scholarly journals Earth’s carbon deficit caused by early loss through irreversible sublimation

2021 ◽  
Vol 7 (14) ◽  
pp. eabd3632
Author(s):  
J. Li ◽  
E. A. Bergin ◽  
G. A. Blake ◽  
F. J. Ciesla ◽  
M. M. Hirschmann

Carbon is an essential element for life, but its behavior during Earth’s accretion is not well understood. Carbonaceous grains in meteoritic and cometary materials suggest that irreversible sublimation, and not condensation, governs carbon acquisition by terrestrial worlds. Through astronomical observations and modeling, we show that the sublimation front of carbon carriers in the solar nebula, or the soot line, moved inward quickly so that carbon-rich ingredients would be available for accretion at 1 astronomical unit after the first million years. On the other hand, geological constraints firmly establish a severe carbon deficit in Earth, requiring the destruction of inherited carbonaceous organics in the majority of its building blocks. The carbon-poor nature of Earth thus implies carbon loss in its precursor material through sublimation within the first million years.

Author(s):  
Lisa Yildiz Brown

Storytelling, it can be argued, is an essential element of the archaeologist’s craft. It is because of the necessity for storytelling that archaeology has one foot in the arts and the other in the sciences. Storytelling is more than interpretation borne of observation and the gathering and testing of evidence. It inevitably brings us as individuals into the reconstructions of the past that we assemble during the course of our work. Yet while it is inevitable that we ‘bring to the ‘‘facts’’ our feelings’, supposition, hypothesis, and theory are not enough. Theoretical constructs are necessary, yet archaeologists are engaged in a constant search to find replacements for those that have failed. Archaeologists, professional and amateur alike, have long agreed in principle that acceptable practice demands good data, well collected, and accurately recorded in order to lend credibility to interpretation. An empirical approach to archaeological research relies on the recording of observable manifestations of culture, reasoning backwards from phenomenon to mechanism. This method of exploring human behaviour directly through observed evidence is not always in vogue but is more satisfying to some archaeologists than juggling conceptual abstractions. Archaeologists are individuals, possessed of distinctive personalities, talents and inclinations. We work differently, see differently, feel differently, but for all that we have a bond of commonality—we all understand imperfectly. Honest dispute engenders scrutiny, inspires exploration and promotes progress in a Weld of investigation in which understanding is imperfect and veriWcation elusive. Debate and challenge are key tools in the advancement of archaeological enquiry and the profession demands that, in the interests of progress, we cast ourselves constantly in the role of devil’s advocate. Honesty dictates, however, that we also acknowledge the sources of our inspiration, the ‘giants’ on whose shoulders we have stood in our search for the new horizons, the building blocks we have used as the basis of our research. Underpinning fruitful research is data, the record of the evidence, in whatever form it takes—the archives of unpublished fieldwork, the mountain of ‘grey literature’ that grows with each passing year, the finds and manuscripts under the bed, the published reports.


2020 ◽  
Vol 12 (3) ◽  
pp. 168-174
Author(s):  
Rashmi Sahu ◽  
Maitraiyee Konar ◽  
Sudip Kundu

Background: Sensing of biomedical signals is crucial for monitoring of various health conditions. These signals have a very low amplitude (in μV) and a small frequency range (<500 Hz). In the presence of various common-mode interferences, biomedical signals are difficult to detect. Instrumentation amplifiers (INAs) are usually preferred to detect these signals due to their high commonmode rejection ratio (CMRR). Gain accuracy and CMRR are two important parameters associated with any INA. This article, therefore, focuses on the improvement of the gain accuracy and CMRR of a low power INA topology. Objective: The objective of this article is to achieve high gain accuracy and CMRR of low power INA by having high gain operational amplifiers (Op-Amps), which are the building blocks of the INAs. Methods: For the implementation of the Op-Amps and the INAs, the Cadence Virtuoso tool was used. All the designs and implementation were realized in 0.18 μm CMOS technology. Results: Three different Op-Amp topologies namely single-stage differential Op-Amp, folded cascode Op-Amp, and multi-stage Op-Amp were implemented. Using these Op-Amp topologies separately, three Op-Amp-based INAs were realized and compared. The INA designed using the high gain multistage Op-Amp topology of low-frequency gain of 123.89 dB achieves a CMRR of 164.1 dB, with the INA’s gain accuracy as good as 99%, which is the best when compared to the other two INAs realized using the other two Op-Amp topologies implemented. Conclusion: Using very high gain Op-Amps as the building blocks of the INA improves the gain accuracy of the INA and enhances the CMRR of the INA. The three Op-Amp-based INA designed with the multi-stage Op-Amps shows state-of-the-art characteristics as its gain accuracy is 99% and CMRR is as high as 164.1 dB. The power consumed by this INA is 29.25 μW by operating on a power supply of ±0.9V. This makes this INA highly suitable for low power measurement applications.


