217 research outputs found

    Inflation with an antisymmetric tensor field

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    We investigate the possibility of inflation with models of antisymmetric tensor field having minimal and nonminimal couplings to gravity. Although the minimal model does not support inflation, the nonminimal models, through the introduction of a nonminimal coupling to gravity, can give rise to stable de-Sitter solutions with a bound on the coupling parameters. The values of field and coupling parameters are sub-planckian. Slow roll analysis is performed and slow-roll parameters are defined which can give the required number of e-folds for sufficient inflation. Stability analysis has been performed for perturbations to antisymmetric field while keeping the metric unperturbed, and it is found that only the sub-horizon modes are free of ghost instability for de-Sitter space.Comment: 10 pages; minor correction to the claim of Sec. IV; to appear in EPJ

    Anisotropic Inflation in Dipolar Bose-Einstein Condensates

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    Early during the era of cosmic inflation, rotational invariance may have been broken, only later emerging as a feature of low-energy physics. This motivates ongoing searches for residual signatures of anisotropic space-time, for example in the power spectrum of the cosmic microwave background. We propose that dipolar Bose-Einstein condensates (BECs) furnish a laboratory quantum simulation platform for the anisotropy evolution of fluctuation spectra during inflation, exploiting the fact that the speed of dipolar condensate sound waves depends on direction. We construct the anisotropic analogue space-time metric governing sound, by linking the time-varying strength of dipolar and contact interactions in the BEC to the scale factors in different coordinate directions. Based on these, we calculate the dynamics of phonon power spectra during an inflation that renders the initially anisotropic universe isotropic. We find that the expansion speed provides an experimental handle to control and study the degree of final residual anisotropy. Gravity analogues using dipolar condensates can thus provide tuneable experiments for a field of cosmology that was until now confined to a single experiment, our universe.Comment: Updated Format, More References Adde

    In vitro biology of pigeon louse Colpocephalum turbinatum (Amblycera: Phthiraptera)

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    In vitro rearing of amblyceran Phthiraptera is a challenging task. A look on the literature reveals that negligible information exists on the in vitro bionomics of avian Amblycera. Present report furnishes information on the in vitro biology of an amblyceran louse, Colpocephalum turbinatum, reared at 35 ± 1?C, 75-82% Relative Humidity, at feather diet. The incubation period of the eggs of louse was determined as 5.37±0.67 days. The duration of first, second and third nymphal instars remained 5.04±0.65, 5.12±0.89 and 5.0±0.57 days, respectively. The longevity of adult female (13.04 ± 3.67 days) was comparatively longer than that of males (9.6±2.87 days). An adult female laid an average of 0.63 egg/day in vitro condition (35±1oC and 75-82% RH, at feather diet)

    Blockchain Technology and Artificial Intelligence Based Decentralized Access Control Model to Enable Secure Interoperability for Healthcare

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    Healthcare, one of the most important industries, is data-oriented, but most of the research in this industry focuses on incorporating the internet of things (IoT) or connecting medical equipment. Very few researchers are looking at the data generated in the healthcare industry. Data are very important tools in this competitive world, as they can be integrated with artificial intelligence (AI) to promote sustainability. Healthcare data include the health records of patients, drug-related data, clinical trials data, data from various medical equipment, etc. Most of the data management processes are manual, time-consuming, and error-prone. Even then, different healthcare industries do not trust each other to share and collaborate on data. Distributed ledger technology is being used for innovations in different sectors including healthcare. This technology can be incorporated to maintain and exchange data between different healthcare organizations, such as hospitals, insurance companies, laboratories, pharmacies, etc. Various attributes of this technology, such as its immutability, transparency, provenance etc., can bring trust and security to the domain of the healthcare sector. In this paper, a decentralized access control model is proposed to enable the secure interoperability of different healthcare organizations. This model uses the Ethereum blockchain for its implementation. This model interfaces patients, doctors, chemists, and insurance companies, empowering the consistent and secure exchange of data. The major concerns are maintaining a history of the transactions and avoiding unauthorized updates in health records. Any transaction that changes the state of the data is reflected in the distributed ledger and can be easily traced with this model. Only authorized entities can access their respective data. Even the administrator will not be able to modify any medical records

    The Rise of Blockchain Internet of Things (BIoT): Secured, Device-to-Device Architecture and Simulation Scenarios

