scholarly journals Biofilm Early Stages of Growth and Accumulation Theoretical Model

Author(s):  
José Carvalho ◽  
Manuel Carrondo ◽  
Luis Bonilla

A theoretical model to translate the evolution over time, in early stages, of growth and accumulation of biofilm bacterial mass is introduced. The model implies the solution of a system of differential-difference master equations. The application of an algorithm like Miller´s tree term recurrence, already known for Bessel functions of first kind, allows an exact calculation of the solutions of such equations, for a wide range of parameters values and time. For biofilm model a five term recurrence is deduced and applied in a backwards computation. A suitable normalisation condition completes the reach of the solution.

Author(s):  
José Carvalho ◽  
Manuel Carrondo ◽  
Luis Bonilla

A theoretical model to translate the evolution over time, in early stages, of growth and accumulation of biofilm bacterial mass is introduced. The model implies the solution of a system of differential-difference master equations. The application of an algorithm like Miller´s tree term recurrence, already known for Bessel functions of first kind, allows an exact calculation of the solutions of such equations, for a wide range of parameters values and time. For biofilm model a five term recurrence is deduced and applied in a backwards computation. A suitable normalisation condition completes the reach of the solution.


1973 ◽  
Vol 56 (5) ◽  
pp. 1178-1182
Author(s):  
Ali El-Refai ◽  
M M Mowafy

Abstract Greenhouse and laboratory experiments were designed to determine the effect of soil-applied carbaryl and diazinon on the phytotoxicity of foliage-sprayed propanil. A time-course study of the activity of propanil-hydrolyzing enzyme in rice indicated a slow increase in the rate of hydrolysis during early stages of growth, followed by a sharp increase for extracts of the 7-week-old samples. The rate of hydrolysis reached its maximum at harvest time (approximately 17 weeks). The enzyme activity of barnyard grass was not detected at different growth stages. The enzyme was inhibited by diazinon and strongly inhibited by carbaryl absorbed and translocated from the soil over a wide range of growth stages of rice. Rice plants were more susceptible at early stages of growth and this confirms the significant correlation between growth stage and enzyme activities. Analyses of tissue extracts by paper chromatography and an enzyme inhibition method agreed closely at all intervals. It seems probable that the inhibition rate of enzyme is related to the persistence and rate of translocation of carbaryl.


Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.


Anticorruption in History is the first major collection of case studies on how past societies and polities, in and beyond Europe, defined legitimate power in terms of fighting corruption and designed specific mechanisms to pursue that agenda. It is a timely book: corruption is widely seen today as a major problem, undermining trust in government, financial institutions, economic efficiency, the principle of equality before the law and human wellbeing in general. Corruption, in short, is a major hurdle on the “path to Denmark”—a feted blueprint for stable and successful statebuilding. The resonance of this view explains why efforts to promote anticorruption policies have proliferated in recent years. But while the subjects of corruption and anticorruption have captured the attention of politicians, scholars, NGOs and the global media, scant attention has been paid to the link between corruption and the change of anticorruption policies over time and place. Such a historical approach could help explain major moments of change in the past as well as reasons for the success and failure of specific anticorruption policies and their relation to a country’s image (of itself or as construed from outside) as being more or less corrupt. It is precisely this scholarly lacuna that the present volume intends to begin to fill. A wide range of historical contexts are addressed, ranging from the ancient to the modern period, with specific insights for policy makers offered throughout.


2021 ◽  
Vol 14 (5) ◽  
pp. 467
Author(s):  
Ana Henriques Mota ◽  
Inês Prazeres ◽  
Henrique Mestre ◽  
Andreia Bento-Silva ◽  
Maria João Rodrigues ◽  
...  

