259 research outputs found
The Effect of Organizational Justice and Perceived Organizational Support on University Staff JobBurnout (Case ofUniversityStaff ofIsfahan)
Abstract: One of the problems human resource managers encounter nowadays is the job burnout phenomenon. This can even happen in universities and cause a decline in work efficiency and a failure to reach long-term purposes. This study aims at manifesting the job burnout state and the effect of organizational justice and perceived organizational support onjob burnoutstaff of the University of Isfahan who are working in administrative sections. The data gathering tools consist of three standard questionnaires for perceived organizational justice, organizational support and job burnout assessment which areadministered among a sample of 150 individuals out of 448 staff working in administrative sections of the University of Isfahan. The volume of the sample is also calculated bystratificationusing Cochran formula. By using of structural equation modeling (SEM) method, it can be said that organizational justice and perceived organizational support has a negative effects onjob burnout, but perceived organizational support doesn't significantly affect onjob burnout
Physical Layer Security for Visible Light Communication Systems:A Survey
Due to the dramatic increase in high data rate services and in order to meet
the demands of the fifth-generation (5G) networks, researchers from both
academia and industry are exploring advanced transmission techniques, new
network architectures and new frequency spectrum such as the visible light
spectra. Visible light communication (VLC) particularly is an emerging
technology that has been introduced as a promising solution for 5G and beyond.
Although VLC systems are more immune against interference and less susceptible
to security vulnerabilities since light does not penetrate through walls,
security issues arise naturally in VLC channels due to their open and
broadcasting nature, compared to fiber-optic systems. In addition, since VLC is
considered to be an enabling technology for 5G, and security is one of the 5G
fundamental requirements, security issues should be carefully addressed and
resolved in the VLC context. On the other hand, due to the success of physical
layer security (PLS) in improving the security of radio-frequency (RF) wireless
networks, extending such PLS techniques to VLC systems has been of great
interest. Only two survey papers on security in VLC have been published in the
literature. However, a comparative and unified survey on PLS for VLC from
information theoretic and signal processing point of views is still missing.
This paper covers almost all aspects of PLS for VLC, including different
channel models, input distributions, network configurations,
precoding/signaling strategies, and secrecy capacity and information rates.
Furthermore, we propose a number of timely and open research directions for
PLS-VLC systems, including the application of measurement-based indoor and
outdoor channel models, incorporating user mobility and device orientation into
the channel model, and combining VLC and RF systems to realize the potential of
such technologies
Measurements-Based Channel Models for Indoor LiFi Systems
Light-fidelity (LiFi) is a fully-networked bidirectional optical wireless
communication (OWC) that is considered a promising solution for high-speed
indoor connectivity. Unlike in conventional radio frequency wireless systems,
the OWC channel is not isotropic, meaning that the device orientation affects
the channel gain significantly. However, due to the lack of proper channel
models for LiFi systems, many studies have assumed that the receiver is
vertically upward and randomly located within the coverage area, which is not a
realistic assumption from a practical point of view. In this paper, novel
realistic and measurement-based channel models for indoor LiFi systems are
proposed. Precisely, the statistics of the channel gain are derived for the
case of randomly oriented stationary and mobile LiFi receivers. For stationary
users, two channel models are proposed, namely, the modified truncated Laplace
(MTL) model and the modified Beta (MB) model. For LiFi users, two channel
models are proposed, namely, the sum of modified truncated Gaussian (SMTG)
model and the sum of modified Beta (SMB) model. Based on the derived models,
the impact of random orientation and spatial distribution of LiFi users is
investigated, where we show that the aforementioned factors can strongly affect
the channel gain and system performance
NEURAL STEM/PROGENITOR CELL TRANSPLANTATION FOR SPINAL CORD INJURY TREATMENT; A SYSTEMATIC REVIEW AND META-ANALYSIS
—Despite the vast improvements of cell therapy in
spinal cord injury treatment, no optimum protocol has been
developed for application of neural stem/progenitor cells. In
this regard, the present meta-analysis showed that the effi-
cacy of the neural stem/progenitor cell (NSPC) transplantation
depends mainly on injury model, intervention phase,
transplanted cell count, immunosuppressive use, and probably
stem cell source. Improved functional recovery post
NSPC transplantation was found to be higher in transection
and contusion models. Moreover, NSPC transplantation in
acute phase of spinal injury was found to have better functional
recovery. Higher doses (>3 � 106 cell/kg) were also
