917 research outputs found
Tensor to Scalar Ratio in Non-Minimal Inflation
We reconsider non-minimal \lambda \phi^4 chaotic inflation which includes the
gravitational coupling term \xi \mathcal{R} \phi^2, where \phi denotes a gauge
singlet inflaton field and \mathcal{R} is the Ricci scalar. For \xi >> 1 we
require, following recent discussions, that the energy scale \lambda^{1/4} m_P
/ \sqrt{\xi} for inflation should not exceed the effective UV cut-off scale m_P
/ \xi, where m_P denotes the reduced Planck scale. The predictions for the
tensor to scalar ratio r and the scalar spectral index n_s are found to lie
within the WMAP 1-\sigma bounds for 10^{-12} < \lambda < 10^{-4} and 10^{-3} <
\xi < 10^2. In contrast, the corresponding predictions of minimal \lambda
\phi^4 chaotic inflation lie outside the WMAP 2-\sigma bounds. We also find
that r > 0.002, provided the scalar spectral index n_s > 0.96. In estimating
the lower bound on r we take into account possible modifications due to quantum
corrections of the tree level inflationary potential.Comment: 10 pages, 6 figure
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Towards Security of GSM Voice Communication
Global system for mobile communication (GSM) is widely used digital mobile service around the world. Although GSM was designed as a secure wireless system, it is now vulnerable to different targeted attacks. There is a need to address security domains especially the confidentiality of communication. This paper presents a novel framework for end to end secure voice communication over the GSM networks using encryption algorithm AES-256. A special Modem and speech coding technique are designed to enable the transmission of encrypted speech using GSM voice channel. To the best of our knowledge, this is first solution that uses single codebook for transmission of secure voice. An efficient low bit-rate (1.9 kbps) speech coder is also designed for use with the proposed modulation scheme for optimal results. Different speech characteristics such as pitch, energy and line spectral frequencies are extracted and preserved before compression and encryption of speech. Previously, the best achieved data rate was 1.6 kbps with three codebooks, whilst the proposed approach achieves 2 kbps with 0% bit error rate. The empirical results show that the methodology can be used for real time applications to transmit encrypted voice using GSM network
Effect of Mercury on Seed Germination and Seedling Growth of Mungbean (Vigna radiata (L.) Wilczek)
Among the toxic elements release in the environment, mercury is considered highly toxic to the growth of plants. The present studies report the effects of different concentrations (1, 3, 5 and 7 mM) of mercury on seed germination and seedling growth performance of mungbea (Vigna radiata) as compared to control. Mercury treatment in the form of mercuric chloride at 1 mM did not show significant reduction in seed germination of V. radiata as compared to control. Increase in concentration of mercury to 3 mM produced significant (p<0.05) reduction in seed germination. Mercury treatment at 7 mM-produced significant (p<0.05) reduction in seedling and root length of the plants. The increase in concentration of mercury treatment at 7 mM was found sufficient to cause significant reductions in seedling dry weight of as compared to control. Mercury treatment at all concentrations decreased seed germination, shoot, and root length and seedling dry weight. Increase in mercury concentration upto 7 mM showed highest percentage of decrease in seed germination (42%), seedling length (70%), root length (66%) and seedling dry weight (47%) of mungbean as relation to control. V. radiata were more sensitive to mercury stress in seedling growth and root elongation than seed germination. The seedlings of V. radiata showed greater tolerance to mercury at 1 mM (85.83 %) and lowest at 7 mM (34.13%). These results show that there is a negative effect towards germination and growth of mungbean by mercury treatment. Minimum use of the mercury containing compounds in fungicide, pesticide and nematicide is recommended. Special care should be taken to monitor the toxic pollutants available in the immediate environment. The accumulation of such types of toxic pollutants in larger concentrations by crop can produce harmful effects to crops and ecosystem as well
Analysis of landslide movements using interferometric synthetic aperture radar: A case study in Hunza-Nagar Valley, Pakistan