Sambucus nigra L. (S. nigra) is a shrub widespread in Europe and western Asia, traditionally used in medicine, that has become popular in recent years as a potential source of a wide range of interesting bioactive compounds. The aim of the present work was to develop a topical S. nigra extract formulation based on ethosomes and thus to support its health claims with scientific evidence. S. nigra extract was prepared by an ultrasound-assisted method and then included in ethosomes. The ethosomes were analyzed in terms of their size, stability over time, morphology, entrapment capacity (EC), extract release profile, stability over time and several biological activities. The prepared ethosomes were indicated to be well defined, presenting sizes around 600 nm. The extract entrapment capacity in ethosomes was 73.9 ± 24.8%, with an interesting slow extract release profile over 24 h. The extract-loaded ethosomes presented collagenase inhibition activity and a very good skin compatibility after human application. This study demonstrates the potential use of S. nigra extract incorporated in ethosomes as a potential cosmeceutical ingredient and on further studies should be performed to better understand the impact of S. nigra compounds on skin care over the time.


2021 ◽  
Vol 13 (2) ◽  
pp. 1-27
Author(s):  
A. Khalemsky ◽  
R. Gelbard

In dynamic and big data environments the visualization of a segmentation process over time often does not enable the user to simultaneously track entire pieces. The key points are sometimes incomparable, and the user is limited to a static visual presentation of a certain point. The proposed visualization concept, called ExpanDrogram, is designed to support dynamic classifiers that run in a big data environment subject to changes in data characteristics. It offers a wide range of features that seek to maximize the customization of a segmentation problem. The main goal of the ExpanDrogram visualization is to improve comprehensiveness by combining both the individual and segment levels, illustrating the dynamics of the segmentation process over time, providing “version control” that enables the user to observe the history of changes, and more. The method is illustrated using different datasets, with which we demonstrate multiple segmentation parameters, as well as multiple display layers, to highlight points such as new trend detection, outlier detection, tracking changes in original segments, and zoom in/out for more/less detail. The datasets vary in size from a small one to one of more than 12 million records.


2003 ◽  
Vol 29 (2-3) ◽  
pp. 363-380
Author(s):  
Mary Anne Bobinski

Healthy People 2010 provides our Nation with the wide range of public health opportunities that exist in the first decade of the 21st century. With 467 objectives in 28 focus areas, Healthy People 2010 will be a tremendously valuable asset … . Healthy People 2010 reflects the very best in public health planning—it is comprehensive, it was created by a broad coalition of experts from many sectors, it has been designed to measure progress over time, and, most important, it clearly lays out a series of objectives to bring better health to all people in this country.The current responses to the traditional health perils … have been weakened. At the same time, it seems to this outsider as though the entire public health establishment is united around the proposition that massive public action should be taken to deal with the new “epidemics,” such as obesity and diabetes … . But the use of the term “epidemic” is just the wrong way to think about this issue. There are no noncommunicable epidemics … . Yet the designation [of] obesity as a public health epidemic is designed to signal that state coercion is appropriate … .


2020 ◽  
Vol 70 (1) ◽  
pp. 181-189
Author(s):  
Guy Baele ◽  
Mandev S Gill ◽  
Paul Bastide ◽  
Philippe Lemey ◽  
Marc A Suchard

Abstract Markov models of character substitution on phylogenies form the foundation of phylogenetic inference frameworks. Early models made the simplifying assumption that the substitution process is homogeneous over time and across sites in the molecular sequence alignment. While standard practice adopts extensions that accommodate heterogeneity of substitution rates across sites, heterogeneity in the process over time in a site-specific manner remains frequently overlooked. This is problematic, as evolutionary processes that act at the molecular level are highly variable, subjecting different sites to different selective constraints over time, impacting their substitution behavior. We propose incorporating time variability through Markov-modulated models (MMMs), which extend covarion-like models and allow the substitution process (including relative character exchange rates as well as the overall substitution rate) at individual sites to vary across lineages. We implement a general MMM framework in BEAST, a popular Bayesian phylogenetic inference software package, allowing researchers to compose a wide range of MMMs through flexible XML specification. Using examples from bacterial, viral, and plastid genome evolution, we show that MMMs impact phylogenetic tree estimation and can substantially improve model fit compared to standard substitution models. Through simulations, we show that marginal likelihood estimation accurately identifies the generative model and does not systematically prefer the more parameter-rich MMMs. To mitigate the increased computational demands associated with MMMs, our implementation exploits recent developments in BEAGLE, a high-performance computational library for phylogenetic inference. [Bayesian inference; BEAGLE; BEAST; covarion, heterotachy; Markov-modulated models; phylogenetics.]


