oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Nuclei in the Cosmos  [PDF]
Edward F. Brown,Timothy C. Beers,B. Alex Brown,Carl Brune,Arthur E. Champagne,Christian Illiadis,William G. Lynch,Brian W. O'Shea,Peter Parker,Robert E. Rutledge,Michael S. Smith,Sumner Starrfield,Andrew W. Steiner,Francis X. Timmes,James W. Truran,Michael Wiescher,Remco G. T. Zegers
Physics , 2009,
Abstract: This white paper, directed to the Stars and Stellar Evolution panel, has three objectives: 1) to provide the Astro2010 Decadal Survey with a vista into the goals of the nuclear physics and nuclear astrophysics community; 2) to alert the astronomical community of joint opportunities for discoveries at the interface between nuclear physics and astronomy; and 3) to delineate efforts in nuclear physics and describe the observational and theoretical advances in astrophysics necessary to make progress towards answering the following questions in the Nuclear Science 2007 Long Range Plan: 1) What is the origin and distribution of the elements? 2) What are the nuclear reactions that power stars and stellar explosions? 3) What is the nature of dense matter? The scope of this white paper concerns the specific area of "low energy" nuclear astrophysics. We define this as the area of overlap between astrophysics and the study of nuclear structure and reactions. Of the questions listed above, two -- What is the origin of the elements? and What is the nature of dense matter? -- were specifically listed in the National Academies Study, "Connecting Quarks with the Cosmos".
Disclosure Indices Design: Does it Make a Difference?  [PDF]
Francisco Bravo Urquiza,Maria Cristina Abad Navarro,Marco Trombetta
Revista de Contabilidad : Spanish Accounting Review , 2009,
Abstract: Measurement of information disclosed by companies is a complex task. Accounting research usually relies on disclosure indices to obtain a proxy for the information disclosed by companies. However, there is no consensus about the best design for these indices. The purpose of this paper is to investigate if there are significant differences among the indices that are used in disclosure studies. Three indices that measure disclosure of forward-looking information are compared: A “quality index” of a multidimensional nature; a “scope index” designed specifically to measure the scope of information, and a “quantity index” that measures information disclosed exclusively in terms of quantity. Results of the empirical analysis indicate that although the indices are correlated, they have a big impact in the rankings of companies. Evidence against the idea of the irrelevance of the particular index chosen is provided.La medición de la información divulgada por las empresas es una tarea compleja. La investigación contable normalmente se apoya en índices de revelación para obtener una aproximación cuantitativa a la información divulgada por las compa ías. Sin embargo, no hay consenso sobre el dise o de estos índices. El objetivo del trabajo es investigar si hay diferencias significativas entre los índices empleados en los estudios sobre divulgación de información. Se comparan tres índices que miden la revelación de información previsional: un índice de calidad, de naturaleza multidimensional; un índice de alcance, dise ado específicamente para medir la cobertura de la información; y un índice de cantidad que mide la información divulgada exclusivamente en términos de cantidad. Los resultados del análisis empírico indican que aunque los índices están correlacionados, tienen un gran impacto en los rankings de las compa ías. El análisis proporciona evidencia en contra de la irrelevancia del dise o de un índice en particular.
Could one make a diamond-based quantum computer?  [PDF]
A Marshall Stoneham,A H Harker,Gavin W Morley
Physics , 2009, DOI: 10.1088/0953-8984/21/36/364222
Abstract: We assess routes to a diamond-based quantum computer, where we specifically look towards scalable devices, with at least 10 linked quantum gates. Such a computer should satisfy the deVincenzo rules and might be used at convenient temperatures. The specific examples we examine are based on the optical control of electron spins. For some such devices, nuclear spins give additional advantages. Since there have already been demonstrations of basic initialisation and readout, our emphasis is on routes to two-qubit quantum gate operations and the linking of perhaps 10-20 such gates. We analyse the dopant properties necessary, especially centres containing N and P, and give results using simple scoping calculations for the key interactions determining gate performance. Our conclusions are cautiously optimistic: it may be possible to develop a useful quantum information processor that works above cryogenic temperatures.
