Virologic Aspects of Mucosal Transmission

2019 ◽  
Vol 15 (1) ◽  
pp. 14-27
Author(s):  
Zachary Ende ◽  
Martin J. Deymier ◽  
Eric Hunter
Keyword(s):  
Infected Individual ◽  
Genetic Bottleneck ◽  
Viral Quasispecies ◽  
Biological Characterization ◽  
Mucosal Transmission ◽  
Effective Interventions ◽  
Stochastic Events ◽  
The Impact ◽  
Selection Of

The transmission of HIV is generally inefficient. Despite the development of a diverse viral quasispecies in a chronically infected individual, a severe genetic bottleneck is observed during transmission, leading to only one or a few genetic variants establishing infection. This genetic bottleneck is the result of both stochastic events and selection pressures, such that viruses with specific traits are favored during transmission. This chapter discusses current models of HIV mucosal transmission, evidence for selection of specific viral traits during this process, and the biological characterization of transmitted founder viruses based on monkey models and human cohorts. The impact of transmitted viral phenotypes on disease progression is also described. Understanding in greater depth the key viral features required for transmission will be essential to the development of effective interventions for HIV prevention.

scholarly journals Characterization of Carrier Phase-Based Positioning in Real-World Jamming Conditions

2021 ◽  
Vol 13 (14) ◽  
pp. 2680
Author(s):  
Søren Skaarup Larsen ◽  
Anna B. O. Jensen ◽  
Daniel H. Olesen
Keyword(s):  
Real World ◽  
Carrier Phase ◽  
Reference Station ◽  
Baseline Length ◽  
Dual Frequency ◽  
Positioning Accuracy ◽  
The Impact ◽  
Single Versus ◽  
Selection Of

GNSS signals arriving at receivers at the surface of the Earth are weak and easily susceptible to interference and jamming. In this paper, the impact of jamming on the reference station in carrier phase-based relative baseline solutions is examined. Several scenarios are investigated in order to assess the robustness of carrier phase-based positioning towards jamming. Among others, these scenarios include a varying baseline length, the use of single- versus dual-frequency observations, and the inclusion of the Galileo and GLONASS constellations to a GPS only solution. The investigations are based on observations recorded at physical reference stations in the Danish TAPAS network during actual jamming incidents, in order to realistically evaluate the impact of real-world jamming on carrier phase-based positioning accuracy. The analyses performed show that, while there are benefits of using observations from several frequencies and constellations in positioning solutions, special care must be taken in solution processing. The selection of which GNSS constellations and observations to include, as well as when they are included, is essential, as blindly adding more jamming-affected observations may lead to worse positioning accuracy.

scholarly journals Fungal Phytotoxins with Potential Herbicidal Activity to Control Chenopodium album

2015 ◽  
Vol 10 (6) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Alessio Cimmino ◽  
Marco Masi ◽  
Marco Evidente ◽  
Antonio Evidente
Keyword(s):  
Chenopodium Album ◽  
Scale Up ◽  
Field Trials ◽  
Herbicidal Activity ◽  
Biological Characterization ◽  
Fungal Toxin ◽  
Structure Activity ◽  
Ascochyta Caulina ◽  
Selection Of

This review deals with the isolation and chemical and biological characterization of phytotoxins produced by Ascochyta caulina and Phoma chenopodiicola proposed as mycoherbicides for the biological control of Chenopodium album, a worldwide spread weed which causes serious problems to some agrarian crops, including sugar beet and maize. Studies on the structure activity relationships and on the modes of actions of toxins isolated are also described, as well as the optimization of analytical methods focused on selection of the best fungal toxin producers. The attempts to scale up production of these phytotoxins aimed to obtain sufficient amounts for their application in greenhouse and field trials are also reported.

DNA Array and Biological Characterization of the Impact of the Maturation Status of Mouse Dendritic Cells on Their Phenotype and Antitumor Vaccination Efficacy

2001 ◽  
Vol 214 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Zhuang Chen ◽  
Scott Dehm ◽  
Keith Bonham ◽  
Huse Kamencic ◽  
Bernie Juurlink ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Dna Array ◽  
Biological Characterization ◽  
The Impact

Calibrator material selection: a key criteria during biomarker assay method development

Bioanalysis ◽  
2021 ◽  
Author(s):  
Sai P Thankamony ◽  
Rong Liu ◽  
Jon E Peterson ◽  
Rasa Santockyte ◽  
Timothy Olah ◽  
...  
Keyword(s):  
Decision Making ◽  
Case Studies ◽  
Method Development ◽  
Material Selection ◽  
Assay Method ◽  
Context Of Use ◽  
The Impact ◽  
Selection Of

