The diversity of supernovae and impostors shortly after explosion

Observational surveys are now able to detect an increasing number of transients, such as core-collapse supernovae (SN) and powerful non-terminal outbursts (SN impostors). Dedicated spectroscopic facilities can follow up these events shortly after detection. Here we investigate the properties of these explosions at early times. We use the radiative transfer code CMFGEN to build an extensive library of spectra simulating the interaction of supernovae and their progenitor's winds/circumstellar medium (CSM). We consider a range of progenitor mass-loss rates (Mdot = 5e-4 to 1e-2 Msun/yr), abundances (solar, CNO-processed, and He-rich), and SN luminosities (L = 1.9e8 to 2.5e10 Lsun). The models simulate events ~1 day after explosion, and we assume a fixed location of the shock front as Rin=8.6e13 cm. We show that the large range of massive star properties at the pre-SN stage causes a diversity of early-time interacting SN and impostors. We identify three main classes of early-time spectra consisting of relatively high-ionisation (e.g. Ovi), medium-ionisation (e.g. Ciii), and low-ionisation lines (e.g. Feii/iii). They are regulated by L and the CSM density. Given a progenitor wind velocity Vinf, our models also place a lower limit of Mdot > 5e-4 (Vinf/150 km/s) Msun/yr for detection of CSM interaction signatures in observed spectra. Early-time SN spectra should provide clear constraints on progenitors by measuring H, He, and CNO abundances if the progenitors come from single stars. The connections are less clear considering the effects of binary evolution. Yet, our models provide a clear path for linking the final stages of massive stars to their post-explosion spectra at early times, and guiding future observational follow-up of transients with facilities such as the Zwicky Transient Facility.Comment: Accepted for publication in A&A. 14 pages, 7 figure

Transanal approach in the radical treatment of children with Hirschsprung disease

Universitatea de Stat de Medicină şi Farmacie „Nicolae Testemiţanu” , IMSP Institutul Mamei şi Copilului, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: În ultimile decenii conduita chirurgicală în maladia Hirschsprung (MH) la copil a cunoscut numeroase transformări în ceea ce vizează abordul chirurgical şi procedeul tehnic propriu-zis de corecţie. Scopul lucrării a fost evaluarea dificultăţilor implimentării practice şi eficienţei curative a procedeului De la Torre-Mondragon în MH la copil. Materiale şi metode: Lotul de studiu a cuprins 12 pacienţi cu MH confirmată, interveniţi chirurgical în intervalul anilor 2016 - 2018, prin abord perineal cu descendarea trans-anală endorectală (TERPT) a colonului, procedeu propus de Luis De la Torre-Mondragon și Ortega-Salgado. Vârsta pacienţilor era cuprinsă între o lună şi 6 ani, dintre care 75% - sugari. Localizarea zonei aganglionare a fost infrarectală în 2, rectală 3, rectal-sigmoidală 7 cazuri. Copii au fost monitorizaţi şi pregătiţi preoperator conform unui program unic, evitînd aplicarea colostomei. Rezultate: Durata medie a intervenției chirurgicale 190±40 min. Lungimea colonului rezectat cuprinsă între 10 și 25 cm. Durata medie de îngrijire în reanimare 2±1 zi, durata medie de spitalizare 14±2 zile. Printre complicaţiile postoperatorii am înregistrat o fistulă anastamotică recto-vaginală, care a fost soluţionată prin aplicarea sigmostomei şi un caz de persistenţă a displaziei neuronale intestinale însoţită de colostază cronică soluţionată prin laparotomie cu rezecţia segmentului afectat de colon procedeul SwensonPelerin. Concluzii: Metoda respectivă este aplicabilă maximal efectiv la nou-nascuţi şi sugari cu o aganglionoză recto-sigmoidală care nu au dezvoltat enterocolita obstructivă şi alte complicaţii poliorganice. În ce priveşte copii de vârstă mai mare această operaţie riscă complicaţii similare procedeelor clasice.Introduction: In the last decades, the surgical management of Hirschsprung disease (HD) in children has evolved through many variations in the surgical approach and technique of the radical treatment. This study had the purpose of evaluating the difficulties of implementation the surgical procedure of De la Torre-Mondragon in practice and to evaluate its curative efficacy. Materials and methods: This study included 12 patients with a confirmed diagnosis of HD, operated between 2016 and 2018 through the transanal one-stage endorectal pull through (TERPT) of the colon, a surgical procedure proposed by Luis De la Torre-Mondragon and Ortega-Salgado. The patients had the age between one month to 6 years, of whom 75% - infants. The location of the aganglionic segment was infrarectal in two cases, rectal – 3, rectosigmoidian – 7. The children were monitored and prepared based on a unique preoperative program, avoiding the colostomy. Results: The mean time of the surgery was 190±40 min. The length of the resected colon was between 10 and 25 cm. The mean length of intensive care unit stay was 2±1 days; the average length of hospital stay was 14±2 days. Among the postoperatory complications, we encountered one anastomotic recto-vaginal fistula, operated through sigmostomy and a case of persistent intestinal neuronal dysplasia with chronic colostasis operated through laparotomy and resection of the affected segment of the colon - SwensonPelerin procedure. Conclusion: This method is maximally effective applied to newborns and infants with a rectosigmoidian aganglionosis without obstructive enterocolitis or other polyorganic complications. As for older children, this procedure implies complications similar to classical procedures

