142 research outputs found
Correction: Guidelines for the prevention, detection and management of the renal complications of COVID-19 in Africa
Get PDFThe 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
Aberrant development of pancreatic beta cells derived from human iPSCs with FOXA2 deficiency
No full text<p>Induced pluripotent stem cells (iPSCs) were generated from a patient with <em>FOXA2 </em>haploinsufficiency (FOXA2<sup>+/-</sup>iPSCs) as well as healthy individual as a control. Then they were differentiated into into all stages of beta cells to understand the role of FOXA2 during pancreatic beta cell development as described in the article entitled "Aberrant development of pancreatic beta cells derived from human iPSCs with FOXA2 deficiency" by Elsayed AK et al. The dataset represent RNA-seq data generated from pancreatic progenitors (PP2) and endocrine progenitors (EP) derived from control iPSCs (Ctr-iPSCs) and from patient-specific FOXA2 haplo-insufficient iPSCs (FOXA2<sup>+/-</sup>iPSCs). </p>
<p>The file name is : Sample name with replicate_overall sample number_read direction_001 where:</p>
<p>- PP2-Ctr R1 and PP2-Ctr R2: Pancreatic progenitors derived from Ctr-iPSCs (control)</p>
<p>-PP2-FOX R1, PP2-FOX R2 and PP2-FOX R3: Pancreatic progenitors derived from FOXA2 haplo-insufficient iPSCs (FOXA2<sup>+/-</sup>iPSCs).</p>
<p>- EP-Ctr R1 and EP-Ctr R2: Endocrine progenitors derived from Ctr-iPSCs (control)</p>
<p>-EP-FOX R1, EP-FOX R2 and EP-FOX R3: Endocrine progenitors derived from FOXA2 haplo-insufficient iPSCs (FOXA2<sup>+/-</sup>iPSCs).</p>
<p>- RNA-seq data was generated from two biological replicates in control and three replicates in patient. </p>
<p>- Read direction: R1 (Forward), R2 (Reverse).</p>
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
The Impact of Low-Power Design Methodology on Digital Libraries
No full textIn recent years, exciting new low-power design methods have been introduced, such as: multiple supply voltages, body bias techniques and power shut-off. In order to use these low power design methods, strict requirements for both libraries and tools are needed. An additional challenge is the introduction of more accurate characterization models for newer technologies (current source models like ECSM and CCS). This has made the task of library checking a serious issue that needs to be automated. The main part of this thesis presents a checker tool that is used to verify the consistency of the different library formats (views) in standard cell libraries. The layout consistency checker in our tool checks the consistency of the layout of pins between GDSII and LEF library views; we devised a new algorithm,Grid Formation and Centre Inclusion, for this checker. The tool also verifies the pin consistency and availability of cells across other library formats, such as: Verilog and Liberty. The tool was tested using different technology libraries (such as 90nm and 40nm), provided by different vendors (such as GLOBALFOUNDRIES); multiple interfacing errors were caught using our library checker tool. A second part at the end of the thesis shows experiments with some of the low-power design techniques used during the design of a digital block, using -for implementation- standard cells from one of the libraries that have been checked with the library checker tool. Benefits of using these techniques are evaluated and trade-offs are discussed. Power-Shut Off (PSO) design technique proved to be the most effective in reducing power consumption, with power savings that reached 20%.Circuits and SystemsElectrical Engineering, Mathematics and Computer Scienc
The Influence of temperature on the growth of the nile tilapia, oreochromis niloticus reared in glass tanks
No full textThe effect of three water temperatures: 20, 25 and 30°C on the growth rate of Nile tilapia, Oreochromis ni/oticus was evaluated using a stocking density of 200 fish/mJ. Fish were reared in glass tanks supplied with thermostatic heaters and biological filters. Fish were fed a local fish food (34% protein) in a dry form once daily for six days per week with 2% of fish body weight. The experiment covered a time period of 135 days from Nov. 1993 to Mar. 1994. The best growth rate was obtained at a temperature of25°C followed by the temperature of 30°C, and the lowest growth rate was achieved at 20°c. The optimum temperature for these fish may be 25°C or slightly more but less than 30°C. The effect of the temperature on the growth rate of Nile tilapia was highly significant (P<O.OOI)
Modeling and optimization of container inspection systems
No full textContainer inspection is vital to maintaining secure ports-of-entry and preventing undesired cargo from entering the United States. The inspection process can be generalized as the collection and analysis of information obtained from multiple sensors. Formulating a mathematical model of container inspection allows for evaluation and improvement of the process. The performance of the system under a specified policy is evaluated using one or more objectives such as misclassification errors (false accept and false reject), costs associated with these errors, inspection cost, inspection time, and others. The main contributions of this research are the modeling, formulation, and optimization of inspection policies under different conditions. Furthermore, the dissertation introduces a new class of problems in scheduling theory in which the allocation of inspections is not defined and appears as a decision variable in the solution. In the initial model, the overall system decision is a Boolean function of the individual station decisions. Under these conditions we define an optimal sequence of stations with respect to the expected cost of inspection and solve simultaneously for the threshold level values and sequence of stations that produce a minimum total cost. This optimization is extended to include the time for inspection as an objective and a multi-objective optimization approach is developed. Next we