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We present the first microacoustic metamaterial filters (MMFs). The bandpass of the reported MMFs is not generated by coupling, electrically or mechanically, various acoustic resonances; instead, it originates from the passbands and stopbands of a chain of three acoustic metamaterial (AM) structures. These structures form an AM transmission line (AMTL) and two AM reflectors (AMRs), respectively. Two single metal strips serve as input and output transducers with a wideband frequency response. Since MMFs do not rely on resonators, they do not require high-resolution trimming or mass-loading steps to accurately tune the resonance frequency difference between various microacoustic resonant devices. These steps often involve finely controlling the thickness of a device layer, with resolutions that can be as low as a few Angstroms when building GHz filters. The acoustic bandwidth of MMFs is mostly determined by geometrical and mechanical parameters of their AM structures. MMFs necessitate external circuit components for impedance matching, in contrast to the existing microacoustic filters that often employ circuit components only to eliminate ripples within their passband. We have designed and constructed the first MMFs from a 400-nm-thick scandium-doped aluminum nitride (AlScN) film using a 30% scandium-doping concentration. These devices operate in the radio frequency (RF) range. We validated these devices' performance through finite-element modeling (FEM) simulations and through measurements of a set of fabricated devices. When matched with ideal circuit components, the built MMFs exhibit filter responses with a center frequency in the ultrahigh-frequency range, a fractional bandwidth (FBW) of ~2.54%, a loss of ~4.9 dB, an in-band group delay between 70 ± 25 ns, and a temperature coefficient of frequency (TCF) of ~22.2 ppm/° C.

Competing Interests: The authors declare no conflicts of interest.

We report on a new class of Ising machines (IMs) that rely on coupled parametric frequency dividers (PFDs) as macroscopic artificial spins. Unlike the IM counterparts based on subharmonic-injection locking (SHIL), PFD IMs do not require strong injected continuous-wave signals or applied dc voltages. Therefore, they show a significantly lower power consumption per spin compared to SHIL-based IMs, making it feasible to accurately solve large-scale combinatorial optimization problems that are hard or even impossible to solve by using the current von Neumann computing architectures. Furthermore, using high quality factor resonators in the PFD design makes PFD IMs able to exhibit a nanowatt-level power per spin. Also, it remarkably allows a speedup of the phase synchronization among the PFDs, resulting in shorter time to solution and lower energy to solution despite the resonators' longer relaxation time. As a proof of concept, a 4-node PFD IM has been demonstrated. This IM correctly solves a set of Max-Cut problems while consuming just 600 nanowatts per spin. This power consumption is 2 orders of magnitude lower than the power per spin of state-of-the-art SHIL-based IMs operating at the same frequency.

Optical frequency combs, featuring evenly spaced spectral lines, have been extensively studied and applied to metrology, signal processing, and sensing. Recently, frequency comb generation has been also extended to MHz frequencies by harnessing nonlinearities in microelectromechanical membranes. However, the generation of frequency combs at radio frequencies (RF) has been less explored, together with their potential application in wireless technologies. In this work, we demonstrate an RF system able to wirelessly and passively generate frequency combs. This circuit, which we name quasi-harmonic tag (qHT), offers a battery-free solution for far-field ranging of unmanned vehicles (UVs) in GPS-denied settings, and it enables a strong immunity to multipath interference, providing better accuracy than other RF approaches to far-field ranging. Here, we discuss the principle of operation, design, implementation, and performance of qHTs used to remotely measure the azimuthal distance of a UV flying in an uncontrolled electromagnetic environment. We show that qHTs can wirelessly generate frequency combs with μWatt-levels of incident power by leveraging the nonlinear interaction between an RF parametric oscillator and a high quality factor piezoelectric microacoustic resonator. Our technique for frequency comb generation opens new avenues for a wide range of RF applications beyond ranging, including timing, computing and sensing., (© 2024. The Author(s).)

Myeloid cells facilitate T cell immune evasion in cancer yet are pliable and have antitumor potential. Here, by cotargeting myeloid activation molecules, we leveraged the myeloid compartment as a therapeutic vulnerability in mouse models of pancreatic cancer. Myeloid cells in solid tumors expressed activation receptors including the pattern recognition receptor Dectin-1 and the TNF receptor superfamily member CD40. In mouse models of checkpoint inhibitor-resistant pancreatic cancer, coactivation of Dectin-1, via systemic β-glucan therapy, and CD40, with agonist antibody treatment, eradicated established tumors and induced immunological memory. Antitumor activity was dependent on cDC1s and T cells but did not require classical T cell-mediated cytotoxicity or blockade of checkpoint molecules. Rather, targeting CD40 drove T cell-mediated IFN-γ signaling, which converged with Dectin-1 activation to program distinct macrophage subsets to facilitate tumor responses. Thus, productive cancer immune surveillance in pancreatic tumors resistant to checkpoint inhibition can be invoked by coactivation of complementary myeloid signaling pathways.

