907 research outputs found
The Osteology Lesson of Sebastiaen Egbertszn (1619)
In 1619 the Amsterdam Guild of Surgeons commissioned a recognized Dutch painter to make a group portrait of the governors. This masterpiece is known as The Osteology Lesson of Sebastiaen Egbertszn. Egbertszn, praelector anatomiae (lecturer in anatomy), is depicted while demonstrating the human bones using the skeleton of an English pirate. The subject of this painting reminds us of the doctrine of osteology as part of the former surgical training. The lives and work of the represented governors of the guild and their teacher Sebastiaen Egbertszn, as well as details of the skeleton, are discussed after examination of the literature and original guild documents pertaining to the painting. The Osteology Lesson of Sebastiaen Egbertszn (1619) is a group portrait of the governors of the Amsterdam Guild of Surgeons. It represents one of a series of nine anatomy lessons commissioned in the 17th and 18th centuries. Sebastiaen Egbertszn, who was the praelector anatomiae (lecturer in anatomy) at that time, is depicted demonstrating human bone anatomy using the skeleton of an executed pirate. Egbertszn died during a plague epidemic only 2 years after the painting was delivered and the identity of the artist remains contentious to this day. It is exhibited in the Amsterdam Museum in Amsterdam, The Netherlands
A Realistic Model under which the Genetic Code is Optimal
The genetic code has a high level of error robustness. Using values of
hydrophobicity scales as a proxy for amino acid character, and the Mean Square
measure as a function quantifying error robustness, a value can be obtained for
a genetic code which reflects the error robustness of that code. By comparing
this value with a distribution of values belonging to codes generated by random
permutations of amino acid assignments, the level of error robustness of a
genetic code can be quantified. We present a calculation in which the standard
genetic code is shown to be optimal. We obtain this result by (1) using
recently updated values of polar requirement as input; (2) fixing seven
assignments (Ile, Trp, His, Phe, Tyr, Arg, and Leu) based on aptamer
considerations; and (3) using known biosynthetic relations of the 20 amino
acids. This last point is reflected in an approach of subdivision (restricting
the random reallocation of assignments to amino acid subgroups, the set of 20
being divided in four such subgroups). The three approaches to explain
robustness of the code (specific selection for robustness, amino acid-RNA
interactions leading to assignments, or a slow growth process of assignment
patterns) are reexamined in light of our findings. We offer a comprehensive
hypothesis, stressing the importance of biosynthetic relations, with the code
evolving from an early stage with just glycine and alanine, via intermediate
stages, towards 64 codons carrying todays meaning.Comment: 22 pages, 3 figures, 4 tables Journal of Molecular Evolution, July
201
Hypothermic in situ perfusion of the porcine liver using Celsior or Ringer-lactate solution
BACKGROUND: Hypothermic perfusion (HP) of the liver is applied during total vascular exclusion (TVE) to reduce ischemic injury during liver resection. No studies have been performed comparing different perfusion solutions for HP. The aim of this experimental study was to compare Ringer-lactate solution (RL) with Celsior solution (Cs) for HP in a pig model of 60-min TVE. METHOD: Twenty pigs underwent 60-min TVE of the liver. Groups were TVE without HP (no-HP, n = 9), TVE with HP using RL (n = 6), and TVE with HP using Cs (n = 5). Blood and liver tissue samples were taken before TVE and during 24-h reperfusion. RESULTS: In the no-HP group, plasma aspartate aminotransferase values were significantly increased during reperfusion (p <0.05), while liver tissue pO(2) levels (p <0.01) were decreased when compared to the HP groups. After 24-h reperfusion, bile production and liver tissue glutathione content were significantly higher (p <0.05) in the Cs group (42.0 +/- 1.7 mL/h and 44.9 +/- 2.2 nmol/mg, respectively) as compared to the RL group (31.5 +/- 3.5 mL/h and 19.6 +/- 1.8 nmol/mg, respectively). CONCLUSION: The protective effect of HP during TVE was confirmed in this study. HP with Cs was more effective in reducing ischemic injury as compared to HP with R
Staging Laparoscopy for Hilar Cholangiocarcinoma: Is it Still Worthwhile?