A New Theory of Cosmology That Preserves the Generally Recognized Symmetries of Cosmos, Explains the Origin of the Energy for Matter Field, but Excludes the Existence of the Big Bang  [PDF]
Fang-Pei Chen
Physics , 2006,
Abstract: While the generally recognized symmetries of cosmos are preserved, conservation laws for gravitational system are reconsidered and the Lagrangian density of pure gravitational field is revised. From these considerations, some of the theoretical foundations of the current cosmology are extended or revised, and a new theory of cosmology is established. This new theory leads to the following distinct properties of cosmos: the energy of matter field might originate from the gravitational field; the big bang might not have occurred; the fields of the dark energy and some parts of the dark matter would not be matter fields but might be gravitational fields, they would only interact with gravitational force but could not interact with other forces. These distinct properties can be tested by future experiments and observations.
What difference does ("good") HRM make?
James Buchan
Human Resources for Health , 2004, DOI: 10.1186/1478-4491-2-6
Abstract: Despite the limited, but growing, evidence base on the impact of HRM on organisational performance in other sectors, there have been relatively few attempts to assess the implications of this evidence for the health sector. This paper examines this broader evidence base on HRM in other sectors and examines some of the underlying issues related to "good" HRM in the health sector.The paper considers how human resource management (HRM) has been defined and evaluated in other sectors. Essentially there are two sub-themes: how have HRM interventions been defined? and how have the effects of these interventions been measured in order to identify which interventions are most effective? In other words, what is "good" HRM?The paper argues that it is not only the organisational context that differentiates the health sector from many other sectors, in terms of HRM. Many of the measures of organisational performance are also unique. "Performance" in the health sector can be fully assessed only by means of indicators that are sector-specific. These can focus on measures of clinical activity or workload (e.g. staff per occupied bed, or patient acuity measures), on measures of output (e.g. number of patients treated) or, less frequently, on measures of outcome (e.g. mortality rates or rate of post-surgery complications).The paper also stresses the need for a "fit" between the HRM approach and the organisational characteristics, context and priorities, and for recognition that so-called "bundles" of linked and coordinated HRM interventions will be more likely to achieve sustained improvements in organisational performance than single or uncoordinated interventions.The importance of the human resources management (HRM) to the success or failure of health system performance has, until recently, been generally overlooked. Health sector reform in many countries in the 1990s focused on structural change, cost containment, the introduction of market mechanisms and consumer choice [1,2] b
The NACRE Thermonuclear Reaction Compilation and Big Bang Nucleosynthesis  [PDF]
Richard H. Cyburt,Brian D. Fields,Keith A. Olive
Physics , 2001, DOI: 10.1016/S1384-1076(01)00053-7
Abstract: The theoretical predictions of big bang nucleosynthesis (BBN) are dominated by uncertainties in the input nuclear reaction cross sections. In this paper, we examine the impact on BBN of the recent compilation of nuclear data and thermonuclear reactions rates by the NACRE collaboration. We confirm that the adopted rates do not make large overall changes in central values of predictions, but do affect the magnitude of the uncertainties in these predictions. Therefore, we then examine in detail the uncertainties in the individual reaction rates considered by NACRE. When the error estimates by NACRE are treated as 1\sigma limits, the resulting BBN error budget is similar to those of previous tabulations. We propose two new procedures for deriving reaction rate uncertainties from the nuclear data: one which sets lower limits to the error, and one which we believe is a reasonable description of the present error budget. We propagate these uncertainty estimates through the BBN code, and find that when the nuclear data errors are described most accurately, the resulting light element uncertainties are notably smaller than in some previous tabulations, but larger than others. Using these results, we derive limits on the cosmic baryon-to-photon ratio $\eta$, and compare this to independent limits on $\eta$ from recent balloon-borne measurements of the cosmic microwave background radiation (CMB). We discuss means to improve the BBN results via key nuclear reaction measurements and light element observations.
