1,142 research outputs found
Software-Engineering Process Simulation (SEPS) model
The Software Engineering Process Simulation (SEPS) model is described which was developed at JPL. SEPS is a dynamic simulation model of the software project development process. It uses the feedback principles of system dynamics to simulate the dynamic interactions among various software life cycle development activities and management decision making processes. The model is designed to be a planning tool to examine tradeoffs of cost, schedule, and functionality, and to test the implications of different managerial policies on a project's outcome. Furthermore, SEPS will enable software managers to gain a better understanding of the dynamics of software project development and perform postmodern assessments
Geophysical investigations of a geothermal anomaly at Wadi Ghadir, eastern Egypt
During regional heat flow studies a geothermal anomaly was discovered approximately 2 km from the Red Sea coast at Wadi Ghadir, in the Red Sea Hills of Eastern Egypt. A temperature gradient of 55 C/km was measured in a 150 m drillhole at this location, indicating a heat flow of approximately 175 mw/sqm, approximately four times the regional background heat flow for Egypt. Gravity and magnetic data were collected along Wadi Ghadir, and combined with offshore gravity data, to investigate the source of the thermal anomaly. Magnetic anomalies in the profile do not coincide with the thermal anomaly, but were observed to correlate with outcrops of basic rocks. Other regional heat flow and gravity data indicate that the transition from continental to oceanic type lithosphere occurs close to the Red Sea margin, and that the regional thermal anomaly is possibly related to the formation of the Red Sea
Nuclear Medium Effects in the Relativistic Treatment of Quasifree Electron Scattering
Non-relativistic reduction of the S-matrix for the quasifree electron
scattering process is studied in order to
understand the source of differences between non-relativistic and relativistic
models. We perform an effective Pauli reduction on the relativistic expression
for the S-matrix in the one-photon exchange approximation. The reduction is
applied to the nucleon current only; the electrons are treated fully
relativistically. An expansion of the amplitude results in a power series in
the nuclear potentials. The series is found to converge rapidly only if the
nuclear potentials are included in the nuclear current operator. The results
can be cast in a form which reproduces the non-relativistic amplitudes in the
limit that the potentials are removed from the nuclear current operator. Large
differences can be found between calculations which do and do not include the
nuclear potentials in the different orders of the nuclear current operator. In
the high missing momentum region we find that the non-relativistic calculations
with potentials included in the nuclear current up to second order give results
which are close to those of the fully relativistic calculation. This behavior
is an indication of the importance of the medium modifications of the nuclear
currents in this model, which are naturally built into the relativistic
treatment of the reaction.Comment: Latex, 26 pages including 5 uuencoded postscript figures. accepted
for publication in Phys. Rev. C
One-Year Results of Simultaneous Topography-Guided Photorefractive Keratectomy and Corneal Collagen Cross-Linking in Keratoconus Utilizing a Modern Ablation Software
Purpose. To evaluate effectiveness of simultaneous topography-guided photorefractive keratectomy and corneal collagen cross-linking in mild and moderate keratoconus. Methods. Prospective nonrandomized interventional study including 20 eyes of 14 patients with grade 1-2 keratoconus that underwent topography-guided PRK using a Custom Ablation Transition Zone (CATz) profile with 0.02% MMC application immediately followed by standard 3 mw/cm2 UVA collagen cross-linking. Maximum ablation depth did not exceed 58 μm. Follow-up period: 12 months. Results. Progressive statistically significant improvement of UCVA from 0.83±0.37 logMAR preoperative, reaching 0.25±0.26 logMAR at 12 months (P<0.001). Preoperative BCVA (0.27±0.31 logMAR) showed a progressive improvement reaching 0.08±0.12 logMAR at 12 months (P=0.02). Mean Kmax reduced from 48.9±2.8 to 45.4±3.1 D at 12 months (P<0.001), mean Kmin reduced from 45.9±2.8 D to 44.1±3.2 D at 12 months (P<0.003), mean keratometric asymmetry reduced from 3.01±2.03 D to 1.25±1.2 D at 12 months (P<0.001). The safety index was 1.39 at 12 months and efficacy index 0.97 at 12 months. Conclusion. Combined topography-guided PRK and corneal collagen cross-linking are a safe and effective option in the management of mild and moderate keratoconus. Precis. To our knowledge, this is the first published study on the use of the CATz ablation system on the Nidek Quest excimer laser platform combined with conventional cross-linking in the management of mild keratoconus
