Acquisition Rate Research Articles

High-speed three-dimensional random access scanning with a linear SLM

High-speed volumetric imaging is crucial for observing fast and distributed processes such as neuronal activity. Multiphoton microscopy helps to mitigate scattering effects inside tissue, but the standard raster scanning approach limits achievable volume rates. Random access point scanning can lead to a considerable speed-up by sampling only pre-selected locations, but existing techniques based on acousto-optic deflectors are still limited to a point rate of up to . This limits the number of parallel targets at the high acquisition rates necessary, for example, in voltage imaging or imaging of fast synaptic events. Here, we introduce SPARCLS, a method for 3D random access point scanning at up to 340 kHz using a single 1D phase modulator. We show the potential of this method by imaging synaptic events with fluorescent glutamate sensors in mammalian organotypic slices as well as in zebrafish larvae.

Sea Surface Height Measurements Using UAV Altimeters with Nadir LiDAR or Low-Cost GNSS Reflectometry

Although UAV height is precisely determined using GNSS, the vertical distance between the UAV and the sea surface should be subtracted to obtain the sea surface height (SSH). This distance can be measured using nadir-looking LiDAR or GNSS reflectometry (GNSS-R); thus, these two methods are examined in this study through three two-minute UAV experimental flights. The measurements of the flight-averaged SSHs made with both approaches were in good agreement with the reference SSH determined from a GNSS buoy, with differences of 0.03 m (LiDAR) and 0.05 m (GNSS-R), although the standard deviation (SD) for GNSS-R (1.72 m) was significantly larger than that for LiDAR (0.20 m). Each 4 Hz GNSS-R measurement was subject to errors caused by surface waves, though over 16 GNSS reflection points within a 70 m diameter footprint were used; these errors were, however, removed in the temporal mean. Extending the footprint diameter to 230 m with stronger data quality controls resulted in a smaller error (0.02 m) and SD (0.79 m). Meanwhile, LiDAR measured the flat-surface SSH at the nadir only, which inherently filtered out slant reflections, resulting in a lower SD. However, this filter reduces data acquisition rates, especially when the UAV attitude tilts.

Quantitative Endogenous Polyamine Analysis via Capillary Electrophoresis/Mass Spectrometry: Characterization and Practical Considerations.

Commonly used analytical techniques for polyamine analysis, including derivatization and mixed-mode liquid chromatography (LC), have inherent disadvantages. Capillary electrophoresis (CE) is uniquely suited to analyze small, highly charged molecules because analytes are separated on the basis of their electrophoretic mobility, not polarity or association with a stationary phase. Microfluidic CE-mass spectrometry (mCE-MS) is a relatively recent addition to commercially available CE offerings that streamlines traditional CE-MS interfacing and has the potential to improve upon classic CE challenges to robustness and reproducibility. MS instrument choice and scanning parameters are strongly influenced by a need for high acquisition rate to adequately sample CE peaks. Alternatively, isotachophoresis on loading can be intentionally avoided to produce sufficiently wide peaks. The mCE platform utilized here performed very well in many metrics; a limit of detection (LOD) as low as 0.25ng/mL was achieved for spermidine, and endogenous spermidine was easily detected in blood with this method. Both of these are challenging tasks for any separation technique and demonstrate a strong use case for the platform. During experimentation, various idiosyncrasies in the commercial CE-MS interface resulted in extensive chip-to-chip variability in both peak shape and LOD, complicating the application to robust absolute quantitation. Practical guidance for similar analyses is provided.

Comparing Cochlear Implant Outcomes in 100 Patients With Sporadic Vestibular Schwannoma Managed With Observation, Radiosurgery, or Microsurgery: A Multi-Institutional Review.

