Cortical Habituation of Acoustic Startle Reflex

The study of acoustic startle reflexes (ASR) has recently shown promising potential in augmenting the recovery of voluntary movement in patients who undergo neuro-rehabilitation. However, these ASRs have been associated with the decrease or inhibition of startle responses over successive stimulation, known as habituation. This study hypothesizes an acoustic startle pathway that involves the dorsolateral prefrontal cortex is inhibiting the ASR. To do this investigation, three paradigms have been developed in conjunction with EEG recordings. Independent component analysis has been implemented to minimize the intrinsic motion artifacts in the acquired data. The results show possible anti-correlation between the EMG startle signal and the activity located along the frontal midline suggesting possible habituation. However, no solid conclusion can be made whether the dorsolateral prefrontal cortex is part of the habituation process in the acoustic startle pathway.Biomedical Engineering, Department o

On-Channel Linear Phase FIR Filter Banks and Application in Image Compression

Abstract—This paper investigates the theory and structure of a large subclass of w-channel linear-phase perfect-reconstruction FIR filter banks—systems with analysis and synthesis filters of length v � a u�w C, where is an arbitrary interger, H ` w, and u � is any positive interger. For this subclass of systems, we first investigate the necessary conditions for the existence of linear-phase perfect-reconstruction filter banks (LPPRFB’s). Next, we develop a complete and minimal factorization for all even-channel linear-phase paraunitary systems (the most general lapped orthogonal transforms to date). Finally, several design examples as well as comparisons with previous generalized lapped orthogonal transforms (GenLOT’s) in image compression are presented to confirm the validity of the theory. I

CHẾ TẠO HỆ GỐM KHÔNG CHÌ ĐỊNH HƯỚNG 0,8Bi0,5Na0,5TiO3 – 0,2Bi0,5K0,5TiO3

In this study, Bi4Ti3O12 templates were synthesized using the molten salt method in Na2CO3 and K2CO3 fluxes. The as-prepared Bi4Ti3O12 templates are composed of plate-like morphologies of lengths 5–20 μm and widths 0.5–1 μm at the heating temperature of 1050 °C. From these Bi4Ti3O12 templates, we studied the synthesis of textured 0.8Bi0.5Na0.5TiO3 – 0.2Bi0.5K0.5TiO3 lead-free ceramics by employing the template grain growth method. The effect of sintering temperature on the structure, microstructure, and degree of orientation of the ceramic materials was investigated. The results show that all the ceramic samples have a pure perovskite phase with a rhombic phase structure in the sintering temperature range from 950 to 1050 °C. At the optimum temperature of 1050 °C, the ceramics exhibit the best physical properties such as density (5.94 g/cm3) (the relative density is 98.84% of the theoretical value). The degree of orientation of the synthesized ceramics has the highest values of 65%.Trong nghiên cứu này, các khuôn Bi4Ti3O12 (BiT) được tổng hợp bằng phương pháp muối nóng chảy trong hỗn hợp Na2CO3 – K2CO3. Các khuôn BiT hình thành và phát triển tốt tại nhiệt độ nung 1050 °C với hình dạng tấm rõ ràng với kính thước trung bình khoảng 5–20 μm và độ dày khoảng 0,5–1 μm. Từ các khuôn BiT trên, chúng tôi đã nghiên cứu chế tạo gốm không chì 0,8Bi0,5Na0,5TiO3 – 0,2Bi0,5K0,5TiO3 sử dụng kỹ thuật định hướng. Ảnh hưởng của nhiệt độ thiêu kết đến cấu trúc và độ định hướng của hệ gốm đã được khảo sát. Tất cả các mẫu gốm đều có pha perovskite tinh khiết với cấu trúc pha mặt thoi trong vùng nhiệt độ thiêu kết từ 950 đến 1050 °C. Tại 1050 °C, hệ gốm có tính chất vật lý tốt nhất: khối lượng riêng của gốm là 5,94 g/cm3 (đạt 98,84% giá trị lý thuyết) và độ định hướng đạt giá trị cao nhất là 65%

