22,945 research outputs found
Will mobile video become the killer application for 3G? - an empirical model for media convergence
Mobile carriers have continually rolled out 3G mobile video applications to increase their revenue and profits. The presumption is that video is superior to the already successful SMS, ringtones, and pictures, and can create greater value to users. However, recent market surveys revealed contradicting results. Motivated by this discrepancy, we propose in this paper a parsimonious model for user acceptance of mobile entertainment as digital convergence. Integrating research on Information Systems, Flow, and Media Psychology, we take a unique approach to user acceptance of digital convergence - platform migration. Our key proposition is that the interaction between media types and the platform-specific constraints is the key determinant of user evaluation. Particularly, users' involvement in the media is determined by both the entertaining time span on the original platform and the attentional constraint of the new platform. The mismatch between the two spans can result in lower level involvement, which in turn cause no or even negative user emotional responses. The model was tested with empirical data. We discuss the theoretical contributions, strategic and design implications, and future research directions derived from this theoretical framewor
Strength asymmetry increases gait asymmetry and variability in older women.
Purpose—The aim of the research was to determine how knee extensor strength asymmetry influences gait asymmetry and variability since these gait parameters have been related to mobility and falls in older adults. Methods—Strength of the knee extensors was measured in 24 older women (65 – 80 yr). Subjects were separated into symmetrical strength (SS, n = 13) and asymmetrical strength (SA, n = 11) groups using an asymmetry cutoff of 20%. Subjects walked at a standard speed of 0.8 m s−1 and at maximal speed on an instrumented treadmill while kinetic and spatiotemporal gait variables were measured. Gait and strength asymmetry were calculated as the percent difference between legs and gait variability as the coefficient of variation over twenty sequential steps. Results—SA had greater strength asymmetry (27.4 ± 5.5%) than SS (11.7 ± 5.4%, P \u3c 0.001). Averaged across speeds, SA had greater single (7.1% vs. 2.5%) and double-limb support time asymmetry (7.0 vs. 4.3%) than SS and greater single-limb support time variability (9.7% vs. 6.6%, all P \u3c 0.05). Group × speed interactions occurred for weight acceptance force variability (P = 0.02) and weight acceptance force asymmetry (P = 0.017) with greater variability at the maximal speed in SA (5.0 ± 2.4% vs. 3.7 ± 1.2%) and greater asymmetry at the maximal speed in SA (6.4 ± 5.3% vs. 2.5 ± 2.3%). Conclusion—Gait variability and asymmetry are greater in older women with strength asymmetry and increase when they walk near their maximal capacities. The maintenance of strength symmetry, or development of symmetry through unilateral exercise, may be beneficial in reducing gait asymmetry, gait variability, and fall risk in older adults
Long-term clinical and radiographic analysis of platform matching and platform switching implants in the esthetic zone: a retrospective cohort study
Background: The aims of this study are to retrospectively compare the clinical, radiographic and esthetic outcomes of platform switching (PS) and platform matching (PM) dental implants in the anterior maxilla after ≥ 10 years of functional loading. Methods: Marginal bone loss (MBL) levels were recorded; furthermore, peri-implant clinical parameters (PPD, BOP, PI) were collected and the Pink and White Esthetic scores (PES/WES) were used to evaluate the esthetic outcomes. Wilcoxon signed rank tests were performed to compare collected parameters among the two groups, with a p-value < 0.05. Results: A final sample of 58 patients was enrolled in this study (PM implants = 29; PS implants = 29). PS implants showed lower MBL levels (1.02 ± 0.81 mm vs. 1.67 ± 0.99 mm, p = 0.028) and PPD values (3.69 ± 1.1 vs. 5.16 ± 1.09 mm, p < 0.001) compared to PM implants. Mean PES values were higher in the PS group compared to the PM group (8.46 ± 0.69 vs. 7.89 ± 0.78, p < 0.005), while there were no differences for WES values (7.82 ± 1.09 vs. 7.71 ± 0.85, p > 0.05) and peri-implant diseases’ prevalence (p > 0.05). Conclusions: After 10 years, PS implants showed statistically significant lower MBL and PPD values and higher PES values compared to PM implants
Validation of Advanced EM Models for UXO Discrimination
