A Sinusoidal Current Driver With an Extended Frequency Range and Multifrequency Operation for Bioimpedance Applications

This paper describes an alternative sinusoidal current driver suitable for bioimpedance applications where high frequency operation is required. The circuit is based on a transconductor and provides current outputs with low phase error for frequencies around its pole frequency. This extends the upper frequency operational limit of the current driver. Multifrequency currents can be generated where each individual frequency is phase corrected. Analysis of the circuit is presented together with simulation and experimental results which demonstrate the proof of concept for both single and dual frequency current drivers. Measurements on a discrete test version of the circuit demonstrate a phase reduction from 25 ^{\circ} to 4 ^{\circ} at 3 MHz for 2 mAp-p output current. The output impedance of the current driver is essentially constant at about 1.1 M \Omega over a frequency range of 100 kHz to 5 MHz due to the introduction of the phase compensation. The compensation provides a bandwidth increase of a factor of about six for a residual phase delay of 4 ^{\circ

A DC Model for Organic Electrochemical Transistors and Analysis of Their Performance as Voltage Amplifiers

Organic electrochemical transistors (OECTs) have received significant attention especially in biomedical applications. Despite many efforts on modeling these transistors, simulating OECT-based circuits is still a challenge due to the absence of accurate mathematical models. In this paper a DC model for p-type depletion-mode OECTs is proposed that more closely mimics their characteristics compared to the Bernards-Malliaras (B-M) model. Although OECTs are mostly used as transconductance amplifiers, their use as voltage amplifiers is investigated here with measurements at various drain-source voltages. Compared to the B-M model, the proposed model has better matching up to 3.6% between simulations and measurements of the analyzed transistors

Delayed gastric emptying and reduced postprandial small bowel water content of equicaloric whole meal bread versus rice meals in healthy subjects: novel MRI insights

BACKGROUND/OBJECTIVES: Postprandial bloating is a common symptom in patients with functional gastrointestinal (GI) diseases. Whole meal bread (WMB) often aggravates such symptoms though the mechanisms are unclear. We used magnetic resonance imaging (MRI) to monitor the intragastric fate of a WMB meal (11% bran) compared to a rice pudding (RP) meal. SUBJECTS/METHODS: 12 healthy volunteers completed this randomised crossover study. They fasted overnight and after an initial MRI scan consumed a glass of orange juice with a 2267 kJ WMB or an equicaloric RP meal. Subjects underwent serial MRI scans every 45 min up to 270 min to assess gastric volumes and small bowel water content and completed a GI symptom questionnaire. RESULTS: The MRI intragastric appearance of the two meals was markedly different. The WMB meal formed a homogeneous dark bolus with brighter liquid signal surrounding it. The RP meal separated into an upper, liquid layer and a lower particulate layer allowing more rapid emptying of the liquid compared to solid phase (sieving). The WMB meal had longer gastric half emptying times (132±8 min) compared to the RP meal (104±7 min), P<0.008. The WMB meal was associated with markedly reduced MRI-visible small bowel free mobile water content compared to the RP meal, P<0.0001. CONCLUSIONS: WMB bread forms a homogeneous bolus in the stomach which inhibits gastric sieving and hence empties slower than the equicaloric rice meal. These properties may explain why wheat causes postprandial bloating and could be exploited to design foods which prolong satiation

Dealing with the difficult student in emergency medicine

Dealing with a student who is perceived as difficult to work with or teach is inevitable in any academic physician's career. This paper will outline the basic categories of these difficulties pertinent to Emergency Medicine rotations in order to facilitate appropriate identification of problems. Strategies for evaluation and reporting of the difficult student are presented. Remediation, based on the type of difficulty, is addressed. Timeliness of reporting, evaluation, and feedback are invaluable to allow for appropriate assessment of the outcome of the remediation plan

Standardized ultrasound evaluation of carotid stenosis for clinical trials: University of Washington Ultrasound Reading Center

