Assessing the Accuracy of a Point of Care Analyzer for Hyperlipidemia in Western Kenya

<p>The prevalence of hyperlipidemia, along with other non-communicable diseases, is on the rise in low- and middle-income countries. Given the resource-limited setting, a myriad of diagnostic challenges exist with traditional laboratory-based lipid tests, including mobility, timeliness, and laboratory infrastructure. Novel technology in the form of "point of care" devices seeks to overcome such barriers by providing immediate results without dependency on significant laboratory infrastructure. CardioChek PA (Polymer Technology Systems, Inc., Indianapolis, United States) is a point of care lipid measuring device and is readily available in Kenya. However, it has not been validated in this setting. In this study, I assess the accuracy of CardioChek PA with respect to standard laboratory-based testing, which is currently the gold standard. </p><p>In Webuye, Kenya, two blood samples were collected from 246 subjects to simultaneously measure the lipid levels via both CardioChek PA and the gold standard. All subjects were adults, and geographic stratified sampling methods were applied. Statistical analysis of the novel device's accuracy was based on percent bias, which is the standardized approach established by the National Cholesterol Education Program (NCEP) of the National Institute of Health (NIH). The NCEP suggests that percent bias be &#8804;±3% for low-density lipoprotein (LDL) cholesterol, &#8804;±5% for high-density lipoprotein (HDL) cholesterol, &#8804;±5% for total cholesterol (TC), and &#8804;±4% for triglycerides (TG). Misclassification rates and absolute percent bias were also analyzed.</p><p>This study found the CardioChek PA analyzer to be substantially inaccurate for LDL cholesterol (-25.9% bias), HDL cholesterol (-8.2% bias), and TC (-15.9% bias). For TG, the CardioChek PA performed well with a percent bias of 0.03%. However, the TG absolute percent bias (27.7%) and proportion of patients outside of the NCEP range (85%) reflected substantial inaccuracy of measurements. Moreover, those patients at higher risk of complications from hyperlipidemia were most likely to be misclassified into a lower risk category. Thus, we conclude that CardioChek PA is inaccurate and not suitable for our clinical setting. Furthermore, the findings highlight the need to validate new diagnostic tools in the appropriate setting prior to scale up regardless of its potential for novel utility.</p>Thesi

Initial Experience with Laparoendoscopic Single-Site Surgery by Use of a Homemade Transumbilical Port in Urology

Purpose: We present our initial experience with laparoendoscopic single-site surgery (LESS) by a single surgeon in the urologic field. Materials and Methods: From May 2009 to April 2010, 30 consecutive patients underwent LESS including seven cases of nephrectomy, five cases of nephroureterectomy with bladder cuff excision, four cases of ureterolithotomy, eight cases of marsupialization, and six cases of varicocelectomy. We performed a retrospective analysis of the medical records of the above patients. The single port was made with a surgical glove and an Alexis?? wound retractor (Applied Medical, Rancho Santa Margarita, CA, USA). The wound retractor was put into the peritoneal space through an umbilical incision, and a laparoscopic triangle was secured by crossing both instruments. All operations were performed by the transperitoneal approach. Results: Mean patient age was 54.8 years. Mean operative time was 171.2??109.1 minutes. Mean estimated blood loss was 265.0??395.5 ml. Mean incision length was 3.2??1.4 cm. Mean length of hospitalization was 5.2??2.9 days. There was one laparoscopic conversion and two open conversions. There were two cases of transient ileus that improved with conservative treatment. Mean visual analogue pain scales on the operative day and first postoperative day were 6.3/10 and 3.1/10, respectively. Conclusions: In our experience, LESS for urologic surgery is feasible, safe, and clinically applicable. We consider the homemade single-port device to be a relatively cost-effective and convenient device. If surgical instruments for LESS and appropriate ports specified for LESS are developed, LESS would be a surgical treatment technique that could be used as an alternative to the conventional types of laparoscopic surgery. ?? The Korean Urological Association, 2010

Metal/graphene sheets as p-type transparent conducting electrodes in GaN light emitting diodes

