Towards high-resolution synchrotron radiation imaging with statistical iterative reconstruction

Synchrotron radiation (SR) X-ray micro-computed tomography (CT) is an effective imaging modality for high-resolution investigation of small objects, with several applications in medicine, biology and industry. However, the limited size of the detector field of view (FOV) restricts the sample dimensions to only a few millimeters. When the sample size is larger than the FOV, images reconstructed using conventional methods suffer from DC-shift and low-frequency artifacts. This classical problem is known as the local tomography or the interior problem. In this paper, a statistical iterative reconstruction method is introduced to eliminate image artifacts resulting from the local tomography. The proposed method, which can be used in several SR imaging applications, enables high-resolution SR imaging with superior image quality compared with conventional methods. Real data obtained from different SR micro-CT applications are used to evaluate the proposed method. Results indicate a noteworthy quality improvement in the image reconstructed from the local tomography measurements

Line and Continuum Variability in Active Galaxies

We compared optical spectroscopic and photometric data for 18 AGN galaxies over 2 to 3 epochs, with time intervals of typically 5 to 10 years. We used the Multi-Object Double Spectrograph (MODS) at the Large Binocular Telescope (LBT) and compared the spectra to data taken from the SDSS database and the literature. We find variations in the forbidden oxygen lines as well as in the hydrogen recombination lines of these sources. For 4 of the sources we find that, within the calibration uncertainties, the variations in continuum and line spectra of the sources are very small. We argue that it is mainly the difference in black hole mass between the samples that is responsible for the different degree of continuum variability. In addition we find that for an otherwise constant accretion rate the total line variability (dominated by the narrow line contributions) reverberates the continuum variability with a dependency $\Delta L_{line} \propto (\Delta L_{cont.})^{\frac{3}{2}}$. Since this dependency is prominently expressed in the narrow line emission it implies that the luminosity dominating part of the narrow line region must be very compact with a size of the order of at least 10 light years. A comparison to literature data shows that these findings describe the variability characteristics of a total of 61 broad and narrow line sources.Comment: 30 pages including the appendix, 18 figures including the appendix. Accepted 2015 September 3. Received 2015 August 24; in original form 2015 July 3 in Monthly Notices of the Royal Astronomical Societ

Heme oxygenase effect on mesenchymal stem cells action on experimental Alzheimer's disease

The objective is to evaluate the effect of heme oxygenase-1 (HO-1) enzyme inducer and inhibitor on Mesenchymal Stem Cells (MSCs) in Alzheimer disease. Materials and Methods: 70 female albino rats were divided equally into 7 groups as follows: group 1: healthy control; group 2: Aluminium chloride induced Alzheimer disease; group 3: induced Alzheimer rats that received intravenous injection of MSCs; group 4: induced Alzheimer rats that received MSCs and HO inducer cobalt protoporphyrin; group 5: induced Alzheimer rats that received MSCs and HO inhibitor zinc protoporphyrin; group 6: induced Alzheimer rats that received HO inducer; group7: induced Alzheimer rats that received HO inhibitor. Brain tissue was collected for HO-1, seladin-1 gene expression by real time polymerase chain reaction, heme oxygenase activity, cholesterol estimation and histopathological examination. Results: MSCs decreased the plaque lesions, heme oxygenase induction with stem cells also decreased plaque lesions however there was hemorrhage in the brain. Both heme oxygenase inducer alone or with stem cells increased seladin-1 expression and decreased cholesterol level. Conclusion: MSCs alone or with HO-1 induction exert a therapeutic effect against the brain lesion in Alzheimer’s disease possibly through decreasing the brain cholesterol level and increasing seladin-1 gene expression

Competing biosecurity and risk rationalities in the Chittagong poultry commodity chain, Bangladesh

This paper anthropologically explores how key actors in the Chittagong live bird trading network perceive biosecurity and risk in relation to avian influenza between production sites, market maker scenes and outlets. They pay attention to the past and the present, rather than the future, downplaying the need for strict risk management, as outbreaks have not been reported frequently for a number of years. This is analysed as ‘temporalities of risk perception regarding biosecurity’, through Black Swan theory, the idea that unexpected events with major effects are often inappropriately rationalized (Taleb in The Black Swan. The impact of the highly improbable, Random House, New York, 2007). This incorporates a sociocultural perspective on risk, emphasizing the contexts in which risk is understood, lived, embodied and experienced. Their risk calculation is explained in terms of social consent, practical intelligibility and convergence of constraints and motivation. The pragmatic and practical orientation towards risk stands in contrast to how risk is calculated in the avian influenza preparedness paradigm. It is argued that disease risk on the ground has become a normalized part of everyday business, as implied in Black Swan theory. Risk which is calculated retrospectively is unlikely to encourage investment in biosecurity and, thereby, points to the danger of unpredictable outlier events

The impact of Stieltjes' work on continued fractions and orthogonal polynomials

Stieltjes' work on continued fractions and the orthogonal polynomials related to continued fraction expansions is summarized and an attempt is made to describe the influence of Stieltjes' ideas and work in research done after his death, with an emphasis on the theory of orthogonal polynomials

A Miniature Energy Harvesting Device for Wireless Sensors in Electric Power System

A novel energy harvesting device called the energy coupler is proposed which can provide power to small wireless sensors in a power system. The energy coupler when coupled electromagnetically to a nearby current carrying conductor scavenges ac power from the conductor. The proposed energy coupler converts the harvested ac power into dc using a passive voltage multiplier circuit. The design of the energy coupler is such that the dc power obtained is adequate to charge a miniature 1.2-V rechargeable battery. It is demonstrated that the energy coupler is capable of delivering 10 mW of dc power to a 50-Ω load. An analytical model is also presented which agrees well with measurement results within a margin of error of 10%

