scholarly journals Studying the present, understanding the past

2021 ◽  
Author(s):  
Caballero ◽  
Paredes-Aliaga ◽  
Costa-Pérez ◽  
Bueno ◽  
Álvarez-Parra ◽  
...  
Keyword(s):  
The Past ◽  
Present Understanding

scholarly journals Flavonoids as natural phenolic compounds and their role in therapeutics: an overview

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Rakesh E. Mutha ◽  
Anilkumar U. Tatiya ◽  
Sanjay J. Surana
Keyword(s):  
Phenolic Compounds ◽  
Therapeutic Potential ◽  
Main Body ◽  
The Past ◽  
Secondary Chemicals ◽  
Natural Phenolic Compounds ◽  
Development And Management ◽  
Major Emphasis ◽  
Present Understanding

Abstract Background Natural plants and plant-derived formulations have been used by mankind from the ancient period of time. For the past few years, many investigations elaborated the therapeutic potential of various secondary chemicals present in the plants. Literature revealed that the various secondary metabolites, viz. phenolics and flavonoids, are responsible for a variety of therapeutic action in humans. Main body In the present review, an attempt has been made to compile the exploration of natural phenolic compounds with major emphasis on flavonoids and their therapeutic potential too. Interestingly, long-term intake of many dietary foods (rich in phenolics) proved to be protective against the development and management of diabetes, cancer, osteoporosis, cardiovascular diseases and neurodegenerative diseases, etc. Conclusion This review presents an overview of flavonoid compounds to use them as a potential therapeutic alternative in various diseases and disorders. In addition, the present understanding of phenolics and flavonoids will serve as the basis for the next scientific studies.

Review and Understanding on Sweep in Axial Compressor Design

2005 ◽  
Author(s):  
Lucheng Ji ◽  
Jiang Chen ◽  
Feng Lin
Keyword(s):  
Axial Compressor ◽  
Blade Design ◽  
The Past ◽  
Compressor Design ◽  
Compressor Performance ◽  
Historical Remarks ◽  
Present Understanding ◽  
Full Operation ◽  
Blade Element

As a means of improving axial compressor performance, sweep technique has been investigated for over half a century and gained wide uses, in the past one decade. However, there is still diverse controversy about the roles of sweep in axial compressor design. In this paper, historical remarks about the sweep are presented firstly. Then, an understanding about the role of sweep is put forward. That is, the sweep is a degree of freedom (DOF) of blade design that emphasizes on matching the aerodynamic loading of every blade element along the whole span within the full operation range. The present understanding about the role of sweep may lead it a more sophisticated use.

Sir Nicholas John Shackleton. 23 June 1937 — 24 January 2006

2011 ◽  
Vol 57 ◽  
pp. 435-462 ◽  
Author(s):  
Ian Nicholas McCave ◽  
Henry Elderfield
Keyword(s):  
Carbon Dioxide ◽  
Global Warming ◽  
Climatic Changes ◽  
Future Climate ◽  
The Past ◽  
Earth’S Climate ◽  
Natural Climate ◽  
Precise Role ◽  
Present Understanding

Nick Shackleton was an international scientist of great renown who fundamentally changed our understanding of how Earth processes work. His research on ancient oceans and climates was both innovative and pioneering, and he clarified the precise role of carbon dioxide in warming and cooling the Earth's climate. His work contributed greatly to our present understanding of the mechanism and causes of global warming. When he began his research, the investigation of past climatic changes was an area of ‘academic’ interest only. Four decades later, his lifetime achievements define the emergence of our understanding of the operation of Earth's natural climate system. This understanding of the past is now central to efforts to predict the future climate we have begun to create. As well as his many scientific accomplishments, Nick Shackleton excelled in another area, that of music, which was almost as important to him as science, and he was a very accomplished clarinet player. In his work he was spirited and curiosity-driven. He let his students and an entire community share in his brilliance and vision.

scholarly journals Beating the acetyl coenzyme A-pathway to the origin of life

2013 ◽  
Vol 368 (1622) ◽  
pp. 20120258 ◽  
Author(s):  
Wolfgang Nitschke ◽  
Michael J. Russell
Keyword(s):  
Phylogenetic Analysis ◽  
Boundary Conditions ◽  
Origin Of Life ◽  
Carbon Metabolism ◽  
Acetyl Coenzyme A ◽  
The Past ◽  
Proposed Model ◽  
The Origin Of Life ◽  
To Come ◽  
Present Understanding