Sources and Mitigation of Harmonics in Industrial Electrical Power Systems: State of the Art
Abstract -Power systems are designed to operate at frequencies of 50 Hz or 60Hz. However, certain types of loads produce currents and voltages with frequencies that are integer multiples of the 50 or 60 Hz fundamental frequency. These higher frequencies represent a form of electrical network pollutions known as ''power system harmonics''. This paper presents an extensive literature review in the petrochemical sector for the power system harmonics such as harmonics fundamentals, harmonics harmful effects on various electrical equipment, harmonic distortion limits and harmonic mitigation techniques. This paper is intended as a guide for those interested in this problem or intending to perform further researches in this area
Study of the Urinary Ratio of 6 β-Hydroxycortisol/Cortisol as a Biomarker of CYP3A4 Activity in Egyptian Patients with Chronic Liver Diseases
The urinary ratio of 6 β-hydroxycortisol/cortisol (6 β-OHC/C) as a biomarker of CYP3A4 metabolizing activity has been studied in Egyptian patients with chronic liver cirrhosis associated with previous hepatic Schistosomiasis infection to determine any possible alteration in enzyme activity. The ratio of 6-β OHC/C was determined in morning urine samples collected from 8:00 a.m. to 12:00 p.m. in healthy adults (n = 36) and patients with liver cirrhosis (n = 57). The median age for control was 27 years (range: 18–50 years) and 50 years (range: 27–75 years) for patients. 6 β-OHC was detected in urine by ELIZA kits (Stabiligen, France). Patients with liver cirrhosis were categorized according to Child Pugh Classification into Child B (n = 28) and Child C (n = 29) classes. Cholestasis was observed in 9/28 of Child B class and 8/29 of Child C class of patients. The control subjects showed gender-related difference in the urinary ratio of 6 β-OHC/C. A significant reduction (P < 0.001) in 6 β-OHC/C ratio was observed only in Child C patients in comparison with control subjects. Regression analysis showed a significant correlation (P < 0.05) between 6 β-OHC/C ratio and serum albumin. The influence of cholestasis on the urinary ratio of 6-β OHC/C was observed on cirrhotic patients of Child B class. In conclusion, patients with chronic liver cirrhosis might have a reduction of metabolizing activity of CYP3A4 enzymes which could be identified by measuring the urinary ratio of 6 β-OHC/C. This reduction is more apparent in severe liver injury (Child C class). Therefore, it is important to understand the metabolic fate of drugs metabolized by 3A4 enzymes in patients with liver cirrhosis to avoid drug accumulation that might lead to development of drug toxicity
Circadian rhythm of metabolic changes associated with summer heat stress in high-producing dairy cattle
The current study aimed to investigate the circadian rhythm of blood metabolic parameters associated with summer heat stress (HS) in dairy cows. Ten healthy lactating Holstein Friesian cows were followed during HS for three successive days at six different time points. Blood was sampled from each cow starting from 07:00AM; at 4-h intervals. Ambient air temperature and relative humidity were recorded, and temperature-humidity index (THI) was calculated as well. Respiration rate (RR) and rectal temperature (RT) were recorded for each cow at the time of blood sampling. Concentrations of glucose, non-esterified fatty acids (NEFA), total cholesterol (TC) and urea were measured in each blood sample. The THI values were >68 at all times of the day, and the highest values were recorded at 11:00AM, 03:00PM and 07:00PM (80.9, 83.7, and 80.8, respectively). All the cows showed a significantly higher RR and RT coinciding with higher THI values (93±4 and 39.6±0.1; 90.2±3.4, and 40.1±0.1; 87.6±4.1, and 39.8±0.1, respectively, P<0.05). The concentrations of glucose were the lowest at 11:00AM and 03:00PM (3.75±0.1 and 3.44±0.1 mmol/L, respectively, P<0.05). Decreased glucose concentrations coincided with increased NEFA concentrations, (0.43±0.01 and 0.56±0.02 mmol/L, respectively, P<0.05), and were highly negatively correlated (r=−0.50, P<0.001). The highest urea and TC concentrations were registered at 11:00AM (6.11±0.15 mmol/L and 109.9±2.2 mg/dl, respectively) whereas the lowest urea and TC values were recorded at 03:00AM (4.97±0.18 mmol/L and 99.5± 1.7 mg/dl, respectively, P<0.05). The results of the present study indicate that there was a circadian variation in glucose, NEFA, urea, and TC resulting in the most unfavorable metabolic condition during the hottest moment of the day in dairy cattle. Earlier work revealed that HS-metabolic changes are reflected in the follicular fluid. The circadian changes observed in the present study associated with HS may imply that also the microenvironment of the oocyte is affected
