Novel CCII-based Field Programmable Analog Array and its Application to a Sixth-Order Butterworth LPF

In this paper, a field programmable analog array (FPAA) is proposed. The proposed FPAA consists of seven configurable analog blocks (CABs) arranged in a hexagonal lattice such that the CABs are directly connected to each other. This structure improves the overall frequency response of the chip by decreasing the parasitic capacitances in the signal path. The CABS of the FPAA is based on a novel fully differential digitally programmable current conveyor (DPCCII). The programmability of the DPCCII is achieved using digitally controlled three-bit MOS ladder current division network. No extra biasing circuit is required to generate specific analog control voltage signals. The DPCCII has constant standby power consumption, offset voltage, bandwidth and harmonic distortions over all its programming range. A sixth-order Butterworth tunable LPF suitable for WLAN/WiMAX receivers is realized on the proposed FPAA. The filter power consumption is 5.4mW from 1V supply; it’s cutoff frequency is tuned from 5.2 MHz to 16.9 MHz. All the circuits are realized using 90nm CMOS technology from TSMC. All simulations are carried out using Cadence

Hydromagnetic boundary layer micropolar fluid flow over a stretching surface embedded in a non-darcian porous medium with radiation

We have studied the effects of radiation on the boundary layer flow and heat transfer of an electrically conducting micropolar fluid over a continuously moving stretching surface embedded in a non-Darcian porous medium with a uniform magnetic field. The transformed coupled nonlinear ordinary differential equations are solved numerically. The velocity, the angular velocity, and the temperature are shown graphically. The numerical values of the skin friction coefficient, the wall couple stress, and the wall heat transfer rate are computed and discussed for various values of parameters

Young LMC clusters: the role of red supergiants and multiple stellar populations in their integrated light and CMDs

The optical integrated spectra of three LMC young stellar clusters (NGC 1984, NGC 1994 and NGC 2011) exhibit concave continua and prominent molecular bands which deviate significantly from the predictions of single stellar population (SSP) models. In order to understand the appearance of these spectra, we create a set of young stellar population (MILES) models, which we make available to the community. We use archival International Ultraviolet Explorer integrated UV spectra to independently constrain the cluster masses and extinction, and rule out strong stochastic effects in the optical spectra. In addition, we also analyze deep colour-magnitude diagrams of the clusters to provide independent age determinations based on isochrone fitting. We explore hypotheses including age-spreads in the clusters, a top-heavy initial mass function, different SSP models and the role of red supergiant stars (RSG). We find that the strong molecular features in the optical spectra can only be reproduced by modeling an increased fraction of about 20 per cent by luminosity of RSG above what is predicted by canonical stellar evolution models. Given the uncertainties in stellar evolution at Myr ages, we cannot presently rule-out the presence of Myr age-spreads in these clusters. Our work combines different wavelengths as well as different approaches (resolved data as well as integrated spectra for the same sample) in order to reveal the complete picture. We show that each approach provides important information but in combination can we better understand the cluster stellar populations.Comment: Accepted for publication in MNRA

Loneliness, friendship, and facebook intrusion. A study in Poland, Slovakia, Syria, Malaysia, and Ecuador

With the increasing popularity of Facebook, a new social phenomenon connected with its extensive use has appeared: namely, Facebook intrusion. The main aim of the study was to examine the mediating role of loneliness in the relation between friendships and Facebook intrusion. We analyzed data from five countries: Poland (N = 399), Slovakia (N = 266), Syria (N = 475), Ecuador (N = 327), and Malaysia (N = 241). The total sample consisted of 1731 participants who had Facebook accounts; 61% of the participants were women. We administered the Facebook Intrusion Scale, the Loneliness Scale, and the Friendship Scale. The results indicated differences in the role of loneliness and friendship in Facebook intrusion, depending on the country. Among young Polish people, friendship decreases loneliness and loneliness decreases Facebook intrusion. Whereas among Ecuadorians friendship decreases loneliness, while loneliness increases Facebook intrusion

