Historical review of great auroras

1992 ◽  
Vol 70 (7) ◽  
pp. 479-487 ◽  
Author(s):  
A. Vallance Jones
Keyword(s):  
Spectral Characteristics ◽  
Historical Review ◽  
Upper Atmosphere ◽  
Theoretical Studies ◽  
The Past ◽  
Instrumental Observations ◽  
Spectroscopic Characteristics ◽  
Low Latitudes ◽  
Observing Techniques

Occurrences of great auroras of the past are discussed together with accounts of visual and instrumental observations. Earlier observations revealed the extraordinarily great heights and unusual spectral characteristics of such displays as well as documenting their penetration to low latitudes. Theoretical studies have led to an understanding of the observed unusual spectroscopic characteristics including their bright red colour and the abnormal vibrational and rotational structure in the molecular bands observed in high-altitude forms. As a result of the increasing sophistication of observing techniques, the phenomena associated with great auroras have passed beyond the characterization of optical and magnetic effects, to include information on associated changes in the composition of the neutral upper atmosphere and effects in the ionosphere. In more recent times, studies have led to increased understanding of the magnetospheric processes that produce these auroras.

scholarly journals Direct Imaging of Exoplanets Living an Exciting Life

2015 ◽  
Vol 10 (S314) ◽  
pp. 213-219
Author(s):  
G. Chauvin
Keyword(s):  
Physical Properties ◽  
Imaging Techniques ◽  
Formation Mechanisms ◽  
Contrast Imaging ◽  
The Past ◽  
High Contrast Imaging ◽  
Nearby Stars ◽  
Formation And Evolution ◽  
Observing Techniques

AbstractWith the development of high contrast imaging techniques and instruments, vast efforts have been devoted during the past decades to detect and characterize lighter, cooler and closer companions to nearby stars, and ultimately image new planetary systems. Complementary to other planet-hunting techniques, this approach has opened a new astrophysical window to study the physical properties and the formation mechanisms of brown dwarfs and planets. In this review, I will briefly describe the different observing techniques and strategies used, the main samples of targeted nearby stars, finally the main results obtained so far about exoplanet discoveries characterization of their physical properties, and study of their occurrence and possible formation and evolution mechanisms.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Creating Meaning in the Present by Reviewing the Past: Communal Memory in the Psalms of Solomon

2014 ◽  
Vol 5 (3) ◽  
pp. 368-392
Author(s):  
Matthew E. Gordley
Keyword(s):  
Jewish Community ◽  
Historical Review ◽  
First Century ◽  
The Past ◽  
Communal Memory ◽  
Psalms Of Solomon ◽  
Creating Meaning

This article examines Psalms of Solomon with an eye toward how these compositions may have functioned within the setting of a first-century B. C. E. Jewish community in Jerusalem. Several of these psalms should be understood as didactic hymns providing instruction to their audience through the medium of psalmody. Attention to the temporal register of Pss. Sol. 8, 9, and 17 shows how the poet’s use of historical review and historical allusion contributed to a vision of present reality and future hope, which the audience was invited to embrace. Issues relating to the place of these psalms in the tradition of Solomonic discourse are also addressed insofar as they contribute to the didactic function of this psalm collection.

‘The Wretch of To-day, may be happy To-morrow’

2017 ◽  
Author(s):  
Sarah Lloyd
Keyword(s):  
Emotional Experience ◽  
The Past

This chapter explores what we can know about the conceptualization and representation of by poorer Britons. It draws on ‘pauper letters’ to parish authorities, written tactically, and on autobiographies and letters composed by the relatively poor, noting echoes of the characterization of happiness by elite social commentators. It draws attention to a growing interest (linked to the development of the concept of nostalgia) in the emotional charge that could be derived from reflection on emotional experience as people contrasted past happiness with present misery, or vice versa. While reading such accounts may lead us to think that we are penetrating the interior lives of marginal people in the past, Lloyd suggests that our response is probably coloured by the fact that we are heirs to these ways of conceptualizing and representing experience. We need to work harder to glean insight from earlier ways of representing happiness and suffering.

