On DNA codes from a family of chain rings

In this work, we focus on reversible cyclic codes which correspond to reversible DNA codes or reversible-complement DNA codes over a family of finite chain rings, in an effort to extend what was done by Yildiz and Siap in [20]. The ring family that we have considered are of size $2^{2^k}$, $k=1,2, \cdots$ and we match each ring element with a DNA $2^{k-1}$-mer. We use the so-called $u^2$-adic digit system to solve the reversibility problem and we characterize cyclic codes that correspond to reversible-complement DNA-codes. We then conclude our study with some examples

Estimation and Goodness of Fit for Multivariate Survival Models Based on Copulas

We provide ways to test the fit of a parametric copula family for bivariate censored data with or without covariates. The proposed copula family is tested by embedding it in an expanded parametric family of copulas. When parameters in the proposed and the expanded copula models are estimated by maximum likelihood, a likelihood ratio test can be used. However, when they are estimated by two-stage pseudolikelihood estimation, the corresponding test is a pseudolikelihood ratio test. The two-stage procedures offer less computation, which is especially attractive when the marginal lifetime distributions are specified nonparametrically or semiparametrically. It is shown that the likelihood ratio test is consistent even when the expanded model is misspecified. Power comparisons of the likelihood ratio and the pseudolikelihood ratio tests with some other goodness-of-fit tests are performed both when the expanded family is correct and when it is misspecified. They indicate that model expansion provides a convenient, powerful and robust approach. We introduce a semiparametric maximum likelihood estimation method in which the copula parameter is estimated without assumptions on the marginal distributions. This method and the two-stage semiparametric estimation method suggested by Shih and Louis (1995) are generalized to regression models with Cox proportional hazards margins. The two-stage semiparametric estimator of the copula parameter is found to be about as good as the semiparametric maximum likelihood estimator. Semiparametric likelihood ratio and pseudolikelihood ratio tests are considered to provide goodness of fit tests for a copula model without making parametric assumptions for the marginal distributions. Both when the expanded family is correct and when it is misspecified, the semiparametric pseudolikelihood ratio test is almost as powerful as the parametric likelihood ratio and pseudolikelihood ratio tests while achieving robustness to the form of the marginal distributions. The methods are illustrated on applications in medicine and insurance. Sequentially observed survival times are of interest in many studies but there are difficulties in modeling and analyzing such data. First, when the duration of followup is limited and the times for a given individual are not independent, the problem of induced dependent censoring arises for the second and subsequent survival times. Non-identifiability of the marginal survival distributions for second and later times is another issue, since they are observable only if preceding survival times for an individual are uncensored. In addition, in some studies, a significant proportion of individuals may never have the first event. Fully parametric models can deal with these features, but lack of robustness is a concern, and methods of assessing fit are lacking. We introduce an approach to address these issues. We model the joint distribution of the successive survival times by using copula functions, and provide semiparametric estimation procedures in which copula parameters are estimated without parametric assumptions on the marginal distributions. The performance of semiparametric estimation methods is compared with some other estimation methods in simulation studies and shown to be good. The methodology is applied to a motivating example involving relapse and survival following colon cancer treatment

SELF-REGULATION OF NOVICE MIDDLE SCHOOL MATHEMATICS TEACHERS IN THE PREPARATION PROCESS FOR TEACHING

This study analyses the self-regulation (goal setting and planning) of the novice middle school mathematics teachers during the preparation phase of teaching. The study is designed as a case study. The participants are six mathematics teachers with less than five-year teaching experience. The data were collected through interviews, observations and document analysis. In regard to the observations, the teaching of certain topics (e.g., basic elements of prisms) were observed to uncover the classroom behavior of the participants. In the semi-structured interviews carried out after the class observations, the participants were asked some questions about their goals and planning concerning the related teaching activities. The findings of the study indicate that the participants do not exhibit the goal setting and planning activities that are consistent with the conceptual learning covered in the mathematics education program. It is also found that they do not set clear goals and develop detailed planning in regard to teaching activities

Marka özgünlüğünün marka tercihi, müşteri tatmini ve marka sadakati üzerindeki etkileri: Bilgisayar markaları üzerine bir araştırma