Biomarker assay method development is a multistep rigorous process and calibrant material selection is integral to ensuring the quality of such assays. However, the impact of selection of calibrator material may often get overlooked. In this article, we highlight three case studies where biomarker calibrant material selection was deemed an essential criterion for consideration. Through these case studies we highlight challenges faced, steps taken and discuss the impact on assay-related decision-making. We also provide additional perspectives for selection and characterization of calibrant proteins in the setting of an evolving biomarker context of use.

scholarly journals The Mesoamerican mid-summer drought: the impact of its definition on occurrences and recent changes

2021 ◽  
Author(s):  
Edwin P. Maurer ◽  
Iris T. Stewart ◽  
Kenneth Joseph ◽  
Hugo G. Hidalgo
Keyword(s):  
Historical Record ◽  
Climate Projections ◽  
Summer Drought ◽  
Seasonal Forecasts ◽  
Drought Pattern ◽  
The Caribbean ◽  
The Impact ◽  
Minimum Intensity ◽  
Selection Of

Abstract. The mid-summer drought, veranillo or canícula, is a phenomenon experienced in many areas, including Mexico, Central America, and the Caribbean. It generally is experienced as reduced rainfall in July–August, in the middle of the typical rainy season (May–September). Many past studies have attempted to quantify changes in mid-summer drought characteristics during the recent past or for future climate projections. To do this, objective definitions of a mid-summer drought’s occurrence, strength and duration have been developed by many researchers. In this effort we adopt a recent set of definitions and examine the impact of varying these on the characterization of mid-summer droughts and the detected changes over the past four decades. We find the selection of a minimum intensity threshold has a dramatic effect on the results of both the area considered as experiencing a mid-summer drought and the changes detected in the recent historical record. The intensity chosen can affect both the magnitude and direction of changes reported in the recent observed record. Further, we find that the typical mid-summer drought pattern may not be occurring during the time it has historically; whether examining past or future changes or developing improved seasonal forecasts, the non-stationarity of its timing should be accommodated.

scholarly journals Mechanical Properties of Thermoplastics Corn Starch (TPCS) Reinforced Pineapple Leaf Fibre (PALF) Composite

2019 ◽  
Vol 8 (4) ◽  
pp. 8817-8821
Keyword(s):  
Corn Starch ◽  
Tensile Modulus ◽  
Impact Testing ◽  
Compression Moulding ◽  
Weight Percentage ◽  
Flexural Testing ◽  
The Impact ◽  
Fibre Loading ◽  
Selection Of

The aim of this study is to investigate the mechanical characterization of bio-composites on thermoplastic corn starch (TPCS) reinforced with 2 mm length of pineapple leaf fibre (PALF). The selection of different weight percentages of fibres (20, 30, 40, 50 and 60) weight percentage (wt.%) of PALF contents were applied in this study. The mixtures of TPCS with different wt.% of PALF were made by using a hot compression moulding at 165 °C for 15 minutes. The mechanical testing that has been performed are tensile, flexural and impact testing to determine the effect of fibre loading on bio-composites characteristics. The results show that by incorporating 40 wt.% loading of PALF, the tensile strength and tensile modulus has increased to the maximum. However, the flexural testing result shows that 50 wt.% loading of PALF show the highest strength and modulus. Meanwhile, the impact testing result shows decrement when the loadings of PALF increases. Scanning electron microscopy (SEM) show that the TPCS with 40 wt.% of PALF have a good miscibility between matrix/fibre in the bio-composites. Overall, the TPCS/PALF composites enhance the properties of the bio-composites for short-life application: that is, plate, container, disposable tray, packaging etc.

scholarly journals A Landscape Analysis of U.S. National Cancer Institute's Cancer Stigma Research Portfolio

2018 ◽  
Vol 4 (Supplement 2) ◽  
pp. 231s-231s
Author(s):  
V. Vedham
Keyword(s):  
Cancer Control ◽  
Portfolio Analysis ◽  
National Institutes Of Health ◽  
Cancer Site ◽  
Effective Interventions ◽  
The Social ◽  
Measurement Tools ◽  
Physical Changes ◽  
The Impact