To compare cochlear implant (CI) speech perception outcomes in patients with sporadic vestibular schwannoma (VS) managed with observation, radiosurgery, or microsurgery. Retrospective review. Eleven tertiary academic medical centers. One hundred patients with sporadic VS who received an ipsilateral CI. Ipsilateral cochlear implantation. Pure-tone thresholds, monosyllabic speech perception testing scores, and rates of open-set speech acquisition. Of the 100 patients studied, 54 underwent microsurgery, 26 underwent radiosurgery, 19 continued observation, and 1 underwent multimodal therapy. Among all patients, the median post-implantation pure-tone average was 31 dB (interquartile range [IQR] 25-39 dB) and the median monosyllabic speech perception score was 30% (IQR 0-60%) at a median of 12 months (IQR 5-25 months) post-implantation. Patients who were managed with microsurgery (median speech perception score 11%, IQR 0-52%) exhibited poorer implant outcomes overall compared with those managed with observation (median speech perception score 52%, IQR 40-72%) or radiosurgery (median speech perception score 30%, IQR 16-60%). Open-set speech perception was achieved in 61% of patients managed with microsurgery, 100% with observation, and 80% with radiosurgery. In a multivariable setting, those managed with observation (p = 0.02) or who underwent radiosurgery (p = 0.04) were significantly more likely to achieve open-set speech perception compared with patients who underwent microsurgery. Cochlear implants offer benefit in selected patients with sporadic VS. Although achieved in over half of people after microsurgery, open-set speech perception is more reliably attained in patients who are treated with observation or radiosurgery compared with microsurgical resection. These data may inform patient counseling and VS tumor management in people who may benefit from implantation.

Clinical and microbiological effectiveness of pulsed-xenon ultraviolet light disinfection in a neonatal intensive care unit in Japan

Meticillin-resistant Staphylococcus aureus (MRSA) is a common causative agent of serious healthcare-related infections in neonatal intensive care units (NICUs). In adult ICUs, pulsed-xenon ultraviolet (PX-UV) disinfection of environmental surfaces, along with alcohol-based hand hygiene and terminal cleaning, has been demonstrated to reduce the MRSA acquisition rate. However, the impact of PX-UV use in NICUs on reducing MRSA transmission remains unexplored. The incidence of newly detected MRSA cases was recorded for all patients between January 2021 and December 2022. UV irradiation was used in addition to terminal manual cleaning. During the baseline period, irradiation was performed on areas following the use by patients with MRSA, while in the intervention period, irradiation was performed after each patient's use. While there was no observed change in the frequency of hand hygiene compliance throughout the study period, the total number of MRSA cases detected per 1,000 patient days decreased significantly. In NICUs, UV irradiation of environmental surfaces, in addition to hand hygiene practices and conventional environmental maintenance, may be effective in reducing MRSA infection.

Uneven distribution of prokaryote-derived horizontal gene transfer in fungi: a lifestyle-dependent phenomenon.

This study sheds new light on the role of horizontal gene transfer (HGT) in fungi, an area that has remained relatively unexplored compared to its well-established prevalence in bacteria. By analyzing 829 fungal genomes, we identified over 20,000 genes that fungi acquired from prokaryotes, revealing the significant impact of HGT on fungal evolution. Our findings highlight that fungal lifestyle traits, such as being parasitic or saprotrophic, play a key role in determining the extent of HGT, with parasites showing the highest gene acquisition rates. We also uncovered unique patterns of HGT occurrence based on fungal morphology and reproduction. Importantly, genes with introns, which are more highly expressed, appear to play a crucial role in fungal adaptation. This research deepens our understanding of how HGT contributes to the metabolic diversity and ecological success of fungi, and it underscores the broader significance of gene transfer in shaping fungal evolution.

Single-shot single-beam coherent Raman scattering thermometry based on optically induced air lasing

Thermometric techniques with high accuracy, fast response and ease of implementation are desirable for the study of dynamic combustion environments, transient reacting flows, and non-equilibrium plasmas. Herein, single-shot single-beam coherent Raman scattering (SS-CRS) thermometry is developed, for the first time to our knowledge, by using air lasing as a probe. We show that the air-lasing-assisted CRS signal has a high signal-to-noise ratio enabling single-shot measurements at a 1 kHz repetition rate. The SS-CRS thermometry consistently exhibits precision of <2.3% at different temperatures, but the inaccuracy grows with the increase in temperature. The high measurement repeatability, 1 kHz acquisition rate and easy-to-implement single-beam scheme are achieved thanks to the unique temporal, spectral and spatial characteristics of air lasing. This work opens a novel avenue for high-speed CRS thermometry, holding tremendous potential for fast diagnostics of transient reacting flows and plasmas.