MAT-708: MONITORING THE CORROSION PROCESS OF REINFORCED CONCRETE FLAT SLAB-COLUMN CONNECTION

The corrosion of the steel reinforcement embedded in a two-way reinforced concrete flat slab around the column stub area was investigated in this study, which aimed to studying the effect of corrosion on the shear punching behavior. Two square flat slab-column connections were cast, the flat slab dimension was 1900 mm × 1900 mm × 150 mm, and the column dimensions was 250 mm × 250 mm. A specific delaminated area was corroded around the column stub to emphasize the effect of corrosion around punching area. The corrosion reached two levels of mass loss uniformly over that specified area: 0% and 26%. Corrosion process was monitored under an accelerated corrosion technique through the application of a constant potential of fifteen volts to reach the targeted uniform corrosion level. Then, the corrode slab-column connection was loaded until failure for each slab occurred. The corrosion performance of the slab was evaluated based on the results of the current measurement, half-cell potential tests, and mass loss. The test results show that the corrosion of reinforcement rebar around the column stub in flat slab causes a significant loss in punching shear capacity and affects the structural integrity by increasing crack widths

Modulation of endoglin expression in islets of langerhans by VEGF reveals a novel regulator of islet endothelial cell function

BACKGROUND: Endoglin/CD105 is an auxiliary receptor for transforming growth factor-β with established roles in vascular remodelling. It has recently been shown that heterozygous endoglin deficiency in mice decreases insulin secretion in an animal model of obesity, highlighting a potential role for endoglin in the regulation of islet function. We have previously identified two different populations of endoglin expressing cells in human and mouse islets which are: (i) endothelial cells (ECs) and (ii) islet mesenchymal stromal cells. The contribution of islet EC endoglin expression to islet development and sensitivity to VEGF is unknown and is the focus of this study. RESULTS: In vitro culture of mouse islets with VEGF164 for 48 h increased endoglin mRNA levels above untreated controls but VEGF did not modulate VEGFR2, CD31 or CD34 mRNA expression or islet viability. Removal of EC-endoglin expression in vivo reduced islet EC area but had no apparent effect on islet size or architecture. CONCLUSION: EC-specific endoglin expression in islets is sensitive to VEGF and plays partial roles in driving islet vascular development, however such regulation appears to be distinct to mechanisms required to modulate islet viability and size

Wave propagation over a beach within a nonlinear theory

Wave propagation over a beach is considered within a nonlinear theory in shallow water. Lagrangian coordinates are used to describe the problem. The solution is expanded in double series involving a small parameter and local oscillations. Two cases are treated: The beach with appreciable inclination on the horizontal (cliff) and the beach of small inclination. We show that finite solutions are obtained, in contrast to the linear theory which involves a logarithmic singularity at the shoreline. For the cliff, it is shown that local oscillations do not appear in the first two orders of approximation, and the incident wave is totally reflected without loss of energy at this order of approximation. The case of an incident wave on the beach is considered. The deformation of this wave is investigated and explicit formulae are obtained for the reflected wave and for the local oscillations, to shed light on the energy transfer due to interaction with the beach

CO2 laser beam welding of AM60 magnesium-based alloy

The authors are grateful to FONDERIE MESSIER HONSEL group that provided the as-cast magnesium alloy workpieces. The authors would like also to acknowledge the technical support of Dr. Moraru of the LSIS Laboratory-Arts et Métiers ParisTech-Aix En Provence-France.Magnesium alloys have a 33% lower density than aluminum alloys, whereas they exhibit the same mechanical characteristics. Their application increases in many economic sectors, in particular, in aeronautic and automotive industries. Nevertheless, their assembly with welding techniques still remains to be developed. In this paper, we present a CO2 laser welding investigation of AM60 magnesium-based alloy. Welding parameters range is determinate for the joining of 3 mm thickness sheets. The effects of process parameters including beam power, welding speed, focusing position, and shielding gas flow are studied. Experimental results show that the main parameters that determine the weld quality are the laser beam power, the welding speed, and the shielding gas flow. The focal point position has a minor effect on weld quality, however, it has an influence on melting zone width. For optimized welding parameters, metallurgical observations show that after laser welding of AM60 alloy dendritic microstructure is observed on melting zone after high solidification rate. A small heat affected zone is also detected. Finally, hardness tests indicate that microhardness of the weld is higher than that of base metal