Contractive Iterated Function Systems Enriched with Nonexpansive Maps

Motivated by a recent paper of Leśniak and Snigireva [Iterated function systems enriched with symmetry, preprint], we investigate the properties of the semiattractor $$A_{\mathcal {F}\cup \mathcal {G}}^*$$ A F ∪ G ∗ of an IFS $$\mathcal {F}$$ F enriched by some other IFS $$\mathcal {G}$$ G . We show that in natural cases, the semiattractor $$A_{\mathcal {F}\cup \mathcal {G}}^*$$ A F ∪ G ∗ is in fact the attractor of certain IFSs related naturally with the IFSs $$\mathcal {F}$$ F and $$\mathcal {G}$$ G . We also give an example when $$A_{\mathcal {F}\cup \mathcal {G}}^*$$ A F ∪ G ∗ is not compact, yet still being the attractor of considered related IFSs. Finally, we use presented machinery to prove that the so called lower transition attractors due to Vince are semiattractors of enriched IFSs.

Statistical Study of Relationship between Structural Properties and Mesomorphic Properties of Some Ester Linkage Mesomorphic Compounds

: A statistical study between ‘Mesophase Lower Transition Temperatures’ (MLTTs) and their structural properties is carried out to understand the effect of structural behaviour on mesomorphic property. Introduction: To establish a “Quantitative Structure and Property Relationship (QSPR) model” a set of randomly selected thirty-nine mesomorphic compounds is constructed. The backward stepwise regression analysis method is used to find out the good correlation between the “Mesophase Lower Transition Temperatures (MLTTs)” data set and “physical descriptors” like AMR, bpol, ASP-0, DELS, SdssC, etc. Physical descriptors are selected based on their good r2 -values and p-values with respective MLTTs. The derived QSPR equation shows a good correlation between structural properties and mesomorphic properties of compounds. Method: Validation of the derived QSPR equation is carried out on the test series of eight compounds. The MLTTs of these compounds are predicted through the statistically derived QSPR equation and then compared with experimentally measured MLTTs. The average percentage error observed between predicted MLTTs and experimentally measured MLTTs is observed 10.95 % for all the thirty-nine compounds of the trial set, and 10.64% for 8 compounds of the test series respectively. Result & Discussion: A low average percentage error suggests a reasonably acceptable degree of accuracy of the generated QSPR model to predict MLTTs of the compounds having a similar type of structure.In the present study not only MLTTs are predicted, but an effort also made to predict “Latent Transition Temperatures” (LTTs) of some non-mesomorphic compounds from derived QSPR equation. Conclusion: This computational study gives a sight to develop new QSPR models for the different-different type of liquid crystals homologous series, through which various types of mesomorphic properties, like mesomorphic thermal stability, mesomorphic upper transition temperature, mesophase length, phase behaviour, etc. can study and predict.

Fine structural tuning of the assembly of ECM peptide conjugates via slight sequence modifications

The self-assembly of nanostructures from conjugates of elastin-like peptides and collagen-like peptides (ELP-CLP) has been studied as means to produce thermoresponsive, collagen-binding drug delivery vehicles. Motivated by our previous work in which ELP-CLP conjugates successfully self-assembled into vesicles and platelet-like nanostructures, here, we extend our library of ELP-CLP bioconjugates to a series of tryptophan/phenylalanine-containing ELPs and GPO-based CLPs [W2Fx-b-(GPO)y] with various domain lengths to determine the impact of these modifications on the thermoresponsiveness and morphology. The lower transition temperature of the conjugates with longer ELP or CLP domains enables the formation of well-defined nanoparticles near physiological temperature. Moreover, the morphological transition from vesicles to platelet-like nanostructures occurred when the ratio of the lengths of ELP/CLP decreased. Given the previously demonstrated ability of many ELP-CLP bioconjugates to bind to both hydrophobic drugs and collagen-containing materials, our results suggest new opportunities for designing specific thermoresponsive nanostructures for targeted biological applications.

Quality control of low-frequency variants in SARS-CoV-2 genomes

During the current outbreak of COVID-19, research labs around the globe submit sequences of the local SARS-CoV-2 genomes to the GISAID database to provide a comprehensive analysis of the variability and spread of the virus during the outbreak. We explored the variations in the submitted genomes and found a significant number of variants that can be seen only in one submission (singletons). While it is not completely clear whether these variants are erroneous or not, these variants show lower transition/transversion ratio. These singleton variants may influence the estimations of the viral mutation rate and tree topology. We suggest that genomes with multiple singletons even marked as high-covered should be considered with caution. We also provide a simple script for checking variant frequency against the database before submission.

