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Focused ultrasound (FUS) neuromodulation can induce therapeutic effects, such as decreasing perceived pain. To ensure safety during FUS and to better understand the role of cavitation during in vivo neuromodulation, factors influencing cavitation activity must be well understood. Tissue temperature may change between patients and heat may accumulate during therapy. Previous studies have shown a dependence of inertial cavitation thresholds on tissue shear modulus, which changes with temperature. Tissue temperature may therefore affect the intensity of cavitation in the tissue, yet this has not been well-characterized. This study sought to assess the relationship between tissue temperature and levels of cavitation under FUS in vivo. Cavitation was recorded during each sonication and analyzed using calculated passive cavitation images and cavitation doses. Two study designs were used to evaluate cavitation across tissue temperatures of 30-38°C. Our results showed that greater cavitation intensities occurred at higher tissue temperatures. Thus, temperature elevation and cavitation events should be monitored during FUS therapies.

The computing education community has explored multiple strategies to address the problem of underrepresentation of African American and Latino students. Recently, the community has started to explore culturally relevant pedagogy (CRP) to increase the effectiveness of curricula and programs designed to increase participation in underrepresented groups. CRP suggests that the use of culture can benefit students by providing them with opportunities to bring their culture into learning. In this poster paper, we explore the use of CRP to introduce 4th and 5th grade African American students to computer science in an 8-week summer camp through the context of social justice.

This paper presents the design of Blocks4DS, a block-based environment for students to learn data structures. As a proof-of-concept, we designed custom blocks to allow students to build and visualize Binary Search Trees (BST). Blocks4DS is built on Blockly and uses vis.js to provide visualizations of the binary search tree and its operations. This paper describes the results from an initial evaluation of usability and student learning.

Energy efficiency of wireless links is very important in modern communication systems. A survey of papers evaluating energy efficiency however shows that evaluation approaches are not consistent, resulting in calculations that are not comparable with each other. Indeed, even the units of the various energy efficiency evaluations are not identical. To address this problem a new model is developed here that takes into account the many dependencies among multiple wireless link parameters important to evaluating energy efficiency of the link. The unit of bits per joule is adopted for this new model. This new model is evaluated for five deployed wireless links that have very different parameters and operating objectives. The need to establish standardized cases to allow direct comparisons is identified and discussed.

While users of spectrum pay large sums of money for spectrum access, they do not sell spectrum to their customers but rather they market data rates. Developing radio technologies that maximize data rate within a finite spectrum slice is a very important goal to such spectrum access businesses. This requires radios to provide high values of spectrum efficiency (bits per second per Hertz-bandwidth (bps/Hz)). This paper is the first to introduce a conventional Nyquist filtered 4096-QAM signal implemented with a switching-circuit based transmitter. Even by having no circuit linearity in the RF path and using polar modulation, the reported signal quality measurements confirm less than 0.9% error-vector magnitude for this 12 bps/Hz constellation. Signal ACLR is -54 dB, peak output power is 2.5 watts, and the transmitter efficiency exceeds 50% when modulated and including all linearization power. The limits of using EVM as a signal quality metric are presented and discussed.

A significant challenge to using dual-modality environments in instruction is that existing dual-modality representations are built into sandbox environments with functionality tailored to a specific purpose (such as Pencil Code’s turtle graphics). However, students in introductory programming classes usually use an Integrated Development Environment (IDE), a software application that provides a suite of tools for programming support. The use of IDEs is common in industry, and thus they bring additional authenticity and scaffolding to the learning experience. We developed an IDE plugin, Amphibian, from Pencil Code’s Droplet Editor to enable switching between blocks and text within IntelliJ IDEA, a common IDE for the Java language. This plugin allows teachers of Java courses, including those of AP CS and in colleges, to incorporate dual-modality representation into their curriculum. It also enables more rigorous research into use of dual-modality environments in classrooms by facilitating use within existing curricula, allowing researchers to remove potentially confounding variables, such as use of different languages, software systems, and development environments.