<p>Abstract</p> <p>Introduction</p> <p>Serial monitoring of patients participating in clinical trials of carotid artery therapy requires noninvasive precision methods that are inexpensive, safe and widely available. Noninvasive ultrasonic duplex Doppler velocimetry provides a precision method that can be used for recruitment qualification, pre-treatment classification and post treatment surveillance for remodeling and restenosis. The University of Washington Ultrasound Reading Center (UWURC) provides a uniform examination protocol and interpretation of duplex Doppler velocity measurements.</p> <p>Methods</p> <p>Doppler waveforms from 6 locations along the common carotid and internal carotid artery path to the brain plus the external carotid and vertebral arteries on each side using a Doppler examination angle of 60 degrees are evaluated. The UWURC verifies all measurements against the images and waveforms for the database, which includes pre-procedure, post-procedure and annual follow-up examinations. Doppler angle alignment errors greater than 3 degrees and Doppler velocity measurement errors greater than 0.05 m/s are corrected.</p> <p>Results</p> <p>Angle adjusted Doppler velocity measurements produce higher values when higher Doppler examination angles are used. The definition of peak systolic velocity varies between examiners when spectral broadening due to turbulence is present. Examples of measurements are shown.</p> <p>Discussion</p> <p>Although ultrasonic duplex Doppler methods are widely used in carotid artery diagnosis, there is disagreement about how the examinations should be performed and how the results should be validated. In clinical trails, a centralized reading center can unify the methods. Because the goals of research examinations are different from those of clinical examinations, screening and diagnostic clinical examinations may require fewer velocity measurements.</p

Brane-World Gravity

The observable universe could be a 1+3-surface (the "brane") embedded in a 1+3+\textit{d}-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the \textit{d} extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak ($\sim$ TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10-dimensional M theory encompasses the known 1+9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review analyzes the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall--Sundrum models. We also cover the simplest brane-world models in which 4-dimensional gravity on the brane is modified at \emph{low} energies -- the 5-dimensional Dvali--Gabadadze--Porrati models. Then we discuss co-dimension two branes in 6-dimensional models.Comment: A major update of Living Reviews in Relativity 7:7 (2004) "Brane-World Gravity", 119 pages, 28 figures, the update contains new material on RS perturbations, including full numerical solutions of gravitational waves and scalar perturbations, on DGP models, and also on 6D models. A published version in Living Reviews in Relativit

Expression of excess receptors and negative feedback control of signal pathways are required for rapid activation and prompt cessation of signal transduction

Cellular signal transduction is initiated by the binding of extracellular ligands to membrane receptors. Receptors are often expressed in excess, and cells are activated when a small number of receptors bind ligands. Intracellular signal proteins are act

Greenhouse gas emissions of realistic dietary choices in Denmark: the carbon footprint and nutritional value of dairy products

Background: Dairy products are important in a healthy diet due to their high nutritional value; they are, however, associated with relatively large greenhouse gas emissions (GHGE) per kg product. When discussing the need to reduce the GHGE caused by the food system, it is crucial to consider the nutritional value of alternative food choices. Objective: The objective of this study was to elucidate the role of dairy products in overall nutrition and to clarify the effects of dietary choices on GHGE, and to combine nutritional value and GHGE data. Methods: We created eight dietary scenarios with different quantity of dairy products using data from the Danish National Dietary Survey (1995–2006). Nutrient composition and GHGE data for 71 highly consumed foods were used to estimate GHGE and nutritional status for each dietary scenario. An index was used to estimate nutrient density in relation to nutritional recommendation and climate impact for solid food items; high index values were those with the highest nutrient density scores in relation to the GHGE. Results: The high-dairy scenario resulted in 27% higher protein, 13% higher vitamin D; 55% higher calcium; 48% higher riboflavin; and 18% higher selenium than the non-dairy scenario. There was a significant correlation between changes in calcium and changes in vitamin D, selenium, and riboflavin content (P=0.0001) throughout all of the diets. The estimated GHGE for the dietary scenario with average-dairy consumption was 4,631 g CO2e/day. Conclusions: When optimizing a diet with regard to sustainability, it is crucial to account for the nutritional value and not solely focus on impact per kg product. Excluding dairy products from the diet does not necessarily mitigate climate change but in contrast may have nutritional consequences

Discovertebral (Andersson) lesions in severe ankylosing spondylitis: a study using MRI and conventional radiography