This work describes the implementation of acoustic metamaterials (AMs) made of a forest of rods at the sides of a suspended aluminum scandium nitride (AlScN) contour-mode resonator (CMR) to increase its power handling without causing degradations of its electromechanical performance. The increase in usable anchoring perimeter with respect to conventional CMR designs, enabled by the adoption of two AM-based lateral anchors, permits to achieve improved heat conduction from the resonator's active region to the substrate. Furthermore, thanks to such AM-based lateral anchors' unique acoustic dispersion features, the attained increase of anchored perimeter does not cause any degradations of the CMR's electromechanical performance, even leading to a ~15% improvement in the measured quality factor. Finally, we experimentally show that using our AM-based lateral anchors leads to a more linear CMR's electrical response, which is enabled by a 32% reduction of its Duffing nonlinear coefficient with respect to the corresponding value attained by a conventional CMR design that uses fully etched lateral sides.

Massive deployments of wireless sensor nodes (WSNs) that continuously detect physical, biological or chemical parameters are needed to truly benefit from the unprecedented possibilities opened by the Internet-of-Things (IoT). Just recently, new sensors with higher sensitivities have been demonstrated by leveraging advanced on-chip designs and microfabrication processes. Yet, WSNs using such sensors require energy to transmit the sensed information. Consequently, they either contain batteries that need to be periodically replaced or energy harvesting circuits whose low efficiencies prevent a frequent and continuous sensing and impact the maximum range of communication. Here, we report a new chip-less and battery-less tag-based WSN that fundamentally breaks any previous paradigm. This WSN, formed by off-the-shelf lumped components on a printed substrate, can sense and transmit information without any need of supplied or harvested DC power, while enabling full-duplex transceiver designs for interrogating nodes rendering them immune to their own self-interference. Also, even though the reported WSN does not require any advanced and expensive manufacturing, its unique parametric dynamical behavior enables extraordinary sensitivities and dynamic ranges that can even surpass those achieved by on-chip sensors. The operation and performance of the first implementation of this new WSN are reported. This device operates in the Ultra-High-Frequency range and is capable to passively and continuously detect temperature changes remotely from an interrogating node.

The present work details a novel approach to increase the transmitting sensitivity of piezoelectric micromachined ultrasonic transducer arrays and performing the direct modulation of digital information on the same device. The direct modulation system can reach 3× higher signal-to-noise ratio level and 3× higher communication range (from 6.2 cm boosted to 18.6 cm) when compared to more traditional continuous wave drive at the same energy consumption levels. When compared for the same transmission performance, the direct modulation consumes 80% less energy compared to the continues wave. The increased performance is achieved with a switching circuit that allows to generate a short high-AC voltage on the ultrasonic array, by using an LC tank and a bipolar junction transistor, starting with a low-DC voltage, making it CMOS-compatible. Since the modulation signal can directly be formed by the transmitted bits (on/off keying encoding) this also serve as the modulation for the data itself, hence direct modulation. The working principle of the circuit is described, optimization is performed relative to several circuital parameters and a high-performance experimental application is demonstrated.

This article proposes the first acoustic discovery architecture (ADA) for intrabody networks (INs). The main objective of ADA is to discover and interrogate, in real-time (RT), all the implanted medical devices (IMDs) that are part of an IN. This permits noninvasive RT diagnosis for patients with multiple IMDs. ADA will allow medical doctors to have vital information, on-the-go, for treating patients and to constantly monitor them. The architecture was implemented in a network simulator emulating a real-life IN, based on preliminary experimental results. ADA is in charge of scanning the body volume, by exploiting the beam-forming and beam-steering capability of piezoelectric micromachined ultrasonic transducers (pMUTs) arrays, and efficiently interrogating all the reached devices for their status. As a result, a full IN map can be reconstructed together with all the vital signs of a patient. ADA shows very good RT capabilities, with a full scanning time from 1500 down to 100 ms and energy consumption from 2.6 down to 0.2 mJ, depending on the scanning accuracy, for a body torso volume of [Formula: see text].

