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We have simulated the evolution of population using the Penna model of aging. In populations of diploid organisms, without recombination between haplotypes or with low cross-over rate, a specific distribution of defective genes has been established. As an effect, relatively higher mortality is observed during the earliest stages of life. When two independently evolving populations were mixed and co-evolved in one environment without crossbreeding, one population won after several generations and this winning population showed stronger "early" death effect. We conclude that in the environmentally limited size of a population (in the model limit set by Verhulst factor) it is a better strategy to sacrifice younger individuals — higher fractions of such populations reach the reproduction age.

We have simulated the evolution of diploid, sexually reproducing populations using the Penna model of aging. We have noted that diminishing the recombination frequency during the gamete production generates a specific diversity of genomes in the populations. When two populations independently evolving for some time were mixed in one environmental niche of the limited size and crossbreeding between them was allowed, the average lifespan of hybrids was significantly shorter than the lifespan of the individuals of parental lines. Another effect of higher hybrid mortality is the faster elimination of one parental line from the shared environment. The two populations living in one environment co-exist much longer if they are genetically separated — they compete as two species instead of crossbreeding. This effect can be considered as the first step to speciation — any barrier eliminating crossbreeding between these populations, leading to speciation, would favor the populations.

We have used the Monte Carlo-based computer models to show that selection pressure could affect the distribution of recombination hotspots along the chromosome. Close to the critical crossover rate, where genomes may switch between the Darwinian purifying selection or complementation of haplotypes, the distribution of recombination events and the force of selection exerted on genes affect the structure of chromosomes. The order of expression of genes and their location on chromosome may decide about the extinction or survival of competing populations.

We elaborate that general intersecting brane models on orbifolds are obtained from type I string compactifications and their T-duals. Symmetry breaking and restoration occur via recombination and parallel separation of branes, preserving supersymmetry. The Ramond–Ramond tadpole cancellation and the toron quantization constrain the spectrum as a branching of the adjoints of SO(32), up to orbifold projections. Since the recombination changes the gauge coupling, the single gauge coupling of type I could give rise to different coupling below the unification scale. This is due to the nonlocal properties of the Dirac–Born–Infeld action. The desirable weak mixing angle sin²θ_W = 3/8 is naturally explained by embedding the quantum numbers to those of SO(10).

We investigate some aspects of the thermal history of the early universe according to Yang–Mills Gravity (YMG); a gauge theory of gravity set in flat space–time. Specifically, equations for the ionization fractions of hydrogen and singly ionized helium during the recombination epoch are deduced analytically and then solved numerically. By considering several approximations, we find that the presence of primordial helium and its interaction with Lyman series photons has a much stronger effect on the overall free electron density in YMG than it does in the standard, General Relativity (GR)-based, model. Compared to the standard model, recombination happens over a much larger range of temperatures, although there is still a very sharp temperature of last scattering around 2000 K. The ionization history of the universe is not directly observable, but knowledge of it is necessary for CMB power spectrum calculations. Such calculations will provide another rigorous test of YMG and will be explored in detail in an upcoming paper.

In the medium of relativistic heavy-ion collisions, dissociation of the quarkonium and its survival have been studied to understand the properties of Quark Gluon Plasma (QGP). The coupled rates of dissociation and recombination reactions in QGP are commonly solved with the Boltzmann transport equation in which the formation and dissociation reactions compete with each other. Since the dissociation of newly formed bound-states is not accounted in the Boltzmann equation, a framework of decoupled rates is developed to assess the combined effect of gluon-induced dissociation and recombination (though it is small for $\mathrm{\Upsilon }$) together with color screening on bottomonium production in heavy-ion collisions at center of mass energy $(\sqrt{s_{\mathrm{\text{NN}}}})=5.02$TeV. To calculate the recombination rates, we have employed an effective method of Bateman solution which ensures the correlated effect between the recombination and the dissociation of the newly combined bottomonium in the QGP medium. The modifications of bottomonium have been estimated in an inflating QGP with the constraints matching with the dynamics of $\mathrm{\text{Pb}}+\mathrm{\text{Pb}}$ collision events at LHC.

