Enhancement of the Dark Matter Abundance Before Reheating: Applications to Gravitino Dark Matter

In the first stages of inflationary reheating, the temperature of the radiation produced by inflaton decays is typically higher than the commonly defined reheating temperature $T_{RH} \sim (\Gamma_\phi M_P)^{1/2}$ where $\Gamma_\phi$ is the inflaton decay rate. We consider the effect of particle production at temperatures at or near the maximum temperature attained during reheating. We show that the impact of this early production on the final particle abundance depends strongly on the temperature dependence of the production cross section. For $\langle \sigma v \rangle \sim T^n/M^{n+2}$, and for $n < 6$, any particle produced at $T_{\rm max}$ is diluted by the later generation of entropy near $T_{RH}$. This applies to cases such as gravitino production in low scale supersymmetric models ($n=0$) or NETDM models of dark matter ($n=2$). However, for $n\ge6$ the net abundance of particles produced during reheating is enhanced by over an order of magnitude, dominating over the dilution effect. This applies, for instance to gravitino production in high scale supersymmetry models where $n=6$.Comment: 16 pages, 5 figure

Transitions de spin dans des matériaux moléculaires polynucléaires du Fe(II)

The potential applications of spin transition (ST) molecular materials in the field of display and data processing has led to a renewal interest for the study of hte phenomenon in the last ten years. Numerous compounds can go from a stable electronic state to another stable state in a reversible and detectable fashion in response to an appropriate and controllable external pertubation. In certain cases, a hysteresis effect is associated to this transition, which confers a memory effect to the system. We have synthesised new iron(II) ST polynuclear molecular materials designed in order to increase intermolecular interactions. The influence of various molecular and physical parameters on the ST regime of Fe(II)-1,2,4-triazole chains has been studied in depth. The first crystal structures of a linear chain and of a tridimensionnal compound have been obtained in the low-spin and high-spin states, and theses have been correlated to the physical properties of these materialsLes applications industrielles des matériaux moléculaires à transition de spin (TS) dans le domaine de l'affichage de l'information ont conduit depuis une dizaine d'années à un regain d'intérêt pour l'étude de ce phénomène. En réponse à une perturbation extérieure appropriée et contrôlable, nombre de ces composés peuvent passer d'un état électronique stable à un autre état stable de façon réversible et détectable. Dans certain cas, un effet d'hystérésis est associé à ce passage, ce qui confère au système un effet mémoire. Nous avons synthétisé de nouveaux matériaux moléculaires polynucléaires à TS du Fe(II), choisis de façon à accroître les interactions intermoléculaires. L'influence de divers paramètres moléculaires et physiques sur le régime de TS de chaînes Fe(II)-1,2,4-triazole a été étudiée. Les premières structures cristallines d'une chaîne linéaire et d'un composé tridimensionnel ont été obtenues dans les états bas-spin et haut-spin, et corrélés aux propriétés physiques de ces matériau

Iron(II) spin transition coordination polymers with a zigzag structure

The synthesis and characterisation of seven iron(ii) 1D chain coordination polymers with tetradentate Schiff-base like equatorial ligands and bis(4-pyridylmethyl)sulfide (bpms) as a flexible bridging axial ligand is reported. This new family of materials displays a wide spectrum of spin transition properties in the solid state ranging from gradual, abrupt, incomplete to even step-wise that have all been characterized by SQUID magnetometry. The X-ray structure analysis of two complexes at several temperatures is discussed in the frame of their spin crossover properties. © 2012 The Royal Society of Chemistry

Comparison among technical and milled wood lignins through principal component analysis of FTIR spectra

