Fabio Kurt Schneider

Using dynamic pupillometry as a simple screening tool to detect autonomic neuropathy in patients with diabetes: a pilot study

BackgroundAutonomic neuropathy is a common and serious complication of diabetes. Early detection is essential to enable appropriate interventional therapy and management. Dynamic pupillometry has been proposed as a simpler and more sensitive tool to detect subclinical autonomic dysfunction. The aim of this study was to investigate pupil responsiveness in diabetic subjects with and without cardiovascular autonomic neuropathy (CAN) using dynamic pupillometry in two sets of experiments.MethodsDuring the first experiment, one flash was administered and the pupil response was recorded for 3 s. In the second experiment, 25 flashes at 1-s interval were administered and the pupil response was recorded for 30 s. Several time and pupil-iris radius-related parameters were computed from the acquired data. A total of 24 diabetic subjects (16 without and 8 with CAN) and 16 healthy volunteers took part in the study.ResultsOur results show that diabetic subjects with and without CAN have sympathetic and parasympathetic dysfunction, evidenced by diminished amplitude reflexes and significant smaller pupil radius. It suggests that pupillary autonomic dysfunction occurs before a more generalized involvement of the autonomic nervous system, and this could be used to detect early autonomic dysfunction.ConclusionsDynamic pupillometry provides a simple, inexpensive, and noninvasive tool to screen high-risk diabetic patients for diabetic autonomic neuropathy.

Au-doped single layer graphene nanoribbons for a record-high efficiency ITO-free tandem polymer solar cell

Polymer solar cells (PSCs) are apparently becoming one of the leading technologies to reduce our dependency on traditional power sources. However, the frequent use of a transparent conductive electrode, indium-tin-oxide (ITO), in the present PSC technologies has increased the overall expenses. In addition, its brittleness in nature could limit the future development of PSCs, particularly in a flexible format. Here, we report on the development of Au-doped single layer graphene nanoribbons (Au-doped SLGNRs) as an option to the transparent conducting electrode (indium tin oxide, ITO) that could yield a single-layer PSC with power conversion and external quantum efficiencies comparable to commonly used transparent electrodes. When the Au-doped SLGNRs are implemented in tandem architecture, a power conversion efficiency (PCE) of 8.48% is achieved. This is the highest efficiency for ITO-free tandem PSCs to date. The improved performance of the Au-doped SLGNR anode is characterized to the structure of the device that enables a hole transport from the active layer into the Au-doped SLGNR anode.

A Fully Programmable Computing Architecture for Medical Ultrasound Machines

Application-specific ICs have been traditionally used to support the high computational and data rate requirements in medical ultrasound systems, particularly in receive beamforming. Utilizing the previously developed efficient front-end algorithms, in this paper, we present a simple programmable computing architecture, consisting of a field-programmable gate array (FPGA) and a digital signal processor (DSP), to support core ultrasound signal processing. It was found that 97.3% and 51.8% of the FPGA and DSP resources are, respectively, needed to support all the front-end and back-end processing for B-mode imaging with 64 channels and 120 scanlines per frame at 30 frames/s. These results indicate that this programmable architecture can meet the requirements of low- and medium-level ultrasound machines while providing a flexible platform for supporting the development and deployment of new algorithms and emerging clinical applications.

Wireless Medical Sensor Networks: Design Requirements and Enabling Technologies

This article analyzes wireless communication protocols that could be used in healthcare environments (e.g., hospitals and small clinics) to transfer real-time medical information obtained from noninvasive sensors. For this purpose the features of the three currently most widely used protocols-namely, Bluetooth(®) (IEEE 802.15.1), ZigBee (IEEE 802.15.4), and Wi-Fi (IEEE 802.11)-are evaluated and compared. The important features under consideration include data bandwidth, frequency band, maximum transmission distance, encryption and authentication methods, power consumption, and current applications. In addition, an overview of network requirements with respect to medical sensor features, patient safety and patient data privacy, quality of service, and interoperability between other sensors is briefly presented. Sensor power consumption is also discussed because it is considered one of the main obstacles for wider adoption of wireless networks in medical applications. The outcome of this assessment will be a useful tool in the hands of biomedical engineering researchers. It will provide parameters to select the most effective combination of protocols to implement a specific wireless network of noninvasive medical sensors to monitor patients remotely in the hospital or at home.

An Approach to the Assessment of Diabetic Neuropathy Based on Dynamic Pupillometry