The objective of this study is to investigate the prevalence of Andersson lesions (AL) in ankylosing spondylitis (AS) patients who will start anti-tumor necrosis factor (TNF) treatment. Radiographs and magnetic resonance imaging (MRI) of the spine were performed before therapy with anti-TNF. ALs were defined as discovertebral endplate destructions on MRI, associated with bone marrow edema and fat replacement or sclerosis, a decreased signal on T1, enhancement after contrast administration (gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA)), and increased signal on T2 and short tau inversion recovery (STIR). Additionally, conventional radiography showed a fracture line, irregular endplates, and increased sclerosis of adjacent vertebral bodies. Fifty-six AS patients were included, 68% males, mean age of 43 years, and mean disease duration of 11 years. The mean bath ankylosing spondylitis disease activity index was 6.4, and 24% of all patients had ankylosis. Only one patient showed a discovertebral abnormality with bone marrow edema of more than 50% of the vertebral bodies adjacent to the intervertebral disk of T7/T8 and T9/T10, a hypodense signal area on T1, and a high signal on STIR. Irregular endplates were depicted, and T1 after Gd-DTPA demonstrated high signal intensity around the disk margins. However, no fracture line was visible on conventional radiology, and therefore, this case was not considered to be an AL. No AL was detected in our AS patients, who were candidates for anti-TNF treatment. One patient showed a discovertebral abnormality on MRI, without a fracture line on conventional radiology. The relative small proportion of patients with a long-established disease might explain this finding for, particularly, an ankylosed spine is prone to develop an AL

Motif Minang Kaluak Paku Kacang Balimbiang pada Busana Kasual

Minangkabau sebagai salah satu suku bangsa yang mengisi kekhasan budaya Indonesia memiliki warisan budaya yang terpencar dalam berbagai aspek kehidupannya. Salah satu warisan budaya adalah seni ukir. Seni ukir yang dikembangkan dengan mengambil ide dari alam memiliki makna-makna filosofi bagi kehidupan masyarakat Minangkabau. Semua jenis ukiran yang dipahatkan di Rumah Gadang menunjukkan unsur penting pembentuk budaya Minangkabau bercerminkan kepada apa yang ada di alam. Salah satu ukiran pada rumah gadang yaitu kaluak paku. Kaluak paku adalah nama salah satu motif ukiran dalam adat Minangkabau. Berasal dari motif gulungan (kelukan/kaluak) pada ujung tanaman pakis (paku) yang masih muda. Ukiran kaluak paku rumah gadang melambangkan tanggung jawab seorang lelaki dalam adat Minangkabau kepada generasi penerus, sebagai ayah dari anak-anaknya dan sebagai mamak dari kemenakan (keponakan). Ukiran rumah gadang kaluak paku minangkabau inilah yang menjadi sumber ide penciptaan busana pada tugas akhir ini. Pada Penciptaan karya ini menggunakan beberapa metode, yaitu metode pendekatan estetis dan ergonomis, metode pengumpulan data dengan studi pustaka, dan motode penciptaan dengan teori Gustami Sp 3 tahap 6 Langkah. Dalam proses pembuatan karya dibutuhkan beberapa data, cara pengumpulan data acuan berdasarkan pengumpulan data pustaka yaitu berupa buku, jurnal pada media sosial, serta aplikasi pada smartphone seperti pinterest. Data yang dikumpulkan yang paling utama adalah gambar bentuk visual dari ukiran tanaman kaluak paku minangkabau dan busana kasual. Penciptaan karya yang dihasilkan yaitu berupa 8 busana kasual. Siluet pada kesuluruhan hasil karya yaitu memiliki siluet A yang mengembang pada bagian bawah. Pada penciptaan karya ini menggunakan bahan utama primisima. Perpaduan warna yang diterapkan menggunakan warna khas minangkabau yang diambil dari warna bendera adatnya “marawa” yaitu merah, hitam, dan kuning. Karya- karya yang dihasilkan dengan penggunaan warna tersebut sangat sesuai dengan tema yang mengangkat ukiran rumah gadang kaluak paku minangkabau. Kata Kunci : Minang, Kaluak Paku Kacang Balimbiang, Kasua