A FUZZY LOGIC APPROACH TO NON-LINEARITY PROBLEM OF LOAD FREQUENCY CONTROLLER

In power systems, both active and reactive power demands are never steady.  Due to sudden load changes, frequency fluctuation problems occur in an interconnected power system. The Load Frequency Control (LFC) reduces the frequency deviation and maintains dynamic performance of the system. Non-linearities have made most of the controllers employed for the LFC inefficient. In this paper, a fuzzy logic proportional integral (PI) controller is proposed to eliminate these setbacks with the conventional controllers. The results showed a reduction in settling time, percent overshoot and steady state error. http://dx.doi.org/10.4314/njt.v35i3.1

Global longitudinal strain at rest predicts significant coronary artery stenosis in patients with peripheral arterial disease

Abstract Funding Acknowledgements Type of funding sources: None. Background Critical peripheral artery disease (PAD) is expression of systemic chronic atherosclerosis, it being often associated with cardiovascular events. The assessment of global longitudinal strain (GLS) at rest by speckle tracking echocardiography could be useful to unmask significant coronary artery disease (CAD) in asymptomatic PAD patients. Purpose To determine whether resting GLS is able to predict significant coronary artery stenosis in PAD patients selected for peripheral or carotid angiography. Methods One-hundred three clinically relevant PAD patients (M/F = 76/27, age = 66.8 ± 10,2 years, 72 with significant lower limb artery stenosis and 31 with carotid artery stenosis ≥50%), asymptomatic for CAD, underwent standard echo-Doppler exam at rest, comprehensive of GLS analysis, prior peripheral and coronary angiography. Information on cardiovascular (CV) risk factors and comorbidities were collected. Patients with know CAD and previous myocardial infarction, left ventricular (LV) ejection fraction < 50% and inadequate echocardiographic imaging were excluded. According to the results of coronary angiography, patients were divided in two groups: with significant coronary artery stenosis (>50% of obstruction. n = 73) and without significant coronary artery lesions (n = 30). Results No intergroup difference in the prevalence of CV risk factors and comorbidities was found. Age, body mass index and blood pressure were comparable between the two groups. LV ejection fraction (59.9 ± 4.2% in patients with significant coronary stenosis vs. 60.2 ± 4.7% in those without coronary stenosis, p = 0.75) and wall motion score index (1.02 ± 0.09 vs 1.03 ± 0.09 respectively, p = 0.67) did not differ significantly. Conversely, GLS was lower in patients with significant coronary artery stenosis than in those without (21.6 ± 2.7% vs. 22.8 ± 2%, p < 0.02) (Figure 1). This difference remained significant comparing the carotid subgroup with coronary stenosis vs. those without (p < 0.05) whereas it did not achieve the statistical significance in patients with lower limb artery lesions (p = 0.42). Conclusion In PAD patients, GLS at rest shoes the capability in identifying patients at higher probability of significant coronary artery stenosis. This involves in particular patients with carotid artery stenosis. GLS might be helpful to select patients who need to extend the peripheral angiographic evaluation to the coronary tree

Normal modes and discovery of high-order cross-frequencies in the DBV white dwarf GD 358

We present a detailed mode identification performed on the 1994 Whole Earth Telescope (WET) run on GD 358. The results are compared with that obtained for the same star from the 1990 WET data. The two temporal spectra show very few qualitative differences, although amplitude changes are seen in most modes, including the disappearance of the mode identified as k=14 in the 1990 data. The excellent coverage and signal-to-noise ratio obtained during the 1994 run lead to the secure identification of combination frequencies up to fourth order, i.e. peaks that are sums or differences of up to four parent frequencies, including a virtually complete set of second-order frequencies, as expected from harmonic distortion. We show how the third-order frequencies are expected to affect the triplet structure of the normal modes by back-interacting with them. Finally, a search for ℓ=2 modes was unsuccessful, not verifying the suspicion that such modes had been uncovered in the 1990 data set

Identification of a wide spectrum of ciliary gene mutations in nonsyndromic biliary atresia patients implicates ciliary dysfunction as a novel disease mechanism

Background: Biliary atresia (BA) is the most common obstructive cholangiopathy in neonates, often progressing to end-stage cirrhosis. BA pathogenesis is believed to be multifactorial, but the genetic contribution, especially for nonsyndromic BA (common form: > 85%) remains poorly defined. Methods: We conducted whole exome sequencing on 89 nonsyndromic BA trios to identify rare variants contributing to BA etiology. Functional evaluation using patients’ liver biopsies, human cell and zebrafish models were performed. Clinical impact on respiratory system was assessed with clinical evaluation, nasal nitric oxide (nNO), high speed video analysis and transmission electron microscopy. Findings: We detected rare, deleterious de novo or biallelic variants in liver-expressed ciliary genes in 31.5% (28/89) of the BA patients. Burden test revealed 2.6-fold (odds ratio (OR) [95% confidence intervals (CI)]= 2.58 [1.15–6.07], adjusted p = 0.034) over-representation of rare, deleterious mutations in liver-expressed ciliary gene set in patients compared to controls. Functional analyses further demonstrated absence of cilia in the BA livers with KIF3B and TTC17 mutations, and knockdown of PCNT, KIF3B and TTC17 in human control fibroblasts and cholangiocytes resulted in reduced number of cilia. Additionally, CRISPR/Cas9-engineered zebrafish knockouts of KIF3B, PCNT and TTC17 displayed reduced biliary flow. Abnormally low level of nNO was detected in 80% (8/10) of BA patients carrying deleterious ciliary mutations, implicating the intrinsic ciliary defects. Interpretation: Our findings support strong genetic susceptibility for nonsyndromic BA. Ciliary gene mutations leading to cholangiocyte cilia malformation and dysfunction could be a key biological mechanism in BA pathogenesis. Funding: The study is supported by General Research Fund, HMRF Commissioned Paediatric Research at HKCH and Li Ka Shing Faculty of Medicine Enhanced New Staff Start-up Fund