We report on the design and operation of a novel class of nonreciprocal acoustic filters operating in the radio frequency (RF) range. These devices use the spectral characteristics of commercial acoustic filters placed in angular momentum biased networks to achieve large nonreciprocity, low insertion loss (I.L.), and wideband operation. Owing to the high rejection exhibited by acoustic filters, these novel devices can achieve an unprecedented suppression of undesired intermodulation products, thus approaching the spectral purity attained by conventional linear-time-invariant (LTI) filtering components. In addition, a new analytical model suitable to capture the behavior of any angular-momentum-biased nonreciprocal device is presented. This model allows us to identify the main characteristics of the transfer function (poles and zeroes) relative to this new class of nonreciprocal filters, thus enabling new synthesis capabilities through standard numerical methods. Ultimately, the performance of a built 1.1-GHz nonreciprocal acoustic filter prototype is reported. This device relies on a modulation implemented through switched capacitors and shows I.L., isolation, and half-power bandwidth values of 4.5 dB, 28 dB, and 20 MHz, respectively, achieved through the use of a 40-MHz modulation frequency. Moreover, by showing an intermodulation distortion lower than -34 dBc, it approaches the operation of LTI circuits.

Background: Burnout can have negative consequences for providers' health and patient care. Mentorship has positive effects including stress mitigation. We sought to evaluate the impact of a mentorship program on burnout in fourth-year medical students during their 4-week emergency medicine subinternship., Methods: This was a prospective, quasi-experimental, mixed-methods study at two institutions. We assessed burnout using the Maslach Burnout Inventory, comprising three subscales: Emotional Exhaustion (EE), Depersonalization (DP), and Personal Accomplishment (PA). We compared changes in burnout scores before and after implementation of a resident-student mentorship program. We compared categorical variables using risk ratios and continuous variables using Wilcoxon rank-sum test. To account for potential confounders, we performed multivariable analysis. Students and mentors completed an evaluative survey. We reported descriptive statistics and performed thematic qualitative analysis on free-response data., Results: A total of 135 students (intervention = 51; control = 84) and 59 mentors participated. Intervention students demonstrated decreased EE and DP and increased PA scores, medians of -2 (-4 to 4), -1 (-3 to 2), and 1 (-1 to 4), respectively, compared to controls, median difference of 0 for all subscales. After adjusting for potential confounders, there was no significant difference in EE (mean difference = -0.2 [-0.5 to 0.2], p = 0.4) or DP scores (mean difference = -0.2 [-1.8 to 1.5], p = 0.9). There was a significant difference in PA scores (mean difference = 2.2 [0.1 to 4.3], p = 0.04). Most students felt the program positively impacted their rotation (39/48) and decreased stress (28/48). Students felt that the program provided career guidance and positively impacted their personal and professional development. The majority (34/37) of mentors enjoyed participating. Qualitative analysis revealed five major themes: relationship building, different perspective, knowledge sharing, personal fulfillment, and self-reflection., Conclusion: We found an increased sense of personal accomplishment after implementation of a mentorship program. Both mentors and mentees viewed the program positively and perceived multiple benefits.

This work describes a new method to enhance the electromechanical coupling coefficient ( k t 2 ) of 2-D mode resonators (2DMRs). This approach exploits the multimodal excitation of different Lamb waves to achieve a quasi-uniform vertical displacement distribution in the electrode regions of 2DMRs. To do so, the 2DMRs reported in this work rely on the use of metal frame structures placed at the edges of each metal strip forming the electrode gratings. To demonstrate the effectiveness of this new technique in enhancing k t 2 , we report the design and simulated performance through the finite-element methods of a 2.5-GHz 2DMR using metal frames. Our analysis proves that this device can simultaneously exhibit high k t 2 in excess of 6.4% and wide lithographic frequency tunability in excess of 10%, thus approaching the reported performance of aluminum nitride (AlN) film bulk acoustic resonators (FBARs) operating within the same frequency range.

This paper reports on a novel simulation method combining the speed of analytical evaluation with the accuracy of finite-element analysis (FEA). This method is known as the rapid analytical-FEA technique (RAFT). The ability of the RAFT to accurately predict frequency response orders of magnitude faster than conventional simulation methods while providing deeper insights into device design not possible with other types of analysis is detailed. Simulation results from the RAFT across wide bandwidths are compared to measured results of resonators fabricated with various materials, frequencies, and topologies with good agreement. These include resonators targeting beam extension, disk flexure, and Lamé beam modes. An example scaling analysis is presented and other applications enabled are discussed as well. The supplemental material includes example code for implementation in ANSYS, although any commonly employed FEA package may be used.