Reakcija β-amino-α,γ-dicianokrotononitrila s acetofenonom: sinteza derivata piridina, piridazina i tiofena s antimikrobnim djelovanjem
Condensation of β-amino-α,γ-dicyanocrotononitrile (1) with acetophenone gave the 2-amino-4-phenylpenta-1,3-diene-1,1,3-tricarbonitrile (2). The latter product was used in a series of heterocyclization reactions when react with different reagents like diazonium salts, hydrazines, hydroxylamine and elemental sulfur to give pyridazine, pyrazole, isoxazole and thiophene derivatives, respectively. On the other hand, it gave pyridine derivatives with aromatic aldehydes followed by reaction with cyanomethylene reagents. The MIC values for the newly synthesized product were measured against E. coli, B. cereus, B. subtilis and C. albicansKondenzacijom β-amino-α,γ-dicijanokrotononitrila 1 s acetofenonom dobiven je 2-amino-4-fenilpenta-1,3-dien-1,1,3-trikarbonitril (2) koji je upotrebljen u reakcijama heterociklizacije s različitim reagensima poput diazonijevih soli, hidrazina, hidroksilamina i elementarnog sumpora pri čemu su nastali derivati piridazina, pirazola, izoksazola, odnosno tiofena. Spoj 2 je u reakciji s aromatskim aldehidima te naknadno sa cijanometilenima dao derivate piridina. Određene su MIC vrijednosti za novosintetizirane spojeve protiv E. coli, B. cereus, B. subtilis i C. albicans
Relativistic versus Nonrelativistic Optical Potentials in A(e,e'p)B Reactions
We investigate the role of relativistic and nonrelativistic optical
potentials used in the analysis of () data. We find that the
relativistic calculations produce smaller () cross sections even in the
case in which both relativistic and nonrelativistic optical potentials fit
equally well the elastic proton--nucleus scattering data. Compared to the
nonrelativistic impulse approximation, this effect is due to a depletion in the
nuclear interior of the relativistic nucleon current, which should be taken
into account in the nonrelativistic treatment by a proper redefinition of the
effective current operator.Comment: Added one new figure, the formalism section has been enlarged and the
list of references updated. Added one appendix. This version will appear in
Phys. Rev. C. Revtex 3.0, 6 figures (not included). Full postscript version
of the file and figures available at
http://www.nikhefk.nikhef.nl/projects/Theory/preprints
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Safety and efficacy of endoscopic submucosal dissection for rectal neoplasia: a multicenter North American experience.
Background and aims Rectal lesions traditionally represent the first lesions approached during endoscopic submucosal dissection (ESD) training in the West. We evaluated the safety and efficacy of rectal ESD in North America. Methods This is a multicenter retrospective analysis of rectal ESD between January 2010 and September 2018 in 15 centers. End points included: rates of en bloc resection, R0 resection, adverse events, comparison of pre- and post-ESD histology, and factors associated with failed resection. Results In total, 171 patients (median age 63 years; 56 % men) underwent rectal ESD (median size 43 mm). En bloc resection was achieved in 141 cases (82.5 %; 95 %CI 76.8-88.2), including 24 of 27 (88.9 %) with prior failed endoscopic mucosal resection (EMR). R0 resection rate was 74.9 % (95 %CI 68.4-81.4). Post-ESD bleeding and perforation occurred in 4 (2.3 %) and 7 (4.1 %), respectively. Covert submucosal invasive cancer (SMIC) was identified in 8.6 % of post-ESD specimens. There was one case (1/120; 0.8 %) of recurrence at a median follow-up of 31 weeks; IQR: 19-76 weeks). Older age and higher body mass index (BMI) were predictors of failed R0 resection, whereas submucosal fibrosis was associated with a higher likelihood of both failed en bloc and R0 resection. Conclusion Rectal ESD in North America is safe and is associated with high en bloc and R0 resection rates. The presence of submucosal fibrosis was the main predictor of failed en bloc and R0 resection. ESD can be considered for select rectal lesions, and serves not only to establish a definitive tissue diagnosis but also to provide curative resection for lesions with covert advanced disease
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