The Problem of Divine Hiddenness

2018 ◽  
Author(s):  
Michael C. Rea
Keyword(s):  
Problem Of Evil ◽  
Philosophical Discussion ◽  
Detailed Characterization ◽  
The Past ◽  
Divine Hiddenness ◽  
The Problem Of Evil ◽  
The Relationship

This chapter provides a detailed characterization of the various meanings of the term “divine hiddenness,” carefully and rigorously articulates the version of the problem of divine hiddenness that has dominated contemporary philosophical discussion for the past twenty-five years, and then explains the relationship between that problem and the problem of evil.

scholarly journals Molecular Pathogenesis of Hodgkin Lymphoma: Past, Present, Future

2020 ◽  
Vol 21 (18) ◽  
pp. 6623 ◽  
Author(s):  
Marc Bienz ◽  
Salima Ramdani ◽  
Hans Knecht
Keyword(s):  
Immune System ◽  
Targeted Therapy ◽  
Signaling Pathways ◽  
Hodgkin Lymphoma ◽  
Genetic Instability ◽  
Host Immune System ◽  
Cellular Interactions ◽  
Classical Hodgkin Lymphoma ◽  
The Past

Our understanding of the tumorigenesis of classical Hodgkin lymphoma (cHL) and the formation of Reed–Sternberg cells (RS-cells) has evolved drastically in the last decades. More recently, a better characterization of the signaling pathways and the cellular interactions at play have paved the way for new targeted therapy in the hopes of improving outcomes. However, important gaps in knowledge remain that may hold the key for significant changes of paradigm in this lymphoma. Here, we discuss the past, present, and future of cHL, and review in detail the more recent discoveries pertaining to genetic instability, anti-apoptotic signaling pathways, the tumoral microenvironment, and host-immune system evasion in cHL.

scholarly journals Synthesis and Characterization of Store-Operated Calcium Entry Inhibitors Active in the Submicromolar Range

2020 ◽  
Vol 21 (24) ◽  
pp. 9777
Author(s):  
Camille Le Guilcher ◽  
Tomas Luyten ◽  
Jan B. Parys ◽  
Mathieu Pucheault ◽  
Olivier Dellis
Keyword(s):  
Cell Activation ◽  
Interleukin 2 ◽  
Calcium Entry ◽  
Ip3 Receptors ◽  
Excitable Cells ◽  
Cellular Targets ◽  
Entry Inhibitors ◽  
The Past ◽  
Store Operated Calcium Entry

The store-operated calcium entry, better known as SOCE, forms the main Ca2+ influx pathway in non-excitable cells, especially in leukocytes, where it is required for cell activation and the immune response. During the past decades, several inhibitors were developed, but they lack specificity or efficacy. From the non-specific SOCE inhibitor 2-aminoethyl diphenylborinate (2-APB), we synthetized 16 new analogues by replacing/modifying the phenyl groups. Among them, our compound P11 showed the best inhibitory capacity with a Ki ≈ 75 nM. Furthermore, below 1 µM, P11 was devoid of any inhibitory activity on the two other main cellular targets of 2-APB, the IP3 receptors, and the SERCA pumps. Interestingly, Jurkat T cells secrete interleukin-2 under phytohemagglutinin stimulation but undergo cell death and stop IL-2 synthesis when stimulated in the presence of increasing P11 concentrations. Thus, P11 could represent the first member of a new and potent family of immunosuppressors.