Autonomic neuropathy (AN) is a common and serious complication of diabetes. Early detection is essential to enable appropriate interventional therapy. It has long been recognized that subjects with diabetic peripheral neuropathy (DPN) are at much greater risk of developing AN, but there is currently no simple screening tool to assess them. The aim of this study was to investigate pupil responsiveness in diabetic subjects with and without DPN using dynamic pupillometry. During the first test, one flash was administered and the pupil response recorded for 3 seconds. In the second test, twenty-five flashes at one-second intervals were administered and the pupil response recorded for 30 seconds. Several time related parameters were computed from the results. A total of 29 diabetic subjects (17 no DPN, 12 DPN) and 25 healthy volunteers took part in the study. In the first test, pupil-iris ratios in darkness, large deviation and plateau were significantly different between groups. Latency time from flash exposure to the start of constriction was significantly longer in diabetic subjects with DPN compared to healthy volunteers. There was no difference in latency times of largest deviation, plateau or duration of constriction between groups. In the second test, the pupil-iris ratios evaluated in the frame preceding the tenth and the twenty-fifth light flash were significantly greater in healthy volunteers than diabetic subjects with DPN. Latency time from the tenth and twenty-fifth flash exposure to the start of constriction was significantly shorter in healthy volunteers than in diabetic subjects with DPN. Our results show that diabetic subjects with DPN have sympathetic and parasympathetic dysfunction evidenced by diminished amplitude reflexes and significant smaller pupil diameter. Dynamic pupillometry may provide a simple, inexpensive and non-invasive tool to screen high-risk diabetic patients for diabetic autonomic neuropathy.

New Demodulation Method for Efficient Phase-Rotation-Based Beamforming

In this paper, we present a new demodulation method to reduce hardware complexity in phase-rotation- based beamforming. Due to its low sensitivity to phase delay errors, quadrature demodulation, which consists of mixing and lowpass filtering, is commonly used in ultrasound machines. However, because it requires two lowpass filters for each channel to remove harmonics after mixing, the direct use of quadrature demodulation is computationally expensive. To alleviate the high computational requirement in quadrature demodulation, we have developed a two-stage demodulation technique in which dynamic receive focusing is performed on the mixed signal instead of the complex baseband signal. Harmonics then are suppressed by using only two lowpass filters. When the number of channels is 32, the proposed two-stage demodulation reduces the necessary number of multiplications and additions for phase-rotation beamforming by 82.7% and 88.2%, respectively, compared to using quadrature demodulation. We have found from simulation and phantom studies that the proposed method does not incur any significant degradation in image quality in terms of axial and lateral resolution. These preliminary results indicate that the proposed two-stage demodulation method could contribute to significantly reducing the hardware complexity in phase-rotation-based beamforming while providing comparable image quality.

P2D-6 Ultrasound Color Doppler Imaging on a Fully Programmable Architecture

Ultrasound color Doppler imaging is widely used for real-time evaluation of blood flow in a user-specified region of interest. However, it is computationally expensive and burdensome for low-end ultrasound machines. In this paper, we have investigated the feasibility of performing color Doppler processing on a low-cost programmable architecture consisting of a field programmable gate array (FPGA) (e.g., Cyclone II, Altera, San Jose, CA) and a digital signal processor (DSP) (e.g., TMS320C64x, Texas Instruments, Dallas, TX). From the feasibility study, we have found that only 63.8% and 49.2% of the resources in the FPGA and DSP, respectively, are utilized to support all the digital processing (i.e., front-end and back-end) for color Doppler imaging with a typical system configuration for portable ultrasound machines. These results indicate that a low-cost programmable architecture can meet the requirements of front-end and back-end processing in ultrasound color Doppler imaging

Biometric-oriented Iris Identification Based on Mathematical Morphology

A new method for biometric identification of human irises is proposed in this paper. The method is based on morphological image processing for the identification of unique skeletons of iris structures, which are then used for feature extraction. In this approach, local iris features are represented by the most stable nodes, branches and end-points extracted from the identified skeletons. Assessment of the proposed method was done using subsets of images from the University of Bath Iris Image Database (1000 images) and the CASIA Iris Image Database (500 images). Compelling experimental results demonstrate the viability of using the proposed morphological approach for iris recognition when compared to a state-of-the-art algorithm that uses a global feature extraction approach.

In Vivo Determination of the Frequency Response of the Tooth Root Canal Impedance versus Distance from the Apical Foramen

Working length (WL) determination is a key factor to the endodontic therapy or root canal treatment success. Almost all therapy procedures depend on this measure and the wrong WL determination may produce severe consequences, like post-therapeutic pain and the need of a new root canal treatment. Electronic foramen locators (EFL) have been replacing the traditional radiographic imaging as they are faster, easier to use and have a higher success rate when measuring WL. EFLs are based on the root canal impedance assessment between two electrodes: one fixed on the endodontic file that is inserted into the root canal, and the other positioned at oral mucosa membrane. There are only few reported studies that qualify or quantify the root canal impedance characteristics. The present work aims to determine the module of tooth root canal frequency response. The preliminary results show the frequency response module variation as a function of endodontic file position inside the root canal and reinforce the methods based on relative impedance over frequency analysis used in modern EFLs.

Image-based red cell counting for wild animals blood

An image-based red blood cell (RBC) automatic counting system is presented for wild animals blood analysis. Images with 2048×1536-pixel resolution acquired on an optical microscope using Neubauer chambers are used to evaluate RBC counting for three animal species (Leopardus pardalis, Cebus apella and Nasua nasua) and the error found using the proposed method is similar to that obtained for inter observer visual counting method, i.e., around 10%. Smaller errors (e.g., 3%) can be obtained in regions with less grid artifacts. These promising results allow the use of the proposed method either as a complete automatic counting tool in laboratories for wild animals blood analysis or as a first counting stage in a semi-automatic counting tool.