Securing Pathways with Orthogonal Robots

The protection of pathways holds immense significance across various domains, including urban planning, transportation, surveillance, and security. This article introduces a groundbreaking approach to safeguarding pathways by employing orthogonal robots. The study specifically addresses the challenge of efficiently guarding orthogonal areas with the minimum number of orthogonal robots. The primary focus is on orthogonal pathways, characterized by a path-like dual graph of vertical decomposition. It is demonstrated that determining the minimum number of orthogonal robots for pathways can be achieved in linear time. However, it is essential to note that the general problem of finding the minimum number of robots for simple polygons with general visibility, even in the orthogonal case, is known to be NP-hard. Emphasis is placed on the flexibility of placing robots anywhere within the polygon, whether on the boundary or in the interior.Comment: 8 pages, 5 figure

Real-Time Optical Monitoring of Endotracheal Tube Displacement

Proper ventilation of a patient with an endotracheal tube (ETT) requires proper placement of the ETT. We present a sensitive, noninvasive, operator-free, and cost-effective optical sensor, called Opt-ETT, for the real-time assessment of ETT placement and alerting of the clinical care team should the ETT become displaced. The Opt-ETT uses a side-firing optical fiber, a near-infrared light-emitting diode, two photodetectors with an integrated amplifier, an Arduino board, and a computer loaded with a custom LabVIEW program to monitor the position of the endotracheal tube inside the windpipe. The Opt-ETT generates a visual and audible warning if the tube moves over a distance set by the operator. Displacement prediction is made using a second-order polynomial fit to the voltages measured from each detector. The system is tested on ex vivo porcine tissues, and the accuracy is determined to be better than 1.0 mm. In vivo experiments with a pig are conducted to test the performance and usability of the system

Evaluation of Visible Diffuse Reflectance Spectroscopy in Liver Tissue: Validation of Tissue Saturations Using Extracorporeal Circulation

Significance: Real-time information about oxygen delivery to the hepatic graft is important to direct care and diagnose vascular compromise in the immediate post-transplant period. Aim: The current study was designed to determine the utility of visible diffuse reflectance spectroscopy (vis-DRS) for measuring liver tissue saturation in vivo. Approach: A custom-built vis-DRS probe was calibrated using phantoms with hemoglobin (Hb) and polystyrene microspheres. Ex vivo (extracorporeal circulation) and in vivo protocols were used in a swine model (n=15) with validation via blood gas analysis. Results: In vivo absorption and scattering measured by vis-DRS with and without biliverdin correction correlated closely between analyses. Lin’s concordance correlation coefficients are 0.991 for μa and 0.959 for μs\u27. Hb measured by blood test and vis-DRS with (R2=0.81) and without (R2=0.85) biliverdin correction were compared. Vis-DRS data obtained from the ex vivo protocol plotted against the PO2 derived from blood gas analysis showed a good fit for a Hill coefficient of 1.67 and P50=34  mmHg (R2=0.81). A conversion formula was developed to account for the systematic deviation, which resulted in a goodness-of-fit (R2=0.76) with the expected oxygen dissociation curve. Conclusions: We show that vis-DRS allows for real-time measurement of liver tissue saturation, an indicator for liver perfusion and oxygen delivery