In comparison with traditional solid p-n junction solar cells, the process of light-to-electric transformation in dye-sensitized solar cells is complicated. In order to obtain a comprehensive understanding of the physical and chemical mechanism in the complicated process, people have proposed some models to describe electron injection, diffusion and recombination occurred in the process. In this paper, we will give a brief review on these models. The electrical characteristic of dye-sensitized solar cell can be well described by the diffusion model, which was originally proposed by Södergren and later further developed by Ferber, Anta, Bisquert et al. The electron injection, diffusion and recombination manifest themselves via three parameters: injection efficiency η_inj, diffusion coefficient D and recombination rate (time) K (τ) in the diffusion equation. Meanwhile, some microscopic models have also been developed to evaluate η_inj, D and K. The dynamical behavior of electron injection can be described by a kinetic theory, and corresponding η_inj can be understood from a conduction-band fluctuation model or a two-energy-level model. The power-law dependence of D and K on electron density can be well explained by trapping model, but the temperature behavior of D cannot be explained by this model. In the potential barrier model, a weak electron-density-dependent D is obtained, and the observed temperature dependence of D in experiment is naturally expected. Although currently the relevant experimental results cannot be consistently explained within one model, we believe that these models still are important for us to understand the physical and chemical mechanism in these microscopical processes and are helpful for us to further improve the photovoltaic performance of dye-sensitized solar cell.

The research results of photoelectric, optical and recombination properties of neutron transmutation doped (NTD) semiconductor solid alloys Si_1-xGe_x(x = 0.008–0.112) are presented in spectral range 0.8–10.6 μm. It is shown that these properties of NTD Si_1-xGe_x are determined by creation of transmutation impurities of Se and Ga as well as by variation of Ge content and compensation. The theoretical and applied aspects of the NTD Si_1-xGe_x have been also considered.

Organic inorganic-based perovskites solar cells (PSCs) are quite prominent as next generation solar cells as they exhibit excellent properties as well as high power conversion efficiency. In spite of the high cost, interfacial recombinations and instability in ambient environment limit their commercialization. Herein, TiO₂-based compact layer (c-TiO₂) with different thicknesses is employed (<50nm) to study the charge transportation at interface and recombination in PSCs fabricated under high humid conditions (R${}_{\text{H}}\sim$ 80%). The thickness of CL was varied from 7nm to 35nm and was optimized by changing the precursor concentration as well as spinning speed. The prepared c-TiO₂ and the mesoporous layer of TiO₂ (m-TiO₂) were thoroughly characterized using Raman spectroscopy, UV-Vis, cyclic voltammetry and electrochemical techniques. Furthermore, CuSCN was used as hole transporting layer (HTL) in PSCs owing to ease of handling and nominal cost. The optimized PSC is found to show that the power conversion efficiency (PCE) improved by 50% on varying the thickness of CL and is stable even under high humid conditions. The elevated performance of PSCs is ascribed to the appropriate thickness of CL which resulted in improved charge transportation and reduced electron hole recombinations.

The mathematics of tangles has been very useful in studying recombinases which act processively and which require DNA to be in a certain configuration in order for the enzyme to act. Electron micrographs of the enzyme-DNA complex show the enzyme as a blob with DNA looping out of it. The configuration of the DNA within the blob cannot be determined form the electron micrographs. However, mathematics can in some cases determine the configuration of the DNA within the enzyme blob as well as the enzyme action.

In this paper, several theorems used to analyze recombinase experiments are summarized. In particular Xer recombinase, an enzyme which does not act processively is analyzed. Unfortunately, for enzymes which do not act processively, infinitely many possibilities exist. Several experiments are proposed to reduce this number and to emphasize both the usefulness and limitations of tangle analysis. Although the local action cannot be mathematically determined without more biological assumptions, it is possible to determine the topology of the synaptic complex through additional biolgical experiments.

We discuss the physical effects of some accelerated world models on the width of the last scattering surface (LSS) of the cosmic microwave background radiation (CMBR). The models considered in our analysis are X-matter (XCDM) and a Chaplygin type gas. The redshift of the LSS does not depend on the kind of dark energy (if XCDM of Chaplygin). Further, for a Chaplygin gas, the width of the LSS is also only weakly dependent on the kind of scenario (if we have dark energy plus cold dark matter or the unified picture).

