310 research outputs found
The mystery of relationship of mechanics and field in the many-body quantum world
We have revealed three fatal errors incurred from a blind transferring of
quantum field methods into the quantum mechanics. This had tragic consequences
because it produced crippled model Hamiltonians, unfortunately considered
sufficient for a description of solids including superconductors. From there,
of course, Fr\"ohlich derived wrong effective Hamiltonian, from which incorrect
BCS theory arose.
1) Mechanical and field patterns cannot be mixed. Instead of field methods
applied to the mechanical Born-Oppenheimer approximation we have entirely to
avoid it and construct an independent and standalone field pattern. This leads
to a new form of the Bohr's complementarity on the level of composite systems.
2) We have correctly to deal with the center of gravity, which is under the
field pattern "materialized" in the form of new quasipartiles - rotons and
translons. This leads to a new type of relativity of internal and external
degrees of freedom and one-particle way of bypassing degeneracies (gap
formation).
3) The possible symmetry cannot be apriori loaded but has to be aposteriori
obtained as a solution of field equations, formulated in a general form without
translational or any other symmetry. This leads to an utterly revised view of
symmetry breaking in non-adiabatic systems, namely Jahn-Teller effect and
superconductivity. These two phenomena are synonyms and share a unique symmetry
breaking.Comment: 24 pages, 9 sections; remake of abstract, introduction and
conclusion; more physics, less philosoph
Centre-of-mass separation in quantum mechanics: Implications for the many-body treatment in quantum chemistry and solid state physics
We address the question to what extent the centre-of-mass (COM) separation
can change our view of the many-body problem in quantum chemistry and solid
state physics. It was shown that the many-body treatment based on the
electron-vibrational Hamiltonian is fundamentally inconsistent with the
Born-Handy ansatz so that such a treatment can never respect the COM problem.
Born-Oppenheimer (B-O) approximation reveals some secret: it is a limit case
where the degrees of freedom can be treated in a classical way. Beyond the B-O
approximation they are inseparable in principle. The unique covariant
description of all equations with respect to individual degrees of freedom
leads to new types of interaction: besides the known vibronic (electron-phonon)
one the rotonic (electron-roton) and translonic (electron-translon)
interactions arise. We have proved that due to the COM problem only the
hypervibrations (hyperphonons, i.e. phonons + rotons + translons) have true
physical meaning in molecules and crystals; nevertheless, the use of pure
vibrations (phonons) is justified only in the adiabatic systems. This fact
calls for the total revision of our contemporary knowledge of all non-adiabatic
effects, especially the Jahn-Teller effect and superconductivity. The vibronic
coupling is responsible only for removing of electron (quasi)degeneracies but
for the explanation of symmetry breaking and forming of structure the rotonic
and translonic coupling is necessary.Comment: 39 pages, 11 sections, 3 appendice
LED Arrays as Cost Effective and Efficient Light Sources for Widefield Microscopy
New developments in fluorophores as well as in detection methods have fueled the rapid growth of optical imaging in the life sciences. Commercial widefield microscopes generally use arc lamps, excitation/emission filters and shutters for fluorescence imaging. These components can be expensive, difficult to maintain and preclude stable illumination. Here, we describe methods to construct inexpensive and easy-to-use light sources for optical microscopy using light-emitting diodes (LEDs). We also provide examples of its applicability to biological fluorescence imaging
Novel AlkB Dioxygenases—Alternative Models for In Silico and In Vivo Studies
Background: ALKBH proteins, the homologs of Escherichia coli AlkB dioxygenase, constitute a direct, single-protein repair system, protecting cellular DNA and RNA against the cytotoxic and mutagenic activity of alkylating agents, chemicals significantly contributing to tumor formation and used in cancer therapy. In silico analysis and in vivo studies have shown the existence of AlkB homologs in almost all organisms. Nine AlkB homologs (ALKBH1–8 and FTO) have been identified in humans. High ALKBH levels have been found to encourage tumor development, questioning the use of alkylating agents in chemotherapy. The aim of this work was to assign biological significance to multiple AlkB homologs by characterizing their activity in the repair of nucleic acids in prokaryotes and their subcellular localization in eukaryotes.
Methodology and Findings: Bioinformatic analysis of protein sequence databases identified 1943 AlkB sequences with eight
new AlkB subfamilies. Since Cyanobacteria and Arabidopsis thaliana contain multiple AlkB homologs, they were selected as model organisms for in vivo research. Using E. coli alkB2 mutant and plasmids expressing cyanobacterial AlkBs, we studied the repair of methyl methanesulfonate (MMS) and chloroacetaldehyde (CAA) induced lesions in ssDNA, ssRNA, and genomic DNA.