2D Self-assembly and Electronic Characterization of Oxygen-Boron-Oxygen-Doped Chiral Graphene Nanoribbons

2021 ◽  
Author(s):  
Lei Jin ◽  
Nerea Bilbao ◽  
Yang Lv ◽  
Xiao-Ye Wang ◽  
Soltani Paniz ◽  
...  
Keyword(s):  
Edge Effects ◽  
Self Assembly ◽  
Quantum Confinement ◽  
Graphene Nanoribbons ◽  
One Dimensional ◽  
The Past ◽  
Different Types

Graphene nanoribbons (GNRs), quasi-one-dimensional strips of graphene, exhibit a nonzero bandgap due to quantum confinement and edge effects. In the past decade, different types of GNRs with atomically precise structures...

scholarly journals B.05 Hemi-laryngopharyngeal spasm (HELPS) syndrome: The discovery, cure, and characterization of a new neurological condition

2017 ◽  
Vol 44 (S2) ◽  
pp. S11-S11
Author(s):  
C Honey ◽  
M Morrison
Keyword(s):  
Surgical Care ◽  
Review Of The Literature ◽  
The Past ◽  
First Case ◽  
Patient Reported ◽  
Operative Outcome ◽  
Small Cohort ◽  
The Common ◽  
Similar Motor

Background: We published the world’s first case of hemi-laryngpharyngeal spasm (HELPS) syndrome cured by microvascular decompression (MVD) of the Xth cranial nerve in 2016. We now present a small cohort of patients (n=3) successfully treated with surgery in order to better delineate the common characteristics of this syndrome, diagnostic tests of choice, nuances of their surgical care and outcomes of their treatment. Methods: The history and physical examination of three patients with HELPS syndrome are presented. Pre-operative laryngoscopy, neuroimaging, response to botox and intra-operative videos are detailed. Post-operative outcome and complications are presented. Results: Each patient reported similar motor (choking) and sensory (coughing) features in their history. Episodic choking relentlessly progressed over the years until it occurred while sleeping and with frightening severity prompting tracheostomy in one patient and intubation in another. A “tickling” sensation deep in the throat triggered episodic coughing that worsened over the years until it occurred while sleeping and with frightening severity (syncope and incontinence). Conclusions: A review of the literature suggests that patients with similar symptoms, often called episodic laryngospasm in the past, have been treated with psychotherapy or antacids. With the recognition that a clearly defined subset of these patients have HELPS syndrome, we can offer them the potential of a neurosurgical cure.

scholarly journals Conjuring up a ghost: structural and functional characterization of FhuF, a ferric siderophore reductase from E. coli

2021 ◽  
Author(s):  
I. B. Trindade ◽  
G. Hernandez ◽  
E. Lebègue ◽  
F. Barrière ◽  
T. Cordeiro ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Paramagnetic Nmr ◽  
E Coli ◽  
The Past ◽  
Internal Cavities ◽  
Structural Differences ◽  
Bond Strengths ◽  
Redox Bohr Effect ◽  
Micromolar Range

AbstractIron is a fundamental element for virtually all forms of life. Despite its abundance, its bioavailability is limited, and thus, microbes developed siderophores, small molecules, which are synthesized inside the cell and then released outside for iron scavenging. Once inside the cell, iron removal does not occur spontaneously, instead this process is mediated by siderophore-interacting proteins (SIP) and/or by ferric-siderophore reductases (FSR). In the past two decades, representatives of the SIP subfamily have been structurally and biochemically characterized; however, the same was not achieved for the FSR subfamily. Here, we initiate the structural and functional characterization of FhuF, the first and only FSR ever isolated. FhuF is a globular monomeric protein mainly composed by α-helices sheltering internal cavities in a fold resembling the “palm” domain found in siderophore biosynthetic enzymes. Paramagnetic NMR spectroscopy revealed that the core of the cluster has electronic properties in line with those of previously characterized 2Fe–2S ferredoxins and differences appear to be confined to the coordination of Fe(III) in the reduced protein. In particular, the two cysteines coordinating this iron appear to have substantially different bond strengths. In similarity with the proteins from the SIP subfamily, FhuF binds both the iron-loaded and the apo forms of ferrichrome in the micromolar range and cyclic voltammetry reveals the presence of redox-Bohr effect, which broadens the range of ferric-siderophore substrates that can be thermodynamically accessible for reduction. This study suggests that despite the structural differences between FSR and SIP proteins, mechanistic similarities exist between the two classes of proteins. Graphic abstract

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