A two-component analysis of spectra to p_t = 12 GeV/c for identified pions and protons from 200 GeV Au–Au collisions is presented. The method is similar to an analysis of the n_ch dependence of p_t spectra from p–p collisions at 200 GeV, but applied to Au–Au centrality dependence. The soft-component reference is a Lévy distribution on transverse mass m_t. The hard-component reference is a Gaussian on transverse rapidity y_t with exponential (p_t power-law) tail. Deviations of data from the reference are described by hard-component ratio r_AA, which generalizes nuclear modification factor R_AA. The analysis suggests that centrality evolution of pion and proton spectra is dominated by changes in parton fragmentation. The structure of r_AA suggests that parton energy loss produces a negative boost Δy_t of a large fraction (but not all) of the minimum-bias fragment distribution, and that lower-energy partons suffer relatively less energy loss, possibly due to color screening. The analysis also suggests that the anomalous p/π ratio may be due to differences in the parton energy-loss process experienced by the two hadron species. This analysis provides no evidence for radial flow.

The quarkonium yield productions in the relativistic Heavy-Ion Collisions and their modifications within the Quark–Gluon Plasma (QGP) produced in the collisions have been investigated for more than four decades. Similarly, phenomenological model studies with various themes have been performed to comprehend the features of the QGP medium along with its associated particle production. This paper proposes a model that combines the effects of color screening, gluon-induced dissociation, and recombination on quarkonium production in heavy-ion collisions involving ($\mathrm{\text{Pb}}+\mathrm{\text{Pb}}$ ions) at a center-of-mass energy of $(\sqrt{s_{\mathrm{\text{NN}}}})=5.02$TeV. Unlike the Boltzmann transport rate equations of dissociation and recombination, the rate equations are decoupled and solved individually using a method involving Bateman solution ensuring the dissociation and recombination of heavy quarks within the QGP medium are accounted well.

In relativistic Heavy-Ion Collisions (HIC), scientists have discussed the bottomonium dissociation and survival to gain insights about the characteristics of Quark Gluon Plasma (QGP). The Boltzmann transport equation is commonly employed to explore the interaction between dissociation and recombination rates in QGP, where the processes of formation and dissociation exhibit competing dynamics. However, the Boltzmann equation does not account for the dissociation of new bound states created in QGP medium. To overcome this restriction, a system of independent rates has been developed. This approach assesses the combined effects of gluon-induced dissociation, recombination (although minor for the ϒ states), and color screening on the generation of bottomonium in HIC. The investigation includes PbPb and XeXe collisions at center-of-mass energies $\sqrt{s_{\mathrm{\text{NN}}}}=5.02$TeV and $\sqrt{s_{\mathrm{\text{NN}}}}=5.44$ TeV, respectively. Recombination rates are computed employing the efficient Bateman solution technique, ensuring a comprehensive examination of the interaction between the recombination and dissociation within the QGP, along with the limitations associated with PbPb and XeXe collision kinetics at the Large Hadron Collider (LHC). The model has demonstrated considerable success in accurately describing the suppression of ϒ$(nS)$ states across collision systems of different sizes.

DNAs of individual chromosomes violate, albeit perhaps by only one in a thousand bases, Chargaff's second parity rule, which is that Chargaff's first parity rule for duplex DNA (A = T, G = C) applies, to a close approximation, to single stranded DNA. If the "top" strand of one chromosome has A > T and the "top" strand of another has T > A, can they complement to approach even parity (A = T)? Assignment of orientation to the six chromosomes of Caenorhabditis elegans is said to have been arbitrary and, of 2⁶ (= 64) possible combinations of top (T) and bottom (B) strands, the GenBank orientation (designated "TTTTTT") is but one. Yet, for the W bases (A and T) the chromosomes in the GenBank orientation complement to reduce the Chargaff difference (A–T) to only 200 bases (i.e. only one in 323,658 bases does not have a potential Watson-Crick pairing partner). This suggests that the assignment was not arbitrary. However, the GenBank orientation for the S bases (G and C) allows an approach to even parity less well than many other orientations, the best of which is BBBBTT (indicating a disparity between the GenBank orientations of the first four autosomes and those of chromosomes V and X). Although only the euchromatic regions of Drosophila melanogaster chromosomes have been sequenced, there are orientations that allow an approach to even parity. We conclude that, with respect to their Chargaff differences, the chromosomes of C. elegans have the potential to engage in interdependent base accounting. Since this might also apply to D. melanogaster, even when heterochromatin-associated DNA rich in tandem repeats (microsatellite DNA) is excluded, then heterochromatic DNA might not normally participate in the hypothetical accounting process.