Impact of universal contact precautions and chlorhexidine bathing on the acquisition of carbapenem-resistant enterobacterales in the intensive care unit: a cohort study

BackgroundFor the prevention of carbapenem-resistant Enterobacterales (CRE) acquisition in the intensive care unit (ICU), the effectiveness of universal contact precautions (UCP) and chlorhexidine gluconate (CHG) bathing is controversial.MethodsWith the aim of evaluating the effectiveness of UCP and CHG on CRE acquisition, this study was conducted in an ICU at a university-affiliated hospital in Seoul. Beginning in April 2017, all patients admitted to the ICU underwent weekly CRE screening and surveillance tests, and beginning in January 2018, UCP and CHG bathing were implemented for all patients. The pre-intervention period spanned from April to December 2017; the post-intervention period spanned from January 2018 to December 2019. The pre- and post-intervention CRE acquisition rates were subsequently compared using Kaplan–Meier analysis and log-rank tests, and independent risk factors for CRE acquisition were analysed using Cox proportional hazard modelling.ResultsOf 1,747 patients, 35 acquired CRE during their ICU stay. The CRE acquisition rate was 1.94 and 1.45 per 1,000 patient-days before and after the intervention, respectively, with no significant difference (p = 0.357). The incidence rate of multidrug-resistant organism (MDRO) colonisation decreased from 19.33 to 13.57 per 1,000 patient-days, with Poisson regression analysis showing a relative risk of 0.85 (95% confidence interval [CI] 0.738–0.945, p = 0.004). Additionally, multivariable Cox regression revealed that CRE acquisition was significantly associated with carbapenem exposure (adjusted hazard ratio [aHR] 2.555, 95% CI 1.208–5.405, p = 0.013) and the presence of more than four patients colonised with CRE during their ICU stay (aHR 2.639, 95% CI 1.157–5.243, p = 0.019). However, UCP and CHG bathing were not significantly associated with CRE acquisition (aHR 0.657, 95% CI 0.301–1.433; p = 0.291).ConclusionsUCP and CHG bathing did not affect the CRE acquisition rate in the ICU of a low-prevalence area. A multimodal strategy including antibiotic stewardship is necessary for controlling the nosocomial spread of MDROs.

Fast Multi-Distance Time-Domain NIRS and DCS System for Clinical Applications.

We have designed and built an improved system for combined Time-Domain Near-Infrared Spectroscopy (TD NIRS) and Diffuse Correlation Spectroscopy (DCS) measurements. The system features two independent channels, enabling TD NIRS and DCS acquisition at short and long source-detector distances to enhance depth sensitivity in layered tissues. Moreover, the device can operate at fast acquisition rates (up to 50 Hz) to monitor hemodynamic oscillations in biological tissues. An OEM (Original Equipment Manufacturer) TD NIRS device enables stable and robust acquisition of photon distribution of time-of-flight. For the DCS signals, the use of a time tagger and a software correlator allows us flexibility in post-processing. A user-friendly GUI controls TD NIRS data acquisition and online data analysis. We present results for the system characterization on calibrated tissue phantoms according to standardized protocols for performance assessment of TD NIRS and DCS devices. In-vivo measurements during rest and during vascular occlusions are also reported to validate the system in real settings.