Sunulan ürün ve hizmetlerin tek başına yeterli olmadığı günümüz ortamında tüketiciler, kendileri için bir anlam ifade edebilecek, kendisini diğer markalardan farklılaştıracak ve .zgün bir değere sahip olan markaları tercih etmektedirler. .zgün olmak işletmeler açısından önemli bir unsur olarak g.rülmektedir. Ancak işletmeler ve literatür açısından artan önemine rağmen, marka .zgünlüğüne yönelik olarak yapılan çalışmalar oldukça kısıtlıdır. Bu araştırmanın amacı, günümüzde markalar açısından fark yaratan bir unsur olarak .zgünlük kavramının pazarlama dinamikleri açısından irdelenmesi ve tüketicilerin tercihleri, tatmin dereceleri ve marka sadakatleri üzerindeki etkisinin incelenmesidir. Bilgisayar markalarına yönelik olarak yapılan araştırmada, 415 tüketiciye ulaşılmış ve verilerin analizinde yapısal eşitlik modeli kullanılmıştır. Araştırma sonucunda tüketicilere farklı deneyimler sunan, güvenilir vaatlerde bulunan ve bunları gerçekleştiren markaların, tüketicilerin tercihlerini önemli .l.üde biçimlendirdikleri g.rülmektedir

Clinical symptoms and diagnostic tools that are related to infertility and hydrosalpinx formation in women with advanced stage endometriosis complicated by endometrioma

Objectives: The study included patients suffering from stage III-IV endometriosis complicated by an endometrioma (OMA). We investigated the association between age, presence of dysmenorrhea/dyspareunia, preoperative CA 125 level, size of OMA on ultrasonographic exam and infertility, as well as the risk of intraoperative detection of hydrosalpinx that was not suspected on pre-operative assessment. Materials and Methods: The study included patients with stage III-IV endometriosis complicated by OMA who underwent a laparoscopic or open surgery due to pre-diagnosis of infertility or adnexal mass. Results: Dysmenorrhea had statistically significant association with infertility (p=0.031). There was no statistically significant relation between age, dyspareunia, preoperative CA 125 level, size of OMA on ultrasonographic exam and infertility (p=0. 203, p=0.561, p=0.561 and p=0.668, respectively). No statistically significant relation was found between age, CA 125 level, dysmenorrhea, dyspareunia and detection of an unilateral/bilateral hydrosalpinx, that was not suspected on pre-operative assessment (p=0.179, p=0.295, p=0.895, p=0.424, respectively). There was an association between OMA size (p=0.023) and detection of unilateral/bilateral hydrosalpinx. Conclusions: Patients who desire to have children but suffer from severe dysmenorrhea must be preoperatively informed about the possibility of having stage III-IV endometriosis. Infertile patients who are about to undergo an operation, especially due to a large OMA, may turn out to have hydrosalpinx. These patients should be informed preoperatively about the possibility of having salpingectomy or the proximal tubal surgery for improving fertility

A Novel Electrochemical Sensor for the Detection of Reactive Red Dye to Determine Water Quality

In this study, tragacanth gum/chitosan/ZnO nanoprism-based electrochemical sensors were prepared for sensing reactive dyes in water. To use an electrochemical sensor, a ~250 nm-sized ZnO nanoprism was synthesized via ultrasonic-assisted green synthesis method, using tragacanth gum and chitosan polymer blend as a matrix. The electrochemical properties of tragacanth gum/chitosan/ZnO nanoprisms were compared against reactive red 35, reactive yellow 15, and reactive black 194. The electrochemical measurement results indicated that prepared tragacanth gum/chitosan/ZnO nanoprism-based electrochemical sensor detected 25 ppm reactive red 35 in 1 min at room temperature. This study reveals new high-potential novel tragacanth gum/chitosan/ZnO nanoprism-based sensing material for the detection of reactive red dye-consisted wastewater with high sensitivity and short response time

Defect assisted optical limiting performance of hexagonal boron nitride nanosheets in aqueous suspension and PMMA nanocomposite films

Defect-assisted nonlinear absorption (NLA) and optical limiting (OL) performance of hexagonal boron nitride nanosheets (h-BNNS) in aqueous suspension and in polymethyl methacrylate matrix (PMMA) as nanocomposite films were studied using open-aperture Z-scan method. To evaluate the transmission in open-aperture Z-scan data, a theoretical model accounting one photon absorption (OPA), two photon absorption (TPA), free carrier absorption (FCA) and saturation of each process was considered. Defect-assisted NLA coefficients and saturation intensity thresholds were extracted from the fitting of the experimental results for 532 and 1064 nm pulse wavelengths. Strong defect-assisted NLA response of h-BNNS was observed while NLA at 532 nm was considerably stronger. This is attributed to the excitation of a greater number of defect states over a wider energy range. Our findings showed that h-BNNS/PMMA nanocomposite films feature highly required properties in OL applications and can function in OL applications in a wide spectral range (-200-1064 nm)

