A Simplified Model for an Evolving Protoplanetary Nebula

2003 ◽  
Vol 592 (2) ◽  
pp. 1193-1200 ◽  
Author(s):  
Sanford S. Davis
Keyword(s):  
Simplified Model ◽  
Protoplanetary Nebula

Artificial Chemistry and Molecular Darwinian Evolution in silico

2003 ◽  
Vol 68 (1) ◽  
pp. 139-177 ◽  
Author(s):  
Vladimír Kvasnička ◽  
Jiří Pospíchal
Keyword(s):  
Graph Theory ◽  
Molecular Level ◽  
Stable State ◽  
Chemical Reactor ◽  
Darwinian Evolution ◽  
Simplified Model ◽  
Asymptotically Stable ◽  
Artificial Chemistry ◽  
Neutral Mutations ◽  
Binary Strings

A simplified model of Darwinian evolution at the molecular level is studied by applying the methods of artificial chemistry. A chemical reactor (chemostat) contains molecules that are represented by binary strings, the strings being capable of replication with a probability proportional to their fitness. Moreover, the process of replication is not fully precise, sporadic mutations may produce new offspring strings, which are slightly different from their parent templates. The dynamics of such an autoreplicating system is described by Eigen's differential equations. These equations have a unique asymptotically stable state, which corresponds to those strings that have the highest rate constants (fitness). Fitness of binary string is calculated as a graph-theory similarity between a folding (phenotype) of respective string and the so-called required folding. The presented method offers a detailed view of mechanisms of the molecular Darwinian evolution, in particular of the meaning and importance of neutral mutations.

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

M-groupoid as a tool for investigating mathematical models of computers

1977 ◽  
Vol 1 (1) ◽  
pp. 71-91
Author(s):  
Jerzy Tiuryn
Keyword(s):  
Mathematical Models ◽  
Simple Approximation ◽  
Simplified Model ◽  
Suitable Choice ◽  
Iterative Systems

An M-groupoid is a simplified model of computer. The classes of M-groupoids, address machines, stored program computers and iterative systems are presented as categories – by a suitable choice of homomorphisms. It is shown that the first three categories are equivalent, whereas the fourth is weaker (it is not equivalent to the previous ones and it can easily be embedded in the category of M-groupoids). This fact proves that M-groupoids form an essentially better and reasonably simple approximation of more complicated models of computers than iterative systems.

scholarly journals On the origin of long-lived particles

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Jared Barron ◽  
David Curtin
Keyword(s):  
Decay Mode ◽  
Large Volume ◽  
Simplified Model ◽  
Production Mode ◽  
Decay Products ◽  
Bsm Physics ◽  
Level 1 ◽  
Displaced Vertex ◽  
Main Detector ◽  
Combining Information

Abstract MATHUSLA is a proposed large-volume displaced vertex (DV) detector, situated on the surface above CMS and designed to search for long-lived particles (LLPs) produced at the HL-LHC. We show that a discovery of LLPs at MATHUSLA would not only prove the existence of BSM physics, it would also uncover the theoretical origin of the LLPs, despite the fact that MATHUSLA gathers no energy or momentum information on the LLP decay products. Our analysis is simple and robust, making it easily generalizable to include more complex LLP scenarios, and our methods are applicable to LLP decays discovered in ATLAS, CMS, LHCb, or other external detectors. In the event of an LLP detection, MATHUSLA can act as a Level-1 trigger for the main detector, guaranteeing that the LLP production event is read out at CMS. We perform an LLP simplified model analysis to show that combining information from the MATHUSLA and CMS detectors would allow the LLP production mode topology to be determined with as few as ∼ 100 observed LLP decays. Underlying theory parameters, like the LLP and parent particle masses, can also be measured with ≲ 10% precision. Together with information on the LLP decay mode from the geometric properties of the observed DV, it is clear that MATHUSLA and CMS together will be able to characterize any newly discovered physics in great detail.

scholarly journals Simplified Mathematical Modelling of Uncertainty: Cost-Effectiveness of COVID-19 Vaccines in Spain