Real-Time Observations of Leaf Vitality Extinction by Dynamic Speckle Imaging

Sap flow within a leaf is a critical indicator of plant vitality and health. This paper introduces an easy-to-use, non-invasive and real-time imaging method for sap microcirculation imaging. From the coherent backscattering of light on a leaf, we show that the acquisition frequency of dynamic speckle can be linked to the microcirculation speed inside the leaf. Unlike conventional methods based on speckle contrast, which use integration times long enough to observe temporal decorrelation within a single image, our approach operates in a regime where speckle patterns appear ‘frozen’ in each frame of a given sequence. This ‘frozen’ state implies that any decorrelation of the speckle pattern within a frame is negligible. However, between successive frames, decorrelation becomes substantial, and it is this inter-frame decorrelation that enables the extraction of dynamic information. In this context, the integration time primarily influences the radiometric levels, while the frame acquisition rate emerges as the key parameter for generating activity index maps. Thus, by accessing different ranges of sap flow activity levels by varying the frame acquisition rate, we reveal, in a non-invasive way, the anatomy of the leaf’s circulatory network with unprecedented richness. We experimentally validate the ability of the method to characterize the vitality of a fig leaf in real time by observing the continuous decrease in sap circulation, first in the smaller vessels and then in the larger ones, following the cutting of the leaf over a 48 h period.

Impact of tumor type and size on macroscopic tissue core retrieval in endoscopic ultrasound-guided fine needle biopsy for pancreatic malignancies.

Endoscopic ultrasonography (EUS) is pivotal for diagnosing and sampling pancreatic tumor tissues. This study aimed to assess how the histological type and size of tumors influence the adequacy of macroscopic tissue cores acquired using EUS-guided fine needle biopsy (FNB). We conducted a retrospective study involving 180 patients with pathologically confirmed pancreatic malignancies at our hospital, a medical center, between July 2020 and June 2023. Personal and clinical data, EUS findings, and pathological results were extracted from the patient records. The macroscopic tissue core acquisition rate was 86.1%. Patients with tumors larger than 3cm had a higher sufficiency rate (93.3%) compared to those with tumors 3cm or smaller (78.9%, p = 0.005). It was more difficult to obtain sufficient tissue cores from neuroendocrine tumors than from adenocarcinomas (67.7% vs. 89.9%, p = 0.001). Interestingly, obtaining a sufficient tissue core only affected the diagnostic rate of adenocarcinoma (93.3% vs. 60%, p < 0.001) but did not significantly influence the diagnostic rate of neuroendocrine tumors. This study highlights that small tumors (< 3cm) and neuroendocrine tumors pose a challenge in obtaining sufficient tissue cores. However, obtaining sufficient tissue cores significantly influences the pathological diagnosis of FNB in adenocarcinoma but not in neuroendocrine tumors.

Unveiling the Potential of Ultraviolet Fluorescence Imaging as a Versatile Inspection Tool: Insights from Extensive Photovoltaic Module Inspections in Multi‐MWp Photovoltaic Power Stations

UV fluorescence imaging (UVF) has the potential to grow into a powerful, informative, and economically attractive inspection method for photovoltaic (PV) power stations. UVF demonstrates the ability to indicate differences in polymer types and degradation states in backsheets and encapsulation materials of PV modules. The data acquisition rate of UVF measurements is 10 to 15 times higher than that achieved by state‐of‐the‐art near‐infrared spectroscopy, enabling the mapping of the bill of materials (BoMs) and degradation state for every module in large PV arrays. Combinations of UVF with vibrational spectroscopies allow the polymer BoMs to be recognized and correlated with aging phenomena such as metal corrosion or potential induced degradation. UVF imaging can also be used for conventional visualization of nonmaterial‐related anomalies, such as hot cells or cell cracks. The low purchase cost of the equipment makes UVF an affordable and high‐throughput diagnostic method yielding comprehensive information that would otherwise only be accessible by combining several slower and more laborious methods. Automated UVF image analysis and refinements of correlations between different BoMs and UVF pattern geometry can further unlock the potential of UVF as a straightforward tool accessible to all stakeholders and promote proactive strategies for the optimization of the reliability and performance of PV power stations.

