Statistical power of epidemiological studies of low dose levels of ionizing radiation and cancer

The purpose of this research is to inspect the statistical power of studies that investigate the effects of low dose ionizing radiation on the incidence of/mortality from cancer. I use a procedure proposed in a similar study to handle a problem regarding the incidence of childhood leukemia from background ionizing radiation. I study this procedure critically and make some adjustments to make its performance better. I also propose some substitute methods to the methods proposed in the aforementioned reference in order to calculate the power. In addition, I propose other methods not used in the study mentioned above. I evaluate the efficiency of my proposed approaches using simulated data. The improved method can be applied to the National Dose Registry of Canada (NDR) to produce the power curves. The outcomes then can be used to propose the most suitable study design. Some of the previous epidemiological studies based on NDR can also be evaluated in terms of power

Hyperreflexivity of the bounded n-cocycle spaces of Banach algebras

The concept of hyperreflexivity has previously been defined for subspaces of $B(X,Y)$, where $X$ and $Y$ are Banach spaces. We extend this concept to the subspaces of $B^n(X,Y)$, the space of bounded $n$-linear maps from $X\times\cdots\times X=X^{(n)}$ into $Y$, for any $n\in \mathbb{N}$. If $A$ is a Banach algebra and $X$ a Banach $A$-bimodule, we obtain sufficient conditions under which \Zc^n(A,X), the space of all bounded $n$-cocycles from $A$ into $X$, is hyperreflexive. To do so, we define two notions related to a Banach algebra: The strong property (\B) and bounded local units (b.l.u). We show that there are sufficiently many Banach algebras which have both properties. We will prove that all C$^*$-algebras and group algebras have the strong property (\B). We also prove that finite CSL algebras and finite nest algebras have this property. We further show that for an arbitrary Banach algebra $A$ and each $n\geq 2$, $M_n(A)$ has the strong property (\B) whenever it is equipped with a Banach algebra norm. In particular, this implies that all Banach algebras are embedded into a Banach algebra with the strong property (\B). With regard to bounded local units, we show that all $C^*$-algebras and many group algebras have b.l.u. We investigate the hereditary properties of both notions to construct more example of Banach algebras with these properties. We apply our approach and show that the bounded $n$-cocycle spaces related to Banach algebras with the strong property (\B) and b.l.u. are hyperreflexive provided that the space of the corresponding $n+1$-coboundaries are closed. This includes nuclear C$^*$-algebras, many group algebras, matrix spaces of certain Banach algebras and finite CSL and nest algebras. We finish the thesis with introducing {\it the hyperreflexivity constant}. We make our results more precise with finding an upper bound for the hyperreflexivity constant of the bounded $n$-cocycle spaces

Upravljanje proizvodnom jedinicom spojenom na mrežu tijekom nesimetričnih napona na mreži temeljeno na kliznom režimu

The increasing presence of inverter-based distributed generation (DG) units in distribution networks (DNs) requires control methods that achieve high performance not only during normal operating conditions, but also under unbalanced conditions. With a high probability, a type of voltage unbalance in DNs is unequal three-phase voltage magnitudes at the fundamental system frequency. This can occur temporarily due to faults or permanently due to uneven distribution of unbalanced loads, on the three-phases of the DN. This paper proposes a sliding mode (SM) based controller for grid-connected DG units, under unbalanced grid voltage condition. The proposed control strategy employs a nonlinear control scheme to directly cancel out the negative-sequence (NS) components of DG output current under unbalanced voltage condition; and directly regulate the positive-sequence (PS) active and reactive power injected by DG units to main-grid. The control method proposed in this paper is shown to be robust and stable system parameter uncertainties. The validity and effectiveness of the proposed controller is verified by using time-domain simulation studies, under the MATLAB/Simulink software environment.Povećanje udjela distribuiranih proizvodnih jedinica povezanih na mrežu frekvencijskim pretvaračima zahtjeva metode upravljanja koje dobro djeluju tijekom normalnih uvjeta na mreži kao i u nesimetričnim uvjetima. Najčešći tip nesimetričnog napona na distribuiranoj jedinici je nesimetrična amplituda trofaznog napona na fundamentalnoj frekvenciji. To se događa privremeno zbog kvarova ili trajno zbog nejednake distribucije nesimetričnih tereta na tri faze distribuirane proizvodne jedinice. U ovom radu predlaže se regulator temeljen na kliznom režimu za upravljanje proizvodnom jedinicom spojenom na mrežu tijekom nesimetričnih napona na mreži. Predložena strategija upravljanja koristi nelinearnu shemu upravljanja kako bi se izravno poništile inverzne komponente izlazne struje tijekom nesimetričnih uvjeta; i izravno upravlja direktnom komponentom radne i jalove snage isporučene u mrežu. Metoda upravljanja predložena u ovom radu pokazala se kao robusna i stabilna uz nesigurne parametre sustava. Opravdanost i učinkovitost predloženog regulatora provjerena je korištenjem simulacija u MATLAB/Simulinku