Attempts to draft plausible scenarios for the origin of life have in the past mainly built upon palaeogeochemical boundary conditions while, as detailed in a companion article in this issue, frequently neglecting to comply with fundamental thermodynamic laws. Even if demands from both palaeogeochemistry and thermodynamics are respected, then a plethora of strongly differing models are still conceivable. Although we have no guarantee that life at its origin necessarily resembled biology in extant organisms, we consider that the only empirical way to deduce how life may have emerged is by taking the stance of assuming continuity of biology from its inception to the present day. Building upon this conviction, we have assessed extant types of energy and carbon metabolism for their appropriateness to conditions probably pertaining in those settings of the Hadean planet that fulfil the thermodynamic requirements for life to come into being. Wood–Ljungdahl (WL) pathways leading to acetyl CoA formation are excellent candidates for such primordial metabolism. Based on a review of our present understanding of the biochemistry and biophysics of acetogenic, methanogenic and methanotrophic pathways and on a phylogenetic analysis of involved enzymes, we propose that a variant of modern methanotrophy is more likely than traditional WL systems to date back to the origin of life. The proposed model furthermore better fits basic thermodynamic demands and palaeogeochemical conditions suggested by recent results from extant alkaline hydrothermal seeps.

scholarly journals Bounding global aerosol radiative forcing of climate change

2020 ◽  
Author(s):  
Nicolas Bellouin ◽  
Keyword(s):  
Radiative Forcing ◽  
Review Paper ◽  
Aerosol Radiative Forcing ◽  
The Past ◽  
Open Questions ◽  
Substantial Progress ◽  
Theoretical Considerations ◽  
Present Understanding ◽  
Lines Of Evidence ◽  
Aerosol Radiative

<p>Aerosol radiative forcing plays an important role in the attribution of past climate changes, estimates of future allowable carbon emissions, and the assessment of potential geoengineering solutions. Substantial progress made over the past 40 years in observing, understanding, and modelling aerosol processes helped quantify aerosol radiative forcing, but uncertainties remain large.</p><p>In spring 2018, under the auspices of the World Climate Research Programme's Grand Science Challenge on Clouds, Circulation and Climate Sensitivity, thirty-six experts gathered to take a fresh and comprehensive look at present understanding of aerosol radiative forcing and identify prospects for progress on some of the most pressing open questions. The outcome of that meeting is a review paper, Bellouin et al. (2019), accepted for publication in Reviews of Geophysics. This review provides a new range of aerosol radiative forcing over the industrial era based on multiple, traceable and arguable lines of evidence, including modelling approaches, theoretical considerations, and observations. A substantial achievement is to focus on lines of evidence rather than a survey of past results or expert judgement, and to make the open questions much more specific.</p><p>This talk will present the key messages and arguments of the review and identify work that show promise for improving the quantification of aerosol radiative forcing.</p>

Characteristics and functions of Na-K-Cl cotransport in epithelial tissues

1987 ◽  
Vol 253 (2) ◽  
pp. C177-C192 ◽  
Author(s):  
S. M. O'Grady ◽  
H. C. Palfrey ◽  
M. Field
Keyword(s):  
Essential Role ◽  
Physiological Role ◽  
Cell Types ◽  
Extensive Literature ◽  
Squid Axon ◽  
Widespread Distribution ◽  
The Past ◽  
Epithelial Tissues ◽  
Present Understanding

This review summarizes our present understanding of Na-K-Cl cotransport and its physiological role in absorption and secretion of electrolytes and water in epithelial tissues. In the past several years an extensive literature about this cotransporter has developed due to its widespread distribution in a variety of cell types and its essential role in fluid and electrolyte transport in several epithelial tissues. We summarize this literature and speculate on the future characterization of this transport system. Although this review focuses on cotransport as it relates to absorptive and secretory processes in epithelia, important information concerning the pharmacology, stoichiometry, and regulation of Na-K-Cl cotransport in nonepithelial systems (i.e., erythrocytes, fibroblasts, squid axon, etc.) has been included to supplement areas that are less well established in the epithelial literature.

scholarly journals Threats of environmental mercury to birds: knowledge gaps and priorities for future research

2009 ◽  
Vol 20 (2) ◽  
pp. 112-123 ◽  
Author(s):  
CHAD L. SEEWAGEN
Keyword(s):  
Egg Production ◽  
Trophic Levels ◽  
Conservation Strategies ◽  
Future Research ◽  
Bird Conservation ◽  
Knowledge Gaps ◽  
Life History Stages ◽  
The Past ◽  
Wildlife Populations ◽  
Present Understanding

SummaryAnthropogenic emissions of mercury have doubled over the past two centuries. Mercury is a dangerous neurotoxin that threatens human health and fish and wildlife populations. The effects of mercury on birds have been relatively well-studied in the laboratory and in nature. Several aspects of neurology, physiology, behaviour, and reproduction have been shown to be adversely affected. Many studies have documented ataxia, lethargy, reduced appetite, reduced egg production, poor hatching success, and aberrant parental care in birds exposed to mercury.The majority of the research done to date, however, has been focused on select taxa (waterbirds), trophic levels (piscivores), habitat types (aquatic systems), geographic regions (North America and Europe), and life history stages (reproduction), leaving the assessment of mercury's threats to birds incomplete. Successful bird conservation strategies are dependent on a comprehensive understanding of the threats facing populations. Here, I discuss the significant knowledge gaps that remain and subsequently suggest priorities for future mercury research in birds. Studies of mercury in terrestrial, insectivorous, and/or passerine species, and how mercury affects migration are especially recommended to fill gaps in our present understanding.

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