Filter design masks for C37.118.1a-compliant frequency-tracking and fixed-filter M-class Phasor Measurement Units (PMUs)

The new amendment to the Phasor Measurement Unit (PMU) standard C37.118.1a makes several significant changes, compared to the standard C37.118.1 (2011). This paper highlights some of the most important changes, with a particular emphasis applied to how those changes relate to the way that an M-class PMU filter needs to be designed. In particular, there is a delicate trade-off between passband flatness (the bandwidth test) and stopband rejection in the Out-Of-Band (OOB) test. For a PMU algorithm using frequency-tracking and adaptive filters, it is shown that passband flatness can be relaxed to about 2.5dB, but that the stopband needs to begin up to 14.8% closer to 0 Hz than for a fixed-filter PMU. This is partly due to the exact procedures of the C37.118.1a “OOB” testing, and partly due to the adaptive nature of a frequency-tracking PMU filter section. Both the above lead to modified filter masks being required for frequency-tracking devices, compared to the mask required for fixed-filter devices. The M-class PMU with reporting rate 25Hz is the most difficult to design, for reasons given in this paper. The validity of the masks is shown using filter bode plots and simulated C37.118.1a test results of a fixed-filter and frequency-tracking device which have been designed to meet the masks defined in this paper

Smart grid measurement uncertainty : definitional and influence quantity considerations

Measurement uncertainty, in general terms, is an expression of the quality of a measurement. It is typically quan- tified by defining the location and spread of the distribution of a hypothetical infinitely large number of measurements of the thing being measured. The Guide to the Expression of Uncertainty in Measurement (GUM) classifies uncertainties according to whether they are evaluated by statistical means or not. The GUM also mentions that an incomplete definition of the measurand can give rise to large uncertainty in the result. For some of the quantities measured in the Smart Grid, it may be that this "definitional uncertainty" could be a major source of problems. Influence quantities may have a bearing on the result of a measurement without being the subject of the measurement. For example, signal harmonics, noise and temperature effects, while not desired as part of a measurement, exist in power system signals being measured, and they have (sometimes significant) effects on the measurement process

Methodology of a reevaluation of cardiovascular outcomes in the RECORD trial: study design and conduct

Background In 2010, after regulatory review of rosiglitazone licensing, the US Food and Drug Administration (FDA) requested a reevaluation of cardiovascular end points in the RECORD trial.<p></p> Methods Automated screening of the original clinical trial database and manual case report form review were performed to identify all potential cardiovascular and noncardiovascular deaths, and nonfatal myocardial infarction (MI) and stroke events. Search techniques were used to find participants lost to follow-up, and sites were queried for additional source documents. Suspected events underwent blinded adjudication using both original RECORD end point definitions and new FDA end point definitions, before analysis by the Duke Clinical Research Institute.<p></p> Results The reevaluation effort included an additional 328 person-years of follow-up. Automated screening identified 396 suspected deaths, 2,052 suspected MIs, and 468 suspected strokes. Manual review of documents by Duke Clinical Research Institute clinical events classification (CEC) coordinators identified an additional 31 suspected deaths, 49 suspected MIs, and 28 suspected strokes. There were 127 CEC queries issued requesting additional information on suspected deaths; 43 were closed with no site response, 61 were closed with a response that no additional data were available, and additional data were received for 23. Seventy CEC queries were issued requesting additional information for suspected MI and stroke events; 31 were closed with no site response, 20 were closed with a response that no additional data were available, and 19 resulted in additional data.<p></p> Conclusions Comprehensive procedures were used for rigorous event reascertainment and readjudication in a previously completed open-label, global clinical trial. These procedures used in this unique situation were consistent with other common approaches in the field, were enhanced to address the FDA concerns about the original RECORD trial results, and could be considered by clinical trialists designing event readjudication protocols for drug development programs that have been completed.<p></p&gt

Results of a reevaluation of cardiovascular outcomes in the RECORD trial

Background The US Food and Drug Administration (FDA) required a reevaluation of cardiovascular (CV) outcomes in the RECORD trial. This provided an opportunity to assess the implications of event adjudication by 2 groups and quantify the differences as well as to use new FDA end point definitions in development.<p></p> Methods Original data were used to systematically identify all potential deaths, myocardial infarctions (MIs), and strokes. Site investigators were approached for additional source documents and information about participants lost to follow-up. Suspected events were adjudicated using standard procedures, and the results were compared with the original trial outcomes.<p></p> Results Follow-up for mortality was 25,833 person-years, including an additional 328 person-years identified during the reevaluation effort. A total of 184 CV or unknown-cause deaths (88 rosiglitazone, 96 metformin/sulfonylurea), 128 participants with an MI (68 rosiglitazone, 60 metformin/sulfonylurea), and 113 participants with a stroke (50 rosiglitazone, 63 metformin/sulfonylurea) were included. The hazard ratio (HR) for rosiglitazone versus metformin/sulfonylurea for the end point of CV (or unknown cause) death, MI, or stroke was 0.95 (95% CI 0.78-1.17) compared with 0.93 (95% CI 0.74-1.15) for the original RECORD results. Treatment comparisons for MI (HR 1.13, 95% CI 0.80-1.59) and mortality (HR 0.86, 95% CI 0.68-1.08) were also the same compared with the original RECORD results. Sensitivity analyses were also consistent with the original RECORD results. Analyses using the FDA definitions showed similar results.<p></p> Conclusions Only a modest number of additional person-years of follow-up were ascertained from this reevaluation of CV end points in RECORD. Observed HRs and CIs from these analyses using the original RECORD or new FDA end point definitions showed similar treatment effects of rosiglitazone compared with the original RECORD results.<p></p&gt