Dental sealant knowledge, opinion, values and practice of Spanish dentists

[Background] Multiple guidelines and systematic reviews recommend sealant use to reduce caries risk. Yet, multiple reports also indicate that sealants are significantly underutilized. This study examined the knowledge, opinions, values, and practice (KOVP) of dentists concerning sealant use in the southwest region of Andalusia, Spain. This is a prelude to the generation of a regional plan for improving children’s oral health in Andalusia.[Methods] The survey’s target population was dentists working in western Andalusia, equally distributed in the provinces of Seville, Cadiz, and Huelva (N=2,047). A convenience sample of meeting participants and meeting participant email lists (N=400) were solicited from the annual course on Community and Pediatric Dentistry. This course is required for all public health sector dentists, and is open to all private sector dentists. Information on the dentist’s KOVP of sealants was collected using four-part questionnaire with 31, 5-point Likert-scaled questions.[Results] The survey population demographics included 190 men (48%) and 206 women (52%) with an average clinical experience of 10.6 (± 8.4) years and 9.3 (± 7.5) years, respectively. A significant sex difference was observed in the distribution of place of work (urban/suburb) (p=0.001), but no sex differences between working sector (public/private). The mean ± SD values for each of the four KOVP sections for pit and fissure sealants were: knowledge = 3.57 ± 0.47; opinion = 2.48 ± 0.47; value = 2.74 ± 0.52; and practice = 3.48 ± 0.50. No sex differences were found in KOVP (all p >0.4). Independent of sex: knowledge statistically differed by years of experience and place of work; opinion statistically differed by years of experience and sector; and practice statistically differed by years of experience and sector. Less experienced dentists tended to have slightly higher scores (~0.25 on a Likert 1–5 scale). Statistically significant correlations were found between knowledge and practice (r=0.44, p=0.00) and between opinion and value (r=0.35, p=0.00).[Conclusions] The results suggest that, similar to other countries, Andalusian dentists know that sealants are effective, have neutral to positive attitudes toward sealants; though, based on epidemiological studies, underuse sealants. Therefore, methods other than classical behavior change (eg: financial or legal mechanisms) will be required to change practice patterns aimed at improving children's oral health.We acknowledge the following sources for invaluable financial support NIMHD 1 R34 DE022272 (NIH2385) and NIDCR 1 U24 MD006964

Assessment of human cytomegalovirus co-infection in Egyptian chronic HCV patients

Human cytomegalovirus (HCMV) is the most common cause of severe morbidity and mortality in immune- compromised individuals. This study was conducted to determine the incidence of HCMV infection in HCV patients who either spontaneously cleared the virus or progressed to chronic HCV infection. The study included a total of eighty four cases (48 females and 36 males) that were referred to blood banks for blood donation with an age range of 18-64 years (mean age 37.62 ± 10.03 years). Hepatitis C virus RNA and HCMV DNA were detected in sera by RT-nested PCR and nested PCR respectively in all subjects. Immunoglobulin G levels for HCV and HCMV were determined. Besides, IgM antibodies for HCMV infection were also determined in subjects' sera. Fifty three out of 84 cases (63%) were positive for HCV-RNA while 31 (37%) cases had negative HCV RNA. Forty six (87%) and 13 (25%) cases out of 53 HCV RNA positive patients were positive for HCMV IgG and IgM antibodies respectively. While 20 of 53 cases (38%) had detectable HCMV DNA. To examine the role of HCMV infection in HCV spontaneous resolution, two groups of HCV patients, group 1) chronic HCV infection (positive HCV RNA and positive IgG antibodies) vs group 2) spontaneous resolution (negative HCV RNA and positive IgG antibodies) were compared. The percentages of positive CMV IgG and IgM results is higher in chronic HCV patient than those in spontaneously cleared HCV patients and the difference is highly statistically significant (P value < 0.001). Also, there is a general trend towards elevated levels of CMV IgG antibodies in HCV chronic patients than those in spontaneously cleared HCV patients (P value < 0.02). HCMV DNA detection in group 1 was more than twice the value observed in group 2 (38% vs 14.3%, P value < 0.001). Moreover, levels of liver enzymes were significantly higher in HCV RNA positive cases co-infected with HCMV DNA than HCMV negative cases (P value < 0.001). The results indicate the role of HCMV in the liver pathogenesis. We conclude that chronic HCV patients co-infected with HCMV infection can be regarded as high risk groups for liver disease progression where they should be monitored for the long term outcome of the disease