885 research outputs found
Moving from Inaction to Action: Challenging Homo- and Transphobia in Middle School English Language Arts
What happens when teachers have opportunities to engage in LGBTQ-affirming practices but choose not to? In the following paper, the authors present a vignette from a middle school context and consider ways to challenge silences to support LGBTQ students in middle school English classrooms. The authors provide discussion and resources to help teachers engage in LGBTQ affirming practices with middle school students
Implementation and Validation of 3-D Ice Accretion Measurement Methodology
A research program has been implemented to develop and validate the use of a commercial 3-D laser scanning system to record ice accretion geometry in the NASA Icing Research Tunnel. A main component of the program was the geometric assessment of the 3- D laser scanning system on a 2-D (straight wing) and a 3-D (swept wing) airfoil geometries. This exercise consisted of comparison of scanned ice accretion to castings of the same ice accretion. The scan data were also used to create rapid prototype artificial ice shapes that were scanned and compared to the original ice accretion. The results from geometric comparisons on the straight wing showed that the ice shape models generated through the scan/rapid prototype process compared reasonably well with the cast shapes. Similar results were obtained with the geometric comparisons on the swept wing. It was difficult to precisely compare the scans of the cast shapes to the original ice accretion scans because the cast shapes appear to have shrunk during the mold/casting process by as much as 0.10-inch. However the comparison of the local ice-shape features were possible and produced better results. The rapid prototype manufacturing process was shown to reproduce the original ice accretion scan normally within 0.01-inch
Generic flow profiles induced by a beating cilium
We describe a multipole expansion for the low Reynolds number fluid flows
generated by a localized source embedded in a plane with a no-slip boundary
condition. It contains 3 independent terms that fall quadratically with the
distance and 6 terms that fall with the third power. Within this framework we
discuss the flows induced by a beating cilium described in different ways: a
small particle circling on an elliptical trajectory, a thin rod and a general
ciliary beating pattern. We identify the flow modes present based on the
symmetry properties of the ciliary beat.Comment: 12 pages, 6 figures, to appear in EPJ
A high efficiency 10W MMIC PA for K-b and satellite communications
This paper discusses the design steps and experimental characterization of a monolithic microwave integrated circuit (MMIC) power amplifier developed for the next generation of K-band 17.3–20.2 GHz very high throughput satellites. The technology used is a commercially available 100-nm gate length gallium nitride on silicon process. The chip was developed taking into account the demanding constraints of the spacecraft and, in particular, carefully considering the thermal constraints of such technology, in order to keep the junction temperature in all devices below 160°C in the worst-case condition (i.e., maximum environmental temperature of 85°C). The realized MMIC, based on a three-stage architecture, was first characterized on-wafer in pulsed regime and, subsequently, mounted in a test-jig and characterized under continuous wave operating conditions. In 17.3–20.2 GHz operating bandwidth, the built amplifier provides an output power >40 dBm with a power added efficiency close to 30% (peak >40%) and 22 dB of power gain
Automatic Optimization of Input Split and Bias Voltage in Digitally Controlled Dual-Input Doherty RF PAs
Digitally controlled Dual-Input Doherty Power Amplifiers (DIDPAs) are becoming increasingly popular due to the flexible input signal splitting between the main and auxiliary stages. Nevertheless, the presence of many degrees of freedom, e.g., input amplitude split and phase displacement as well as biasing for multiple stages, often involves inefficient trial-and-error procedures to reach a suitable PA performance. This article presents automated parameter setting based on coordinate descent or Bayesian optimizations, demonstrating an improvement in the performance in terms of RF output power and power-added efficiency (PAE) in the presence of broadband-modulated signals, yet maintaining suitable linear behavior for, e.g., communications applications
Persistent homology to analyse 3D faces and assess body weight gain
