scholarly journals Apoplasm hydrostatic pressure on growth of cylindrical cells

2004 ◽  
Vol 16 (1) ◽  
pp. 17-24 ◽  
Author(s):  
José Dalton Cruz Pessoa ◽  
Adonai Gimenes Calbo
Keyword(s):  
Cell Growth ◽  
Water Solution ◽  
Extension Rate ◽  
Conductivity Equation ◽  
Cell Potential ◽  
Transversal Section ◽  
Physico Chemical ◽  
Reference Plant ◽  
Definition Of

According to the model frequently used as reference, plant cell growth occurs only when turgor surpasses a threshold. This model was proposed considering a cylindrical cell of constant wall thickness immerged in a water solution, with viscoelastic behaviour, hydraulic conductivity, variable extensibility, and unidirectional elongation. The author, Lockhart (1965), did not consider the effects of apoplasm hydrostatic potential, a subject treated later by Calbo and Pessoa (1994) who argued that this component of cell potential would interfere with cell growth rate. To evaluate this effect, where possible the same deductive procedures as those employed by Lockhart were used here, which resulted in a set of equivalent equations for cell growth, turgor and water potential, developed with respect to physico-chemical variables. Relationships were derived from the conductivity equation, the definition of extensibility, Hook's law, and considering that the tension on cell wall transversal section is proportional to turgor and apoplasm hydrostatic potential. The numeric solutions for the equations showed that suction increased extension rate at the beginning of cell growth. Some experiments on plant growth and structural models of cell walls are discussed to point out the role of suction on wall tensioning and cell hydration during cell elongation.

Activation of cytochrome c to a peroxidase compound I-type intermediate by H2O2: relevance to redox signalling in apoptosis

2004 ◽  
Vol 71 ◽  
pp. 97-106 ◽  
Author(s):  
Mark Burkitt ◽  
Clare Jones ◽  
Andrew Lawrence ◽  
Peter Wardman
Keyword(s):  
Cytochrome C ◽  
Hydroxyl Radical ◽  
Redox Regulation ◽  
Chemotherapeutic Agents ◽  
Tyrosyl Radical ◽  
Compound I ◽  
Definitive Evidence ◽  
Enhanced Production ◽  
Physico Chemical

The release of cytochrome c from mitochondria during apoptosis results in the enhanced production of superoxide radicals, which are converted to H2O2 by Mn-superoxide dismutase. We have been concerned with the role of cytochrome c/H2O2 in the induction of oxidative stress during apoptosis. Our initial studies showed that cytochrome c is a potent catalyst of 2′,7′-dichlorofluorescin oxidation, thereby explaining the increased rate of production of the fluorophore 2′,7′-dichlorofluorescein in apoptotic cells. Although it has been speculated that the oxidizing species may be a ferryl-haem intermediate, no definitive evidence for the formation of such a species has been reported. Alternatively, it is possible that the hydroxyl radical may be generated, as seen in the reaction of certain iron chelates with H2O2. By examining the effects of radical scavengers on 2′,7′-dichlorofluorescin oxidation by cytochrome c/H2O2, together with complementary EPR studies, we have demonstrated that the hydroxyl radical is not generated. Our findings point, instead, to the formation of a peroxidase compound I species, with one oxidizing equivalent present as an oxo-ferryl haem intermediate and the other as the tyrosyl radical identified by Barr and colleagues [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498-15503]. Studies with spin traps indicated that the oxo-ferryl haem is the active oxidant. These findings provide a physico-chemical basis for the redox changes that occur during apoptosis. Excessive changes (possibly catalysed by cytochrome c) may have implications for the redox regulation of cell death, including the sensitivity of tumour cells to chemotherapeutic agents.