The Impact of Digital Transformation on Service Models and Employee Skill Requirements in Taiwan's Real Estate Brokerage Industry

This paper investigates how digital transformation impacts service delivery models and employee skill requirements in Taiwan's real estate brokerage industry. Through a multiple-case comparison approach, data was collected from 200 participants across real estate firms to examine organizational adaptation to technological change. The research employed structural equation modeling and hierarchical linear modeling to analyze relationships between compensation satisfaction (β = 0.45, p &lt; 0.001), digital competency levels, and internal case circulation patterns. Results demonstrate that digital technologies significantly reshape brokerage operations, with digitalized companies achieving 32% higher client acquisition rates and 45% reduction in transaction processing time. Analysis reveals that employee digital literacy accounts for 28% of performance variance, while organizational support systems explain 23% of technology adoption rates. The findings extend service innovation literature by establishing empirical links between compensation systems and digital transformation success, providing a practical framework for technology integration in Taiwan's real estate sector. This research offers evidence-based recommendations for firms implementing digitalization strategies and developing employee capabilities in response to industry evolution.

Application of active piezoresistive cantilevers in high-eigenmode surface imaging

Abstract One of the most important limitations of the atomic force microscopy (AFM) is scanning speed, whose high values are required for contemporary high-resolution, long-range diagnostic applications. The measurement bandwidth of an AFM depends on several factors, but usually results from the time constant of the oscillating cantilever, which is correlated with its resonance frequency and quality factor. We propose a method to overcome this problem by performing the surface measurements when the cantilever is vibrating in higher eigenmodes. In this paper we demonstrate the application of active piezoresistive cantilevers operating in this mode. The active piezoresistive cantilever comprises a piezoresistive deflection sensor, a deflection actuator and a nanotip. It is a complete micro-electro-mechanical system, ensuring the highest reliability of cantilever vibration control and detection. Higher eigenmode operations are usually difficult to implement as they usually result in lower deflection and lower sensitivity of the probe vibration deflection. Here we present an experimental modification of the structure of an active piezoresistive cantilever using focused ion beam machining that mitigates both weaknesses. This has enabled the cantilever to scan the surface at a scanning rate of 10 lines s−1 with a maximum speed of 500 μm s−1 and a data acquisition rate of 10 kS s−1, when the probe is vibrating at 380 kHz in the second eigenmode. We also describe a traceable calibration routine (based on analysis of the response of the piezoresistive detector, the output of the HeNe interferometer and precise control of the deflection actuator), together with the cantilever modification process and the development of the measurement setup. We show measurement results of dedicated calibration samples and silicon carbide crystal lattice references.

Advancing language learning: The impact and challenges of Computer-Assisted Language Learning (CALL)

Abstract. Computer-Assisted Language Learning (CALL) represents a transformative approach in modern education, integrating technology to enhance language acquisition effectively. This comprehensive review examines the various dimensions of CALL, focusing on its deployment through interactive software, online courses, mobile applications, and the accompanying challenges. Quantitative analyses reveal significant improvements in learner engagement and cognitive load management due to multimedia and interactive content. Moreover, the adaptability of CALL to cater to individual learning needs through personalized and adaptive learning systems demonstrates a superior proficiency acquisition rate. Despite these advancements, CALL implementation faces substantial barriers including technological limitations, the need for extensive teacher training, and concerns regarding data privacy and security. This article assesses the statistical impact of these elements on language learning outcomes and suggests strategies for overcoming the associated challenges. Through mixed-methods research and longitudinal studies, the effectiveness of CALL platforms is substantiated, highlighting their pivotal role in reshaping language education across diverse demographic and geographic spectrums.

Enhancing Clinical History Taking Through the Implementation of a Streamlined Electronic Questionnaire System at a Pediatric Headache Clinic: Development and Evaluation Study.