Book Review: "Can NGOs make a difference? The challenge of development alternatives"
KD Helliker
African Sociological Review / Revue Africaine de Sociologie , 2008,
Abstract: Anthony J. Bebbington, Samuel Hickey and Diana C. Miltin, eds.,"Can NGOs Make a Difference? The Challenge of Development Alternatives". London, Zed Books, 2008. Reviewed by Kirk D. Helliker Department of Sociology Rhodes University Grahamstown South Africa
Does Quantity Make a Difference? The importance of publishing many papers  [PDF]
Peter van den Besselaar,Ulf Sandstrom
Computer Science , 2015,
Abstract: Do highly productive researchers have significantly higher probability to produce top cited papers? Or does the increased productivity in science only result in a sea of irrelevant papers as a perverse effect of competition and the increased use of indicators for research evaluation and accountability focus? We use a Swedish author disambiguated data set consisting of 48,000 researchers and their WoS-publications during the period of 2008 2011 with citations until 2014 to investigate the relation between productivity and production of highly cited papers. As the analysis shows, quantity does make a difference.
The intracellular region of Notch ligands: does the tail make the difference?
Alessandro Pintar, Alfredo De Biasio, Matija Popovic, Neli Ivanova, Sándor Pongor
Biology Direct , 2007, DOI: 10.1186/1745-6150-2-19
Abstract: This article was reviewed by Frank Eisenhaber, L Aravind, and Eugene V. Koonin.Notch-mediated signal transduction controls cell fate and is a key process in tissue patterning and morphogenesis [1]. Both receptors and ligands are membrane-bound proteins, the first ones being non-covalent, membrane-spanning heterodimers, the latters single pass, type I membrane proteins [1]. In response to ligand binding, the membrane-spanning subunit of the receptor (NTM) is cleaved by an extracellular ADAM-type (A Disintegrin And Metalloprotease) proteinase. This cleavage facilitates a further cleavage of NTM, within the trans-membrane region, carried out by the presenilin/γ-secretase protease and releases the intracellular domain (ICN) from the membrane [2]. This series of controlled proteolytic events is referred to as "regulated intra-membrane proteolysis" or RIP. Once translocated into the nucleus, the ICN interacts with nuclear factors that activate transcription, the main target being a transcription factor (CSL) called CBF1/RBP in mammals, Suppressor of Hairless in Drosophila, and LAG-1 in C. elegans.The core mechanism of the Notch pathway can be thus viewed as the release of a transcriptional regulator from the membrane, triggered by ligand/receptor interactions and controlled at various levels. The established role of Notch signaling in angiogenesis [3], in T cell development [4], in the maintenance of stem cells [5], in genetic disorders [6] as well as in cancer [7,8] has been extensively reviewed. The Notch pathway has been identified as a new potential target for cancer therapy [9,10] and might also be involved in cognitive disorders [11]. Other aspects of Notch signaling, such as its regulation by endocytic processes [12] and receptor glycosylation [13], and the cross-talk between Notch and other signaling pathways [14,15] have also been reviewed.Here, we focus on a relatively recent and potentially novel aspect of Notch signaling in mammals: the role of the intracellul
ADAR Enzyme and miRNA Story: A Nucleotide that Can Make the Difference  [PDF]
Sara Tomaselli,Barbara Bonamassa,Anna Alisi,Valerio Nobili,Franco Locatelli,Angela Gallo
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms141122796
Abstract: Adenosine deaminase acting on RNA (ADAR) enzymes convert adenosine (A) to inosine (I) in double-stranded (ds) RNAs. Since Inosine is read as Guanosine, the biological consequence of ADAR enzyme activity is an A/G conversion within RNA molecules. A-to-I editing events can occur on both coding and non-coding RNAs, including microRNAs (miRNAs), which are small regulatory RNAs of ~20–23 nucleotides that regulate several cell processes by annealing to target mRNAs and inhibiting their translation. Both miRNA precursors and mature miRNAs undergo A-to-I RNA editing, affecting the miRNA maturation process and activity. ADARs can also edit 3' UTR of mRNAs, further increasing the interplay between mRNA targets and miRNAs. In this review, we provide a general overview of the ADAR enzymes and their mechanisms of action as well as miRNA processing and function. We then review the more recent findings about the impact of ADAR-mediated activity on the miRNA pathway in terms of biogenesis, target recognition, and gene expression regulation.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.