Acute Flaccid Paralysis and Its Differential Diagnosis in in Kurdistan Province, Western Iran; an 11-Year Surveillance

Objective: The surveillance of acute flaccid paralysis (AFP) is a key strategy for monitoring the progress of poliomyelitis eradication and is a sensitive measure for detecting potential cases of poliomyelitis and poliovirus infection. This study was conducted to describe the characteristics of patients reported with AFP, and to evaluate the performance of the surveillance system in Kurdistan province, western Iran, using indicators recommended by the World Health Organization (WHO). Methods: This observational study was conducted from January 2000 to December 2010 at the Kurdistan Center for Disease Control and the Department of Pediatrics. All children who fulfilled the WHO definition for AFP were included in our study. The stool samples of all the children were sent for poliovirus isolation. All the patients were evaluated for 60 days after the onset of symptoms to identify the signs of residual weakness. Findings: One-hundred thirty nine children aged <15 years were reported to the Center for Diseases Control with AFP. In 138 (99%) stool samples no poliovirus was isolated. None of the patients was diagnosed as having acute poliomyelitis or polio-compatible paralysis. Guillain-Barré syndrome was the most frequent final diagnosis (79 cases) followed by Transverse Myelitis (7 cases) and Encephalitis (6 cases). By detecting 1.3 to 3.6 (mean 3.2) AFP cases per 100 000 population in Kurdistan during the study period, we achieved the WHO target for AFP surveillance. All performance indicators but one consistently met the WHO requirements and therefore demonstrated the effectiveness of the AFP surveillance program in Kurdistan. Conclusion: The effective surveillance system in Kurdistan and its evaluation may serve as a model for the surveillance of other infectious diseases

General method for state-space modeling and nonlinear control of single-phase cascaded multilevel inverters with LCL coupling

Due to the nonlinear behavior of grid-connected cascaded multilevel inverters (GCCMI), the use of nonlinear controllers can guarantee system stability over a wide range of operation. Therefore, state-space modeling is required to design nonlinear controllers. In this manuscript, a comprehensive method is proposed for the general state-space modeling of an n-level GCCMI with LCL coupling. To validate the accuracy of obtained state-space model, an experimental setup of a cascaded multilevel inverter including two H-bridges has been implemented. The outputs of the state-space model are compared with the simulation and experimental results of the GCCMI. This shows that the proposed model is compatible with a real closed-loop system. The simulations were performed using EMTDC/PSCAD software. In the following, the designed general model is used to develop a nonlinear controller based on the Lyapunov stability criteria for a multilevel shunt active power filter (SAPF). Results show that the designed controller is stable and robust in a wide range of operating point changes

Prognostic factors of 28 days survival rate in patients with a first acute myocardial infarction based on gender in Isfahan, Iran (2000-2009)

BACKGROUND: Determinant prognostic factors of 28 days survival rate in patients with a first acute myocardial infarction (AMI) based on gender in teen year�s period in Isfahan, Iran, was the aim of this study. METHODS: This study is a prospective hospital-based study that consisted, all patients with AMI admitted to all hospitals (private and universal hospitals) in Isfahan and Najafabad (Iran) during 2000-2009. To determinant the prognostic factors of 28 days survival rate in patients based on gender, analysis conducted separately for male and female. In analysis, we use of t-test, log Rank tests, Kaplan�Meier method, and univariate and multivariate Cox regression model. RESULTS: Short-term (28 days) survival rate was 92.5 in male and 86.7 in female (P < 0.001). The adjusted hazard ratio (HR) of death for age group 80 years and older was 12.7 95% confidence interval (CI): 5.14-31.3 in male and 8.78 (95% CI: 1.2-63.1) in female. HR for acute transmural MI of the unspecified site in male was 8.9 (95% CI: 4.68-16.97) and in female 9.33 (95% CI: 4.42-19.7). HR for receive of streptokinase in male was 1.11 (95% CI: 0.94-1.31) and in female was 0.69 (95% CI: 0.56-0.84). CONCLUSION: Short-term survival rate in male was a higher than female. In male age, anatomic location of MI and hospital status and in female streptokinase use and anatomic location of MI was the most important prognostic factors of survival in-patient with AMI in Isfahan. © 2015, Isfahan University of Medical Sciences(IUMS). All rights reserved