Rectifiers

"There are at present four common methods of con verting the alternating current into direct current. These are in order of use, the motor generator set, the rotary converter, mercury vapor rectifier and the Murphy rectifier. A short description of these and connections for the last two will be given."--p.

Microvascular cerebral hemodynamics in pediatric sickle cell disease with Diffuse Correlation Spectroscopy

Sickle cell disease is a genetic blood disorder that has profound effects on the brain. Chronic anemia combined with both macro- and micro-vascular perfusion abnormalities that arise from stenosis or occlusion of blood vessels, increased blood viscosity, adherence of red blood cells to the vascular endothelium, and impaired autoregulatory mechanisms in sickle cell disease patients all culminate in susceptibility to cerebral infarction. Indeed, the risk of stroke is 250 times higher in children with sickle cell disease than in the general population. Unfortunately, while transcranial Doppler ultrasound (TCD) has been widely clinically adopted to longitudinally monitor macrovascular perfusion in these patients, routine clinical screening of microvascular perfusion abnormalities is challenging with current modalities (e.g., positron emission tomography, magnetic resonance imaging) given their high-cost, requirement for sedation in children \u3c 6y, and need for trained personnel. In this pilot study, we first assess the feasibility of a low-cost, noninvasive optical technique known as Diffuse Correlation Spectroscopy (DCS) to quantify an index of resting-state cortical cerebral blood flow in 11 children with SCD along with 11 sex- and age-matched healthy controls. As expected, blood flow index was significantly higher in sickle subjects compared to healthy controls (p \u3c 0.001). Within sickle subjects, blood flow index was inversely proportional to resting-state arterial hemoglobin levels (p = 0.012), consistent with expected anemia-induced compensatory vasodilation that aims to maintain adequate oxygen delivery to the tissue. Further, in a subset of patients measured with transcranial Doppler ultrasound, DCS-measured blood flow was correlated with TCD-measured blood flow velocity in middle cerebral artery (Rs = 0.68), although the trend was not statistically significant (p=0.11). These results are consistent with those of several previous studies using traditional neuroimaging techniques to quantify cerebral blood flow, suggesting that DCS may be a promising low-cost tool for assessment of tissue-level cerebral blood flow in pediatric sickle cell disease. Finally, given that sickle cell disease is often associated with severe anemia, we next assessed the potentially confounding effects of hematocrit on the DCS-measured blood flow index using a microfluidic tissue-simulating phantom. For a fixed flow rate in the microfluidic channels, we show that blood flow index is inversely correlated with hematocrit, and we present a means to correct the measured blood flow index for hematocrit in anemic conditions

Actinomycosis of the Gallbladder Mimicking Carcinoma: a Case Report with US and CT Findings

We describe a case of actinomycosis of the gallbladder mimicking carcinoma. Sonography showed a hypoechoic mass replacing gallbladder lumen and engulfing a stone; contrast-enhanced computed tomography showed a heterogeneously enhanced thickened gallbladder wall with subtle, disrupted luminal surface enhancement, which formed a mass. As a result of the clinical and radiologic presentation, our impression was of gallbladder carcinoma. Actinomycosis should be included in the differential diagnosis when sonography and computed tomography findings show a mass engulfing the stone in the gallbladder and extensive pericholecystic infiltration with extension to neighboring abdominal wall muscle

Comparison of CHARM-2 and Surface Potential Measurement to Monitor Plasma Induced Gate Oxide Damage

Abstract Plasma process induced gate oxide damage was found in early process development stages. Device data showed unacceptable burn-in failure. By utilizing multiple test vehicles, the underlying cause of oxide damage was identified. This study showed that no single methodology is adequate for controlling the damage. A combination of the monitoring techniques is required to understand root cause of damage and how to optimize the process or equipment. The plasma process was optimized and verified with CHARM-2 monitor response. Further device data verification indicated no gate oxide damage was found with new improved process. The fast turn around time of plasma monitors were essential to understand and determine the plasma damage source. Understanding the relationship between plasma monitor response and plasma process is a key point to identify the source of damage. A fingerprint of plasma process is very useful for process control and defect reduction

Legal and illegal ruck cleanouts in South African non-professional youth rugby

CITATION: Kruger, S. et al. 2022. Legal and illegal ruck cleanouts in South African non-professional youth rugby. International Journal of Sports Science & Coaching, 1-9. doi:10.1177/17479541221122439.The original publication is available at https://journals.sagepub.com/home/spoThe ruck area is responsible for the second-highest number of rugby union injuries, therefor it is necessary to investigate and understand the ruck better for improved player safety. The study aimed to investigate and compare incidents of legal and illegal ruck cleanouts in non-professional youth rugby. Using Nacpsort Scout Plus software, 118 South African Rugby Union under 18 Youth Week tournament matches were coded between 2015 and 2019. In total, 35 545 ruck cleanouts were coded, of which 32 641 (91.8%) were legal and 2 904 (8.2%) were illegal. Of the 2 904 illegal cleanouts, 2 676 (92.2%) were deemed ‘not dangerous’ and 228 (7.8%) were considered ‘dangerous’. The ‘dangerous’ ruck cleanouts represented 0.6% of the total ruck cleanouts. Of the most common illegal ruck cleanouts, “not supporting own body weight” were mostly ‘not dangerous’ (2 498; 99.4%, p=0.01); and all “neck rolls” were considered ‘dangerous’ (147; 100.0%, p=0.02). The findings of the study suggest player behaviour can still be improved, with regular participation in regular safe and effective technique training drills. The risk of injury during the ruck can further be influenced positively by coaches, through regular coaching and training of safe and effective ruck techniques.https://journals.sagepub.com/doi/full/10.1177/17479541221122439Post-print versio

Improving a gold standard: treating human relevance judgments of MEDLINE document pairs

Given prior human judgments of the condition of an object it is possible to use these judgments to make a maximal likelihood estimate of what future human judgments of the condition of that object will be. However, if one has a reasonably large collection of similar objects and the prior human judgments of a number of judges regarding the condition of each object in the collection, then it is possible to make predictions of future human judgments for the whole collection that are superior to the simple maximal likelihood estimate for each object in isolation. This is possible because the multiple judgments over the collection allow an analysis to determine the relative value of a judge as compared with the other judges in the group and this value can be used to augment or diminish a particular judge’s influence in predicting future judgments. Here we study and compare five different methods for making such improved predictions and show that each is superior to simple maximal likelihood estimates