14 research outputs found
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Liver function markers and obesity-associated phenotypes: genetic and association studies
The primary goal was to study the influence of adipocyte number and volume, inflammation, insulin resistance, and genetic factors on indicators of liver injury, surrogate marker of non alcoholic fatty liver disease (NAFLD). The secondary goal was to explore the occurrence of NAFLD and its relationship with variations in liver function biomarkers. The first objective was to determine the association of plasma levels of monocyte chemoattractant protein-1 (MCP-1) with omental adipocyte number, insulin resistance and circulating concentrations of liver injury markers, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in unrelated baboons. Significant associations of MCP-1 with other measured traits were established. The second objective was to examine if adiposity-related parameters are under genetic influence and to evaluate their genetic correlations with AST in pedigreed baboons. Adipocyte volume and number, body weight and plasma AST were heritable. Genetic correlations between adiposity-related phenotypes and AST were significant. A genome wide scan yielded a strong signal for adipocyte volume on chromosome 6. The third aim was to explore the genetic factors that influence variations in plasma levels of [gamma] glutamyl transferase (GGT) and albumin (ALB), and to evaluate their genetic correlations with cardiovascular risk factors in pedigreed baboons. Significant linkages for GGT and albumin were identified on chromosome 20_22 and chromosome 10, respectively. Genetic correlations between ALB and cardiovascular risk factors were significant. No statistically significant associations were found between GGT and cardiovascular-related phenotypes. The fourth objective was to investigate the prevalence of NAFLD and its association with altered liver protein levels in unrelated baboons. The influence of weight and insulin resistance on the occurrence of NAFLD was inconclusive. Significant relationships between the variations in plasma levels of liver injury biomarkers and severity of the disease could not be established. In conclusion, the first three studies provided observational and genetic evidence of a relationship between liver function markers and adiposity-related factors in baboons. However, the results of the fourth study do not provide conclusive evidence to suggest that body weight and insulin resistance play a significant role in the development of NAFLD in these baboons.Nutritional Science
Artificial Models for Determining Antenna Parameters for a Resonant Frequency
Abstract In this paper, two models are developed based on artificial intelligence which can be used to estimate the length, width and position of the radiating element which are the design parameters of square monopole antenna required to make it operate in a particular frequency band of 4.5 GHz and 8.9 GHz. All the antennas designed using these models gives a wideband of 4.5GHz -5 GHz. One of the two models were developed using Artificial neural network (ANN
A Frequency Reconfigurable MIMO Antenna with Bandstop Filter Decoupling Network for Cognitive Communication
A compact reconfigurable MIMO antenna was developed for cognitive radio applications in this research work. A bandstop filter-based decoupling network was employed in this MIMO antenna to keep mutual coupling at a minimum. A single PIN diode was connected in the filter configuration for the purpose of reconfiguration. Controlling the ON/OFF conditions of the PIN diode, it became possible to achieve a MIMO operating frequency of 4.75 GHz in mode 1 and 1.77 GHz in mode 2, respectively. At 4.75 GHz, isolation was 42.68 dB, while at 1.77 GHz, isolation was 26.52 dB. The proposed reconfigurable MIMO antenna achieved a peak gain and radiation efficiency of 6.63 dBi and 92.04 percent in mode 1 and 4.41 dBi and 89.64 percent in mode 2. MIMO characteristics such as an envelope correlation coefficient (ECC) less than 0.253, diversity gain (DG) greater than 9.675 dB, a mean effective gain (MEG) measurement ratio of less than 0.00388 dB, and channel capacity loss (CCL) of less than 0.06528 bits/s/Hz were measured for both operational frequency bands. To make it simple to integrate into small wireless devices, the overall size of the antenna is limited to 48聽mm脳24聽mm聽0.28聽位0脳0.12聽位0
Split Ring Resonator-Based Bandstop Filter for Improving Isolation in Compact MIMO Antenna
The ever-growing expectation for high data rates has led to the introduction of multiple-input multiple-output (MIMO) technologies to wireless connectivity. Such a system requires an MIMO antenna with high isolation. At the same time, the MIMO dimension should not be compromised for achieving high isolation. Thus, isolation techniques that do not allow an increase in dimension need to be fostered for MIMO antenna design. In this paper, a novel low-profile, miniaturized MIMO antenna with high isolation was developed considering a split ring resonator (SRR)-based bandstop filter as a decoupling network. The bandstop filter was designed with a unit cell split ring resonator structure and was deployed between two closely spaced monopole MIMO antenna elements to obtain isolation as high as 39.25 dB at 2.61 GHz. Two open-circuit stub lines were attached with the MIMO feeding network to achieve good impedance matching at resonance frequency. The proposed antenna exhibited a peak gain of 3.8 dBi and radiation efficiency of 84%. It had a low envelop correlation coefficient (ECC < 0.12), high diversity gain (DG > 9.95 dB), low mean effective gain ratio (MEG 1/MEG 2 < 0.05 dB), and low channel capacity loss (CCL < 0.042 bits/s/Hz) at resonance frequency. The overall antenna dimension was restricted to 44 mm 脳22 mm (0.38 位0脳0.19 位0) for its easy integration in compact wireless devices