Neural intestinal lesions additional to anorectal malformations in children

Universitatea de Stat de Medicină şi Farmacie „Nicolae Testemiţanu”, IMSP Institutul Mamei şi Copilului, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Una din problemele nesoluţionate în managementul malformaţiilor ano-rectale (MAR) la copii rămîne în continuare retardarea diagnosticului displaziilor neuronale intestinale (DNI) şi aganglionozei colonice (AC) asociate acestor malformaţii. Scopul: Prezentarea experienţei clinicii noastre în diagnosticul şi tratamentul leziunilor neuronale intestinale asociate MAR. Material şi metode: În studiu au fost incluşi 16 copii operaţi în perioada neonatală şi de sugar pentru MAR, care postoperator prezentau colostază cronică, rebelă la tratamentul conservativ. Durata medie de evaluare la distanţa a copiilor constipaţi a constituit 8±2 ani. Pacienţii au fost examinaţi clinic şi paraclinic general, prin irigografie, manometrie ano-rectală şi colonică, electromiografia sfincterului anal extern, examen histomorfologic complex, inclusiv testarea histochimică şi imunohistochimică a bioptatelor de colon. Rezultate: În urma studiului, prin irigografie am stabilit semne de megadolicocolon pe stînga la toţi copii evaluaţi. Manometria anorectala a permis depistarea reflexului rectoanal de inhibiţie (RRAI) în 10 cazuri şi lipsa RRAI în 6 cazuri. Toţi copii au fost supuşi biopsiei în plin strat din neorectul format, cu efectuarea examenului histo- şi imunohistochimic a bioptatelor care a depistat: aganglionoză – 2 cazuri; DNI – 7 cazuri; imaturitatea plexului neuronal – 3; heterotopia plexului submucos – 2 cazuri; hipoganglionoză – 2 cazuri, ceea ce a confirmat asocierea leziunilor neuronale intestinale în MAR. Ulterior 9 copii cu leziuni neuronale intestinale au suportat rezecţie de colon pe stînga, cu neo-formarea ampulei rectale. Concluzii: Luînd în consideraţie probabilitatea asocierii DNI cu MAR considerăm argumentată biopsia de colon (sigma, ampula rectală) în cadrul aplicării colostomei sau plastiei perineale a MAR. În cazul depistării aganglionozei se recomandă rezecţia primară de colon în timpul proctoplastiei. DNI nu prezintă indicaţii pentru rezecţia primară de colon în timpul proctoplastiei, copii rămînînd sub evidenţă.Background: One of the unresolved problems in the management of anorectal malformations in children remains the retardation of the diagnosis of intestinal neural dysplasia (DNI) and colonic aganglionosis associated with these malformations. Purpose: Presentation of our clinical experience in the diagnosis and treatment of neural intestinal lesions associated with anorectal malformations. Methods and materials: The study included 16 children in the neonatal and infant period operated for anorectal malformations, which postoperatively presented chronic constipation, refractory to conservative treatment. The follow up at distance of the constipated children had an average length of 8 ± 2 years. Patients were clinically and paraclinically examined by barium enema, anorectal and colonic manometry, electromyography of external anal sphincter, complex histomorphologic examination, including histochemical and immunohistochemical testing of colon biopsy. Results: Following the study, we discovered signs of mega dolicocolon in all evaluated children by barium enema. Anorectal manometry allowed the detection of rectal inhibition reflex (RRAI) in 10 cases and the absence of RRAI in 6 cases. All children were subjected to full-length biopsy from the neorectum, by performing the histo- and immunohistochemical examination of the biopsy that found: aganglionosis - 2 cases; DNI - 7 cases; neuronal plexus immaturity - 3; submucosal plexus heterotopia - 2 cases; hypoganglionosis - 2 cases, which confirmed the association of intestinal neuronal lesions in MAR. Subsequently, nine children with intestinal neuronal lesions underwent colon resection on the left, with neoformation of the rectal ampoule. Conclusion: Taking into account the probability of the association between DNI and MAR, we should consider the colon biopsy (sigma, rectum ampule) in the application of colorectal or perineal plaster of anorectal malformations. If primary aganglionosis is detected, primary colon resection during proctoplasty is recommended. DNI is not an indication for primary resection of the colon during proctoplasty and these children should be monitored