The work reported here details basic validation of our advanced physics-based
EMI forward and inverse models against data collected by the NRL TEMTADS
system. The data was collected under laboratory-type conditions using both
artificial spheroidal targets and real UXO. The artificial target models are
essentially exact, and enable detailed comparison of theory and data in support
of measurement platform characterization and target identification. Real UXO
targets cannot be treated exactly, but it is demonstrated that quantitative
comparisons of the data with the spheroid models nevertheless aids in
extracting key target discrimination information, such as target geometry and
hollow target shell thickness.Comment: 15 pages, 16 figure
Low disordered, stable, and shallow germanium quantum wells: a playground for spin and hybrid quantum technology
Buried-channel semiconductor heterostructures are an archetype material
platform to fabricate gated semiconductor quantum devices. Sharp confinement
potential is obtained by positioning the channel near the surface, however
nearby surface states degrade the electrical properties of the starting
material. In this paper we demonstrate a two-dimensional hole gas of high
mobility ( cm/Vs) in a very shallow strained germanium
channel, which is located only 22 nm below the surface. This high mobility
leads to mean free paths , setting new benchmarks for holes in
shallow FET devices. Carriers are confined in an undoped Ge/SiGe
heterostructure with reduced background contamination, sharp interfaces, and
high uniformity. The top-gate of a dopant-less field effect transistor controls
the carrier density in the channel. The high mobility, along with a percolation
density of , light effective mass (0.09
m), and high g-factor (up to ) highlight the potential of undoped
Ge/SiGe as a low-disorder material platform for hybrid quantum technologies
Cesium standard for satellite application
A Cesium frequency standard that was developed for satellite applications is discussed. It weighs 23 lbs. and uses 23.5 watts of power, achieves a stability of 1 x ten to the minus 13th power/100,000 seconds, and is radiation hardened. To achieve the weight and reliability requirements, both thick and thin film hybrid circuits were utilized. A crystal oscillator is used to improve short-term stability and performance on a moving platform
Quality of life and visual function in Nigeria: findings from the National Survey of Blindness and Visual Impairment
Aims To assess associations of visual function (VF) and quality of life (QOL) by visual acuity (VA), causes of blindness and types of cataract procedures in Nigeria. Methods Multi-stage stratified cluster random sampling was used to identify a nationally representative sample of persons aged >= 40 years. VF/QOL questionnaires were administered to participants with VA = 6/12. Results VF/QOL questionnaires were administered to 2076 participants. Spearman's rank correlation showed a strong correlation between decreasing VA and VF/QOL scores (p< 0.0001) with greatest impact on social (p< 0.0001) and mobility-related activities (p< 0.0001). People who were blind due to glaucoma had lower VF and QOL scores than those who were blind due to cataract. Mean VF and QOL scores were lower after couching compared with conventional cataract surgery (mean VF score=51.0 vs 63.0 and mean QOL score=71.3 vs 79.3). Finally, VF and QOL scores were lower among populations with specific characteristics. Conclusions Populations with the following characteristics should be targeted to improve VF and QOL: people who are blind, older people, women, manual labourers, people living in rural areas, those living in the northern geopolitical zones, those practising Islamic and Traditionalism faith, those not currently married and those who have undergone couching
Microscale application of column theory for high resolution force and displacement sensing
We present the design, fabrication and experimental validation of a novel
device that exploits the amplification of displacement and attenuation of
structural stiffness in the post-buckling deformation of slender columns to
obtain pico-Newton force and nanometer displacement resolution even under an
optical microscope. The extremely small size, purely mechanical sensing scheme
and vacuum compatibility of the instrument makes it compatible with existing
visualization tools of nanotechnology. The instrument has a wide variety of
potential applications ranging from electro-mechanical characterization of one
dimensional solids to single biological cells
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