A comparison of renal phosphorus regulation in thermally-injured and multiple trauma patients receiving specialized nutrition support

To compare phosphorus intake and renal phosphorus regulation between thermally injured patients and multiple trauma patients, 40 consecutive critically ill patients, 20 with thermal injury and 20 with multiple trauma, who required enteral tube feeding were evaluated. Phosphorus intakes were recorded for 14 days from the initiation of tube feeding which was started 1 to 3 days post-injury. Serum for determination of phosphorus concentrations was collected at days 1, 3, 7, and 14 of the study period. A 24-hour urine collection was obtained during the first and second weeks of nutrition support for urinary phosphorus excretion, fractional excretion of phosphorus, renal threshold phosphate concentration, and phosphorus clearance. Average total daily phosphorus intake during the 14-day study for thermally injured patients and multiple trauma patients was 0.99 ± 0.26 mmol/kg/d vs 0.58 ± 0.21 mmol/kg/d, respectively, p \u3c .001. Serum phosphorus concentration on the third day of observation was significantly lower in the thermally injured group than those with multiple trauma (1.9 ± 0.8 mg/dL vs 3.0 ± 0.8 mg/dL, p ≤ .01). A trend toward hypophosphatemia in the thermally injured group persisted by the seventh day of feeding (2.7 ± 1.2 mg/dL vs 3.3 ± 0.6 mg/dL, p ≤ .04). Differences in urinary phosphorus excretion was not statistically significant between the thermally injured and multiple trauma groups (271 ± 213 mg/d vs 171 ± 181 mg/d for week 1, and 320 ± 289 mg/d vs 258 ± 184 mg/d for week 2, respectively). Urinary phosphorus clearance, fractional excretion of phosphorus, or renal threshold phosphate concentrations were also not significantly different between thermally injured and multiple trauma patients. During nutrition support, serum phosphorus concentrations are lower in thermally injured patients compared with multiple trauma patients despite receiving a significantly greater intake of phosphorus. Renal phosphorus regulation does not significantly contribute to the profound hypophosphatemia observed in thermally injured patients when compared with multiple trauma patients during nutrition support

Accuracy of predictive methods to estimate resting energy expenditure of thermally-injured patients

Background The purpose of this study was to evaluate the bias and precision of 46 methods published from 1953 to 2000 for estimating resting energy expenditure (REE) of thermally injured patients. Methods Twenty-four adult patients with ≥20% body surface area burn admitted to a burn center who required specialized nutrition support and who had their REE measured via indirect calorimetry (IC) were evaluated. Patients with morbid obesity, human immunovirus, malignancy, pregnancy, hepatic or renal failure, neuromuscular paralysis, or those requiring a FiO2 \u3e50% or positive end expiratory pressure (PEEP) ≥10 cm H2O were excluded. One steady-state measured REE measurement (MEE) was obtained per patient. The methods of Sheiner and Beal were used to assess bias and precision of these methods. The formulas were considered unbiased if the 95% confidence interval (CI) for the error (kilocalories per day) intersected 0 and were considered precise if the 95% CI for the absolute error (%) was within 15% of MEE. Results MEE was 2780 ± 567 kcal/d or 158% ± 34% of the Harris Benedict equations. None of the methods was precise (≤15% CI error). Over one-half (57%) of the 46 methods had a 95% confidence interval error \u3e30% of the MEE. Forty-eight percent of the methods were unbiased, 33% were biased toward overpredicting MEE, and 19% consistently underpredicted MEE. The pre-1980s methods more frequently overpredicted MEE compared with the 1990 to 2000 (p \u3c .01) and 1980 to 1989 (p \u3c .05) published methods, respectively. The most precise unbiased methods for estimating MEE were those of Milner (1994) at a mean error of 16% (CI of 10% to 22%), Zawacki (1970) with a mean error of 16% (CI of 9% to 23%), and Xie (1993) at a mean error of 18% (CI of 12% to 24%). The conventional 1.5 times the Harris Benedict equations was also unbiased and had a mean error of 19% (CI of 9% to 29%). Conclusions Thermally injured patients are variably hypermetabolic and energy expenditure cannot be precisely predicted. If IC is not available, the most precise, unbiased methods were those of Milner (1994), Zawacki (1970), and Xie (1993)