Accurate history taking is essential for diagnosis, treatment, and patient care, yet miscommunications and time constraints often lead to incomplete information. Consequently, there has been a pressing need to establish a system whereby the questionnaire is duly completed before the medical appointment, entered into the electronic health record (EHR), and stored in a structured format within a database. This study aimed to develop and evaluate a streamlined electronic questionnaire system, BEST-Survey (Bundang Hospital Electronic System for Total Care-Survey), integrated with the EHR, to enhance history taking and data management for patients with pediatric headaches. An electronic questionnaire system was developed at Seoul National University Bundang Hospital, allowing patients to complete previsit questionnaires on a tablet PC. The information is automatically integrated into the EHR and stored in a structured database for further analysis. A retrospective analysis compared clinical information acquired from patients aged <18 years visiting the pediatric neurology outpatient clinic for headaches, before and after implementing the BEST-Survey system. The study included 365 patients before and 452 patients after system implementation. Answer rates and positive rates of key headache characteristics were compared between the 2 groups to evaluate the system's clinical utility. Implementation of the BEST-Survey system significantly increased the mean data acquisition rate from 54.6% to 99.3% (P<.001). Essential clinical features such as onset, location, duration, severity, nature, and frequency were obtained in over 98.7% (>446/452) of patients after implementation, compared to from 53.7% (196/365) to 85.2% (311/365) before. The electronic system facilitated comprehensive data collection, enabling detailed analysis of headache characteristics in the patient population. Most patients (280/452, 61.9%) reported headache onset less than 1 year prior, with the temporal region being the most common pain location (261/703, 37.1%). Over half (232/452, 51.3%) experienced headaches lasting less than 2 hours, with nausea and vomiting as the most commonly associated symptoms (231/1036, 22.3%). The BEST-Survey system markedly improved the completeness and accuracy of essential history items for patients with pediatric headaches. The system also streamlined data extraction and analysis for clinical and research purposes. While the electronic questionnaire cannot replace physician-led history taking, it serves as a valuable adjunctive tool to enhance patient care.

Persistent threat avoidance following negative reinforcement is not associated with elevated state anxiety.

Obsessive-Compulsive Disorder (OCD) is a debilitating illness consisting of obsessions and compulsions. OCD severity and treatment response are correlated with avoidant behaviors thought be performed to alleviate obsession-related anxiety. However, little is known about either the role of avoidance in the development of OCD or the interplay between anxiety states and avoidance behaviors. We have developed an instrumental negative reinforcement (i.e. active avoidance) paradigm in which mice must lever-press to avoid upcoming foot shocks. We show that mice (both sexes) can learn this task with high acquisition rates (75%) and that this behavior is largely stable when introducing uncertainty and modifying task structure. Furthermore, mice continue to perform avoidance responses on trials where lever pressing is not reinforced and increase response rates as they are maintained on this paradigm. With this paradigm, we did not find a relationship between negative reinforcement history and anxiety-related behaviors in well-established anxiety assays. Finally, we performed exploratory analyses to identify candidate regions involved in well-trained negative reinforcement using expression of the immediate early gene c-Fos. We detected correlated c-Fos expression in 1) cortico-striatal regions which regulate active avoidance in other paradigms and 2) amygdala circuits known to regulate conditioned defensive behaviors.Significance Statement Studies in patients with OCD suggest that compulsions are performed to avoid perceived threats and modulate anxiety tied to obsessions and/or compulsions. The negative reinforcement of avoidance and alleviated anxiety could therefore be a key driver of compulsive behaviors. However, there are still outstanding questions concerning the relationship between these two behaviors and the neural circuits involved in mediating negative reinforcement. We have developed an operant negative reinforcement paradigm in mice with discrete avoid and escape behaviors that can be learned without prior reward training with high throughput (75% acquisition) with responding that persists during nonreinforced trials. However, no differences were observed between negative reinforcement vs. unshocked and inescapably shocked controls, suggesting that continued negative reinforcement did not impact anxiety.