2014 ◽  
Vol 70 (11) ◽  
pp. 1054-1056 ◽  
Author(s):  
Qiang Li ◽  
Hui-Ting Wang

A new cadmium dicyanamide complex, poly[tetramethylphosphonium [μ-chlorido-di-μ-dicyanamido-κ4N1:N5-cadmium(II)]], [(CH3)4P][Cd(NCNCN)2Cl], was synthesized by the reaction of tetramethylphosphonium chloride, cadmium nitrate tetrahydrate and sodium dicyanamide in aqueous solution. In the crystal structure, each CdIIatom is octahedrally coordinated by four terminal N atoms from four anionic dicyanamide (dca) ligands and by two chloride ligands. The dicyanamide ligands play two different roles in the building up of the structure; one role results in the formation of [Cd(dca)Cl]2building blocks, while the other links the building blocks into a three-dimensional structure. The anionic framework exhibits a solvent-accessible void of 673.8 Å3, amounting to 47.44% of the total unit-cell volume. The cavities in the network are occupied by pairs of tetramethylphosphonium cations.


2021 ◽  
pp. 26-32
Author(s):  
Stephen R. Connor

This chapter describes all aspects of policy, including definitions, who is it that sets policy, how policy is made, how policy is implemented, the elements of effective policies, the differences between policies and regulations, the policies that are important for palliative care, global versus national policy differences, and barriers to the creation and implementation of palliative care policies. Understanding policy is important, as it is one of the fundamental building blocks of palliative care under the World Health Organization’s public health model. This model underscores the pre-eminence of policy, as it makes possible all the other elements. Palliative care professionals should understand the complexity inherent in policy and embrace it as an important area to master.


Author(s):  
Meir Sendor

This chapter analyses the common and unfortunate trend in interfaith dialogue of ‘neutralizing’ the Other. In an attempt to find commonality, neutralization introduces syncretism and relativism into interfaith discourse. Worse still, it does violence to the unique character of each religion and its practitioners who participate in the dialogue. According to Emmanuel Levinas, to proceed in this way is to doom the possibility of real relationship from the start and to fall prey to the most insidious and destructive habit of Western thought: the deception of the Neutral that derives from the tyranny of the Same. Meanwhile, Jacques Derrida repeatedly explored the nature of hospitality at length, employing it as a paradigm for the dynamics of interfaith relations. Finally, Paul Ricoeur's notion of the conscience, of the reciprocity of Otherness, of the response within responsibility, contributes an essential element to the groundwork for an authentic relationship outlined by Levinas and Derrida.


Author(s):  
Jeffrey Kovac

What makes chemistry unique? And how does this uniqueness reflect on chemistry’s unique concerns with ethics? As Roald Hoffmann (1995) argues, it is because chemistry is in the “tense middle,” occupying a space between several pairs of extremes. Perhaps most important, chemistry has always inhabited a frontier between science and technology, the pure and the applied, the theoretical and the practical (Bensaude-Vincent and Simon 2008). Unlike the other natural sciences, chemistry traces its origins both to philosophy and the craft tradition. Chemists are discoverers of knowledge and creators of new substances. The objects of study in chemistry, molecules and the macroscopic systems made up of molecules, are intermediate between the very small, the elementary particles, and the very large, the cosmos. Chemical systems are the right size to affect humans directly, for better or worse. They are the building blocks of biological organisms, they are the substances we eat and drink, they are the drugs that have improved human health dramatically over the past century, they comprise the materials we use to construct the products we use daily, but they are also the environmental pollutants that can plague our world. Chemicals can also be used as weapons. Being in the middle means that chemists face a unique set of ethical issues that I try to explicate in this chapter. These issues derive, in part, from the nature of chemistry as a science, a science that does not fit the neat picture drawn in the first chapter of textbooks. They also derive from the fact that ethics is an inquiry into right human conduct: What is a good life? Chemistry has perhaps contributed more to the betterment of human life than any other science, but at the same time has also contributed significantly to the deterioration of the environment. As explained in Chapter 3, much of chemistry is conducted in Pasteur’s quadrant, where both the search for fundamental knowledge and considerations of use are important. Chemical synthesis is perhaps the central activity of chemistry.