On the basis of GFP fusions, we investigated the subcellular localization of ALKBHs in A. thaliana and established its mostly nucleo-cytoplasmic distribution. Some of the ALKBH proteins were found to change their localization upon MMS treatment.
Conclusions: Our in vivo studies showed highly specific activity of cyanobacterial AlkB proteins towards lesions and nucleic acid type. Subcellular localization and translocation of ALKBHs in A. thaliana indicates a possible role for these proteins in the repair of alkyl lesions. We hypothesize that the multiplicity of ALKBHs is due to their involvement in the metabolism of nucleo-protein complexes; we find their repair by ALKBH proteins to be economical and effective alternative to degradation and de novo synthesis
Quantum Measurement Theory in Gravitational-Wave Detectors
The fast progress in improving the sensitivity of the gravitational-wave (GW)
detectors, we all have witnessed in the recent years, has propelled the
scientific community to the point, when quantum behaviour of such immense
measurement devices as kilometer-long interferometers starts to matter. The
time, when their sensitivity will be mainly limited by the quantum noise of
light is round the corner, and finding the ways to reduce it will become a
necessity. Therefore, the primary goal we pursued in this review was to
familiarize a broad spectrum of readers with the theory of quantum measurements
in the very form it finds application in the area of gravitational-wave
detection. We focus on how quantum noise arises in gravitational-wave
interferometers and what limitations it imposes on the achievable sensitivity.
We start from the very basic concepts and gradually advance to the general
linear quantum measurement theory and its application to the calculation of
quantum noise in the contemporary and planned interferometric detectors of
gravitational radiation of the first and second generation. Special attention
is paid to the concept of Standard Quantum Limit and the methods of its
surmounting.Comment: 147 pages, 46 figures, 1 table. Published in Living Reviews in
Relativit
Potential climatic transitions with profound impact on Europe
We discuss potential transitions of six climatic subsystems with large-scale impact on Europe, sometimes denoted as tipping elements. These are the ice sheets on Greenland and West Antarctica, the Atlantic thermohaline circulation, Arctic sea ice, Alpine glaciers and northern hemisphere stratospheric ozone. Each system is represented by co-authors actively publishing in the corresponding field. For each subsystem we summarize the mechanism of a potential transition in a warmer climate along with its impact on Europe and assess the likelihood for such a transition based on published scientific literature. As a summary, the ‘tipping’ potential for each system is provided as a function of global mean temperature increase which required some subjective interpretation of scientific facts by the authors and should be considered as a snapshot of our current understanding. <br/
The Transcription Factor PU.1 Regulates γδ T Cell Homeostasis
T cell development results in the generation of both mature αβ and γδ T cells. While αβ T cells predominate in secondary lymphoid organs, γδ T cells are more abundant in mucosal tissues. PU.1, an Ets family transcription factor, also identified as the spleen focus forming virus proviral integration site-1 (Sfpi1) is essential for early stages of T cell development, but is down regulated during the DN T-cell stage.In this study, we show that in mice specifically lacking PU.1 in T cells using an lck-Cre transgene with a conditional Sfpi1 allele (Sfpi1(lck-/-)) there are increased numbers of γδ T cells in spleen, thymus and in the intestine when compared to wild-type mice. The increase in γδ T cell numbers in PU.1-deficient mice is consistent in γδ T cell subsets identified by TCR variable regions. PU.1-deficient γδ T cells demonstrate greater proliferation in vivo and in vitro.The increase of γδ T cell numbers in Lck-Cre deleter strains, where deletion occurs after PU.1 expression is diminished, as well as the observation that PU.1-deficient γδ T cells have greater proliferative responses than wild type cells, suggests that PU.1 effects are not developmental but rather at the level of homeostasis. Thus, our data shows that PU.1 has a negative influence on γδ T cell expansion
Megascopic Quantum Phenomena. A Critical Study of Physical Interpretations
A megascopic revalidation is offered providing responses and resolutions of
current inconsistencies and existing contradictions in present-day quantum
theory. As the core of this study we present an independent proof of the
Goldstone theorem for a quantum field formulation of molecules and solids.