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    Most Internet of Things (IoT) resources are exposed to security risks due to their essential functionality. IoT devices, such as smartphones and tablets, have a limited network, computation, and storage capacity, making them more vulnerable to attacks. In addition, the huge volume of data generated by IoT devices remains an open challenge for existing platforms to process, analyze, and discover underlying trends to create a convenient environment. As a result, to deliver acceptable services, a new solution is necessary to secure data accountability, increase data privacy and accessibility, and extract hidden patterns and usable knowledge. Moving the Internet of Things to a distributed ledger system might be the most effective way to solve these issues. One of the most well-known and extensively utilized distributed ledger systems is the blockchain. Due to its unique properties, such as privacy, accountability, immutability, and anonymity, blockchain technology has recently attracted a lot of interest. Using IoT in conjunction with blockchain technology can bring several benefits. This paper reviews the current state of the art different BIoT architectures, with a focus on current technologies, applications, challenges, and opportunities. The test findings prove that the decentralized authentication platform-based blockchain-based IoT (BIoT) device-to-device architecture has a significantly higher throughput than the gateway-based architecture. To encrypt the elliptical curve cryptographic (ECC) and to generate keys, the Chinese remainder theorem (CRT)-based scheme is proposed and compared with the secure hash algorithm (SHA-256). Finally, ECC-CRT is used to access system performance in terms of latency, throughput, and resource consumption, simulated through the Contiki Cooja (CC) simulator, and alter orderer and peer nodes for performance study in BIoT. A comprehensive analysis and simulation results show that the proposed scheme is secure against a variety of known attacks, including the man-in-the-middle (MiM) attack, and outperforms the SHA-256 cryptographic algorithm. Moreover, the significance of blockchain and IoT, as well as their analysis of proposed architecture, is discussed. This paper will help readers and researchers understand the IoT and its applicability to the real world

    Thrombospondin-1 expression and modulation of Wnt and hippo signaling pathways during the early phase of Trypanosoma cruzi infection of heart endothelial cells

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    The protozoan parasite, Trypanosoma cruzi, causes severe morbidity and mortality in afflicted individuals. Approximately 30% of T. cruzi infected individuals present with cardiac pathology. The invasive forms of the parasite are carried in the vascular system to infect other cells of the body. During transportation, the molecular mechanisms by which the parasite signals and interact with host endothelial cells (EC) especially heart endothelium is currently unknown. The parasite increases host thrombospondin-1 (TSP1) expression and activates the Wnt/β-catenin and hippo signaling pathways during the early phase of infection. The links between TSP1 and activation of the signaling pathways and their impact on parasite infectivity during the early phase of infection remain unknown. To elucidate the significance of TSP1 function in YAP/β-catenin colocalization and how they impact parasite infectivity during the early phase of infection, we challenged mouse heart endothelial cells (MHEC) from wild type (WT) and TSP1 knockout mice with T. cruzi and evaluated Wnt signaling, YAP/β-catenin crosstalk, and how they affect parasite infection. We found that in the absence of TSP1, the parasite induced the expression of Wnt-5a to a maximum at 2 h (1.73±0.13), P\u3c 0.001 and enhanced the level of phosphorylated glycogen synthase kinase 3β at the same time point (2.99±0.24), PT. cruzi infection. Importantly, dysregulation of this crosstalk by pre-incubation of WT MHEC with a β-catenin inhibitor, endo-IWR 1, dramatically reduced the level of infection of WT MHEC. Parasite infectivity of inhibitor treated WT MHEC was similar to the level of infection of TSP1 KO MHEC. These results indicate that the β-catenin pathway induced by the parasite and regulated by TSP1 during the early phase of T. cruzi infection is an important potential therapeutic target, which can be explored for the prophylactic prevention of T. cruzi infection

    Soluble fms-Like Tyrosine Kinase 1 (sFlt1), Endoglin and Placental Growth Factor (PlGF) in Preeclampsia among High Risk Pregnancies

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    Background: Differences in circulating concentrations of antiangiogenic factors sFlt1 and soluble endoglin (sEng) and the pro-angiogenic growth factor PlGF are reported to precede the onset of preeclampsia weeks to months in low-risk pregnant women. The objective of this study was to investigate whether similar changes can be detected in pregnant women at high-risk to develop the syndrome. Methods: This study is a secondary analysis of the NICHD MFMU trial of aspirin to prevent preeclampsia in high-risk pregnancies. Serum samples were available from 194 women with pre-existing diabetes, 313 with chronic hypertension, 234 with multifetal gestation, and 252 with a history of preeclampsia in a previous pregnancy. Samples collected across pregnancy were analyzed in a blinded fashion for sFlt1, sEng and PlGF. Results: The odds of developing preeclampsia were significantly increased among women with multiple fetuses for each 2- fold elevation in sFlt1, sEng and the ratio of angiogenic factors (e.g. OR 2.18, 95% CI 1.46-3.32), and significantly decreased for each 2-fold elevation in circulating PlGF (OR 0.50, 95% CI 0.30-0.82) between 7 and 26 weeks' gestation. Cross-sectional analysis of the angiogenic factors across gestation showed significant differences during the third trimester in women who develop preeclampsia compared with appropriate controls in all high-risk groups. However, when data were examined in relation to the gestational week when preeclampsia was diagnosed only sFlt1 was significantly higher 2 to 5 weeks before the clinical onset of preeclampsia and only in women with previous preeclampsia. Conclusions: The pattern of elevated concentrations of sFlt1 and sEng, and low PlGF in high-risk pregnant subjects who develop preeclampsia is similar to that reported in low-risk pregnant women. However, differences in these factors among high-risk women who do and do not develop preeclampsia are modest, and do not appear to be clinically useful predictors in these high-risk pregnant women
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