Characterization of an embedded RF-MEMS switch

An RF-MEMS capacitive switch for mm-wave integrated circuits, embedded in the BEOL of 0.25μm BiCMOS process, has been characterized. First, a mechanical model based on Finite-Element-Method (FEM) was developed by taking the residual stress of the thin film membrane into account. The pull-in voltage and the capacitance values obtained with the mechanical model agree very well with the measured values. Moreover, S-parameters were extracted using Electromagnetic (EM) solver. The data observed in this way also agree well with the experimental ones measured up to 110GHz. The developed RF model was applied to a transmit/receive (T/R) antenna switch design. The results proved the feasibility of using the FEM model in circuit simulations for the development of RF-MEMS switch embedded, single-chip multi-band RF ICs

Relationship between serum bilirubin levels and metabolic syndrome in patients with schizophrenia spectrum disorders

Objective: We investigated the relationship between serum bilirubin levels and metabolic syndrome (MetS), and the longitudinal effects of baseline serum bilirubin concentrations on MetS in patients with schizophrenia spectrum disorders undergoing atypical antipsychotics. Methods: The sample of this study consisted of 131 patients with schizophrenia spectrum disorders. Waist circumference, blood pressure, and levels of triglycerides, high-density lipoprotein cholesterol, fasting glucose, and insulin were evaluated at baseline and at month six. Serum bilirubin levels were measured at baseline. Serum bilirubin levels of the patients with and without MetS criteria were compared. We also compared patients with high and low bilirubin levels (upper and lower 50th percentiles of serum bilirubin levels) in terms of MetS criteria, MetS frequency, and course of MetS. Results: Serum direct bilirubin levels were more consistently related to MetS and MetS-related variables. The waist circumference and triglyceride criteria for MetS were significantly related to low serum direct bilirubin at baseline; waist circumference and fasting glucose criteria, and insulin resistance were associated with low serum direct bilirubin at follow-up. MetS diagnosis and the presence of the waist circumference criterion were more frequent at the baseline and the follow-up in low bilirubin group. At the end of the follow-up period, the rate of reverse MetS was significantly higher in the high bilirubin group. Conclusion: Our results have suggested that serum direct bilirubin levels showed a more reliable and stable relationship with abdominal obesity for MetS components.in patients with schizophrenia spectrum disorders using antipsychotics. Further studies are required. Copyright © 2017, Korean College of Neuropsychopharmacology

Magnetic critical behavior of two-dimensional random-bond Potts ferromagnets in confined geometries

We present a numerical study of 2D random-bond Potts ferromagnets. The model is studied both below and above the critical value $Q_c=4$ which discriminates between second and first-order transitions in the pure system. Two geometries are considered, namely cylinders and square-shaped systems, and the critical behavior is investigated through conformal invariance techniques which were recently shown to be valid, even in the randomness-induced second-order phase transition regime Q>4. In the cylinder geometry, connectivity transfer matrix calculations provide a simple test to find the range of disorder amplitudes which is characteristic of the disordered fixed point. The scaling dimensions then follow from the exponential decay of correlations along the strip. Monte Carlo simulations of spin systems on the other hand are generally performed on systems of rectangular shape on the square lattice, but the data are then perturbed by strong surface effects. The conformal mapping of a semi-infinite system inside a square enables us to take into account boundary effects explicitly and leads to an accurate determination of the scaling dimensions. The techniques are applied to different values of Q in the range 3-64.Comment: LaTeX2e file with Revtex, revised versio

Study of two bioactive peptides in vacuum and solvent by molecular modeling

The thermodynamic and structural properties of Tyrosine-Glycine-Leusine- Phenylalanine (YGLP, in a one letter code) and Lysine-Valine-Leusine-Proline- Valine-Proline-Glutamine (KVLPVPQ) peptide sequences were studied by three-dimensional molecular modeling in vacuum and solution. All the three-dimensional conformations of each peptide sequences were obtained by multicanonical simulations with using ECEPP/2 force field and each simulation started from completely random initial conformation. Solvation contributions are included by a term that is proportional to solvent-accessible surface areas of peptides. In the present study, we calculated the average values of total energy, specific heat, fourth-order cumulant and end-to-end distance for two peptide sequences of milk protein as a function of temperature. With using major advantage of this simulation technique, Ramachandran plots were prepared and analysed to predict the relative occurrence probabilities of ß-turn, ?-turn and helical structures. Although structural predictions of these sequences indicate both the presence of high level of ?-turns and low level of ß-turns in vacuum and solvent, it was observed that these probabilities in vacuum were higher than the ones in solvent model. © World Scientific Publishing Company

Solvation model effects on two specific peptides of milk protein

The equilibrium thermodynamic properties of two bioactive peptide sequences which have great effects on blood pressure were studied by three-dimensional molecular modeling in an aqueous solution. Our first peptide, Tyrosine-Glycine-Leucine-Phenylalanine (YGLF, in a one letter code), is found in the primary structure of bovine milk whey protein ?-LA (residue 50-53). The other peptide, Lysine-Valine-Leusine-Proline-Valine-Proline-Glutamine (KVLPVPQ) takes in the ß-casein (ß-CN) (residue 169-175) part of milk. All the three-dimensional conformations of each peptide sequences were obtained by multicanonical simulations with the use of an ECEPP/2 force field, and the solvation contributions are included by a term that is proportional to the solvent accessible surface area of the peptide. Each simulation was started from a completely random initial conformation. No ?-priori information about the ground-state was used in the simulations. In the present study, in order to determine the solvation model dependency of the thermodynamic properties, we calculated the average values of the total energy, specific heat, fourth-order cumulant, and end-to-end distance for these peptide sequences of milk protein as a function of temperature in two solvation models. We observed that the specific heat of each peptide shows a different behavior in the solvation models, which have one or two peaks as a function of temperature. That is why we have also investigated the structural properties to gain insight into the relation of these peaks with the structural transitions. Our results indicate that the calculated thermodynamic and structural properties of each peptide really depend on the chosen solvent model. © 2007 The Physical Society of the Republic of China

The study of helix-coil transition of polyalanine with single histogram method

We have studied helix-coil transition in all-atom model of polyalanine in vacuum and distance-dependent dielectric function solvent model. Molecules of up to length 30 residues were investigated by Monte Carlo method. The single histogram method was performed to obtain thermodynamic quantities such as average energy and specific heat. We have also calculated probability distribution of energy and Binder cumulant as well as autocorrelation times for both case in order to identify the order of phase transition by using finite-size scaling arguments. Even though the probability distributions showed a single Gaussian peak, especially for this solvent model, the significant differences between the vacuum and solvent model were observed at their specific heat maximum values and Binder cumulant behaviors. While Binder cumulant has a deep valley for vacuum, it is not sensitive for the distance-dependent dielectric function solvent model. Our data are consistent with recently obtained results for polyalanine by multicanonical method. © 2006 Elsevier B.V. All rights reserved.02.02.602.003We acknowledge the support of the Hacettepe University Scientific Research Fund through the project 02.02.602.003