327 research outputs found
Efficiency of tree-based water status indicators at the onset of water deficit in citrus
No full text5 páginas.-- 3 figuras.-- 5 tablas.-- 18 referenciasThis experiment evaluates the potential of using parameters based on tree trunk fluctuations for detecting water deficit in citrus trees under two different water saving-irrigation strategies: sustained deficit irrigation and partial root-zone drying. Three irrigation treatments were applied: 1) Control: trees were irrigated with 100% of their evapotranspirative needs (ETc); 2) 60 sustained deficit irrigation (SDI): 60% ETc; and 3) partial root-zone drying (PRD): 100% ETc needs, applied to only one-half of root zone. Maximum daily shrinkage (MDS), trunk growth rate (TGR), and MDS ratio (ratio between MDS of stressed trees and control trees) were determined. Day-to-day MDS values varied largely and could not be used to determine tree water deficit. TGR did not show significant differences among treatments at this level of stress. Nevertheless, the MDS ratio was a reliable indicator to measure tree water status, and it was more sensitive for detecting water deficit at the onset of a water deficit in trees under SDI than in trees under PRD.The authors thank the Consejo Superiorde Investigaciones Científicas (CSIC) for funding the stay of S. Elsayed-Farag at the Texas A&M University-Kingsville
Citrus Center and her JAE-predoc fellowship and Ayako Kusakabe, research associate at the Citrus Center, for her technical support.Peer reviewe
Correction: Guidelines for the prevention, detection and management of the renal complications of COVID-19 in Africa
No full textThe authors of the article ‘Guidelines for the prevention, detection and management of the renal complications of COVID-19 in Africa’ [1] wish to acknowledge the contribution of Professor Hussein El Fishawy. Our guidelines drew on various sources, including the Egyptian Ministry of Health guidelines, portions of which were adapted and reproduced with permission from the Egyptian Ministry of Health. Two of the authors of those guidelines, Professors Elsayed and Zaki, are also coauthors of our paper. Professor El Fishawy was the third author of the Egyptian guidelines and we would like to acknowledge his contribution to our review through this source, especially with respect to the treatment algorithms for patients with kidney transplants and those with acute kidney injury. Reference1. Elsayed HM, Wadee S, Zaki MS, Were AJO, Ashuntantang GE, Bamgboye EL, et al. Guidelines for the prevention, detection and management of the renal complications of COVID-19 in Africa. Afr J Nephrol. 2020; 23(1):109-126
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Association of objective measures of volume status with blood pressure, cardiac structure, and cardiac function among patients receiving maintenance hemodialysis
No full textBackground Intradialytic hypertension, defined as an increase in BP from pre- to post-hemodialysis (HD), affects
5%–15% of patients receiving maintenance HD and is associated with cardiovascular and all-cause mortality.
Hypervolemia is believed to be a major etiological factor, yet the association of more objective biomarkers of
volume status with intradialytic hypertension is not well described.
Methods In a post hoc analysis of the Frequent Hemodialysis Network Daily Trial (n5234), using data from
baseline, 1-, 4-, and 12-month visits (n5800), we used random-effects regression to assess the association of
bioimpedance estimates of volume (vector length) with post-HD systolic BP (continuous) and any increase in
systolic BP (categorical) from pre- to post-HD. We adjusted models for randomized group; age; sex; self-reported
race; Quételet (body mass) index; vascular access; HD vintage; hypertension; history of heart failure; diabetes;
residual kidney function (urea clearance); pre-HD systolic BP; ultrafiltration rate; serum-dialysate sodium
gradient; and baseline values of hemoglobin, phosphate, and equilibrated Kt/V urea.
Results The mean age of participants was 50614 years, 39% were female, and 43% were Black. In adjusted
models, shorter vector length (per 50 V/m) was associated with higher post-HD systolic BP (2.9 mm Hg; 95%
confidence interval [CI], 1.6 to 4.3) and higher odds of intradialytic hypertension (odds ratio 1.66; 95% CI, 1.07 to
2.55). Similar patterns of association were noted with a more stringent definition of intradialytic hypertension
(.10 mm Hg increase from pre- to post-HD systolic BP), where shorter vector length (per 50 V/m) was
associated with a higher odds of intradialytic hypertension (odds ratio 2.17; 95% CI, 0.88 to 5.36).
