2,841 research outputs found
The contemporary challenges facing college of education students as future educational leaders at Sultan Qaboos University from their view points : Survey study
The contemporary challenges of young people are matter of high priority, and one of the crucial issues since they are considered as a major part of human capital in Arab States and over the entire world. This study was conducted to investigate the contemporary challenges facing young people as perceived by faculty of education students at Sultan Qaboos University in Sultanate of Oman. Also, the study aimed to determine the extent to which students view points facing contemporary challenges according to their gender, study area, residency, academic year, and grade point average. The main instrument was a questionnaire consisted of (55) items represented the contemporary challenges to gather data from (403) randomly selected participants. The reliability co-efficient of the questionnaire (Chronbach- Alpha) was (0.90) for total items. Means, standard deviation, t-test and analysis of One Way ANOVA were used to analyze data. The result of the study reveled significant differences at (=0.05) level due to gender variable in cultural, humanity and information and media domains for the benefit of females. The findings also show statistically significant differences in students' responses in the culture and humanity domain according to the study year variable in favor of forth-year-student compare with the first-year-student. Concerning the contemporary challenges facing young people, the sequence ranks of students' responses begin with the highest mean (4.12) for the information and media, fellow by consuming(3.95), economical (3.89), humanity (3.75) and culture (3.54) respectively. Depending on the results of the study, several recommendations were concluded and suggested
Multidimensional random sampling for Fourier transform estimation
This research considers the Fourier transform calculations of multidimensional signals. The calculations are based on random sampling, where the sampling points are nonuniformly distributed according to strategically selected probability functions, to provide new opportunities that are unavailable in the uniform sampling environment. The latter imposes the sampling density of at least the Nyquist density. Otherwise, alias frequencies occur in the processed bandwidth which can lead to irresolvable processing problems. Random sampling can mitigate Nyquist limit that classical uniform-sampling-based approaches endure, for the purpose of performing direct (with no prefiltering or downconverting) Fourier analysis of (high-frequency) signals with unknown spectrum support using low sampling density. Lowering the sampling density while achieving the same signal processing objective could be an efficient, if not essential, way of exploiting the system resources in terms of power, hardware complexity and the acquisition-processing time.
In this research we investigate and devise novel random sampling estimation schemes for multidimensional Fourier transform. The main focus of the investigation and development is on the aspect of the quality of estimated Fourier transform in terms of the sampling density. The former aspect is crucial as it serves towards the heart objective of random sampling of lowering the sampling density. This research was motivated by the applicability of the random-sampling-based approaches in determining the Fourier transform in multidimensional Nuclear Magnetic Resonance (NMR) spectroscopy to resolve the critical issue of its long experimental time
Hiding information in image using circular distribuition
В статье рассматриваются метод скрытия информации при передаче сообщений через сеть Интернет. Основой метода является скрытие информации в носителе другого типа, или стеганография. Предлагается метод скрытия звуковых сообщений, в котором в качестве носителя выбран файл изображения в формате bmp. Алгоритм основан на применении кругового распределения.Today the art send & reserve the hidden information become largely used in information security system especially in public places. Because the Internet as a whole does not use secure links, thus information in transit may be vulnerable to interception as well. Therefore, different methods have been proposed so far for hiding information in different cover media. The data in one medium can be hidden in another medium. The carrier medium can be image, audio or video. Of the different carrier media, image is best chosen as the carrier due to its frequency on the internet. This project aim to hiding audio file in the pixels of the carrier image using the Steganography "circular distribution algorithm" in image type BMP. The hiding audio is manipulated in way to keep host image with same size and without producing any significant distortion, also this project aim to extracting hiding audio from image without affect any problem in image and audio
A dependency-based search strategy for feature selection
Feature selection has become an increasingly important field of research. It aims at finding optimal feature subsets that can achieve better generalization on unseen data. However, this can be a very challenging task, especially when dealing with large feature sets. Hence, a search strategy is needed to explore a relatively small portion of the search space in order to find "semi-optimal" subsets. Many search strategies have been proposed in the literature, however most of them do not take into consideration relationships between features. Due to the fact that features usually have different degrees of dependency among each other, we propose in this paper a new search strategy that utilizes dependency between feature pairs to guide the search in the feature space. When compared to other well-known search strategies, the proposed method prevailed. © 2009 Elsevier Ltd. All rights reserved
Hip fracture in young and old subjects : aspects on risk factors and outcome
Hip fractures, the most serious osteoporosis-related fractures, mainly affect older
people. The functional outcome for many hip fracture patients remains to be improved.