State-of-the-art sensors use active electronics to detect and discriminate light, sound, vibration and other signals. They consume power constantly, even when there is no relevant data to be detected, which limits their lifetime and results in high costs of deployment and maintenance for unattended sensor networks. Here we propose a device concept that fundamentally breaks this paradigm-the sensors remain dormant with near-zero power consumption until awakened by a specific physical signature associated with an event of interest. In particular, we demonstrate infrared digitizing sensors that consist of plasmonically enhanced micromechanical photoswitches (PMPs) that selectively harvest the impinging electromagnetic energy in design-defined spectral bands of interest, and use it to create mechanically a conducting channel between two electrical contacts, without the need for any additional power source. Our zero-power digitizing sensor prototypes produce a digitized output bit (that is, a large and sharp off-to-on state transition with an on/off conductance ratio >10 12 and subthreshold slope >9 dec nW -1 ) when exposed to infrared radiation in a specific narrow spectral band (∼900 nm bandwidth in the mid-infrared) with the intensity above a power threshold of only ∼500 nW, which is not achievable with any existing photoswitch technologies.

Through the use of a laser Doppler vibrometer, it is shown that a 31% variation in quality factor can occur due to the effect of undercutting of the device layers outside of the anchors of a 220-MHz aluminum nitride contour-mode resonator. This undercutting is a result of the isotropic etch process used to release the device from the substrate. This paper shows that the variation in Q is a function of the release distance, L , between the active region of the resonator and the edge of this released region. This paper also determined a design modification that eliminated this issue and achieved a Q of 3048, which is independent of L .

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe dermatologic reactions with mucocutaneous involvement that carry elevated mortality rates. They differ along a spectrum of severity based upon body surface area affected. These conditions, usually caused by a drug or infection, are believed to result from cell-mediated and often drug-specific cytotoxic reactions against keratinocytes, leading to widespread dermal-epidermal detachment. Studies attempting to identify potential curative therapies such as intravenous immune globulin (IVIG) and corticosteroids remain inconclusive. However, improved outcomes have been demonstrated by early withdrawal of offending medications, early transfer to an intensive care unit or burn unit, and aggressive supportive care. Due to the rare incidence of SJS and TEN, its recurrence among survivors hints at future vulnerability for these patients, and notorious offending medications should thus be avoided. This clinical review will highlight the diagnostic and therapeutic challenges posed by SJS and TEN, while emphasizing the need to maintain them high on the emergency medicine physician's differential. The review will also detail the supportive measures to take for preventing the rapid progression of mucocutaneous complications and subsequent sepsis-related mortality.

We present the first parametric oscillator based on the use of a 226.7 MHz aluminum nitride contour-mode resonator. This topology enables an improvement in the phase noise of 16 dB at 1 kHz offset with respect to a conventional feedback-loop oscillator based on the same device. The recorded phase noise is -106 dBc/Hz at 1 kHz offset.

Manipulable substrates promote species-typical behavior and decrease abnormal behavior in a variety of primate species. However, the effects of providing litter to arboreal primates are not as well studied, and there is little information specifically concerning enrichment for guenons. To inform the captive management of an under-studied species, we evaluated deep litter substrate as environmental enrichment for a family group of Wolf's guenons, Cercopithecus wolfi. We expected it to promote species-typical behavior and to act as an intervention by reducing aggressive behaviors targeted toward a juvenile group member by his parents. We compared the guenons' behavior during baseline periods in which normal husbandry routines were followed to periods when the entire floor of their enclosure was covered with 30 cm of straw or wood wool. We then evaluated the group's preference between litters by comparing their relative use. The guenons spent more time feeding and were more active during both litter conditions, but relative to their respective baselines, they spent more time examining straw and less time examining wood wool. Straw, but not wood wool, promoted some affiliative behavior as well as greater tolerance of the juvenile's social proximity to others. However, the addition of deep litter did not ameliorate patterns of agonistic behavior among our subjects. Our results suggest that straw conferred greater behavioral benefits than wood wool as a deep litter substrate for this guenon group and may constitute a form of environmental enrichment for this species., (© 2009 Wiley-Liss, Inc.)

We have studied apoptosis in lymph node and peripheral blood mononuclear cells (PBMCs) from HIV-infected children and adults and SIV-infected rhesus macaques. In lymph nodes, we found that apoptosis and productive infection occurred only rarely in the same cell. There was, however, a direct correlation between the numbers of apoptotic and productively-infected cells. In HIV-infected children, we found a direct correlation between disease severity and percentage CD4+ T cell apoptosis (p = 0.001). Both CD4+ and CD8+ T cell apoptosis were directly related to CD4+ T cell depletion (p = 0.006 and p = 0.01, respectively). In addition, we found a trend towards diminished CD4+ T cell apoptosis on anti-retroviral agents. These findings suggest that apoptosis of uninfected cells may be important in HIV pathogenesis and that measurement of apoptosis may be a useful marker of disease activity.