Conclusions Shorter vector length, a bioimpedance-derived proxy of hypervolemia, was independently associated with higher post-HD systolic BP and risk of intradialytic hypertension
Représentations littéraires du sacré dans le roman maghrébin de langue française
No full textThis interdisciplinary study explores how Driss Chraïbi’s L’Homme du Livre (1995), Assia Djebar’s Loin de Médine (1991), and Anissa Boumediène’s La fin d’un monde (1991) present accounts of particular historical moments in early Islam. This study explores the role of the imagination as well as freedom of invention when reconstructing historical events. It engages the novels through a study of the interplay between the literary text and the sources and traditions that impact and shape the text narrative. Gaining direct access to the original sources in Arabic serves to analyze how religious and early historical materials are considered in and reflected by the fictional texts. Because the sources tend to differ in both content and approach, this study examines their preoccupations in order to determine the criteria of selection applied by each novelist.Ph.D.Includes bibliographical referencesIncludes vitaby Hanan Elsaye
Modulation of the transient outward K+ channel, Kv1.4, by extracellular acidosis, extracellular K+ and polyunsaturated fatty acids
No full textDuring metabolic inhibition caused by myocardial ischemia, the extracellular pH reduces, while the concentrations of extracellular K+ and free polyunsaturated fatty acids (PUFAs) increase. Acidosis, raised extracellular K+ and PUFAs nodulate the rapidly inactivating K+ channel, Kv1.4, that contributes to the transient outward K+ current (1to) in the heart, including in the human.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Intrathecal Drug Delivery Systems Survey: Trends in Utilization in Pain Practice [Corrigendum]
No full textAbd-Sayed A, Fiala K, Weisbein J, et al. J Pain Res. 2022;15:1305–1314.
The authors have advised there is an error in the author list on page 1305. The author name “Alaa Abd-Sayed” should read “Alaa Abd-Elsayed”.
The authors apologize for this error
Bioactive Compounds from Marine Sources
No full textFucoidan is a class of biopolymers mainly found in brown seaweeds. Due to its diverse medical importance, homogenous supply as well as a GMP-compliant product is of a special interest. Therefore, in addition to optimization of its extraction and purification from classical resources, other techniques were tried (e.g., marine tissue culture and heterologous expression of enzymes involved in its biosynthesis). Results showed that 17.5% (w/w) crude fucoidan after pre-treatment and extraction was obtained from the brown macroalgae F. vesiculosus. Purification by affinity chromatography improved purity relative to the commercial purified product. Furthermore, biological investigations revealed improved anti-coagulant and anti-viral activities compared with crude fucoidan. Furthermore, callus-like and protoplast cultures as well as bioreactor cultivation were developed from F. vesiculosus representing a new horizon to produce fucoidan biotechnologically. Moreover, heterologous expression of several enzymes involved in its biosynthesis by E. coli (e.g., FucTs and STs) demonstrated the possibility to obtain active enzymes that could be utilized in enzymatic in vitro synthesis of fucoidan. All these competitive techniques could provide the global demands from fucoidan.Fuciodane sind Biopolymere mit sulfatiertem Homo- oder Heteropolysaccharidrückgrat. Sie kommen hauptsächlich in Braunalgen (Phaeophyta) vor. Durch ihre medizinische Bedeutung ist eine einheitliche Versorgung und GMP-konforme Produktion von besonderem Interesse. Aus diesem Grund wurden in dieser Arbeit verschiedene Techniken zur Fucoidan-Produktion angewendet (z.B. Optimierung von Extraktion und Aufreinigung aus klassischen Quellen, marine Gewebekultur und heterologe Expression von Enzymen, die in die Biosynthese von Fucoidan involviert sind). Die Ergebnisse zeigen, dass nach Vorbehandlung und Extraktion 17,5 % w/w Fucoidan aus der Braunalge F. vesiculosus gewonnen werden konnte. Durch Aufreinigung mittels Affinitätschromatographie konnte eine höhere Reinheit im Vergleich zu einem kommerziellen Produkt erreicht werden. Biologische Analysen ergaben verbesserte antikoagulante und antivirale Eigenschaften. Kallus- und Protoplastkulturen von F. vesiculosus, sowie Kulturen im Bioreaktor repräsentieren neue Wege, Fucoidan biotechnologisch herzustellen. Außerdem demonstrierte die heterologe Expression von mehreren Enzymen der Fucoidan-Biosynthese in E. coli (z.B. FucTs und STs) die Möglichkeit, aktive Enzyme zu erhalten, die in enzymatischer de-novo-Synthese von Fucoidan eingesetzt werden können. All diese Entwicklungen könnten dabei helfen, die globale Nachfrage an Fucoidan zu befriedigen