Hip fractures in young patients are uncommon, but lifelong disability may prevail. The
aim of this thesis was to examine possibly modifiable factors correlated with functional
outcome in older subjects with hip fracture. Furthermore, to study background data and
trauma mechanism in young and middle-aged patients with femoral neck fracture.
Finally, the frequency of osteoporosis and sarcopenia in younger patients with a hip
fracture was examined.
Study I A total of 850 patients with hip fractures were included. Outcomes including
return to independent living, pressure ulcer (PU), length of hospital stay (LOS), and
mortality were considered in relation to time between admission and surgery. Patients
operated upon later than 36 and 48 hours after admission were less likely to return to
independent living while there was no significant difference when using the 24-hour
cut-off limit. The incidence of PU and LOS in the groups operated on later was
increased at all 3 cut-off limits. The mortality rate did not differ.
Study II A total of 246 patients with femoral neck fracture and cognitive impairment
were included. All were able to walk before the fracture. Significant predictors of
preserved walking ability and ADL function at 4- and 12-month follow-up were:
discharge to rehabilitation unit, walking ability, and ADL function prior to fracture,
whereas surgical method was not. Patients discharged to rehabilitation unit were less
likely to be wheelchair bound at any follow-up occasion.
Study III Included were 27 young (20-49 years of age) and 158 middle-aged (50-69
years of age) patients with a femoral neck fracture. They were studied regarding trauma
mechanisms and risk factors for osteoporosis and hip fracture. A minority of both the
young and middle age group had a high-energy trauma as a cause for the hip fracture.
Life style factors and other non-trauma related risk factors appeared to be main
contributors to the occurrence of the hip fracture in both age groups
Study IV The study population was the same as in Study III. Bone mineral density
(BMD) and fat-free mass (FFM) were determined by Dual X-ray Absorptiometry
(DXA). FFM index (FFMI) was calculated as the ratio of FFM (kg) and height squared.
One third of the study population had FFMI below the 10th percentile of a of an ageand
gender-matched reference population, i.e. indicating sarcopenia. All young patients
had a femoral neck BMD below the mean for age and 90% of the middle-aged patients
had osteopenia (56%) or osteoporosis (34%).
In conclusion, the result of this thesis indicates that early operation of patients with
hip fracture improves the ability to return to independent living, reduces the incidence
of pressure ulcers and reduces the length of hospital stay. Discharge to rehabilitation
unit, a factor we can influence, and previous function were both associated with
preserved walking ability and ADL function in cognitively impaired patients with hip
fracture. A minority, both in the young and middle-aged patients had a high-energy
trauma as a cause for the hip fracture. And most of these patients have one or more risk
factors for hip fracture and low BMD regardless of the trauma mechanism. One third
has signs of sarcopenia i.e. low muscle mass
Resveratrol inhibits proteinase-activated receptor-2-induced release of soluble vascular endothelial growth factor receptor-1 from human endothelial cells
We recently reported that (i) activation of the proinflammatory receptor, proteinase-activated receptor-2 (PAR-2) caused the release of an important biomarker in preeclampsia, soluble vascular endothelial growth factor receptor-1 (sVEGFR-1, also known as sFlt-1) from human umbilical vein endothelial cells (HUVECs), and (ii) that the anti-oxidant and anti-inflammatory agent, resveratrol, is capable of inhibiting the proinflammatory cytokine-induced sVEGFR-1 release from human placenta. Based
on these findings and because PAR-2 is up-regulated by proinflammatory cytokines, we sought to determine whether resveratrol can inhibit PAR-2-induced sVEGFR-1 release. PAR-2 expressing cells, HUVECs and human embryonic kidney cells (HEK-293) transfected with a human VEGFR-1 promoter-luciferase reporter construct were incubated with PAR-2-activating peptide and/or resveratrol. Cell supernatants were assayed for sVEGFR-1 by enzyme-linked immunosorbent assay (ELISA), and VEGFR-1 promoter-luciferase assay was performed on the harvested cell lysates. Preincubation of HEK-293 cells with resveratrol significantly inhibited PAR-2-induced VEGFR-1 promoter activity without affecting cell viability as assessed by MTT assay. The addition of resveratrol also blocked PAR-2-mediated sVEGFR-1 release from HUVECs. The present study demonstrates that resveratrol suppressed both VEGFR-1 promoter activity and sVEGFR-1 protein release induced by PAR-2 activation, which further endorses our recent findings of a potential therapeutic role for resveratrol in preeclampsia
Switched Flux Permanent Magnet Brushless Machines for Electric Vehicles
This thesis investigates different topologies of switched flux permanent magnet (SFPM) machines and variable flux (VF) methods for high speed applications.