Electrically conductive high–performance thermoplastic filaments for fused filament fabrication

Conductive polyetherimide (PEI)-based filaments can fill the gap between the design and manufacturing of functional and structural components through additive manufacturing. This study systematically describes the fabrication of carbon nanotube (CNTs)-reinforced PEI filaments, complemented by a custom-built extrusion process facilitating low weight fraction of nanomaterials. Neat PEI and CNTs/PEI filaments at different CNTs fractions ranging from 0.1 to 7 wt. % were fabricated. Supported by morphology analysis, the rheological percolation was found to be higher (0.25 wt. % CNTs/PEI) than electrical percolation (0.1 wt. % CNTs/PEI) since the system reached an electrical percolation within the formation of a continuous conductive path at lower CNTs loadings. With the 7 wt. % CNTs loading, the highest electrical conductivity of CNTs/PEI filaments was reported as 2.57 × 10−1 S/cm. A 55% enhancement in tensile modulus was achieved when 5 wt. % CNTs were introduced, but in a trade-off in elongation at break ca. 65%

Self-reported adherence and pharmacy refill adherence are both predictive for an undetectable viral load among HIV-infected migrants receiving cART

HIV-infected migrants were shown to have poorer treatment outcomes than Dutch HIV-infected patients, often due to worse treatment adherence. Self-reported adherence would be an easy way to monitor adherence, but its validity relative to pharmacy refill adherence has not been extensively evaluated in migrants. All HIV-infected migrants older than 18 years and in care at the two Rotterdam HIV-treatment centers were eligible. Refill data with leftover medication (PRL) (residual pill count) were obtained from their pharmacies up to 15 months prior to inclusion. Self-reported adherence to combination Antiretroviral Therapy was assessed by four questions about adherence at inclusion. Additionally, risk factors for pharmacy refill non-adherence were examined. In total, 299 HIV-infected migrants were included. Viral load (VL) was detectable in 11% of the patients. Specificity of PRL was 53% for patients with an adherence of 100% and decreased with lower cut-off values. Sensitivity and negative predictive value (NPV) were 68% and 15% and increased with lower cut-off values. Positive predictive value (PPV) was around 93% for all cut-off values. Using the self-reported questions, 139 patients (47%) reported to be adherent. Sensitivity was 49% and specificity was 72%. PPV and NPV were 95% and 13%. No risk factors for pharmacy refill non-adherence were found in multivariable analyses. Both PRL and self-reported adherence, can predict undetectable VL in HIV-infected migrants. PPV and NPV are similar for both methods. This study shows that using four self-reported items is sufficient to predict adherence which is crucial for optimal clinical outcome in HIV-infected migrants

Ultrafast electron/energy transfer and intersystem crossing mechanisms in bodipy-porphyrin compounds

Meso-substituted borondipyrromethene (BODIPY)-porphyrin compounds that include free base porphyrin with two different numbers of BODIPY groups (BDP-TTP and 3BDP-TTP) were designed and synthesized to analyze intramolecular energy transfer mechanisms of meso-substituted BODIPY-porphyrin dyads and the effect of the different numbers of BODIPY groups connected to free-base porphyrin on the energy transfer mechanism. Absorption spectra of BODIPY-porphyrin conjugates showed wide absorption features in the visible region, and that is highly valuable to increase light-harvesting efficiency. Fluorescence spectra of the studied compounds proved that BODIPY emission intensity decreased upon the photoexcitation of the BODIPY core, due to the energy transfer from BODIPY unit to porphyrin. In addition, ultrafast pump-probe spectroscopy measurements indicated that the energy transfer of the 3BDP-TTP compound (about 3 ps) is faster than the BDP-TTP compound (about 22 ps). Since the BODIPY core directly binds to the porphyrin unit, rapid energy transfer was seen for both compounds. Thus, the energy transfer rate increased with an increasing number of BODIPY moiety connected to free-base porphyrin