Challenges of Fear Conditioning Research in the Age of RDoC

2017 ◽  
Vol 225 (3) ◽  
pp. 189-199 ◽  
Author(s):  
Tina B. Lonsdorf ◽  
Jan Richter
Keyword(s):  
Fear Conditioning ◽  
Clinical Diagnosis ◽  
Research Domain Criteria ◽  
Major Focus ◽  
The Future ◽  
Definition Of ◽  
Methodological Considerations ◽  
Research Domain

Abstract. As the criticism of the definition of the phenotype (i.e., clinical diagnosis) represents the major focus of the Research Domain Criteria (RDoC) initiative, it is somewhat surprising that discussions have not yet focused more on specific conceptual and procedural considerations of the suggested RDoC constructs, sub-constructs, and associated paradigms. We argue that we need more precise thinking as well as a conceptual and methodological discussion of RDoC domains and constructs, their interrelationships as well as their experimental operationalization and nomenclature. The present work is intended to start such a debate using fear conditioning as an example. Thereby, we aim to provide thought-provoking impulses on the role of fear conditioning in the age of RDoC as well as conceptual and methodological considerations and suggestions to guide RDoC-based fear conditioning research in the future.

Business Model Literature Overview

2014 ◽  
pp. 79-130 ◽  
Author(s):  
Ales Novak
Keyword(s):  
Business Model ◽  
Financial Reporting ◽  
Business Models ◽  
Potential Role ◽  
Financial Instruments ◽  
Business Logic ◽  
Literature Overview ◽  
Ifrs 9 ◽  
Definition Of

The term ?business model' has recently attracted increased attention in the context of financial reporting and was formally introduced into the IFRS literature when IFRS 9 Financial Instruments was published in November 2009. However, IFRS 9 did not fully define the term ‘business model'. Furthermore, the literature on business models is quite diverse. It has been conducted in largely isolated fashion; therefore, no generally accepted definition of ?business model' has emerged. Therefore, a better understanding of the notion itself should be developed before further investigating its potential role within financial reporting. The aim of this paper is to highlight some of the perceived key themes and to identify other bases for grouping/organizing the literature based on business models. The contributions this paper makes to the literature are twofold: first, it complements previous review papers on business models; second, it contains a clear position on the distinction between the notions of the business model and strategy, which many authors identify as a key element in better explaining and communicating the notion of the business model. In this author's opinion, the term ‘strategy' is a dynamic and forward-looking notion, a sort of directional roadmap for future courses of action, whereas, ‘business model' is a more static notion, reflecting the conceptualisation of the company's underlying core business logic. The conclusion contains the author's thoughts on the role of the business model in financial reporting.

The Role of Moral Education on the Dress Code in the Higher Learning Institution

Sains Insani ◽  
2016 ◽  
Vol 1 (1) ◽  
pp. 10-14
Author(s):  
Ira Meilita Ibrahim ◽  
Taufik A. Latif ◽  
Afi Roshezry Abu Bakar ◽  
Muthualagan Thangavelu
Keyword(s):  
Moral Education ◽  
Private University ◽  
Public University ◽  
Higher Learning ◽  
Private Institutions ◽  
Dress Code ◽  
Institutions Of Higher Learning ◽  
The World ◽  
Definition Of

The advancement of European dress to the rest of the world was linked to the definition of civilization as “a stage of social development considered to be more advanced” and “polite and good-mannered”. The widespread of their fashion style in the 19th and 20th centuries influenced the way the rest of the world attire. The fashion trend and dressing style thus change the purpose of dressing through time. The dressing style in campuses especially in private institutions of higher learning is under particular scrutiny, as it is often said to be inappropriate for a learning environment. This study looked at the importance of moral education, and its role in implementing the dress code for students among university students especially between two types of university i.e. public university and private university. It looked on the dressing style of students, both male and female, and the factors that lead to their dressing pattern which is common among students. This study also advocated the students’ understanding of the content of dress codes in their learning institution and the role played by moral education in regard to dress code. The overall study highlighted students’ perception towards the implementation of the dress code and punishment in their learning institution. The methodologies used to carry out this study are questionnaires and interviews. This study will therefore ascertain the important of dress code among students at higher learning institution and the role of moral education in cultivating values in order to dress properly or decently. Key Words: moral education, dress code, higher learning institution, civilization.

