A reconfigurable wideband and multiband antenna using dual-patch elements for compact wireless devices

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 IEEEA reconfigurable wideband and multiband C-Slot patch antenna with dual-patch elements is proposed and studied. It occupies a compact volume of 50 × 50 × 1.57 (3925 mm3), including the ground plane. The antenna can operate in two dual-band modes and a wideband mode from 5 to 7 GHz. Two parallel C-Slots on the patch elements are employed to perturb the surface current paths for excitation of the dual-band and the wideband modes. Two switches, implemented using PIN diodes, are placed on the connecting lines of a simple feed network to the patch elements. Dual-band modes are achieved by switching “ON” either one of the two patch elements, while the wideband mode with an impedance bandwidth of 33.52% is obtained by switching “ON” both patch elements. The frequencies in the dual-band modes can be independently controlled using positions and dimensions of the C-Slots without affecting the wideband mode. The advantage of the proposed antenna is that two dual-band operations and one wideband operation can be achieved using the same dimensions. This overcomes the need for increasing the surface area normally incurred when designing wideband patch antennas. Simulation results are validated experimentally through prototypes. The measured radiation patterns and peak gains show stable responses and are in good agreements. Coupling between the two patch elements plays a major role for achieving the wide bandwidth and the effects of mutual coupling between the patch elements are also studied

Adoption of Mobile Money Transfer Technology: Structural Equation Modeling Approach

In recent years, rapid spread of mobile phones use in the developing countries is as a consequence ofthe introduction of prepaid cards and the fallen prices of mobile handsets. One of such uses is the useof mobile phones in financial services industry. This study investigates the key factors that influencethe Ghanaian consumers' acceptance and use of mobile money transfer technology using keyconstructs from the Technology Acceptance Model (TAM) and Diffusion of Innovation (DoI) theory.We analyzed the data using a Structural Equation Modeling (SEM) to evaluate the strength of therelationship between the constructs. The results were consistent with the key TAM and DoI constructs.Keywords: Technology Acceptance Model, Adoption, Mobile Money Transfer Technology, Diffusionof Innovation theory, Ghana

Observed changes in surface atmospheric energy over land

The temperature of the surface atmosphere over land has been rising during recent decades. But surface temperature, or, more accurately, enthalpy which can be calculated from temperature, is only one component of the energy content of the surface atmosphere. The other parts include kinetic energy and latent heat. It has been advocated in certain quarters that ignoring additional terms somehow calls into question global surface temperature analyses. Examination of all three of these components of atmospheric energetics reveals a significant increase in global surface atmospheric energy since the 1970s. Kinetic energy has decreased but by over two orders of magnitude less than the increases in both enthalpy and latent heat which provide approximately equal contributions to the global increases in heat content. Regionally, the enthalpy or the latent heat component can dominate the change in heat content. Although generally changes in latent heat and enthalpy act in concert, in some regions they can have the opposite signs

Tensin1 expression and function in chronic obstructive pulmonary disease

open access articleChronic obstructive pulmonary disease (COPD) constitutes a major cause of morbidity and mortality. Genome wide association studies have shown significant associations between airflow obstruction or COPD with a non-synonymous SNP in the TNS1 gene, which encodes tensin1. However, the expression, cellular distribution and function of tensin1 in human airway tissue and cells are unknown. We therefore examined these characteristics in tissue and cells from controls and people with COPD or asthma. Airway tissue was immunostained for tensin1. Tensin1 expression in cultured human airway smooth muscle cells (HASMCs) was evaluated using qRT-PCR, western blotting and immunofluorescent staining. siRNAs were used to downregulate tensin1 expression. Tensin1 expression was increased in the airway smooth muscle and lamina propria in COPD tissue, but not asthma, when compared to controls. Tensin1 was expressed in HASMCs and upregulated by TGFβ1. TGFβ1 and fibronectin increased the localisation of tensin1 to fibrillar adhesions. Tensin1 and α-smooth muscle actin (αSMA) were strongly co-localised, and tensin1 depletion in HASMCs attenuated both αSMA expression and contraction of collagen gels. In summary, tensin1 expression is increased in COPD airways, and may promote airway obstruction by enhancing the expression of contractile proteins and their localisation to stress fibres in HASMCs

Microenvironment-induced downregulation of miR-193b drives ovarian cancer metastasis

The cross-talk between ovarian cancer (OvCa) cells and the metastatic microenvironment is an essential determinant of successful colonization. MicroRNAs (miRNAs) have several critical roles during metastasis; however, the role of microenvironmental cues in the regulation of miRNAs in metastasizing cancer cells has not been studied. Using a three-dimensional culture model that mimics the human omentum, one of the principal sites of OvCa metastasis, we identified and characterized the microenvironment-induced downregulation of a tumor suppressor miRNA, miR-193b, in metastasizing OvCa cells. The direct interaction of the OvCa cells with mesothelial cells, which cover the surface of the omentum, caused a DNA methyltransferase 1-mediated decrease in the expression of miR-193b in the cancer cells. The reduction in miR-193b enabled the metastasizing cancer cells to invade and proliferate into human omental pieces ex vivo and into the omentum of a mouse xenograft model of OvCa metastasis. The functional effects of miR-193b were mediated, in large part, by the concomitant increased expression of its target, urokinase-type plasminogen activator, a known tumor-associated protease. These findings link paracrine signals from the microenvironment to the regulation of a key miRNA in cancer cells. Targeting miR-193b, which is essential for metastatic colonization of cancer cells could prove effective in the treatment of OvCa metastasis

Cumulative social risk and type 2 diabetes in US adults: The National Health and Nutrition Examination Survey (NHANES) 1999–2006

Background: The cumulative effects of adverse social factors on the diabetes risk remains to be clarified. Design: Cross-sectional analysis of the US National Health and Nutrition Examination Survey (NHANES) 1999–2006. Methods: We included 10,276 adults aged ≥20 years. Diabetes mellitus was defined by physician diagnosis or fasting plasma glucose (≥126 mg/dl) or glycated hemoglobin (≥6.5%). Social risk factors (low family income, low education level, minority racial/ethnic group status, and single-living status) and health-related behaviors (physical activity and dietary intake) were self-reported. Social risk factors were combined in a cumulative social risk index (range 0 to ≥3) and logistic regression used to assess the association of cumulative social risk and diabetes, taking into account complex survey design and sampling weights. Results: Of 10,276 participants, 1515 (weighted proportion – 10%) had diabetes, 3295 (32.3%) and 1830 (9.0%) were exposed to ≥1 adverse social risk factor and ≥3 social risk factors, respectively. Diabetes was associated with increasing cumulative social risk in a graded manner (p for trend <0.001). Compared with a cumulative social risk score of 0, the age- and sex-adjusted diabetes odds for a cumulative social risk score of ≥3 was 2.84 (95% confidence interval: 2.23–3.62), and 2.72 (95% confidence interval: 2.05–3.60) after further adjustment for family history of diabetes, body mass index, smoking, dietary intake and leisure time physical activity. Health behaviors and adiposity only partially influenced the cumulative social risk and diabetes relationship. Conclusions: Simultaneous exposure to several adverse social risk factors significantly influences the odds of diabetes. Better prevention and control of diabetes needs accounting for all aspects of social disadvantage