Along with phonons two types of new quasiparticles appear: rotons and
translons. In full analogy with Lorentz covariance, combining space and time
coordinates, a new covariance is necessary, binding together the internal and
external degrees of freedom, without explicitly separating the centre-of-mass,
which normally applies in both classical and quantum formulations. The
generally accepted view regarding the lack of a simple correspondence between
the Goldstone modes and broken symmetries, has significant consequences: an
ambiguous BCS theory as well as a subsequent Higgs mechanism. The application
of the archetype of the classical spontaneous symmetry breaking, i.e. the
Mexican hat, as compared to standard quantum relations, i.e. the Jahn-Teller
effect, superconductivity or the Higgs mechanism, becomes a disparity. In
short, symmetry broken states have a microscopic causal origin, but transitions
between them have a teleological component. The different treatments of the
problem of the centre of gravity in quantum mechanics and in field theories
imply a second type of Bohr complementarity on the many-body level opening the
door for megascopic representations of all basic microscopic quantum axioms
with further readings for teleonomic megascopic quantum phenomena, which have
no microscopic rationale: isomeric transitions, Jahn-Teller effect, chemical
reactions, Einstein-de Haas effect, superconductivity-superfluidity, and
brittle fracture.Comment: 117 pages, 17 sections, final revised version from 20 May 2019 but
uploaded after the DOI was know
Classical Morphology of Plants as an Elementary Instance of Classical Invariant Theory
It has long been known that structural chemistry shows an intriguing correspondence with Classical Invariant Theory (CIT). Under this view, an algebraic binary form of the degree n corresponds to a chemical atom with valence n and each physical molecule or ion has an invariant-theoretic counterpart. This theory was developed using the Aronhold symbolical approach and the symbolical processes of convolution/transvection in CIT was characterized as a potential “accurate morphological method”. However, CIT has not been applied to the formal morphology of living organisms. Based on the morphological interpretation of binary form, as well as the process of convolution/transvection, the First and Second Fundamental Theorems of CIT and the Nullforms of CIT, we show how CIT can be applied to the structure of plants, especially when conceptualized as a series of plant metamers (phytomers). We also show that the weight of the covariant/invariant that describes a morphological structure is a criterion of simplicity and, therefore, we argue that this allows us to formulate a parsimonious method of formal morphology. We demonstrate that the “theory of axilar bud” is the simplest treatment of the grass seedling/embryo. Our interpretations also represent Troll's bauplan of the angiosperms, the principle of variable proportions, morphological misfits, the basic types of stem segmentation, and Goethe's principle of metamorphosis in terms of CIT. Binary forms of different degrees might describe any repeated module of plant organisms. As bacteria, invertebrates, and higher vertebrates are all generally shared a metameric morphology, wider implications of the proposed symmetry between CIT and formal morphology of plants are apparent
Investigating Population Genetic Structure in a Highly Mobile Marine Organism: The Minke Whale Balaenoptera acutorostrata acutorostrata in the North East Atlantic
Inferring the number of genetically distinct populations and their levels of connectivity is of key importance for the sustainable management and conservation of wildlife. This represents an extra challenge in the marine environment where there are few physical barriers to gene-flow, and populations may overlap in time and space. Several studies have investigated the population genetic structure within the North Atlantic minke whale with contrasting results. In order to address this issue, we analyzed ten microsatellite loci and 331 bp of the mitochondrial D-loop on 2990 whales sampled in the North East Atlantic in the period 2004 and 2007–2011. The primary findings were: (1) No spatial or temporal genetic differentiations were observed for either class of genetic marker. (2) mtDNA identified three distinct mitochondrial lineages without any underlying geographical pattern. (3) Nuclear markers showed evidence of a single panmictic population in the NE Atlantic according STRUCTURE's highest average likelihood found at K = 1. (4) When K = 2 was accepted, based on the Evanno's test, whales were divided into two more or less equally sized groups that showed significant genetic differentiation between them but without any sign of underlying geographic pattern. However, mtDNA for these individuals did not corroborate the differentiation. (5) In order to further evaluate the potential for cryptic structuring, a set of 100 in silico generated panmictic populations was examined using the same procedures as above showing genetic differentiation between two artificially divided groups, similar to the aforementioned observations. This demonstrates that clustering methods may spuriously reveal cryptic genetic structure. Based upon these data, we find no evidence to support the existence of spatial or cryptic population genetic structure of minke whales within the NE Atlantic. However, in order to conclusively evaluate population structure within this highly mobile species, more markers will be required
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