Semi-empirical model atmospheres for the chromosphere of the sunspot penumbra and umbral flashes

Context. The solar chromosphere and the lower transition region are believed to play a crucial role in the heating of the solar corona. Models that describe the chromosphere (and the lower transition region), accounting for its highly dynamic and structured character are, so far, found to be lacking. This is partly due to the breakdown of complete frequency redistribution (CRD) in the chromospheric layers and also because of the difficulty in obtaining complete sets of observations that adequately constrain the solar atmosphere at all relevant heights. Aims. We aim to obtain semi-empirical model atmospheres that reproduce the features of the Mg II h&k line profiles that sample the middle chromosphere with focus on a sunspot. Methods. We used spectropolarimetric observations of the Ca II 8542 Å spectra obtained with the Swedish 1 m Solar Telescope and used NICOLE inversions to obtain semi-empirical model atmospheres for different features in and around a sunspot. These were used to synthesize Mg II h&k spectra using the RH1.5D code, which we compared with observations taken with the Interface Region Imaging Spectrograph (IRIS). Results. Comparison of the synthetic profiles with IRIS observations reveals that there are several areas, especially in the penumbra of the sunspot, where most of the observed Mg II h&k profiles are very well reproduced. In addition, we find that supersonic hot down-flows, present in our collection of models in the umbra, lead to synthetic profiles that agree well with the IRIS Mg II h&k profiles, with the exception of the line core. Conclusions. We put forward and make available four semi-empirical model atmospheres. Two for the penumbra, reflecting the range of temperatures obtained for the chromosphere, one for umbral flashes, and a model representative of the quiet surroundings of a sunspot.

Iron(II) Spin Crossover (SCO) Materials Based on Dipyridyl-N-Alkylamine

We present here a new series of spin crossover (SCO) Fe(II) complexes based on dipyridyl-N-alkylamine and thiocyanate ligands, with the chemical formulae [Fe(dpea)2(NCS)2] (1) (dpea = 2,2’-dipyridyl-N-ethylamine), I-[Fe(dppa)2(NCS)2], (2) II-[Fe(dppa)2(NCS)2], and (2’) (dppa = 2,2’-dipyridyl-N-propylamine). The three complexes displayed nearly identical discrete molecular structures, where two chelating ligands (dpea (1) and dppa (2 and 2’)) stand in the cis-positions, and two thiocyanato-κN ligands complete the coordination sphere in the two remaining cis-positions. Magnetic studies as a function of temperature revealed the presence of a complete high-spin (HS) to low-spin (LS) transition at T1/2 = 229 K for 1, while the two polymorphs I-[Fe(dppa)2(NCS)2] (2) and II-[Fe(dppa)2(NCS)2] (2’) displayed similar magnetic behaviors with lower transition temperatures (T1/2 = 211 K for 2; 212 K for 2’). Intermolecular contacts in the three complexes indicated the absence of any significant interaction, in agreement with the gradual SCO behaviors revealed by the magnetic data. The higher transition temperature observed for complex 1 agrees well with the more pronounced linearity of the Fe–N–C angles recently evidenced by experimental and theoretical magnetostructural studies.

The impact of the transition from primary school to secondary school on young adolescents

IntroductionPrevious research suggests that adult anxiety disorders begin in adolescence and the transition from primary school to secondary school is the first challenge many young adolescents face, which could test their resilience for the first time.ObjectivesTo examine students’ anxiety scores before and after their transition, and what protective and risk factors are present during this challenge.AimsTo determine how the transition can impact anxiety in children, and if protective factors can help decrease the disruption that the transition can cause.MethodsOne hundred and eighty-four pupils completed questionnaires in their last term of primary school and during the first term of secondary school. At time 1: the attachment, school membership, and bullying and victimization measures were compared with pupils’ anxiety scores, along with whether their friends or siblings will be attending the same secondary school as them. These analyses will also be conducted once the pupils start secondary school, at time 2.ResultsSecure attachment was associated with lower anxiety and transition anxiety (F(2.56) = 7.255, P = .002; F(2.52) = 19.245, P = .000; F(2.181) = 10.181, P = .000; F(2.53) = 20.545, P = .000). School membership was associated with lower transition anxiety (F(2.181) = 4.151, P = .017; F(2.181) = 3.632, P = .028). Low victimisation was also associated with low anxiety and transition anxiety (F(2.181) = 14.024, P = .000; F(2.181) = 14.529, P = .000; F(2.181) = 9.381, P = .000).ConclusionsThese preliminary results suggest that attachment, school membership and victimisation all impact on pupils anxiety before they transition to secondary school. Therefore, schools could work together to increase school membership and decrease victimisation, particularly for pupils who they suspect will struggle with the transition.Disclosure of interestThe authors have not supplied their declaration of competing interest.