Time-resolved laser speckle contrast imaging (TR-LSCI) of cerebral blood flow

To address many of the deficiencies in optical neuroimaging technologies such as poor spatial resolution, time-consuming reconstruction, low penetration depth, and contact-based measurement, a novel, noncontact, time-resolved laser speckle contrast imaging (TR-LSCI) technique has been developed for continuous, fast, and high-resolution 2D mapping of cerebral blood flow (CBF) at different depths of the head. TR-LSCI illuminates the head with picosecond-pulsed, coherent, widefield near-infrared light and synchronizes a newly developed, high-resolution, gated single-photon avalanche diode camera (SwissSPAD2) to capture CBF maps at different depths. By selectively collecting diffuse photons with longer pathlengths through the head, TR-LSCI reduces partial volume artifacts from the overlying tissues, thus improving the accuracy of CBF measurement in the deep brain. CBF map reconstruction was dramatically expedited by incorporating highly parallelized computation. The performance of TR-LSCI was evaluated using head-simulating phantoms with known properties and in-vivo rodents with varied hemodynamic challenges to the brain. Results from these pilot studies demonstrated that TR-LSCI enabled mapping CBF variations at different depths with a sampling rate of up to 1 Hz and spatial resolutions ranging from tens of micrometers on the head surface to 1-2 millimeters in the deep brain. With additional improvements and validation in larger populations against established methods, we anticipate offering a noncontact, fast, high-resolution, portable, and affordable brain imager for fundamental neuroscience research in animals and for translational studies in humans.Comment: 22 pages, 7 figures, 4 table

Real-Time Assessment of Liver Optical Properties in In-Vivo Animal Models Using Visible Diffuse Reflectance Spectroscopy (VIS-DRS)

Liver diseases are a significant cause of global health burden accounting for roughly 2 million deaths annually, among which half are caused by liver cirrhosis and the remaining half is due to hepatitis and hepatocellular carcinoma (HCC). These numbers suggest that both chronic and acute liver diseases contribute considerably to morbidity and mortality at the global level, and these numbers are expected to increase. These formidable numbers call for public health improvement. Liver needs maintenance of enough oxygen supply in order to function properly. As a result, it is pivotal to monitor the oxygen saturation of the liver in patients, especially during and after liver transplantation. Hypoxia or insufficient oxygen supply can lead to organ dysfunction and loss. Thus, there is a limited time to make interventions and restore oxygen supply back to normal. Diffuse reflectance spectroscopy (DRS) techniques have been used for different applications, including cancer research in liver, cervix, kidney and colon, oxygen saturation monitoring, and tissue damage assessment. Studies using DRS have shown promising results in determining morphological and physiological tissue information by extracting tissue optical properties, such as scattering coefficient and absorption coefficient, to quantify hemoglobin concentration and tissue oxygen saturation. In Aim 1 of the current study, we use a home-made fiber optic probe based visible DRS (vis-DRS) to investigate the effects of hemodilution(anemia) and the fraction of inspired oxygen (FiO2) changes on liver tissue oxygenation and oxygen-hemoglobin dissociation curve. We hypothesize that vis-DRS can produce accurate and reproducible measurement of Hb and tissue oxygenation in highly pigmented liver tissue in vivo. In Aim 2, we study the use of vis-DRS for real-time monitoring of laser ablation of liver tumors in rats. The utilization of thermal ablative techniques, including laser ablation, is currently on the rise since, in 80% to 95% of patients, surgery and resection are not a viable solution. In this study, 808 nm laser at different power settings (1, 1.5, and 2 watts) has been utilized to treat liver tumors in rats, and tumor optical properties have been continuously recorded during ablation. The correlation between different laser powers and changes in liver optical properties has been investigated

Real-Time Assessment of Liver Optical Properties in In-Vivo Animal Models Using Visible Diffuse Reflectance Spectroscopy