introduce an independent error term that accounts for measurement error contributed by the sensor and propose some strategies, including repeat inspection, to improve the system’s performance. We investigate an approach to approximating the efficient frontier for three objectives. We then consider distinct risk categories and due times for containers. Approaches are developed to determine the optimal allocation and scheduling of inspection operations to minimize false acceptance and tardiness objectives. The problem is presented as a variation of the open shop scheduling problem with no predefined operations. A solution approach to this simultaneous allocation and scheduling problem is proposed and its performance is compared with an enumerative approach. The results show that the proposed approach produces near-optimal solutions in a much shorter time than full enumeration and is capable of solving large problems for which the enumerative approach is intractable.Ph.D.Includes bibliographical referencesIncludes vitaby Christina M. Youn
Aggregation enhanced excimer emission (AEEE) with efficient blue emission based on pyrene dendrimers
No full textLead Nitrate Induced Histopathological Alterations in the Liver and Intestine of African Catfish Clarias gariepinus Exposed to Sublethal Concentrations
Get PDF552-557Studies were carried out on the liver and intestine tissue of Clarias gariepinus after exposure to sublethal concentrations of LC50 lead nitrate for 20 days. Fish were distributed into four groups, control (0 mg/L, LC50 of Pb(NO3)2) and three groups exposed to 20, 40 and 60% of the LC50 of Pb(NO3)2 (16.12, 32.24 and 48.37 mg/L respectively). Section of hepatic and intestine tissues showed the normal structure for control group. However, treated hepatic tissues of fish exhibited altered its characteristic architecture, with remarkably high vacuolation in hepatocytes and hepatoctolysis. Also, central vein was dilated and increased hemorrhage in the sections of almost samples from treated fish. Increased number of fibroblasts and Kuppffer cells were observed in the examined sections from treated fish when compared to the control. Therefore, fish treated with 60% LD50 of Pb(NO3)2 observed the proliferation of fibrous in connective tissue particularly near sinusoids and substituting liver parenchyma. Therefore, intestinal sections from the different treated fish groups revealed an evident harmful to intestinal tissue, especially in enterocytes and structures of villi. Also, disturbed longitudinal and circular muscularis were observed, to abnormally dilated, lamina propria, was infiltrated with a huge numbers of inflammatory leukocytes. Mucous secreting goblet cells proliferated and multiplied in all exposed fish
Design, construction and field testing of a manually feeding semiautomatic sugarcane dud chipper
No full textSugarcane is the main sugar crop, and sugar is an important agricultural product in Egypt. There are many problems with the technology used in the current planting method of sugarcane, which has a great impact on the planting quality of sugarcane, which have a series of problems, such as low cutting efficiency and poor quality. Therefore, the aim of the current study was to design, construct, and field testing of a semiautomatic sugarcane bud chipper assisted with pivot knives for cutting sugarcane buds and germinating them in plastic trays inside a greenhouse until they reached an average length of 35 cm, and then planting them in the field. In the field tests five cutting speeds (35, 40, 45, 50, and 56 rpm. (Revolution Per minute), three cutting knives (1.5, 2.0, and 2.5 mm) were used for cutting sugarcane stalks with four different diameters (1.32, 1.82, 2.43, and 2.68 cm). The obtained results showed that the values of the damage index and invisible losses were within acceptable limits (ranging between - 1.0 and 0.0) for all the variables under the test. Still, the lowest damage index and invisible losses were recorded with the buds that were cut with a knife of 1.5 mm thickness and cutting speeds less than 50 rpm. The skipping rate increases with the increase in cutting speed and stalk diameter, ranging between 0.0 to 13%. The maximum machine productivity was 110 Buds per minute at a cutting speed of 35 rpm and stalk diameter of 1.32 cm. The paper's findings have important application values for promoting the designing and development of sugarcane bud chipper and sugarcane planting technology in the future
SHARC : self-healing analog with RRAM and CNFETs
No full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 49-50).Next-generation applications require processing on massive amount of data in real-time, exceeding the capabilities of electronic systems today. This has spurred research in a wide-range of areas: from new devices to replace silicon-based field-effect transistors (FETs) to new circuit and system architectures with fine-grained and dense integration of logic and memory. However, isolated improvements in just one area is insufficient. Rather, enabling these next-generation applications will require combining benefits across all levels of the computing stack: leveraging new devices to realize new circuits and architectures. For instance, carbon nanotube (CNT) field-effect transistors (CNFETs) for logic and Resistive Random-Access Memory (RRAM) for memory are two promising emerging nanotechnologies for energy-efficient electronics. However, CNFETs suffer from inherent imperfections (such as of metallic CNTs, m-CNTs), which have prohibited realizing large-scale CNFET circuits in the past. This work proposes a circuit design technique that integrates and combines the benefits of both CNFETs with RRAM to realize three-dimensional (3D) circuits that are immune to m-CNTs. Leveraging this technique, we show the first experimental demonstration of CNFET-based analog mixed-signal circuits.by Aya G. Amer.S.M.S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienc
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