Hydraulic Jump in Circular Open Channels with Mild Slope

A hydraulic jump is a well-known transitionalphenomenon from supercritical to subcritical flows withundulations of water-surface. In this transition, the water flowhas a high-velocity, water surface rises abruptly, surface rollersare formed, intense mixing occurs, the air is entrained, and alarge amount of energy is dissipated. In the present studycharacteristics of the hydraulic jumps in circular open channelswith a mild sloped have been discussed under a wide range ofexperimental conditions. The study aims to determine the effectof the channel’s mild slope on the characteristics of thehydraulic jumps with circular channels. A theoretical study hasbeen done and led to obtaining equations that can be used to getspecific force for the hydraulic jump that occurred in circularopen channels. A theoretical study is based on usingmomentum, and Froude’s number equations. An experimentalstudy has been investigated using Laboratory 40 experimentalruns in circular section flume for eight different dischargesranged from 3.92 to 12.07 l/sec were given with mild slopeequals 0.000833. In total, the experiments were conducted overa range of Froude numbers from 1.78 to 8.87. The experimentalworks concluded some dimensionless curves and new usefulformulas to get the length of the jump, energy dissipated andefficiency. The conjugated depth ratio is determined and plottedversus the upstream Froude number, downstream Froudenumber, head loss, and efficiency for different values of criticaldepths. The resulting graphs and equations of the present studyare readily applicable for a design for the hydraulic jumps inthe circular open channels with mild slope

Power management and control strategies for off-grid hybrid power systems with renewable energies and storage

This document is the Accepted Manuscript of the following article: Belkacem Belabbas, Tayeb Allaoui, Mohamed Tadjine, and Mouloud Denai, 'Power management and control strategies for off-grid hybrid power systems with renewable energies and storage', Energy Systems, September 2017. Under embargo. Embargo end date: 19 September 2018. The final publication is available at Springer via https://doi.org/10.1007/s12667-017-0251-y.This paper presents a simulation study of standalone hybrid Distributed Generation Systems (DGS) with Battery Energy Storage System (BESS). The DGS consists of Photovoltaic (PV) panels as Renewable Power Source (RPS), a Diesel Generator (DG) for power buck-up and a BESS to accommodate the surplus of energy, which may be employed in times of poor PV generation. While off-grid DGS represent an efficient and cost-effective energy supply solution particularly to rural and remote areas, fluctuations in voltage and frequency due to load variations, weather conditions (temperature, irradiation) and transmission line short-circuits are major challenges. The paper suggests a hierarchical Power Management (PM) and controller structure to improve the reliability and efficiency of the hybrid DGS. The first layer of the overall control scheme includes a Fuzzy Logic Controller (FLC) to adjust the voltage and frequency at the Point of Common Coupling (PCC) and a Clamping Bridge Circuit (CBC) which regulates the DC bus voltage. A maximum power point tracking (MPPT) controller based on FLC is designed to extract the optimum power from the PV. The second control layer coordinates among PV, DG and BESS to ensure reliable and efficient power supply to the load. MATLAB Simulink is used to implement the overall model of the off-grid DGS and to test the performance of the proposed control scheme which is evaluated in a series of simulations scenarios. The results demonstrated the good performance of the proposed control scheme and effective coordination between the DGS for all the simulation scenarios considered.Peer reviewedFinal Accepted Versio

Efecto de la radiación gamma sobre el perfil lipídico de los aceites de semillas de soja, cacahuete y sésamo

Seeds of soybean, peanut, and sesame were exposed to various doses of gamma irradiation (0.0, 0.5, 1.0, 2.0, 3.0, 5.0 and 7.5 kGy). Fatty acid and unsaponifiable profiles of the extracted oils were separated by gas chromatography mass spectroscopy. The results demonstrated that the ratios of unsaturated to saturated total fatty acids (TU/TS) and total hydrocarbons to sterols (TH/TSt) were significantly altered upon irradiation. These changes were clearly observed in the oil extracted from irradiated sesame seeds compared with the oils from irradiated peanuts and soybean. The major change in fatty acid composition was the decrease in the quantity of unsaturated fatty acids (C18:1 and C18:2) in all cases. In contrast, the sterol fractions such as cholesterol, campesterol, stigmasterol and β-sitosterol levels of irradiated seeds were generally lower than that of the un-irradiated seeds.Semillas de soja, cacahuete y de sésamo se expusieron a diferentes dosis de radiación gamma (0,0, 0,5, 1,0, 2,0, 3,0, 5,0 y 7,5 kGy). Se determinaron los perfiles de ácidos grasos y el insaponificable de los aceites mediante cromatografía de gases y espectrometría de masas. Los resultados demostraron que las relaciones de ácidos insaturados a ácidos grasos totales saturados (TU/TS) e hidrocarburos totales a esteroles (TH/TSt) se alteró significativamente tras la irradiación. Estos cambios se observaron claramente en el aceite extraído de las semillas de sésamo irradiados, en comparación con los aceites de soja y cacahuetes irradiados. El mayor cambio en la composición de ácidos grasos fue la disminución de la cantidad de ácidos grasos insaturados (C18:1 y C18:2) en todos los casos. En contraste, los niveles de las fracciones de esteroles como colesterol, campesterol, estigmasterol y β-sitosterol de las semillas irradiadas fueron en general más bajo que el de las semillas sin irradiados