Degradation modeling of ink fading and diffusion of printed images
No full textColor printing plays an important role in the modern society. It is known that the color of printed images degrades gradually due to the fading and diffusion of the inks. Color degradation leads to a distortion or loss of the original information in printed images. Therefore, it is desirable to understand how the color of printed images changes over time. In this dissertation, we present degradation models to predict the characteristics of the ink fading and diffusion of printed images.
We begin by modeling the ink degradation from a physics-based perspective. Color images are printed by projecting small ink dots on medium, usually paper. This technique is called halftone printing. Halftone printing of color images results in a variety of ink mixtures and subsequently their potential catalytic fading. For the most commonly used Cyan-Magenta-Yellow-Black (CMYK) ink set, sixteen possible ink mixtures are generated during printing. A state transition diagram is then proposed for the ink fading in this multi-ink printing scenario. The ink area coverage is used as the performance indicator. Assuming constant fading and diffusion rates, we develop an ink fading model based on the differential equations according to the state transition diagram and an autoregressive ink diffusion model by discretizing the two-dimensional diffusion equation. The two models are then integrated into a single degradation model.
Further examination of the developed degradation models reveals that the fading or diffusion rate is equivalent to the hazard rate in reliability engineering. It is known that the hazard rate of the exponential failure time distribution is constant. Hence, the developed degradation model with constant fading and diffusion rates is equivalent to the multistate Markov process model with exponential transition time distribution. By using non-exponential transition time distributions, the fading and diffusion rates become time-varying and a more general semi-Markov process degradation model is developed accordingly.
Moreover, stochastic process models are investigated to provide stochastic area coverage prediction for the ink degradation. We first model the ink fading using the Hull-White/Vasicek (HWV) stochastic process. The HWV ink fading model considers that the variance of the ink area coverage shrinks as it approaches zero. Besides, spatial convolution is used to model ink diffusion. The two models are integrated into a spatio-temporal stochastic degradation model for the ink fading and diffusion of printed images. The cases of recurrent and non-recurrent time-varying fading and diffusion rates are investigated.
Inks on the paper degrade, so does the paper. The degradation of paper condition may in turn affect the degradation of the inks. Therefore, the investigation of the degradation modeling of ink fading and ink diffusion with ink-paper interactions is needed. Two aspects of the ink-paper interactions are considered, i.e., the effect of paper aging such as depolymerization and yellowing, and the fiber orientation of the paper.
The degradation process of printed images usually takes a very long time. An accelerated degradation model and the optimal design of accelerated degradation test planning is developed for accurate degradation prediction of printed images. The effects of three constant environmental stresses: temperature, humidity, and illumination (intensity), are investigated, and experimental data are used to validate the proposed model. The results show strong agreements between the proposed ink fading and ink diffusion prediction model and the actual experimental data.Ph.D.Includes bibliographical reference
Reliability estimation of balanced systems with multi-dimensional distributed units
No full textBalanced systems with multi-dimensional distributed units are emerging in a diverse range of industries. This includes Unmanned Aerial Vehicles (UAV) with multi-level of rotary wings, Spherical Unmanned Vehicles (SUV), Spherical Phased Array Antenna (SPAA), etc. In this dissertation, we present the reliability estimation for such systems. In particular, we consider two configurations: 1) balanced systems with units distributed circularly on multi-level and 2) balanced systems with units distributed spherically.