Although several novel topologies of SFPM machines have been proposed and investigated recently, their torque-speed capability has not been studied systematically. Therefore, the torque-speed capability as well as the open circuit and electromagnetic performance of conventional SFPM machines with three different stator/rotor pole combinations, i.e. 12/10, 12/13 and 12/14, and three novel SFPM machine topologies, i.e. multi-tooth, E-core and C-core are analysed and investigated by the finite element (FE) method and experiments. Moreover, in order to improve the flux-weakening capability of these machines a variable flux method using flux adjusters (FAs) is employed and the corresponding electromagnetic performance of the machines are investigated, analysed and compared. Both FE and measured results show when the FAs are used the torque-speed capability of the three conventional machines can be improved significantly, while no improvement is shown in the three novel topologies primarily due to the large winding inductances.
The technique of using flux adjusters has been improved by reducing the number of FAs. Thus, a new mechanical variable-flux machine topology, which uses only half of FAs outside the stator at alternative stator poles, is proposed, developed and analysed. Open circuit results, electromagnetic performance and torque- and power-speed curves of the 12/10, 12/13 and 12/14 stator/rotor pole SFPM machines with alternative FAs are predicted and compared by 2D and 3D-FE, and experimentally validated.
Furthermore, a novel SFPM machine topology with radial and circumferential PMs is proposed, investigated and optimized. This topology reduces the stator flux leakage and offers high magnetic utilization. Moreover, this topology can also be developed as a mechanical variable flux machine.
Finally, three SFPM machines with variable flux techniques, i.e. mechanically movable flux adjusters (MMFA), mechanically rotatable permanent magnet set (MRMS) and hybrid excitation with backside DC coils (HEBC) are analysed. Their open circuit results and electromagnetic performance with emphasis on torque-speed characteristic are investigated and compared. Additionally, the required power to switch between flux weakening and strengthening states, flux weakening capability and permanent magnet demagnetization withstand capability are predicted, analysed and compared.
The influence of end-effect on the torque-speed capability in the conventional, multi-tooth, E-core and C-core SFPM machines is investigated. Measurements and 3D-FE are performed to obtain the torque-speed curve in order to validate the findings of the research. The 3D-FE predicted results match well with the measured results, while the 2D-FE predicted results are lower due to the high end-effect in the SFPM machines
Spatio-Temporal Context in Agent-Based Meeting Scheduling
Meeting scheduling is a common task for organizations of all sizes. It involves searching for a time and place when and where all the participants can meet. However, scheduling a meeting is generally difficult in that it attempts to satisfy the preferences of all participants. Negotiation tends to be an iterative and time consuming task. Proxy agents can handle the negotiation on behalf of the individuals without sacrificing their privacy or overlooking their preferences. This thesis examines the implications of formalizing meeting scheduling as a spatiotemporal negotiation problem. The “Children in the Rectangular Forest” (CRF) canonical model is applied to meeting scheduling. By formalizing meeting scheduling within the CRF model, a generalized problem emerges that establishes a clear relationship with other spatiotemporal distributed scheduling problems. The thesis also examines the implications of the proposed formalization to meeting scheduling negotiations. A protocol for meeting location selection is presented and evaluated using simulations
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