A New Imaging Platform for Visualizing Biological Effects of Non-Invasive Radiofrequency Electric-Field Cancer Hyperthermia

Herein, we present a novel imaging platform to study the biological effects of non-invasive radiofrequency (RF) electric field cancer hyperthermia. This system allows for real-time in vivointravital microscopy (IVM) imaging of radiofrequency-induced biological alterations such as changes in vessel structure and drug perfusion. Our results indicate that the IVM system is able to handle exposure to high-power electric-fields without inducing significant hardware damage or imaging artifacts. Furthermore, short durations of low-power (< 200 W) radiofrequency exposure increased transport and perfusion of fluorescent tracers into the tumors at temperatures below 41°C. Vessel deformations and blood coagulation were seen for tumor temperatures around 44°C. These results highlight the use of our integrated IVM-RF imaging platform as a powerful new tool to visualize the dynamics and interplay between radiofrequency energy and biological tissues, organs, and tumors

Portable RF system retrofitted to the IVM.

<p>(A) The RF system integrated into the intravital microscope (IVM) for real-time imaging under RF exposure. (B) Mouse manipulation for imaging–an incision is made to expose and gently manipulate the 4T1 tumor for IVM imaging. (C) 4T1 tumor under IVM illumination with a x4 objective lens.</p

High-temperature vessel degradation.

<p>(A)–(D) Impact of RF exposure on vessel architecture at four different time-points: 0:22, 6:53, 16:18, and 20:31 minutes, respectively. The tumor temperatures and RF power at those time points are shown in the upper-middle and upper-right hand side sections, respectively. Figure (E) illustrates the change in temperature and power with respect to time. Vessel degradation can be seen for temperatures > 41°C. A complete breakdown of the vessel architecture can be seen for temperatures > 47°C.</p

Modulation of tumor temperature using RF exposure.

<p>(A) Thermal fiber optic probe placement. Probes #1–3 are positioned (i) under the skin but above the tumor; (ii) under the skin in between the tumor and the main body; and (iii) under the skin next to the intraperitoneal cavity. (B) Extracted thermal probe data. The recorded temperature of the probes was modulated by turning on and off the RF system (+RF and–RF). The system was turned off once the tumor temperature (probe #1) reached 45°C, 43°C, and 41°C, respectively, and was turned on when all probes had values in the range ~29–31°C. (C) The IR camera simultaneously measured the surface temperature of the points where the thermal probes were located.</p

Portable RF system setup and generated electric field.

<p>(A) Portable RF system consists of the transmitting unit (TX) and receiving head (RX) that generates a high-power electric field across the specimen (e.g. mouse). The system is driven by a variable power fixed RF amplifier (0–200 W, 13.56 MHz) that is cooled during operation by a water chiller. Heat production is monitored using an infrared (IR) camera or direct insertion of fiber optical probes. (B) Circuit representation of the portable RF system. (C) Setup for extracting electric-field intensities. An electric-field probe (EFP) is placed at specific points along the x- and z-axis in between the TX and RX heads and measures the voltage at each point for 20 W RF-power. (D) The electric field is derived from the voltage data and is plotted as an intensity contour plot.</p

Real-time RF-IVM imaging and post capture analysis.

<p>RF exposure shows transport of fluorescently bound albumin across the perfusion barrier into tumor region. Figure (A) and (B) depict the blue image channel (albumin) before and after (4.5 min) RF exposure. This data is shown superimposed with the tumor (red) channel in Figure (C) and (D). Figure (E) Control mouse (no RF) was imaged for 30 minutes on both channels. There is no transport of albumin into the tumor across the perfusion barrier. (F) Time lapsed images of the data shown in Figure (A) and (B). Figure (G) 4T1 tumor slices immunohistologically stained to the antibodies CD31 (green, vasculature endothelial cells), and albumin (red) for both RF (left image) and non-RF (right image) groups. Figure (H) depicts positive area fraction (PAF) of albumin accumulation in tumor slices. Finally, (I) is a quantitative video analysis of relative increase in albumin fluorescence (RAIF) in multiple 4T1 tumor surfaces exposed to RF under IVM (n = 4).</p