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 566
Author(s):  
Julio Emilio Marco-Franco ◽  
Pedro Pita-Barros ◽  
Silvia González-de-Julián ◽  
Iryna Sabat ◽  
David Vivas-Consuelo
Keyword(s):  
Cost Effectiveness ◽  
Health Planning ◽  
Cost Effective ◽  
Incremental Cost Effectiveness Ratio ◽  
Reliable Data ◽  
Simplified Model ◽  
Fatality Rate ◽  
Cost Effectiveness Ratio ◽  
Funeral Homes ◽  
The Cost

When exceptional situations, such as the COVID-19 pandemic, arise and reliable data is not available at decision-making times, estimation using mathematical models can provide a reasonable reckoning for health planning. We present a simplified model (static but with two-time references) for estimating the cost-effectiveness of the COVID-19 vaccine. A simplified model provides a quick assessment of the upper bound of cost-effectiveness, as we illustrate with data from Spain, and allows for easy comparisons between countries. It may also provide useful comparisons among different vaccines at the marketplace, from the perspective of the buyer. From the analysis of this information, key epidemiological figures, and costs of the disease for Spain have been estimated, based on mortality. The fatality rate is robust data that can alternatively be obtained from death registers, funeral homes, cemeteries, and crematoria. Our model estimates the incremental cost-effectiveness ratio (ICER) to be 5132 € (4926–5276) as of 17 February 2021, based on the following assumptions/inputs: An estimated cost of 30 euros per dose (plus transport, storing, and administration), two doses per person, efficacy of 70% and coverage of 70% of the population. Even considering the possibility of some bias, this simplified model provides confirmation that vaccination against COVID-19 is highly cost-effective.

scholarly journals Search for squarks and gluinos in final states with jets and missing transverse momentum using 139 fb−1 of $$ \sqrt{s} $$ = 13 TeV pp collision data with the ATLAS detector

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Simplified Model ◽  
Supersymmetric Particle ◽  
Final States ◽  
Proton Proton ◽  
Missing Transverse Momentum ◽  
First And Second Generation ◽  
Proton Proton Collisions

Abstract A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded by the ATLAS experiment in proton-proton collisions at a centre-of-mass energy of $$ \sqrt{s} $$ s = 13 TeV during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. The results are interpreted in the context of various R-parity-conserving models where squarks and gluinos are produced in pairs or in association and a neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 2.30 TeV for a simplified model containing only a gluino and the lightest neutralino, assuming the latter is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.85 TeV are excluded if the lightest neutralino is massless. These limits extend substantially beyond the region of supersymmetric parameter space excluded previously by similar searches with the ATLAS detector.

scholarly journals 284 Obesity and type I endometrial carcinoma: an overly simplified model?

2020 ◽  
Author(s):  
C Liao ◽  
M Richardson ◽  
K Tran ◽  
C Chan ◽  
AK Mann ◽  
...  
Keyword(s):  
Endometrial Carcinoma ◽  
Simplified Model ◽  
Type I

scholarly journals Use of Extended Cover Factor Theory in UV Protection of Woven Fabric

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1188
Author(s):  
Klara Kostajnšek ◽  
Krste Dimitrovski
Keyword(s):  
Woven Fabrics ◽  
Uv Protection ◽  
Woven Fabric ◽  
Simplified Model ◽  
Light Penetration ◽  
Protective Properties ◽  
Cover Factor ◽  
Coefficient Of Reflection ◽  
Uv Protective Properties

The paper presents an extension of existed cover factor theory more suitable for the evaluation of light penetration through a net woven fabrics structure. It also introduces a new simplified model of predicting the ultraviolet (UV) protective properties of woven fabrics assuming that the coefficient of reflection (KR), transmission (KT), and absorption (KA) of constitutive yarns are known. Since usually they are not, the procedure of preparation of simulation of proper woven fabric samples without interlacing and with known constructional parameters is also presented. The procedure finishes with a fast and cheap detection of missed coefficient for any type of yarns. There are differences between theoretical and measured results, which are not particularly significant in regard to the purpose and demands of investigation.

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