Multi-channel pre-beamformed data acquisition system for research on advanced ultrasound imaging methods

The lack of open access to the pre-beamformed data of an ultrasound scanner has limited the research of novel imaging methods to a few privileged laboratories. To address this need, we have developed a pre-beamformed data acquisition (DAQ) system that can collect data over 128 array elements in parallel from the Ultrasonix series of research-purpose ultrasound scanners. Our DAQ system comprises three system-level blocks: 1) a connector board that interfaces with the array probe and the scanner through a probe connector port; 2) a main board that triggers DAQ and controls data transfer to a computer; and 3) four receiver boards that are each responsible for acquiring 32 channels of digitized raw data and storing them to the on-board memory. This system can acquire pre-beamformed data with 12-bit resolution when using a 40-MHz sampling rate. It houses a 16 GB RAM buffer that is sufficient to store 128 channels of pre-beamformed data for 8000 to 25 000 transmit firings, depending on imaging depth; corresponding to nearly a 2-s period in typical imaging setups. Following the acquisition, the data can be transferred through a USB 2.0 link to a computer for offline processing and analysis. To evaluate the feasibility of using the DAQ system for advanced imaging research, two proof-of-concept investigations have been conducted on beamforming and plane-wave B-flow imaging. Results show that adaptive beamforming algorithms such as the minimum variance approach can generate sharper images of a wire cross-section whose diameter is equal to the imaging wavelength (150 μm in our example). Also, planewave B-flow imaging can provide more consistent visualization of blood speckle movement given the higher temporal resolution of this imaging approach (2500 fps in our example). © 2012 IEEE.published_or_final_versio

Friction stir welding of EH46 steel grade at dwell stage: Microstructure evolution

This work aims to understand the effect of changes in friction stir welding (FSW) process parameters on the resulting microstructure specifically the effect of the plunge depth and tool rotational speed, during the “dwell” period on the resulting microstructure. A series of (FSW) of 14.8-mm-thick EH46 steel plate using a hybrid polycrystalline boron nitride FSW tool with spindle speeds of 120 and 200 revolutions per minute have been produced with increasing plunge depths from 0.1 to 0.7 mm. Thermocouples embedded around the top surface of each plunge case were used to measure the peak temperature during the process. The plunge depths were measured using the infinite focus microscopy, and the microstructure of all the heat affected regions was investigated extensively by scanning electron microscopy. It was found that phase transformation is sensitive to the variation on plunge depth. Small increase in plunge depth caused a significant change in the microstructure. Increasing tool rotational speed was also found to cause a significant difference in the microstructure

How is service procurement different from goods procurement? Exploring ex ante costs and ex post problems in IT procurement

Several studies suggest that, in practice, service procurement is more challenging than goods procurement. The underlying but largely implicit argument is that the procurement process for services involves higher buyer uncertainty and therefore requires extra efforts to mitigate this uncertainty. Drawing on Transaction Cost Economics, we use a database of information technology transactions to investigate the relationship between transaction characteristics and social embeddedness, and ex ante cost and ex post problems. We explore whether the same relationships hold across transactions that involve only goods versus transactions that also involve services. Our findings support conventional wisdom that managing the procurement process for transactions involving services is more challenging than for transactions involving goods. However, when controlling for typical transaction characteristics, there is no difference between transactions involving goods and transactions that also involve services

Control of intestinal stem cell function and proliferation by mitochondrial pyruvate metabolism.