shown to be optimum for transplantation, but immunosuppressive
agent administration negatively affected the motor
function recovery. Scaffold use in NSPC transplantation
could also effectively raise functional recovery. � 2016 Published
by Elsevier Ltd. on behalf of IBR
Value of chest computed tomography scan in diagnosis of COVID-19; a systematic review and meta-analysis
Purpose: Real-time polymerase chain reaction (RT-PCR) and chest computed tomography (CT) scan are main diagnostic modalities of coronavirus disease 2019 (COVID-19). However, there is still no consensus on which of these methods is superior to the other. Therefore, the present meta-analysis was designed to answer to the question whether CT scan can be used in diagnosis of COVID-19 or not. Methods: Searches were performed in Medline, Embase, Scopus, and Web of Science databases until the end of April 2020. Two researchers gathered the data of diagnostic accuracy studies that had attempted to evaluate sensitivity and specificity of CT scan in diagnosis of COVID-19. Results: Data of 9 studies were included. Area under the curve of ground glass opacity (GGO), consolidation, pleural effusion, other CT features, and simultaneous observation of GGO with other CT features was 0.64 (95 CI 0.60�0.69), 0.30 (95 CI 0.26�0.34), 0.60 (95 CI 0.56�0.64), 0.61 (95 CI 0.56�0.65), and 0.90 (95 CI 0.87�0.92), respectively. Sensitivity and specificity of simultaneous observation of GGO with other CT scan features was higher than all of the other signs. Sensitivity, specificity, and diagnostic odds ratio of this sign was calculated to be 0.90, 0.89, and 20, respectively. Conclusion: Simultaneous observation of GGO and other features of viral pneumonia in CT scan had optimum performance in detection of COVID-19. However, it is suggested to make the final diagnosis based on both CT scan and RT-PCR, as none of the two diagnostic modalities are reliable alone. © 2020, Italian Association of Nuclear Medicine and Molecular Imaging
Geohazards analysis of Pisa tunnel in a fractured incompetent rocks in Zagros Mountains, Iran.
The Pisa 2 tunnel with 740 m in length and 20° N trend is located along the Kazerun fault zone in Simply Folded Belt of Zagros, Iran. This tunnel has been excavated in the fractured incompetent marl layers with high expansive pressure of up to 2 kg/cm2. In this study, the geological hazards along the tunnel have been recognized and categorized. This study revealed that, in the long-term usage of the tunnel, the lining did not endure against the loading and the secondary leakages. It is mainly attributed due to the non-efficiencies of drainage and isolation systems in the tunnel site. Therefore, it caused asphalt damage, drainage damage, and wall distortion. FLAC3D software has been used in this research. We conducted various analyses for pre-excavation stress states, syn-excavation, and post-excavation strain states. The results showed no indication of instability and critical deformations during the excavation time. It also revealed that due to the non-efficiencies of drainage and isolation systems against secondary leakages and consequently marl expansion, the volumetric and shear strains (i.e., expansions and displacements) have exceeded from the critical states of strain along the tunnel. For various remedy purpose, this paper attempted several measures that can be taken in order to modify the drainage and isolation systems along the tunnel area. The reconstruction of drainage systems with suitable reinforced concrete and adequate slope has been proposed. The width of channel and isolation of backside of lining and implementation of multi-order outlets (i.e., backside of lining) for draining of groundwater into where the main drainage systems are located in the tunnel gallery were suggested
The use of modified atmosphere packaging for improvement shelf life of fresh Oncorhynchus mykiss
In this study, influence of modified atmosphere packaging on shelf life of trout (Oncorhynchus mykiss) (whole fish without visceral and without head and tail fish) stored in 4 to 6ºc was examined. Fish stored in MAP condition and control samples, in different time, were tested for spoilage chemical factors (TVN, PV and pH), microbial parameters (total viable count, clostridium botulinum) and sensory factors too. Mixed gases including co2 (30-50%), N2 (40-65%) and o2 (0 to 20%) were used for trout (without head and tail =6 treatments) and (whole fish without visceral and control = 2 treatments) statistical the analysis results showed that examined factors were significant difference during storage (P<0.001). Mixed gases haven t had inhibitory effect on spoilage factors (chemical and microbial parameters). However spoilage process was delayed. Increasing of chemical and microbial changes in control samples was higher than treatment samples especially TVN. The results also showed that shelf life of control samples stored 4-6ºc were between 6-12 days but in MAP samples were 19 days. Mixed gases including CO2 (40%), N2 (55%) and O2 (5%) were the best formula and the shelf life of fish (without head and tail) was 16 days where it was 19 days in whole fish (Lack of visceral). The results showed that storage of trout in MAP condition facilities storage and increasing of fish shelf life too
Coupling of DEM and remote-sensing-based approaches for semi-automated detection of regional geostructural features in Zagros mountain, Iran.