In the few past years, the usage of CdTe thin-film solar cells has increased considerably due to their high efficiency, performance stability and cost effectiveness. In this work, a conventional structure of FTO–$i$-SnO₂–CdS–CdTe was simulated initially to verify the simulation process. An ultrathin absorber layer was considered to make the device more economical. A $p$-type copper oxide thin film was employed at the back contact as a hole transport–electron blocking layer (HT–EBL). Besides, the use of a bilayer ZnS–CdS compound and a monolayer CdS:Zn compound as the electron transport layer was also studied. The proposed modeled cell parameters then were optimized to increase the efficiency.

We have analyzed the relations between the mutational pressure, recombination and selection pressure in the bit-string model with sexual reproduction. For specific sets of these parameters, we have found three phase transitions with one phase where populations can survive. In this phase, recombination enhances the survival probability. Even if recombination is associated, to some extent, with additional mutations it could be advantageous to reproduction, indicating that the frequencies of recombinations and recombination-associated mutations can self-organize in Nature. Partitioning the diploid genome into pairs of chromosomes independently assorted during gamete production enables recombinations between groups of genes without the risk of mutations and is also advantageous for the strategy of sexual reproduction.

Fitness landscapes can be decomposed into elementary landscapes using a Fourier transform that is determined by the structure of the underlying configuration space. The amplitude spectrum obtained from the Fourier transform contains information about the ruggedness of the landscape. It can be used for classification and comparison purposes. We consider here three very different types of landscapes using both mutation and recombination to define the topological structure of the configuration spaces. A reliable procedure for estimating the amplitude spectra is presented. The method is based on certain correlation functions that are easily obtained from empirical studies of the landscapes.

A study on recombination of neutral oxygen atoms on the surface of different metals is presented. The source of oxygen atoms was a weakly ionized highly dissociated oxygen plasma created in an inductively coupled radio-frequency discharge. Ionized particles as well as excited molecules were effectively recombined and de-excited on the walls of a noncatalytic tube between the discharge and the experimental chamber, so the gas in the latter consisted only of well-thermalized neutral molecules and atoms. The density of oxygen atoms in the experimental chamber was measured with a catalytic probe. Depending on discharge parameters, the O density was between 2×10²⁰ and 5×10²¹ m^-3. Thin foils of different metals were mounted in the experimental chamber and exposed to oxygen atoms. Due to heterogeneous surface recombination of oxygen atoms on the surface of the samples, the metal temperature was increased well above the ambient temperature. The recombination coefficient was calculated from the foil temperature using physical formalism. Among the materials tested the highest recombination coefficient of 0.41 was found for pure polycrystalline iron. The recombination coefficient for flat and well-oxidized nickel, copper, stainless steel, and niobium were found to be 0.27, 0.23, 0.07, and 0.09, respectively, while the recombination coefficient for nanostructured niobium was 0.8. The accuracy of these values was estimated to be about 30%.

The recombination processes leading to tunneling afterglow and photostimulated luminescence were studied in systems based on ionic host crystals with low-dimensional structures (semiconductor quantum dots) formed as a result of the self-organized growth. The systems of AgBr nanocrystals embedded into the KBr crystal lattice and CsPbBr₃ nanocrystals embedded into the CsBr crystal lattice were investigated. The energy of electron–hole recombination in matrices was shown to transfer to quantum dots. To identify the structure of recombining electron and hole centers, magnetic resonance detected optically by monitoring the tunneling afterglow was used.