Boltzmann Statistics

An Introduction to Thermal Physics ◽

10.1093/oso/9780192895547.003.0006 ◽

2021 ◽

pp. 220-256

Author(s):

Daniel V. Schroeder

Keyword(s):

Simple Model ◽

Thermal Behavior ◽

Lower Energy ◽

Boltzmann Distribution ◽

Model Systems ◽

Fixed Temperature ◽

Stellar Spectra ◽

Paramagnetic Materials ◽

Energy States ◽

Boltzmann Statistics

When a system is held at a fixed temperature, its higher-energy states are less probable than its lower energy states by an amount that depends on how the energy compares to the temperature. The formula that quantifies this idea is called the Boltzmann distribution. This chapter derives the Boltzmann distribution and shows how to use it to predict the thermal behavior of any system whose microscopic states we can enumerate. The examples go beyond the three simple model systems studied already in Chapters 2 and 3 to include detailed properties of gases, stellar spectra, and paramagnetic materials.

Download Full-text

X-ray and UV Radiation Damage of dsDNA/Protein Complexes

Molecules ◽

10.3390/molecules26113132 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3132

Author(s):

Paweł Wityk ◽

Dorota Kostrzewa-Nowak ◽

Beata Krawczyk ◽

Michał Michalik ◽

Robert Nowak

Keyword(s):

Dna Damage ◽

Simple Model ◽

Uv Radiation ◽

Protein Complexes ◽

Chemical Processes ◽

Model Systems ◽

Degradation Pathways ◽

X Ray ◽

Physico Chemical ◽

Sensitization Process

Radiation and photodynamic therapies are used for cancer treatment by targeting DNA. However, efficiency is limited due to physico-chemical processes and the insensitivity of native nucleobases to damage. Thus, incorporation of radio- and photosensitizers into these therapies should increase both efficacy and the yield of DNA damage. To date, studies of sensitization processes have been performed on simple model systems, e.g., buffered solutions of dsDNA or sensitizers alone. To fully understand the sensitization processes and to be able to develop new efficient sensitizers in the future, well established model systems are necessary. In the cell environment, DNA tightly interacts with proteins and incorporating this interaction is necessary to fully understand the DNA sensitization process. In this work, we used dsDNA/protein complexes labeled with photo- and radiosensitizers and investigated degradation pathways using LC-MS and HPLC after X-ray or UV radiation.

Download Full-text

Williams Syndrome As a Model for Elucidation of the Pathway Genes - the Brain - Cognitive Functions: Genetics and Epigenetics

Acta Naturae ◽

10.32607/20758251-2014-6-1-9-22 ◽

2014 ◽

Vol 6 (1) ◽

pp. 9-22 ◽

Cited By ~ 11

Author(s):

Е. А. Nikitina ◽

A. V. Medvedeva ◽

G. А. Zakharov ◽

Е. V. Savvateeva-Popova

Keyword(s):

Simple Model ◽

Williams Syndrome ◽

Cognitive Functions ◽

Single Gene ◽

Model Systems ◽

Epigenetic Events ◽

Simple Model System ◽

And Behavior ◽

Brain Behavior ◽

The Brain

Genomic diseases or syndromes with multiple manifestations arise spontaneously and unpredictably as a result of contiguous deletions and duplications generated by unequal recombination in chromosomal regions with a specific architecture. The Williams syndrome is believed to be one of the most attractive models for linking genes, the brain, behavior and cognitive functions. It is a neurogenetic disorder resulting from a 1.5 Mb deletion at 7q11.23 which covers more than 20 genes; the hemizigosity of these genes leads to multiple manifestations, with the behavioral ones comprising three distinct domains: 1) visuo-spatial orientation; 2) verbal and linguistic defect; and 3) hypersocialisation. The shortest observed deletion leads to hemizigosity in only two genes: eln and limk1. Therefore, the first gene is supposed to be responsible for cardiovascular pathology; and the second one, for cognitive pathology. Since cognitive pathology diminishes with a patients age, the original idea of the crucial role of genes straightforwardly determining the brains morphology and behavior was substituted by ideas of the brains plasticity and the necessity of finding epigenetic factors that affect brain development and the functions manifested as behavioral changes. Recently, non-coding microRNAs (miRs) began to be considered as the main players in these epigenetic events. This review tackles the following problems: is it possible to develop relatively simple model systems to analyze the contribution of both a single gene and the consequences of its epigenetic regulation in the formation of the Williams syndromes cognitive phenotype? Is it possible to use Drosophila as a simple model system?

Download Full-text