First, balanced systems with units distributed circularly on multi-level are generalized as (k₁, k₂)-out-of-(n, m) pairs: G balanced systems. We consider two scenarios: 1) all units perform the same function and 2) adjacent pairs perform complementary functions. For both scenarios, unbalanced system is considered as failed. When units fail and cause the system imbalance, we explore two approaches to rebalance the system: 1) forcing down units on other locations and 2) resuming units that are previously forced down (if any). When units in a system perform the same function, operational states are defined as balanced states with at least k₁ operating pairs and each operating pair has at least k₂ units on each side. The system reliability is obtained by enumerating all of the operational states and summing the probabilities of those states. For (k₁, k₂)-out-of-(n, m) pairs: G balanced systems with adjacent pairs performing complementary functions, in addition to maintaining system balance, the adjacent operating pairs are required to perform complementary functions. Thus, if a pair fails, one of the adjacent pairs is forced down. Similarly, the system reliability is obtained by enumerating all of the operational states. It becomes computational expensive when the number of units in each pair and/or the number of pairs are large. In that case, efficient algorithms are developed to obtain the reliability for such systems.
The balanced system with units distributed spherically is generalized as a spherical k-n-i: G balanced system. We consider two balancing requirements: 1) rotational balance is maintained so that the system is not rotating w.r.t. roll, yaw and pitch axes and 2) symmetrical balance is essential in improving the systems’ stability. We present mathematical approaches to determine the balance status of a system. Similarly, the unbalanced system is rebalanced by 1) forcing down units on other locations and 2) resuming previously forced-down units. The system reliability is obtained by the enumeration of operational states and calculation of operational states’ probabilities. We develop an efficient algorithm for reliability estimation when the number of units in the system is large.
Degradation models are developed for the (k₁, k₂)-out-of-(n, m) pairs: G balanced systems to further investigate the system reliability when degradation data are available. The degradation processes of units in the system are either stationary (inverse Gaussian process) or non-stationary (improved inverse Gaussian process). We propose a degradation balance mechanism in which the ‘most’ degraded units are forced down temporarily during the degradation process so that the system is less possible to fail due to imbalance. A closed-form lower bound reliability is presented when the balance mechanism is not applied. When it is applied, reliability is obtained by Monte Carlo simulation.
From the reliability study of the both configurations, it is observed that the reliability of a balanced system with multi-dimensional distributed units depends not only on the system’s total number of units and the least number of operating units, but also on the system configurations and balance requirements. Systems with more units do not necessarily provide a higher reliability since they are more likely to fail due to imbalance. Thus, optimal system design is key to maximize the system reliability which is investigated through numerical examples in this dissertation.Ph.D.Includes bibliographical reference
Assessment of auditory functions in chronic hepatitis C patients treated by sofosbuvir
No full textObjective: Evaluating the auditory function in patients with chronic hepatitis C treated with sofosbuvir and ribavirin.
Methods: This study involved 80 patients with chronic hepatitis C who agreed to receive sofosbuvir and ribavirin. All participants were subjected to baseline otological and audiological assessment just before treatment. The audiological assessment included standard pure tone audiometry, extended high-frequency audiometry, immitancemetry and otoacoustic emissions (OAEs) (transient and distortion product). According to baseline hearing threshold measurements, the study population was divided into 2 groups. Group 1 included 42 patients with normal hearing sensitivity (250–8000 Hz), and Group 2 included 38 patients with sensorineural hearing loss. After 24 weeks of therapy, otological and audiological assessments were repeated and compared between the two groups and before and after therapy.
Results: Post-treatment hearing threshold evaluation showed no significant difference from pretreatment evaluation at all tested frequencies. There was no statistically significant difference between pre and post-treatment otoacoustic emissions results.
Conclusion: Therapy with sofosbuvir and ribavirin in chronic hepatitis C has no noticeable effects on cochlear functions
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