infections
Isotopic Composition of Fragments in Nuclear Multifragmentation
The isotope yields of fragments, produced in the decay of the quasiprojectile
in Au+Au peripheral collisions at 35 MeV/nucleon and those coming from the
disassembly of the unique source formed in Xe+Cu central reactions at 30
MeV/nucleon, were measured. We show that the relative yields of neutron-rich
isotopes increase with the excitation energy in multifragmentation reaction. In
the framework of the statistical multifragmentation model which fairly well
reproduces the experimental observables, this behaviour can be explained by
increasing N/Z ratio of hot primary fragments, that corresponds to the
statistical evolution of the decay mechanism with the excitation energy: from a
compound-like decay to complete multifragmentation.Comment: 10 pages. 4 Postscript figures. Submitted to Physical Review C, Rapid
Communicatio
'Backgating' model including self-heating for low-frequency dispersive effects in III-V FETs
A new approach is proposed which takes into account both traps and thermal phenomena for the modelling of deviations between static and dynamic drain current characteristics in III-V field effect transistors. The model is based on the well-known `backgating' concept and can easily be identified on the basis of conventional static drain current characteristics and small-signal, low-frequency S parameters. Experimental results confirm the accuracy of the proposed mode
On-wafer I/V measurement setup for the characterization of low-frequency dispersion in electron devices
Large-signal dynamic modelling of 111-V FETs
cannot he simply based on DC i/v characteristics, when
accurate performance prediction is needed. In fact,
dispersive phenomena due to self-heating and/or traps
(surface state densities and deep level traps) must be taken
into account since they cause important deviations in the
low-frequency dynamic drain current. Thus, static drain
current characteristics should he replaced with a suitable
model which also accounts for low-frequency dispersive
effects. The research community has proposed different
modelling approaches and quite often a characterisation by
means of pulsed i/v measurement systems has been suggested
as the more appropriate for the identification of lowfrequency
drain current models. In the paper, a new largesignal
measurement setup is presented which is based on
simple low-frequency sinusoidal excitations and it is easily
reproducible with conventional general-purpose lab
instrumentation. Moreover, the proposed setup is adopted in
the paper to extract a hackgating-like model for dispersive
phenomen
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