Background: Successful characterization of cancer stigma among various populations has the potential to inform effective interventions targeted at combatting the social ignominy. Instances of social discrediting range from misconceptions about cancer treatment that prevent early detection to biases due to physical changes of cancer survivors, such as alopecia, mastectomy or colostomy. Cancer stigmas not only pose substantial challenges to disease control, they also exacerbate global disparities in health outcomes. To understand the current landscape of domestic and global cancer stigma research funded by the National Cancer Institute (NCI), a portfolio analysis of active awards between FY10-FY17 was conducted. Aim: This portfolio analysis aims to define the scope of NCI-funded research related to cancer stigma. Methods: The National Institutes of Health IMPAC II database was queried to retrieve NCI-funded grants related to cancer stigma using iterations of the term 'stigma', as well as other key words such as 'social isolation', 'shame' and 'disgrace', between FY10-FY17. After removing grant supplements and competitive renewals, grant abstracts and specific aims were reviewed to confirm projects fell within the parameters of cancer stigma research. Grants were then stratified by Common Scientific Outline (CSO) code; cancer site; and international components. Results: Forty-eight distinct NCI-funded projects that addressed cancer stigma were identified. Of those, 90% (n = 43) were coded to CSO code 'Cancer Control, Survivorship and Outcomes.' Additionally, over half (54%) of the projects focused on breast (13) or lung (13) cancer. All grants were awarded to US institutions, 6 of which included foreign collaborators. Four (8%) NCI-funded grants focus on the development of measures or instruments to uniformly quantify experiences of cancer stigma. Extramural grants with a cancer stigma component represented 0.1% of NCI's total FY 2008-2017 investment of over $25 billion USD. Conclusion: Building a knowledge base of the major contributors to cancer stigma and its impact on the illness experience is critical to improved treatment outcomes. A substantial proportion of NCI-supported stigma grants have been funded as smaller, exploratory projects. This may suggest that larger investments in time and resources are needed to fully comprehend the impact of stigma along the cancer continuum. A lack of NCI-funded tools to measure stigma across contexts and cultures is representative of the broader scientific literature, and poses challenges to the production of standardized data which could highlight global disparities. A comprehensive cancer stigma literature review and NCI portfolio analysis will illuminate research gaps and provide an avenue for recommendations of culturally tailored, evidence-based measurement tools, studies, or interventions.

scholarly journals Transcriptomic and metabolomic characterization of post-hatch metabolic reprogramming during hepatic development in the chicken

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Heidi A. Van Every ◽  
Carl J. Schmidt
Keyword(s):  
Artificial Selection ◽  
Molecular Mechanisms ◽  
Cellular Proliferation ◽  
Metabolic Reprogramming ◽  
Liver Growth ◽  
Major Organ ◽  
Hepatic Development ◽  
The Impact ◽  
Selection Of

Abstract Background Artificial selection of modern meat-producing chickens (broilers) for production characteristics has led to dramatic changes in phenotype, yet the impact of this selection on metabolic and molecular mechanisms is poorly understood. The first 3 weeks post-hatch represent a critical period of adjustment, during which the yolk lipid is depleted and the bird transitions to reliance on a carbohydrate-rich diet. As the liver is the major organ involved in macronutrient metabolism and nutrient allocatytion, a combined transcriptomics and metabolomics approach has been used to evaluate hepatic metabolic reprogramming between Day 4 (D4) and Day 20 (D20) post-hatch. Results Many transcripts and metabolites involved in metabolic pathways differed in their abundance between D4 and D20, representing different stages of metabolism that are enhanced or diminished. For example, at D20 the first stage of glycolysis that utilizes ATP to store or release glucose is enhanced, while at D4, the ATP-generating phase is enhanced to provide energy for rapid cellular proliferation at this time point. This work has also identified several metabolites, including citrate, phosphoenolpyruvate, and glycerol, that appear to play pivotal roles in this reprogramming. Conclusions At Day 4, metabolic flexibility allows for efficiency to meet the demands of rapid liver growth under oxygen-limiting conditions. At Day 20, the liver’s metabolism has shifted to process a carbohydrate-rich diet that supports the rapid overall growth of the modern broiler. Characterizing these metabolic changes associated with normal post-hatch hepatic development has generated testable hypotheses about the involvement of specific genes and metabolites, clarified the importance of hypoxia to rapid organ growth, and contributed to our understanding of the molecular changes affected by decades of artificial selection.

Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability

1968 ◽  
Vol 26 ◽  
pp. 442-443 ◽  
Author(s):  
L.E. Murr ◽  
A.B. Draper
Keyword(s):  
Electron Microscopy ◽  
State Physics ◽  
Test Material ◽  
Milling Machine ◽  
Rotary Table ◽  
Solid State Physics ◽  
Materials Properties ◽  
Transmission Electron ◽  
Selection Of

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

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