Modular shadowgraph imaging for zooplankton ecological studies in diverse field and mesocosm settings

AbstractVarious iterations of shadowgraph imaging have been used to quantify zooplankton in situ with high spatial resolution. Because these systems can image relatively large volumes of water, they are especially useful for resolving less common meso‐ or macrozooplankton taxa (&lt; 50 ind. m−3), such as larval fishes and gelatinous animals. However, larger volume imagers are typically integrated with heavy towed vehicles and deployed from research vessels, which introduces high costs and limits sampling approaches. Here we demonstrate that versatile configurations of shadowgraph imaging, including modular benchtop, handheld, and towed, compact vehicle systems (along with customizable software), allow for tailoring sampling to a variety of marine and freshwater settings (including mesocosms). These systems encompass a suite of possible architectures, designed for adapting the imaging depth of field, acquisition rates, sensor configuration, and deployment method to fit a wide range of sampling protocols, with high vertical resolution (~ 5 cm) and adequate taxonomic capabilities for &gt; 0.5 mm organisms. The benchtop system facilitates an interactive approach to observe and quantify zooplankton behaviors and optical properties. Video footage from the benchtop system generates thousands of regions of interest min−1 for target organisms with variable orientations and swimming postures. When used in conjunction with in situ imaging, the benchtop system can build large machine learning training libraries targeted toward rare or morphologically diverse zooplankton, which often includes the larval stages of economically valuable taxa. These modular hardware and software components increase affordability and versatility while broadening the scope of scientific questions addressed by plankton imaging systems.

Frequency-domain instrument with custom ASIC for dual-slope near-infrared spectroscopy.

Real-time and non-invasive measurements of tissue concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) are invaluable for research and clinical use. Frequency-domain near-infrared spectroscopy (FD-NIRS) enables non-invasive measurement of these chromophore concentrations in human tissue. We present a small form factor, dual-wavelength, miniaturized FD-NIRS instrument for absolute optical measurements, built around a custom application-specific integrated circuit and a dual-slope/self-calibrating (DS/SC) probe. The modulation frequency is 55MHz, and the heterodyning technique was used for intensity and phase readout, with an acquisition rate of 0.7Hz. The instrument consists of a 14 × 17cm2 printed circuit board (PCB), a Raspberry Pi 4, an STM32G491 microcontroller, and the DS/SC probe. The DS/SC approach enables this instrument to be selective to deeper tissue and conduct absolute measurements without calibration. The instrument was initially validated using a tissue-mimicking solid phantom, and upon confirming its suitability for in vivo, a vascular occlusion experiment on a human subject was conducted. For the phantom experiments, an average of 0.08° phase noise and 0.10% standard deviation over the mean for the intensities was measured at a source-detector distance of 35mm. The absorption and reduced scattering coefficients had average precisions (variation of measurement over time) of 0.5% and 0.9%, respectively, on a window of ten frames. Results from the in vivo experiment yielded the expected increase in HbO2 and HbR concentration for all measurement types tested, namely SC, DS intensity, and DS phase.

Investigating the Limits of Familiarity-Based Navigation.

Insect-inspired navigation strategies have the potential to unlock robotic navigation in power-constrained scenarios, as they can function effectively with limited computational resources. One such strategy, familiarity-based navigation, has successfully navigated a robot along routes of up to 60 m using a single-layer neural network trained with an Infomax learning rule. Given the small size of the network that effectively encodes the route, here we investigate the limits of this method, challenging it to navigate longer routes, investigating the relationship between performance, view acquisition rate and dimension, network size, and robustness to noise. Our goal is both to determine the parameters at which this method operates effectively and to explore the profile with which it fails, both to inform theories of insect navigation and to improve robotic deployments. We show that effective memorization of familiar views is possible for longer routes than previously attempted, but that this length decreases for reduced input view dimensions. We also show that the ideal view acquisition rate must be increased with route length for consistent performance. We further demonstrate that computational and memory savings may be made with equivalent performance by reducing the network size-an important consideration for applicability to small, lower-power robots-and investigate the profile of memory failure, demonstrating increased confusion across the route as it extends in length. In this extension to previous work, we also investigate the form taken by the network weights as training extends and the areas of the image on which visual familiarity-based navigation most relies. Additionally, we investigate the robustness of familiarity-based navigation to view variation caused by noise.