Most differentiated cells convert glucose to pyruvate in the cytosol through glycolysis, followed by pyruvate oxidation in the mitochondria. These processes are linked by the mitochondrial pyruvate carrier (MPC), which is required for efficient mitochondrial pyruvate uptake. In contrast, proliferative cells, including many cancer and stem cells, perform glycolysis robustly but limit fractional mitochondrial pyruvate oxidation. We sought to understand the role this transition from glycolysis to pyruvate oxidation plays in stem cell maintenance and differentiation. Loss of the MPC in Lgr5-EGFP-positive stem cells, or treatment of intestinal organoids with an MPC inhibitor, increases proliferation and expands the stem cell compartment. Similarly, genetic deletion of the MPC in Drosophila intestinal stem cells also increases proliferation, whereas MPC overexpression suppresses stem cell proliferation. These data demonstrate that limiting mitochondrial pyruvate metabolism is necessary and sufficient to maintain the proliferation of intestinal stem cells

Cannulation of the Axillary Artery for Cardiopulmonary Bypass: Safeguards and Pitfalls.

BACKGROUND: The ascending aorta is the customary site for arterial cannulation for cardiopulmonary bypass. Favorable experience at our institution and elsewhere using axillary artery cannulation in treating type A aortic dissections has caused us to broaden our indications for using this site for arterial cannulation for cardiopulmonary bypass. METHODS: Medical records, operative notes, and perfusion records were reviewed in all patients in whom the axillary artery was cannulated directly or by a graft for cardiopulmonary bypass from January 1, 2000 through August 30, 2002. RESULTS: Seventy-five patients underwent axillary artery cannulation during the 32-month interval. Eleven patients had ascending aortic dissections, 20 had extensively diseased ascending aortas, and 44 were individuals undergoing repeat cardiac procedures. The right axillary artery was used in 72 patients and the left in 3. In 16 patients the artery was cannulated directly, and in 59 the arterial cannula was inserted into a prosthetic graft that had been anastomosed to the axillary artery. Axillary artery cannulation was satisfactory in 95% (71 of 75) of the cases in which it was used. CONCLUSIONS: Cannulation of the axillary artery for cardiopulmonary bypass is a dependable approach for procedures including reoperations, aortic dissections, and extensively diseased ascending aortas

All Politics is Local: The Renminbi's Prospects as a Future Global Currency

Recent years have seen a heated discussion over Chinese capital account liberalization and internationalization of China’s currency, the renminbi (RMB). Against the backdrop of a weak U.S. economy and China’s growing international economic clout, there has been speculation about the RMB replacing the U.S. dollar as the world’s leading currency. Subramanian (2011: 1), for instance, maintains that “the renminbi could become the premier reserve currency by the end of this decade, or early next decade.” Much of the current discourse recalls past discussions when other currencies, especially the Japanese yen (Burstein 1988; Kwan 1994; Taguchi 1994) and the Euro (Chinn and Frankel 2007), were seen as candidates to “dethrone” the dollar

Screening and identification of cellulase producing yeast-like microorganisms from Brazilian biomes

The main goals of the present study included the screening and identification of cellulase producing wild yeasts, isolated from samples collected from different Brazilian biomes. They were selected according to their capabilities of degrading carboxymethyl cellulose (CMC) and micro-crystalline cellulose (SERVACEL®), as single carbon sources in solid medium. After the step of solid medium selection, yeast cells were grown in liquid medium containing cellulose (SERVACEL®); in shake flasks at temperature of 30°C and 150 rpm agitation for 288 h. Three specific activities were evaluated: endoglucanase (CMCase), total activity (filter paper activity), and cellobiase. From a total of 390 strains of wild yeasts previously isolated, 16 strains performed cellulose hydrolysis, verified by the colorless halo in the solid medium. Among these 16 strains, 5 stood out as presenting higher levels of enzyme activity. The following step, screening in liquid medium, indicated only one strain as a potential producer of cellulases, named as AAJ6, for which the highest hydrolytic activity on carboxymethyl cellulose (0.33 U/ml) and filter paper (0.039 U/ml) was recorded. Afterwards, this wild yeast strain (AAJ6) was molecularly identified by sequencing the ITS1-5.8S-ITS2 and D1/D2 domains of the subunit (26 S) ribosomal DNA. Sequencing resulted in the identification of this strain as yeast-like fungus Acremonium strictum.Keywords: Acremonium strictum, screening, identification, yeast-like, cellulase