2019 ◽  
Vol 13 ◽  
pp. 04020
Author(s):  
Giovan Battista Mattii ◽  
Eleonora Cataldo ◽  
Linda Salvi ◽  
Sofia Sbraci ◽  
Francesca Paoli ◽  
...  

In the early stages of planting, the shelter can provide for young vines protection against damage of various kinds. Despite their widespread use, few surveys have been devoted to the study of innovative shelter types and the possible influence of these protections on the physiology and development of plants. In the present experiment, which took place in 2017 in a Tuscan winery, the effects of vine protections by the company OSO (Prato) on single leaf gas exchanges and on the shoot growth in the first year of planting were studied. Three types of shelters with a circular section (completely perforated, partially perforated and closed) have been compared with the traditional full-wall shelters with square section. During the growing season, sprout growth measures, leaf area, leaf gas exchanges and water potential were carried out on the young vines. At the end of the season, shoots were sampled to measure the dry matter accumulated during the season. Among the shelters taken into consideration, it emerges that the completely perforated type guarantees the best development, with differences that are almost always significant for most of the measured parameters with traditional shelters. On the contrary, the closed typology has led to a reduction in growth, in gas exchanges and in water potential. In conclusion, the type completely perforated could constitute a valid alternative to the traditional one because, besides being a useful means for the protection of the vine, it could benefit the development of the root system in the early stages of growth.


Author(s):  
Marios Patinios ◽  
James A. Scobie ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
Gary D. Lock

In gas turbines, hot mainstream flow can be ingested into the wheel-space formed between stator and rotor disks as a result of the circumferential pressure asymmetry in the annulus; this ingress can significantly affect the operating life, performance, and integrity of highly stressed, vulnerable engine components. Rim seals, fitted at the periphery of the disks, are used to minimize ingress and therefore reduce the amount of purge flow required to seal the wheel-space and cool the disks. This paper presents experimental results from a new 1.5-stage test facility designed to investigate ingress into the wheel-spaces upstream and downstream of a rotor disk. The fluid-dynamically scaled rig operates at incompressible flow conditions, far removed from the harsh environment of the engine which is not conducive to experimental measurements. The test facility features interchangeable rim-seal components, offering significant flexibility and expediency in terms of data collection over a wide range of sealing flow rates. The rig was specifically designed to enable an efficient method of ranking and quantifying the performance of generic and engine-specific seal geometries. The radial variation of CO2 gas concentration, pressure, and swirl is measured to explore, for the first time, the flow structure in both the upstream and downstream wheel-spaces. The measurements show that the concentration in the core is equal to that on the stator walls and that both distributions are virtually invariant with radius. These measurements confirm that mixing between ingress and egress is essentially complete immediately after the ingested fluid enters the wheel-space and that the fluid from the boundary layer on the stator is the source of that in the core. The swirl in the core is shown to determine the radial distribution of pressure in the wheel-space. The performance of a double radial-clearance seal is evaluated in terms of the variation of effectiveness with sealing flow rate for both the upstream and the downstream wheel-spaces and is found to be independent of rotational Reynolds number. A simple theoretical orifice model was fitted to the experimental data showing good agreement between theory and experiment for all cases. This observation is of great significance as it demonstrates that the theoretical model can accurately predict ingress even when it is driven by the complex unsteady pressure field in the annulus upstream and downstream of the rotor. The combination of the theoretical model and the new test rig with its flexibility and capability for detailed measurements provides a powerful tool for the engine rim-seal designer.


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