Text languages are perceived by many computer science students as difficult, intimidating, and/or tedious in nature. Conversely, blocks-based environments are perceived as approachable, but many students see them as inauthentic. Bidirectional hybrid environments provide textual and blocks-based representations of the same code, thereby offering students the opportunity to seamlessly transition between representations to build a conceptual bridge between blocks and text. However, it is not known how use of hybrid environments impacts perceptions of programming. To investigate, we conducted a study in a public middle school with six classes (n=129). We found that students who used hybrid environments perceived text more positively than those who moved directly from blocks to text. The results of this research suggest that hybrid programming environments can help to transition students from blocks to text-based programming while minimizing negative perceptions of programming.

Data rate is increased on-air by using 16,384 QAM, a 14 bits/symbol constellation. Implemented with a Digital Software Radio transmitter technique, signal ACLR is below -50 dB, peak output power is 2.5 watts, and the transmitter efficiency exceeds 50% when modulated including all linearization power. Measured on-air link operation confirms performance and practicality to use this high order signal constellation while also reducing operating power costs.

Spectrum is a precious resource, which encourages system design developments that improve bandwidth efficiency. This paper is the first to introduce the performance of the 1024-QAM signal implemented with the nonlinear switch-mode mixer modulator (SM$^{3}$) power circuit element. Measurements of modulation precision show less than 0.4% error-vector magnitude. Signal ACLR is -54 dB, peak output power is 2.5 watts, and the transmitter efficiency exceeds 50% under modulation and including all linearization.

Block-based programming environments have increased students' interest in computer science (CS). Research suggests that block-based programming environments have positively impacted students' retention, effectiveness, efficiency, engagement, attitudes, and perceptions towards computing. We know that when novice programmers are learning to program in block-based programming environments, they need to understand the components of these environments, how to apply programming concepts, and how to create artifacts. However, few studies have been done to understand the impacts that usability of block-based programming environments may have on students' programming. In this poster, we present results from a two-part study designed to understand the impact that usability of the programming environment has on novice programmers when learning to program in Scratch. Our findings indicate that usability challenges may affect students' ability to navigate and create programs within block-based programming environments.

The decision to use OFDM-based modulation for 5G-NR forces a low-valued ceiling on achievable energy efficiency from any linear power amplifier. The 5G network also has an objective to significantly increase its energy efficiency with respect to the energy draw of the LTE network. To get the desired efficiency improvement, at the transmitter, requires circuit nonlinearity. This paper introduces a transmitter design that accurately produces 5G-NR modulation while maintaining an operating energy efficiency exceeding 40%, well above the 14% of typical LTE linear transmitters. Circuit nonlinearity is maximized, using switch-based RF design, in order to maximize transmitter efficiency. Sampled signal processing is therefore required, and is used here within a polar modulation architecture. Measurements of this approach implemented using GaN HEMT technology, are provided which include the efficiency impact of crest factor reduction signal processing.

The 5G network has a goal to significantly increase its energy efficiency with respect to the energy draw of the LTE network. The decision to use OFDM-based modulation for 5G-NR forces a low-valued ceiling on achievable energy efficiency from any linear power amplifier. This ceiling is lowest for amplifiers operating at frequencies near and above 30 GHz: the millimeter-wave bands. Transistors behave differently at these high frequencies, and the modulation used must change to match to these different characteristics. Ring oriented constellations with polar filtering meet these changed conditions.

A fully integrated RFDAC based phase modulator in 40nm bulk CMOS is presented. To boost in-band linearity and the frequency range of operation, a harmonic rejection RFDAC architecture that suppresses the 3rd and 5th harmonics is proposed. The achieved frequency agility of the phase modulator is verified over a 0.6–2.5GHz range yielding EVM of −34.5dB and −36dB for an 18Mb/s and 75Mb/s GMSK signals, respectively. The power consumption of the proposed phase modulator is 33 mW at 2.4GHz

A two-stage D-band differential cascode power amplifier is presented, integrated using the IHP 0.13 pm SiGe BiCMOS technology. A compact layout of the cascode stage is proposed to minimize the parasitics contributing to potential instability, achieving 13 dB of gain/stage while operating at 46% of f T , using stage peaking. The PA is analyzed using Booth chart techniques showing that the amplifier can operate with greatly reduced supply and bias while maintaining linearity dynamic range. The fabricated prototype achieves P1dB, Psat, and IIP2 of 0.2 dBm, 6.2 dBm, and 25.5 dBm respectively with 26 dB overall gain. The AM-PM conversion of the PA is experimentally characterized showing phase fluctuations lower than ±1.5° in a 10 GHz bandwidth. Furthermore, it exhibits 1 dB deviation of power gain over 40 dB input power range with 0.4 V supply variation.

