Search results for "Attenuator"
showing 10 items of 14 documents
Prognostic significance of circulating PD-1, PD-L1, pan-BTN3As, BTN3A1 and BTLA in patients with pancreatic adenocarcinoma
2019
PDAC is one of the most heterogeneous cancers with low chemotherapeutic sensitivity due to a dense stroma, a weak vasculature and significant biological aggressivity. In cancer, suppressive immune checkpoints are often hyper-activated to ensure an effective evasion of tumor cells from immune surveillance. These immune checkpoints include in part, the B7/butyrophilin-like receptors such as butyrophilin sub-family 3A/CD277 receptors (BTN3A), the B and T lymphocyte attenuator (BTLA) belonging to the B7-like receptors and the programmed death protein (PD-1) with its ligand PD-L1. We evaluated the plasma level of these markers in 32 PDAC patients (learning cohort) by ad hoc developed ELISA’s and…
High resistance measurement circuit for fiber materials: Application to moisture content estimation
2018
Abstract Measuring very high resistance values is a difficult task since low voltage or currents are present and thus, noise and amplification must be carefully done, especially when low resistance values are required to be measured using the same circuit, too. This work proposes a novel and accurate measurement instrument for a wide range of resistance values oriented to portable applications, i.e. low power and low supply voltage (5 V) for battery operated equipment, with a small circuit design including analog sensing, digital interface (data reading and control) using a microcontroller and external communication. The proposed circuit includes an inverter attenuator with layout and confi…
Study of the use of methanol-filled Er-doped suspended-core fibres in a temperature-sensing ring laser system
2013
We report on an experimental/numerical investigation into the use of methanol-filled Er-doped suspended-core fibres (SCFs) in temperature-sensing ring laser systems. We have adopted a ring laser configuration that includes an Er-doped SCF as a temperature-dependent attenuator (TDA) with a step-index Er-doped fibre (EDF) as the laser active medium. The laser performance dependence on the temperature was measured both in continuous wave (CW) and transient regimes. CW laser output power and build-up time values are compared with those of similar laser systems based on other types of Er-doped PCFs or using other laser configurations. A notable variation of 0.73% °C−1 was achieved in CW operatio…
A novel noise figure and gain test set for microwave devices
2002
A new instrument for the measurement of noise and gain of microwave devices is presented. It differs from the commercial ones in the accomplishment of the gain measurement and is also useful for measuring mismatched devices such as transistors, The instrument is driven via HP-IB by a PC and a user-friendly virtual panel is designed to perform all the required operations. Also included is the possibility of removing the second-stage noise contribution and correcting various sources of error (source ENR variations, temperature variations, etc.). The test set provides a very good accuracy for both matched and mismatched devices, usually limited by source ENR accuracy and step attenuator repeat…
Artifacts and Errors in Cross-Spectrum Phase Noise Measurements : Invited lecture
2021
Inserting an attenuator between the oscillator under test and the phase noise analyzer, one expects that the white phase noise increases monotonically with the attenuation. By contrast, we observe that with some oscillators the white noise has sharp minimum for a given value of the attenuation, which clearly indicates problem. With other oscillators, it increases monotonically with the attenuation, but the values are not consistent with the thermal energy introduced by the attenuator. In both cases artifacts are present, which takes the form of a sharp notch in the spectrum, occurring where the white FM noise crosses the white PM noise. Such anomalous behavior is the tip of the iceberg, and…
Graphene as a tunable resistor
2014
We present the design of a graphene-based electronically tuneable microstrip attenuator operating at a frequency of 5 GHz. The use of graphene as a variable resistor is discussed and the modelling of its electromagnetic properties at microwave frequencies is fully addressed. The design of the graphene-based attenuator is described. The structure integrates a patch of graphene, whose characteristics can range from being a fairly good conductor to a highly lossy material, depending on the applied voltage. By applying the proper voltage through two high-impedance bias lines, the surface resistivity of graphene can be modified, thereby changing the insertion loss of the microstrip attenuator.
<title>Fiber optical intensity-ratio refractometer with digital display</title>
1994
Simplicity, cost efficiency, and higher fidelity compared to the single-channel design are the main advantages stimulating the recent interest on fiber optic intensity-ratio sensors. Optical and electronic designs of refractometric sensors of this kind are discussed here. Two optical schemes of retroreflective probes with one input and two output fibers are proposed. The probe sensitivity to liquid refractivity changes in the interval 1.33 < n < 1.41 is studied by computer simulation. An originally developed one-ADC-based signal processing circuit providing digital display of the intensity-ratio determined n-values is described as well.
Extended analysis of a genome-wide association study in primary sclerosing cholangitis detects multiple novel risk loci
2012
Background & Aims: A limited number of genetic risk factors have been reported in primary sclerosing cholangitis (PSC). To discover further genetic susceptibility factors for PSC, we followed up on,a second tier of single nucleotide polymorphisms (SNPs) from a genome-wide association study (GWAS). Methods: We analyzed 45 SNPs in 1221 PSC cases and 3508 controls. The association results from the replication analysis and the original GWAS (715 PSC cases and 2962 controls) were combined in a meta-analysis comprising 1936 PSC cases and 6470 controls. We performed an analysis of bile microbial community composition in 39 PSC patients by 16S rRNA sequencing. Results: Seventeen SNPs representing 1…
Improved All-Fiber Acousto-Optic Tunable Bandpass Filter
2017
An all-fiber acousto-optic tunable bandpass filter based on a 1.185-mm long coreless core mode blocker is reported. Experimental results demonstrate a minimal insertion loss of 1.2 dB at the optical resonant wavelength of 1527.7 nm with 3-dB optical bandwidth of 0.83 nm. The optimization of the device takes into account the attenuation of the acoustic wave and leads to an asymmetric configuration in which the coupling section is shorter than the recoupling part. Under the effect of a standing flexural wave the device can be operated as a bandpass modulator. The device exhibits a maximum modulation depth of 28%, 4 dB of insertion loss and 0.97 nm of optical bandwidth at 4.774 MHz.
Micro-optical components for parallel optical networks
2002
Key components for parallel optical links are fabricated cost-effectively using LIGA technology. Multifiber ferrules and mechanical splices, 1/spl times/2 and 4/spl times/4 single-mode matrix switches and micro lens arrays with passive alignment structures are presented.