With the growth of biomass processing in biorefineries, there is an increasing need to develop rapid and simple methods for biomass characterization. One important component of biomass that is of signification interest in pyrolysis and liquefaction research is lignin, which is the world’s predominant source of renewable aromatic carbon. Due to its complex, heterogeneous nature and distinct variations among different biomass feedstocks, the characterization of lignins presents a unique challenge. In this study, we will show that clear divisions and comparisons can be made among a variety of lignins based on their FTIR spectra quantitatively assessed through principal component analysis (PCA). The eight lignins so far characterized are: two varieties of softwood kraft, one hardwood kraft, corn stover milled wood lignin (MWL), Douglas fir MWL, hybrid poplar MWL, wheat straw soda, and wheat straw organosolv. These samples were analyzed using a Bruker Alpha FTIR-ATR instrument (in addition to other characterization techniques). The spectra were baseline corrected and normalized, and the intensities of 15 peaks were recorded. The 15 spectral peaks were chosen based on previous work published by Li and McDonald (Industrial Crops and Products, 62, 2014, 67-76). PCA and data visualization was done using Python in the Jupyter Notebook environment. Fig. 1: Explained Variance of Each PC Principal component analysis revealed that among the eight lignins, they can be qualitatively grouped based on both their feedstock variety (e.g., hardwood, softwood) and isolation method (i.e., kraft, MWL, soda, organosolv). Quantification of the explained variances for each principal component (PC) suggests that three PC’s are necessary to capture over 90% of the variation among the samples (Figure 1). The principal component plots (Figure 2) show that softwood kraft lignins are clustered, corn stover and Douglas fir MWLs are clustered, and hardwood kraft and wheat straw soda are clustered. The two wheat straw and two hardwood samples tend to have positive values for PC1, while the softwoods and corn stover are negative. The MWLs are closely grouped along PC2, and the organosolv wheat straw is uniquely large along PC3. Depending on which of the three PC plots are assessed, other possible groupings can be reasonably drawn, suggesting that the FTIR spectral characteristics of lignins are distinctly affected by both their original biomass feedstock and isolation or extraction method. The analysis of FTIR spectra with PCA is a simple and efficient way to quickly assess the characteristics of an unknown or poorly-understood lignin sample, based on its comparison with other well-studied lignins. Previous work has shown that PCA is a robust technique for analyzing bio-oil MS data (Jia, et al., Energy & Fuels, 29, 2015, 7364-7374; Pattiya, et al., Fuel, 89(1), 2010, 244-253), and this work shows that such analysis can easily be extended to FTIR spectra of contrasting lignins. Continuing research will further assess the FTIR data for other important characteristics (both qualitative and quantitative), as well as to include additional technical lignins in the analyses. Please click Additional Files below to see the full abstract

Spin Transition Sensors Based on β-Amino-Acid 1,2,4-Triazole Derivative

A β-aminoacid ester was successfully derivatized to yield to 4H-1,2-4-triazol-4-yl-propionate (βAlatrz) which served as a neutral bidentate ligand in the 1D coordination polymer [Fe(βAlatrz)3](CF3SO3)2·0.5H2O (1·0.5H2O). The temperature dependence of the high-spin molar fraction derived from 57Fe Mossbauer spectroscopy recorded on cooling below room temperature reveals an exceptionally abrupt single step transition between high-spin and low-spin states with a hysteresis loop of width 4 K (Tc↑ = 232 K and Tc↓ = 228 K) in agreement with magnetic susceptibility measurements. The material presents striking reversible thermochromism from white, at room temperature, to pink on quench cooling to liquid nitrogen, and acts as an alert towards temperature variations. The phase transition is of first order, as determined by differential scanning calorimetry, with transition temperatures matching the ones determined by SQUID and Mössbauer spectroscopy. The freshly prepared sample of 1·0.5H2O, dried in air, was subjected to annealing at 390 K, and the obtained white compound [Fe(βAlatrz)3](CF3SO3)2 (1) was found to exhibit a similar spin transition curve however much temperature was increased by (Tc↑ = 252 K and Tc↓ = 248 K). The removal of lattice water molecules from 1·0.5H2O is not accompanied by a change of the morphology and of the space group, and the chain character is preserved. However, an internal pressure effect stabilizing the low-spin state is evidenced

PARMESAN: Meteorological Timeseries and Turbulence Analysis Backed by Symbolic Mathematics