THYROID STIMULATORS AND THYROID STIMULATION

1971 ◽  
Vol 66 (3) ◽  
pp. 558-576 ◽  
Author(s):  
Gerald Burke
Keyword(s):  
Regulatory System ◽  
Control Site ◽  
Thyroid Cell ◽  
Primary Control ◽  
Physico Chemical ◽  
Site Of Action ◽  
Long Acting

ABSTRACT A long-acting thyroid stimulator (LATS), distinct from pituitary thyrotrophin (TSH), is found in the serum of some patients with Graves' disease. Despite the marked physico-chemical and immunologic differences between the two stimulators, both in vivo and in vitro studies indicate that LATS and TSH act on the same thyroidal site(s) and that such stimulation does not require penetration of the thyroid cell. Although resorption of colloid and secretion of thyroid hormone are early responses to both TSH and LATS, available evidence reveals no basic metabolic pathway which must be activated by these hormones in order for iodination reactions to occur. Cyclic 3′, 5′-AMP appears to mediate TSH and LATS effects on iodination reactions but the role of this compound in activating thyroidal intermediary metabolism is less clear. Based on the evidence reviewed herein, it is suggested that the primary site of action of thyroid stimulators is at the cell membrane and that beyond the(se) primary control site(s), there exists a multifaceted regulatory system for thyroid hormonogenesis and cell growth.

Two Representations of the Moscow Art Theater Audience

2020 ◽  
Vol 17 (5) ◽  
pp. 462-476
Author(s):  
Alexander A. Ushkarev ◽  
Galina G. Gedovius ◽  
Tatyana V. Petrushina
Keyword(s):  
Online Community ◽  
Modern Art ◽  
Virtual Space ◽  
Demographic Parameters ◽  
Cultural Consumption ◽  
Cultural Activity ◽  
Behavioral Differences ◽  
Technological Revolution ◽  
Definition Of

The technological revolution of recent decades has already brought art to the broadest masses, and the unexpected intervention of the pandemic has significantly accelerated the process of migration of theatrical art to the virtual space, causing the corresponding dynamics of the audience. What is the theater audience in the era of digitalization and the spread of alternative forms of cultural consumption? How does the theater build its relationship with the audience today? In search of answers, we conducted a series of sociological surveys of the Chekhov Moscow Art Theater’s audience — both at the theater’s performances and in the online community of its fans. The purpose of this phase of the study was to answer the fundamental questions: do spectators surveyed in the theater and those surveyed online represent the same audience; what are their main differences; and what are the drivers of their spectator behavior? The article presents the main results of a comparative analysis of two images of the Moscow Art Theatre’s audience based on a number of content parameters by two types of surveys, as well as the results of a regression analysis of the theater attendance. The study resulted in definition of the qualitative and behavioral differences between the theater visitors and the viewers surveyed online, and identification of the factors of theater attendance for both of the represented audience groups. The study made it possible to clarify the role of age and other socio-demographic parameters in cultural activity, as well as the influence of preferred forms of cultural consumption (live contacts or online views) on one’s attitude to art, motivation and spectator behavior. The conclusions of the study, despite the uniqueness of the object, reflect the general patterns of the modern art audience’s dynamics.

DIGITAL ECONOMY AND GLOBALIZATION: THE IMPORTANCE OF DIGITAL ENTREPRENEURSHIP DEVELOPMENT

2020 ◽  
Vol 6 (3) ◽  
pp. 17-20
Author(s):  
Farxod Tursunov ◽  
Keyword(s):  
Business Models ◽  
Digital Economy ◽  
Management Systems ◽  
Entrepreneurship Development ◽  
New Business ◽  
Definition Of ◽  
Digital Enterprise ◽  
New Business Models ◽  
Digital Entrepreneurship

The article discusses the role of the digital economy in the development of the country, how it becomes the basis of the economy, new business models and management systems. The opinion of scientistsis analyzed, a definition of a digital enterprise is given

Sign in / Sign up

Export Citation Format

Share Document