Sequential single doses of cisapride, erythromycin, and metoclopramide in critically ill patients intolerant to enteral nutrition: A randomized, placebo-controlled, crossover study

Objective: To evaluate the comparative efficacy of enteral cisapride, metoclopramide, erythromycin, and placebo for promoting gastric emptying in critically ill patients with intolerance to gastric enteral nutrition (EN). Design: A randomized, crossover study. Setting: Adult medical intensive care unit at a university-affiliated private hospital and trauma intensive care unit at a university teaching hospital. Patients: Ten adult, critically ill, mechanically ventilated patients not tolerating a fiber-containing EN product defined as a single aspirated gastric residual volume \u3e150 mL or two aspirated gastric residual volumes \u3e120 mL during a 12-hr period. Interventions: Patients received 10 mg of cisapride, 200 mg of erythromycin ethylsuccinate, 10 mg of metoclopramide, and placebo as 20 mL of sterile water every 12 hrs over 48 hrs. Acetaminophen solution (1000 mg) was administered concurrently. Gastric residual volumes were assessed, and plasma acetaminophen concentrations were serially determined by TDx between 0 and 12 hrs to evaluate gastric emptying. Measurements and Main Results: Gastric residual volumes during the study were not significantly different between agents. No differences in area under the concentration vs. time curve or elimination rate constant were identified between agents. Metoclopramide and cisapride had a significantly shorter mean residence time of absorption than erythromycin (6.3 ± 4.5 [SEM] mins and 10.9 ± 5.8 vs. 30.1 ± 4.5 mins, respectively [p \u3c .05]). Metoclopramide (9.7 ± 15.3 mins) had a significantly shorter time to peak concentration compared with erythromycin and placebo (60.7 ± 8.1 and 50.9 ± 13.5 mins, respectively [p \u3c .05]). The time to onset of absorption was significantly shorter for metoclopramide vs. cisapride (5.7 ± 4.5 vs. 22.9 ± 5.7 mins [p \u3c .05]). Conclusion: In critically ill patients intolerant to EN, single enteral doses of metoclopramide or cisapride are effective for promoting gastric emptying in critically ill patients with gastric motility dysfunction. Additionally, metoclopramide may provide a quicker onset than cisapride

Renal phosphorus regulation in thermally-injured and multiple trauma patients receiving enteral nutrition

Abstract from the 22nd Clinical Congress of the American Society for Parenteral and Enteral Nutrition, Orlando, FL, January 18-21, 1998

Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

Meteorological and air-quality model simulations are analyzed alongside observations to investigate the role of the Chesapeake Bay breeze on surface air quality, pollutant transport, and boundary layer venting. A case study was conducted to understand why a particular day was the only one during an 11-day ship-based field campaign on which surface ozone was not elevated in concentration over the Chesapeake Bay relative to the closest upwind site and why high ozone concentrations were observed aloft by in situ aircraft observations. Results show that southerly winds during the overnight and early-morning hours prevented the advection of air pollutants from the Washington, D.C., and Baltimore, Maryland, metropolitan areas over the surface waters of the bay. A strong and prolonged bay breeze developed during the late morning and early afternoon along the western coastline of the bay. The strength and duration of the bay breeze allowed pollutants to converge, resulting in high concentrations locally near the bay-breeze front within the Baltimore metropolitan area, where they were then lofted to the top of the planetary boundary layer (PBL). Near the top of the PBL, these pollutants were horizontally advected to a region with lower PBL heights, resulting in pollution transport out of the boundary layer and into the free troposphere. This elevated layer of air pollution aloft was transported downwind into New England by early the following morning where it likely mixed down to the surface, affecting air quality as the boundary layer grew

Intake of dietary soy isoflavones in relation to perimenstrual symptoms of Korean women living in the USA

This study was conducted to identify the potential relationship between the dietary intake level of soy isoflavones and perimenstrual symptomatology. The research design was a cross-sectional study. The sample was made up of 84 Korean women living in the USA, aged 28–40 years. The Moos Menstrual Distress Questionnaire (MDQ) and the Food Frequency Questionnaire were used as measurement tools. The soy isoflavone intake was significantly correlated with MDQ scores in the menstrual phase. In conclusion, the beneficial effect of dietary soy isoflavones on certain menstrual symptoms was established, suggesting that soy isoflavones could be one of the dietary factors related to the complexity of premenstrual syndrome (PMS). The positive effect of soy isoflavones on PMS warrants further study.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72547/1/j.1442-2018.2006.00270.x.pd