We demonstrate the use of graphene based transparent sheets as a p-type current spreading layer in GaN light emitting diodes (LEDs). Very thin Ni/Au was inserted between graphene and p-type GaN to reduce contact resistance, which reduced contact resistance from similar to 5.5 to similar to 0.6 Omega/ cm(2), with no critical optical loss. As a result, LEDs with metal-graphene provided current spreading and injection into the p-type GaN layer, enabling three times enhanced electroluminescent intensity compared with those with graphene alone. We confirmed very strong blue light emission in a large area of the metal-graphene layer by analyzing image brightness.open281

Calibration of a Stereo Radiation Detection Camera Using Planar Homography

This paper proposes a calibration technique of a stereo gamma detection camera. Calibration of the internal and external parameters of a stereo vision camera is a well-known research problem in the computer vision society. However, few or no stereo calibration has been investigated in the radiation measurement research. Since no visual information can be obtained from a stereo radiation camera, it is impossible to use a general stereo calibration algorithm directly. In this paper, we develop a hybrid-type stereo system which is equipped with both radiation and vision cameras. To calibrate the stereo radiation cameras, stereo images of a calibration pattern captured from the vision cameras are transformed in the view of the radiation cameras. The homography transformation is calibrated based on the geometric relationship between visual and radiation camera coordinates. The accuracy of the stereo parameters of the radiation camera is analyzed by distance measurements to both visual light and gamma sources. The experimental results show that the measurement error is about 3%

An Efficient Calibration Method for a Stereo Camera System with Heterogeneous Lenses Using an Embedded Checkerboard Pattern

We present two simple approaches to calibrate a stereo camera setup with heterogeneous lenses: a wide-angle fish-eye lens and a narrow-angle lens in left and right sides, respectively. Instead of using a conventional black-white checkerboard pattern, we design an embedded checkerboard pattern by combining two differently colored patterns. In both approaches, we split the captured stereo images into RGB channels and extract R and inverted G channels from left and right camera images, respectively. In our first approach, we consider the checkerboard pattern as the world coordinate system and calculate left and right transformation matrices corresponding to it. We use these two transformation matrices to estimate the relative pose of the right camera by multiplying the inversed left transformation with the right. In the second approach, we calculate a planar homography transformation to identify common object points in left-right image pairs and treat them with the well-known Zhangs camera calibration method. We analyze the robustness of these two approaches by comparing reprojection errors and image rectification results. Experimental results show that the second method is more accurate than the first one

Duplexer using microwave photonic band gap structure

We propose a frequency selective duplexer using microwave photonic band gap (PBG) structures. It uses two different PBGs to control the propagation of electromagnetic waves in the microwave region. In this structure, an additional narrow reflection band appears in the transmission spectrum when the PBG structure is not properly located relative to the T junction. By considering multiple reflections, it is proved that this additional reflection band in each PBG structure results from the interference between the input wave and the reflected wave from the other PBG structure. An effective way to prevent this interference effect is also discussed

Anderson transition of in-gap quasiparticles in a quasi-two-dimensional disordered superconductor

The Anderson transition of Bogoliubov-de Gennes (BdG) quasiparticles in superconducting state has been studied theoretically for last three decades. However, its experimental proof is lacking. In particular, the relationship of the superconducting order-parameter fluctuations and the Anderson transition of BdG quasiparticles have not been well understood. Our study, based on scanning tunneling microscopy measurements, investigates how BdG quasiparticles become Anderson-localized and delocalized as a function of energy and applied magnetic field in a quasi-two-dimensional Fe-based superconductor with sufficient zero-bias BdG quasiparticles. The anomalous multifractal spectra based on the spatial distributions of the pairing gaps and the coherent peak heights suggest that superconducting fluctuations play a key role in the delocalization of in-gap BdG quasiparticles. Our real-space Hartree-Fock-BCS-Anderson simulations and renormalization group analysis with pairing fluctuations support quasiparticle localization and suggest that enhanced pairing fluctuations lead to delocalization of BdG quasiparticles and "weak localization" of phase-fluctuating Cooper pairs in quasi-two-dimensional disordered superconductors. The present study proposes that the 10-fold way classification scheme has to be generalized to take order-parameter fluctuations in actual quantum matter. Also, it shed light on how ac energy loss due to quasiparticles at Fermi level can be controlled in a quasi-2d superconductor with sufficient pairing fluctuation