2017 ◽  
Vol 8 (4) ◽  
pp. 34-74
Author(s):  
Abdulkader Alfantookh ◽  
Saad Haj Bakry

The Gulf Cooperation Council (GCC) countries, with their rich oil resources, are facing the problem of fallen oil prices on the one hand, and reduced oil reserves on the other. As a result, they are moving toward less dependence on oil, and increasing dependence on people and knowledge. This paper develops a wide scope “people and knowledge index (PKI)” using relevant international indicators made available by various international organizations. The index includes “ten building blocks.” Four of these blocks are concerned with the “core issues” of people and knowledge; while the other six blocks are related to the “environment issues” according to which people and knowledge interact. The paper assesses the GCC countries according to the index revealing their strengths and weaknesses, and enabling the derivation of guidelines for their future development. The resulting guidelines consider how the GCC countries can direct their future development toward a high and growing standard of living, while reducing dependence on oil. Finally, the future use of the new index is highlighted.


Metaphysica ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 129-149
Author(s):  
Nils-Frederic Wagner ◽  
Iva Apostolova

AbstractStandard views of personal identity over time often hover uneasily between the subjective, first-person dimension (e. g. psychological continuity), and the objective, third-person dimension (e. g. biological continuity) of a person’s life. Since both dimensions capture something integral to personal identity, we show that neither can successfully be discarded in favor of the other. The apparent need to reconcile subjectivity and objectivity, however, presents standard views with problems both in seeking an ontological footing of, as well as epistemic evidence for, personal identity. We contend that a fresh look at neutral monism offers a novel way to tackle these problems; counting on the most fundamental building blocks of reality to be ontologically neutral with regards to subjectivity and objectivity of personal identity. If the basic units of reality are, in fact, ontologically neutral – but can give rise to mental as well as physical events – these basic units of reality might account for both subjectivity and objectivity in personal identity. If this were true, it would turn out that subjectivity and objectivity are not conflictive dimensions of personal identity but rather two sides of the same coin.


Author(s):  
Mark Le Roux ◽  
Yolanda Dreyer

Archaeology of homophobia: Building blocks of power. The article investigates present-day discourses which demonstrate coercive power with regard to sexuality according to which people are attributed an identity. Such hegemony restricts existential authenticity. The article shows that, although sexual minorities could have public rights according to constitutional law, they still experience marginalisation because of victimisation on account of a heteronormative societal discourse. The article consists of an introductory section in which Michel Foucault’s notion of ‘the archaeology of knowledge’ is used to explore levels of perceptions in society which illustrate perceptions and ideas on homophobia. The first section focuses on the phenomenon of stigmatisation. The second section describes the process of stereotyping taboos that result in the phenomenon of internalised homophobia. The article concludes with a deconstruction of homophobia by emphasising the recognition of the Other by means of a contradiscourse to heteronormativity.


2019 ◽  
Vol 14 (2) ◽  
pp. 169-188
Author(s):  
Eva Smolka ◽  
Dorit Ravid

Abstract Verbs constitute one of the basic building blocks of a clause, setting the structure of arguments and expressing the relationships among nouns in various thematic roles. In general terms, verbs are lexical items expressing verb-oriented notions such as activities, processes, and states. In morphology-rich languages, the syntactic and lexical roles of verbs are mediated by typologically-oriented morphological means. The current Special Issue contrasts the structure and functions of verbs in languages from two morphologically rich, yet typologically different families. The articles in the Special Issue present spoken and written aspects of verbs in usage and development in German (a Germanic language) on the one hand, in Hebrew, Neo-Aramaic, and Arabic (Semitic languages), on the other. From a theoretical linguistic perspective, we ask how the different typological features of these languages affect the function of verbs in sentences, and from a psycholinguistic perspective, we ask how typological differences affect the processing of verbs in the mature minds of adults and in the developing minds of children.


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