The isochore concept in the human genome sequence was challenged in an analysis by the International Human Genome Sequencing Consortium (IHGSC). We argue here that a statement in the IHGSC's analysis concerning the existence of isochores is misleading, because the homogeneity was not examined at a large enough length scale and consequently an inappropriate statistical test was applied. A test of the existence of isochores should be equivalent to a test of homogeneity or equality of windowed GC%. The statistical test applied in the IHGSC's analysis, the binomial test, is a test of whether individual bases are independent and identically-distributed (iid). For testing the existence of isochores, or homogeneity in windowed GC%, we propose to use another statistical test: the analysis of variance (ANOVA). It can be shown that DNA sequences that are rejected by the binomial test may not be rejected by the ANOVA test.
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http://dx.doi.org/10.1016/s1476-9271(02)00090-7 | DOI Listing |
Spectrochim Acta A Mol Biomol Spectrosc
January 2025
Key Laboratory of High-temperature and High-pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081 Guizhou, China. Electronic address:
High-pressure and high-temperature Raman spectra of natural pyromorphite, vanadinite and mimetite were measured up to 11 GPa and 973 K, respectively. No phase transition was observed within the temperature and pressure ranges in this study. Raman modes for pyromorphite, vanadinite and mimetite vary with temperature or pressure linearly.
View Article and Find Full Text PDFNat Commun
December 2024
J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA.
Phase stability, and the limits thereof, are a central concern of materials thermodynamics. However, the temperature limits of equilibrium liquid stability in chemical systems have only been widely characterized under constant (typically atmospheric) pressure conditions, whereunder these limits are represented by the eutectic. At higher pressures, the eutectic will shift in both temperature and chemical composition, opening a wide thermodynamic parameter space over which the absolute limit of liquid stability, i.
View Article and Find Full Text PDFRep Prog Phys
August 2024
School of Physical and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.
Physics-based first-principles pressure-volume-temperature equations of state (EOS) exist for solids and gases but not for liquids due to the long-standing fundamental problems involved in liquid theory. Current EOS models that are applicable to liquids and supercritical fluids at liquid-like density under conditions relevant to planetary interiors and industrial processes are complex empirical models with many physically meaningless adjustable parameters. Here, we develop a generally applicable physics-based (GAP) EOS for liquids including supercritical fluids at liquid-like density.
View Article and Find Full Text PDFJ Chem Phys
June 2024
Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden.
Here, we investigate the hypothesis that despite the existence of at least two high-density amorphous ices, only one high-density liquid state exists in water. We prepared a very-high-density amorphous ice (VHDA) sample and rapidly increased its temperature to around 205 ± 10 K using laser-induced isochoric heating. This temperature falls within the so-called "no-man's land" well above the glass-liquid transition, wherein the IR laser pulse creates a metastable liquid state.
View Article and Find Full Text PDFPhys Chem Chem Phys
June 2023
Department of Physics, The University of Texas at El Paso, El Paso, TX 79902, USA.
Polymorphism and phase transitions in sodium diuranate, NaUO, are investigated with density functional perturbation theory (DFPT). Thermal properties of crystalline α-, β- and γ-NaUO polymorphs are predicted from DFPT phonon calculations, , the first time for the high-temperature γ-NaUO phase (3̄ symmetry). The standard molar isochoric heat capacities predicted within the quasi-harmonic approximation are for 2/ α-NaUO and 2/ β-NaUO, respectively.
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