This study was designed to evaluate the benefit of staging laparoscopy (SL) in patients with suspected hilar cholangiocarcinoma (HCCA) during the past 10 years. Only 50-60% of patients with HCCA who undergo laparotomy are ultimately amenable to a potentially curative resection. In a previous study, we recommended routine use of SL to prevent unnecessary laparotomies. The accuracy of imaging techniques, however, has significantly improved during the past decade, which is likely to impact the yield and accuracy of SL. From 2000 to 2010, 195 patients with suspected HCCA were analyzed. The yield and accuracy of SL were calculated by dividing total number of avoided laparotomies by the total number of laparoscopies or by all patients with unresectable disease, respectively. Factors associated with better yield and accuracy were assessed. Of 195 patients with HCCA, 175 underwent SL. The yield of SL was 14% and the accuracy was 32%. Operative morbidity of SL was 3%, and operative morbidity of laparotomy for unresectable disease was 33%. No clear factors that influenced the yield of SL were found. Overall yield and accuracy of SL for HCCA in the present series decreased to 14% and 32%, respectively, compared with earlier reports. This finding is likely the result of improved imaging techniques that evolved during the past decade. The place of SL in the workup of patients with HCCA needs to be reconsidered, and one should decide whether the declining additional value of SL still outweighs the drawbacks of S
Application profiling and resource management for MapReduce
Scale of data generated and processed is exponential growth in the Big Data ear. It poses a challenge that is far beyond the goal of a single computing system. Processing such vast amount of data on a single machine is impracticable in term of time or cost. Hence, distributed systems, which can harness very large clusters of commodity computers and processing data within restrictive time deadlines, are imperative. In this thesis, we target two aspects of distributed systems: application profiling and resource management. We study a MapReduce system in detail, which is a programming paradigm for large scale distributed computing, and presents solutions to tackle three key problems. Firstly, this thesis analyzes the characteristics of jobs running on the MapReduce system to reveal the problem—the Application scope of MapReduce has been extended beyond the original design goal that was large-scale data processing. This problem enables us to present a Workload Characteristic Oriented Scheduler (WCO), which strives for co-locating tasks of possibly different MapReduce jobs with complementing resource usage characteristics. Secondly, this thesis studies the current job priority mechanism focusing on resource management. In the MapReduce system, job priority only exists at scheduling level. High priority jobs are placed at the front of the scheduling queue and dispatched first. Resource, however, is fairly shared among jobs running at the same worker node without any consideration for their priorities. In order to resolve this, this thesis presents a non-intrusive slot layering solution, which dynamically allocates resource between running jobs based on their priority and efficiently reduces the execution time of high priority jobs while improves overall throughput. Last, based on the fact of underutilization of resource at each individual worker node, this thesis propose a new way, Local Resource Shaper (LRS), to smooth resource consumption of each individual job by automatically tuning the execution of concurrent jobs to maximize resource utilization while minimizing resource contention
Ontsmetten met Easy Ice Clean ("Coldblast") "Proof of principle"
In dit onderzoek is er gekeken naar de potentie en het proof of principle van de Cold Jet techniek van Easy Ice Clean in de tuinbouw. Met dit onderzoek is getracht te beantwoorden of de Cold Jet techniek potentie heeft als alternatieve ontsmettingstechniek voor chemische middelen. De techniek die in dit onderzoek een rol speelde is een techniek die gebruik maakt van droogijs (bevroren CO2). Droogijspellets worden onder grote druk op een te reinigen oppervlak gestraald. Als gevolg van de koude shock en de kracht van de straal kunnen oppervlakken worden gereinigd en misschien wel worden ontsmet. Deze techniek kan een milieuvriendelijke oplossing zijn voor het reinigen van oppervlakken zoals tafels, vloeren, materialen en kassen bij uiteenlopende glastuinbouwteelten. Op basis van het uitgevoerde experiment kan worden geconcludeerd dat de droogijsstraal techniek een onvoldoende ontsmettend effect heeft om een alternatief te zijn voor chemische ontsmettingsmiddelen. De techniek heeft potentie in de glastuinbouw bij het schoonmaken van ernstig vervuilde oppervlakken en complexe apparatuur en installaties. Ook installaties en apparatuur die gevoelig zijn voor water (corrosie) kunnen met deze methode wel grondig worden schoon gemaakt. Ook kan de techniek in combinatie met andere aanvullende technieken wel leiden tot een schoon én ontsmet oppervlak
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