In this paper, we analyse patterns in face shape variation due to weight gain. We propose the use of persistent homology descriptors to get geometric and topological information about the configuration of anthropometric 3D face landmarks. In this way, evaluating face changes boils down to comparing the descriptors computed on 3D face scans taken at different times. By applying dimensionality reduction techniques to the dissimilarity matrix of descriptors, we get a space in which each face is a point and face shape variations are encoded as trajectories in that space. Our results show that persistent homology is able to identify features which are well related to overweight and may help assessing individual weight trends. The research was carried out in the context of the European project SEMEOTICONS, which developed a multisensory platform which detects and monitors over time facial signs of cardio-metabolic risk
Ka-band 4 W GaN/Si MMIC power amplifier for CW radar applications
In this contribution it is reported the design, implementation and characterization of a 4-stage single-ended Ka-band power amplifier based on 100 nm GaN/Si commercial process. The amplifier, designed for CW radar applications, has been measured under small-signal and pulsed large-signal conditions. The amplifier exhibits an output power above 4W, together with power added efficiency in excess of 28 % and operative gain larger than 25dB over the 34GHz-38GHz frequency range
A Novel Stacked Cell Layout for High Frequency Power Applications
This letter presents an innovative stacked cell, where the common source device is split in two smaller devices leading to a more compact and symmetric structure, with almost negligible parasitics associated to the transistors connection. This novel configuration is rigorously compared, for the first time, with the two classical approaches commonly adopted to physically connect the two devices. The three different layouts are fabricated in Gallium Nitride technology for high frequency power applications, and experimentally compared by means of an extensive measurement campaign performed on several loads and in different bias conditions, ranging from class AB to C. The proposed novel configuration outperforms the other two in all conditions, thanks to the advantages of adopting two smaller devices with reduced parasitics, higher gain and higher power density. These features are common to different technologies, thus making the novel topology widely applicable for the design of high frequency stacked cells
Re-envisioning Teacher Education: Using DisCrit Perspectives to Disrupt Deficit Thinking
This paper suggests that teacher educators engage in research that investigates practices and curriculum to consider how they might best confront issues of equity and deficit thinking in individual courses and disciplines. Rooted in the tenets of culturally responsive teaching and culturally sustaining pedagogy, the authors explore how DisCrit theory further informs understandings of hegemonic schooling practices, imploring faculty to upset the implicitly biased narratives that are so often reproduced in teacher education
A 6-point TACS score predicts in-hospital mortality following total anterior circulation stroke
Background and Purpose: Little is known about the factors associated with in-hospital mortality following total anterior circulation stroke (TACS). We examined the characteristics and comorbidity data for TACS patients in relation to in-hospital mortality with the aim of developing a simple clinical rule for predicting the acute mortality outcome in TACS. Methods: A routine data registry of one regional hospital in the UK was analyzed. The subjects were 2,971 stroke patients with TACS (82% ischemic; median age=81 years, interquartile age range=74–86 years) admitted between 1996 and 2012. Uni- and multivariate regression models were used to estimate in-hospital mortality odds ratios for the study covariates. A 6-point TACS scoring system was developed from regression analyses to predict in-hospital mortality as the outcome. Results: Factors associated with in-hospital mortality of TACS were male sex [adjusted odds ratio (AOR)=1.19], age (AOR=4.96 for ≥85 years vs. <65 years), hemorrhagic subtype (AOR=1.70), nonlateralization (AOR=1.75), prestroke disability (AOR=1.73 for moderate disability vs. no symptoms), and congestive heart failure (CHF) (AOR=1.61). Risk stratification using the 6-point TACS Score [T=type (hemorrhage=1 point) and territory (nonlateralization=1 point), A=age (65–84 years=1 point, ≥85 years=2 points), C=CHF (if present=1 point), S=status before stroke (prestroke modified Rankin Scale score of 4 or 5=1 point)] reliably predicted a mortality outcome: score=0, 29.4% mortality; score=1, 46.2% mortality [negative predictive value (NPV)=70.6%, positive predictive value (PPV)=46.2%]; score=2, 64.1% mortality (NPV=70.6, PPV=64.1%); score=3, 73.7% mortality (NPV=70.6%, PPV=73.7%); and score=4 or 5, 81.2% mortality (NPV=70.6%, PPV=81.2%). Conclusions: We have identified the key determinants of in-hospital mortality following TACS and derived a 6-point TACS Score that can be used to predict the prognosis of particular patients
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