In recent years, remote-sensing data have increasingly been used for the interpretation of objects and mapping in various applications of engineering geology. Digital elevation model (DEM) is very useful for detection, delineation, and interpretation of geological and structural features. The use of image elements for interpretation is a common method to extract structural features. In this paper, linear features were extracted from the Landsat ETM satellite image and then DEM was used to enhance those objects using digital-image-processing filtering techniques. The extraction procedures of the linear objects are performed in a semi-automated way. Photographic elements and geotechnical elements are used as main keys to extract the information from the satellite image data. This paper emphasizes on the application of DEM and usage of various filtering techniques with different convolution kernel size applied on the DEM. Additionally, this paper discusses about the usefulness of DEM and satellite digital data for extraction of structural features in SW of Zagros mountain, Iran
The comprehensive study of possibility ecological control Mnemiopsis leidyi in Caspian Sea activity: The study and recognization parasitic fauna and Bacterial flore in ctenophore (Mnemiopsis leidyi and Bereo ovata)
Bacterial flora and parasitic fauna of M. leidyi an exotic invader jelly fish to Caspian Sea ecosystem and B. ovata to Black sea an alternative biological control agent was studied. During summer 1382 to spring 1383, using routine Bacteriological work. 72 sample of sea water Caspian Sea obtained from depth 20 and 50 meters, 36 sample of M. leidyi from depth 20 meters, 10 sample of B. ovata and 3 sample of sea water (Black sea) were collected and according to Bacteriological was studied. 216 sample of M. leidyi from depth 10 to 50 meters of Caspian Sea and 47 sample of B. ovata from Black and Marmarreh Sea (Turkey) were collected and was studied. In this study no parasite from was identified in M. leidyi (Caspian sea) but 64 percentage and 73 percentage of B. ovata (Marmarreh and Black sea respectively) contaminated to Trichodina ctenophore at varians concentration B. ovata of Black sea (130 min 1050 max) and B. ovata Marmarre sea (420 min 2100 max). While B. ovata kept at high salinity of 21 ppt was more contaminated with this pretrichial protozoan (Trichodina) than in low salinity (12/5 ppt). in comparision of bacterial flore in two cetenophore (M. leidyi and B. ovata) was observed that some of bacteria such as micrococcus sp, Aeromonas sp. Bacillus coagulans in both ctenophore and some other bacteria such as Agromobacterium and chromobacterium only observed in B. ovata but other researcher have reported fram Caspin sea and some of bacteria to specific Shewanella , Vibrio harveiy and bacillus linens was observed in B. ovata . Of course specific bacteria cannot transfer to Caspian Sea (different of salinity black sea (2/1%) to Caspian Sea (1/25 %)). Therefore if B. ovata to introduce to south Caspian Sea for biological control population M. leidyi. it is necessary at first some of viral pathogen in aquatic animal (fish) such as VNN, IPN,IHN,VHS,SVC was studied and then with confidence 95% non-infestation B. ovata to viruses and pass from bath anti parasite and anti-bacterial must be introduce to south Caspian sea
- …