From a geological standpoint, northern Pakistan is one of the most active and unstable areas in the world. As a consequence, many massive landslides have occurred in the area in historical times that have destroyed infrastructure, blocked the Hunza River, and damaged the Karakoram Highway repeatedly. However, despite the high frequency of large magnitude landslide events, and the consequent damages, the entire area is largely understudied, mainly due to the difficult logistics and the large distances involved. This work is aimed at applying the potential use of Interferometric Synthetic Aperture Radar (InSAR) for landslide identification and investigation for the Hunza-Nagar Region. Sentinel-1 images covering a period of more than two years (February 2017-August 2019) were used and processed by adopting the small baseline subset (SBAS) method. The obtained deformation rate measured along the line of sight (VLOS) varies from -114 to 20 mm/year. The downslope velocity deformation rates (Vslope) range from 0 to -300 mm/year. The Vslope stability threshold for our study area was calculated to be -14 mm/year from the Vslope standard deviation. Four active landslides with Vslope exceeding 14 mm/year were recognizable and have been confirmed by field inspection. The identified landslides listed from the most active to least active are the Humarri, Mayoon, Khai, and Ghulmet landslides, respectively. VLOS exceeding 114 mm/year was observed in the Humarri landslide, which posed a threat of damming a lake on the Hispar River and was also a risk to the Humarri Village located below the landslide. The maximum mean deformation detected in the Ghulmet, andMayoon landslide was in the order of 30 mm/year and 20 mm/year, respectively. More importantly, it was found that in places, the slope deformation time series showed a patchy correlation with precipitation and seismic events in the area. This may indicate a complex, and possibly uncoupled, relationship between the two controlling agents promoting the deformation. However, the collective impact of the two factors is evident in the form of a continuously descending deformation curve and clearly indicates the ground distortion. The results indicate a potentially critical situation related to the high deformation rates measured at the Humarri landslide. On this specific slope, conditions leading to a possible catastrophic failure cannot be ruled out and should be a priority for the application of mitigation measures
Why do patients with limb ischaemia present late to a vascular surgeon? A prospective cohort study from the developing world
OBJECTIVE:
To look into the factors responsible for delay in presentation of Iimb ischemia patients to a vascular surgeon. METHODS:
The prospective cohort study was conducted at the Aga Khan University Hospital, Karachi, from October 01, 2016, to August 10, 2018. Patients coming with delayed presentation of both acute and chronic limb ischemia were included. All the patients were assessed by qualified vascular surgeons. SPSS 23 was used for data analysis. RESULTS:
Of the 55 patients, 33(60%) had acute and 22(40%) had chronic limb ischaemia. Mean age of acute cases was 44±23.72 years and it was 60±12.49 years for chronic cases. Overall, the commonest reason behind delay was non-referral by primary physician which was the case with 11(33.3%) patients in the acute group, and 13(59%) in the chronic group. The limb loss in the acute group was 20(60%) and 8(36%) in the chronic group.. CONCLUSION:
Delayed presentation of patients with limb ischaemia is mainly due to non-referral. A robust campaign needs to be launched to reduce the rate of limb loss
Asymmetric and Symmetric Link Between Quality of Institutions and Sectorial Foreign Direct Investment Inflow in India: A Fresh Insight Using Simulated Dynamic ARDL Approach
This study explores the bicausality between institutional quality and FDI inflow both aggregated and sector-wise, i.e., the agricultural, manufacturing, and tertiary sectors in the Indian economy, by applying simulated autoregressive distributed lag (SARDL) dynamic new techniques, an extended variant of orthodox ARDL and NARDL. The study confirms that aggregated and sectorial FDI are enhanced by adequate institutional quality, and similarly, FDI promotes quality institutions. The nexus between institutional quality and FDI inflow is an inspiration for India to compete with developed economies by enhancing its institutional quality. The study observes cointegration and bidirectional causality between institutional quality and aggregated FDI. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.We are very thankful to the Graduate School of Economics and Management, Ural Federal University, for technical support
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