Liver diseases are a significant cause of global health burden accounting for roughly 2 million deaths annually, among which half are caused by liver cirrhosis and the remaining half is due to hepatitis and hepatocellular carcinoma (HCC). These numbers suggest that both chronic and acute liver diseases contribute considerably to morbidity and mortality at the global level, and these numbers are expected to increase. These formidable numbers call for public health improvement. Liver needs maintenance of enough oxygen supply in order to function properly. As a result, it is pivotal to monitor the oxygen saturation of the liver in patients, especially during and after liver transplantation. Hypoxia or insufficient oxygen supply can lead to organ dysfunction and loss. Thus, there is a limited time to make interventions and restore oxygen supply back to normal. Diffuse reflectance spectroscopy (DRS) techniques have been used for different applications, including cancer research in liver, cervix, kidney and colon, oxygen saturation monitoring, and tissue damage assessment. Studies using DRS have shown promising results in determining morphological and physiological tissue information by extracting tissue optical properties, such as scattering coefficient and absorption coefficient, to quantify hemoglobin concentration and tissue oxygen saturation. In Aim 1 of the current study, we use a home-made fiber optic probe based visible DRS (vis-DRS) to investigate the effects of hemodilution(anemia) and the fraction of inspired oxygen (FiO2) changes on liver tissue oxygenation and oxygen-hemoglobin dissociation curve. We hypothesize that vis-DRS can produce accurate and reproducible measurement of Hb and tissue oxygenation in highly pigmented liver tissue in vivo. In Aim 2, we study the use of vis-DRS for real-time monitoring of laser ablation of liver tumors in rats. The utilization of thermal ablative techniques, including laser ablation, is currently on the rise since, in 80% to 95% of patients, surgery and resection are not a viable solution. In this study, 808 nm laser at different power settings (1, 1.5, and 2 watts) has been utilized to treat liver tumors in rats, and tumor optical properties have been continuously recorded during ablation. The correlation between different laser powers and changes in liver optical properties has been investigated

Hepatic artery Flow, Inspired Oxygen, and Hemoglobin Determine Liver Tissue Saturation Measured with Visible Diffuse Reflectance Spectroscopy (vis-DRS) in an in Vivo Swine Model

Background Prompt diagnosis of vascular compromise following pediatric liver transplantation and restoration of oxygen delivery to the liver improves organ survival. vis-DRS allows for real-time measurement of liver tissue saturation. Methods The current study used vis-DRS to determine changes in liver saturation during clinically relevant conditions of reduced oxygen delivery. In an in vivo swine model (n = 15), we determined liver tissue saturation (StO2) during stepwise reduction in hepatic artery flow, different inspiratory oxygen fraction (FiO2), and increasing hemodilution. A custom vis-DRS probe was placed directly on the organ. Results Liver tissue saturation decreased significantly with a decrease in hepatic artery flow. A reduction in hepatic artery flow to 25% of baseline reduced the StO2 by 15.3 ± 1.4% at FiO2 0.3 (mean ± SE, p \u3c .0013), and by 8.3 ± 1.9% at FiO2 1.0 (p = .0013). After hemodilution to 7–8 g/dl, StO2 was reduced by 31.8% ± 2.7%, p \u3c .001 (FiO2 0.3) and 26.6 ± 2.7%, p \u3c .001 (FiO2: 1.0) respectively. Portal venous saturation during low hepatic artery flow was consistently higher at FiO2 1.0. The gradient between portal venous saturation and liver tissue saturation was consistently greater at lower hemoglobin levels (7.0 ± 1.6% per g/dl hemoglobin, p \u3c .001). Conclusions Vis-DRS showed prompt changes in liver tissue saturation with decreases in hepatic artery blood flow. At hepatic artery flows below 50% of baseline, liver saturation depended on FiO2 and hemoglobin concentration suggesting that during hepatic artery occlusion, packed red blood cell transfusion and increased FiO2 may be useful measures to reduce hypoxic damage until surgical revascularization

Real-Time Optical Monitoring of Endotracheal Tube Displacement

Proper ventilation of a patient with an endotracheal tube (ETT) requires proper placement of the ETT. We present a sensitive, noninvasive, operator-free, and cost-effective optical sensor, called Opt-ETT, for the real-time assessment of ETT placement and alerting of the clinical care team should the ETT become displaced. The Opt-ETT uses a side-firing optical fiber, a near-infrared light-emitting diode, two photodetectors with an integrated amplifier, an Arduino board, and a computer loaded with a custom LabVIEW program to monitor the position of the endotracheal tube inside the windpipe. The Opt-ETT generates a visual and audible warning if the tube moves over a distance set by the operator. Displacement prediction is made using a second-order polynomial fit to the voltages measured from each detector. The system is tested on ex vivo porcine tissues, and the accuracy is determined to be better than 1.0 mm. In vivo experiments with a pig are conducted to test the performance and usability of the system