PARMESAN (the Python Atmospheric Research Package for MEteorological TimeSeries and Turbulence ANalysis) is a Python package providing common functionality for atmospheric scientists doing time series or turbulence analysis. Several meteorological quantities such as potential temperature, various humidity measures, gas concentrations, wind speed and direction, turbulence and stability parameters can be calculated. Furthermore, signal processing functionality such as properly normed variance spectra for frequency analysis is available. In contrast to existing packages with similar goals, its routines for physical quantities are derived from symbolic mathematical expressions, enabling inspection, automatic rearrangement, reuse and recombination of the underlying equations. Building on this, PARMESAN's functions as well as their comprehensive parameter documentation are mostly auto-generated, minimizing human error and effort. In addition, sensitivity/error propagation analysis is possible as mathematical operations like derivations can be applied to the underlying equations. Physical consistency in terms of units and value domains are transparently ensured for PARMESAN functions. PARMESAN's approach can be reused to simplify implementation of robust routines in other fields of physics.Comment: 7 pages, 5 figures, submitted to JOSS (Journal of Open Source Software) on 17 September 202

Tractional Retinal Detachment Related to Hemoglobin C Trait Retinopathy: A Case Report

Hemoglobin C (HbC) disease is an uncommon disease that is generally considered benign, causing only occasionally painless hematuria, osteomyelitis, and dental abnormalities. Ocular manifestations have rarely been described in these patients. Here we report a novel ophthalmological manifestation of the disease. A 20-year-old woman presented with progressive visual loss in her right eye due to tractional retinal detachment. The left eye was apparently normal, but wide-field fluorescence angiography showed mild peripheral ischemia with multiple vascular abnormalities. Vitrectomy was performed and the systemic workup revealed the presence of hemoglobinopathy C in heterozygous form. HbC disease can be sight-threating due to retinal proliferation, similar to sickle cell retinopathy. Patients affected with this disease should undergo regular surveillance. Ultra-wide angiography is a helpful examination to detect peripheral ischemia in the earlier stages

SNP mining in C. clementina BAC end sequences; transferability in the Citrus genus (Rutaceae), phylogenetic inferences and perspectives for genetic mapping

<p>Abstract</p> <p>Background</p> <p>With the increasing availability of EST databases and whole genome sequences, SNPs have become the most abundant and powerful polymorphic markers. However, SNP chip data generally suffers from ascertainment biases caused by the SNP discovery and selection process in which a small number of individuals are used as discovery panels. The ongoing International Citrus Genome Consortium sequencing project of the highly heterozygous Clementine and sweet orange genomes will soon result in the release of several hundred thousand SNPs. The primary goals of this study were: (i) to estimate the transferability within the genus <it>Citrus </it>of SNPs discovered from Clementine BACend sequencing (BES), (ii) to estimate bias associated with the very narrow discovery panel, and (iii) to evaluate the usefulness of the Clementine-derived SNP markers for diversity analysis and comparative mapping studies between the different cultivated <it>Citrus </it>species.</p> <p>Results</p> <p>Fifty-four accessions covering the main <it>Citrus </it>species and 52 interspecific hybrids between pummelo and Clementine were genotyped on a GoldenGate array platform using 1,457 SNPs mined from Clementine BES and 37 SNPs identified between and within <it>C. maxima, C. medica, C. reticulata </it>and <it>C. micrantha</it>. Consistent results were obtained from 622 SNP loci. Of these markers, 116 displayed incomplete transferability primarily in <it>C. medica, C. maxima </it>and wild <it>Citrus </it>species. The two primary biases associated with the SNP mining in Clementine were an overestimation of the <it>C. reticulata </it>diversity and an underestimation of the interspecific differentiation. However, the genetic stratification of the gene pool was high, with very frequent significant linkage disequilibrium. Furthermore, the shared intraspecific polymorphism and accession heterozygosity were generally enough to perform interspecific comparative genetic mapping.</p> <p>Conclusions</p> <p>A set of 622 SNP markers providing consistent results was selected. Of the markers mined from Clementine, 80.5% were successfully transferred to the whole <it>Citrus </it>gene pool. Despite the ascertainment biases in relation to the Clementine origin, the SNP data confirm the important stratification of the gene pools around <it>C. maxima, C. medica </it>and <it>C. reticulata </it>as well as previous hypothesis on the origin of secondary species. The implemented SNP marker set will be very useful for comparative genetic mapping in <it>Citrus </it>and genetic association in <it>C. reticulata</it>.</p