In recent years, block-based programming languages have been employed as learning tools to help students starting out with programming. How we design the layout of the available blocks likely impacts the success of the student. In this study, we compare student performance in three conditions consisting of different layouts of block categories in a block-based language: a grouping based on computer science (CS) concepts, a grouping based on block functionality, and one with no groupings. We measured task completion time, quality of the final code product, and perceived system usability. We found that although time and quality did not differ across conditions, the students in the functionality condition reported higher usability scores than the students in the CS concepts condition. These results can inform how we design block-based interfaces to improve learner satisfaction without affecting their performance.

Energy efficiency in communications of all types is of growing importance to society. All efficiency loss is due to power dissipation in the electronic circuitry used to implement the communication standard. Selection of the modulation adopted by a standards working group has a dominant role in how much of the energy efficiency available from electronic technologies and circuit structures can be made visible to the communications application. Prediction of whether a particular modulation in consideration will either allow implementers to realize high values of energy efficiency — or will force implementers to use circuit techniques which place a low ceiling on the achievable energy efficiency — is an important step that must be performed during modulation selection deliberations. Prediction of this efficiency cap, if any, is readily achieved by the calculation proposed in this mostly tutorial paper. An initial comparison of presently used signal modulations is provided.

While polar modulation is a transmitter technique that is known to maximize energy efficiency, it also has no circuit linearity and traditionally is unable to produce signals that contain envelope zeros such as QAM and LTE. This polar transmitter solves this weakness and is modulation agnostic across the decade-wide tuning bandwidth of 200–2500 MHz. In particular, a conventional Nyquist filtered 256QAM signal is generated with error vector magnitude (EVM) less than 1.5% across the frequency range, and is below 1% across the bottom decade of frequency — without use of digital predistortion (DPD) linearization. Peak output power is 2.5 watts.

Power consumption of the communications infrastructure, particularly that which is LTE-based, is driven by the efficiency of the transmitter. Lower efficiency in the transmitter scales to needs for both larger power supplies and greater resources needed to remove the power dissipated by both the transmitter and its power supply. Improvement in transmitter efficiency therefore leverages, through these other functions, to provide a significant drop of input power draw while maintaining the same quality of service through the network. This corresponds worldwide to more than a million ton reduction of CO2 from electric generation per year at present levels of LTE network buildout.

Maximizing the operating energy efficiency of any wireless communication link requires a global optimization not only across the entire system block diagram, but also including the signal modulation and aspects of the link operating protocol. Achieving this global optimization is first examined for the transmitter, receiver, and baseband circuitry. Then the important aspects of signal modulation necessary to access these circuit optimizations, with examples from existing systems along with proposed signals for "5G" including Internet of Things (IoT) and massive MIMO, are presented. This is followed by the correspondingly important protocol aspects needed for link efficiency. Operating temperature consequences of signal modulation selection, and its corresponding PA efficiency ceiling, are explored for the envisioned massive-MIMO antenna arrays. A realization of this global energy efficiency optimization in actual circuitry with measurements completes this paper.

Implementing any massive MIMO array involves managing transmitter power dissipation heat from each element. This power dissipation is strongly lower-bounded by the signal adopted by present communication standards, which forces an energy efficiency minimum. This also causes a difficult thermal problem in the array implementation. Achieving an energy efficient massive MIMO implementation is shown to require the use of strongly nonlinear transmitters, needing signal designs that are compatible with this nonlinearity while maintaining bandwidth efficiency.