Tensor Networks for Solving Realistic Time-independent Boltzmann Neutron Transport Equation

Tensor network techniques, known for their low-rank approximation ability that breaks the curse of dimensionality, are emerging as a foundation of new mathematical methods for ultra-fast numerical solutions of high-dimensional Partial Differential Equations (PDEs). Here, we present a mixed Tensor Train (TT)/Quantized Tensor Train (QTT) approach for the numerical solution of time-independent Boltzmann Neutron Transport equations (BNTEs) in Cartesian geometry. Discretizing a realistic three-dimensional (3D) BNTE by (i) diamond differencing, (ii) multigroup-in-energy, and (iii) discrete ordinate collocation leads to huge generalized eigenvalue problems that generally require a matrix-free approach and large computer clusters. Starting from this discretization, we construct a TT representation of the PDE fields and discrete operators, followed by a QTT representation of the TT cores and solving the tensorized generalized eigenvalue problem in a fixed-point scheme with tensor network optimization techniques. We validate our approach by applying it to two realistic examples of 3D neutron transport problems, currently solved by the PARallel TIme-dependent SN (PARTISN) solver. We demonstrate that our TT/QTT method, executed on a standard desktop computer, leads to a yottabyte compression of the memory storage, and more than 7500 times speedup with a discrepancy of less than 1e-5 when compared to the PARTISN solution.Comment: 38 pages, 9 figure

Grids of stellar models with rotation IV. Models from 1.7 to 120 M-circle dot at a metallicity Z=0.0004

The effects of rotation on stellar evolution are particularly important at low metallicity, when mass loss by stellar winds diminishes and the surface enrichment due to rotational mixing becomes relatively more pronounced than at high metallicities. Here we investigate the impact of rotation and metallicity on stellar evolution. Using similar physics as in our previous large grids of models at Z = 0.002 and Z = 0.014, we compute stellar evolution models with the Geneva code for rotating and nonrotating stars with initial masses (Mini) between 1.7 and 120 M⊙ and Z = 0.0004 (1/35 solar). This is comparable to the metallicities of the most metal poor galaxies observed so far, such as I Zw 18. Concerning massive stars, both rotating and nonrotating models spend most of their core-helium burning phase with an effective temperature higher than 8000 K. Stars become red supergiants only at the end of their lifetimes, and few red supergiants are expected. Our models predict very few to no classical Wolf–Rayet stars as a results of weak stellar winds at low metallicity. The most massive stars end their lifetimes as luminous blue supergiants or luminous blue variables, a feature that is not predicted by models with higher initial metallicities. Interestingly, due to the behavior of the intermediate convective zone, the mass domain of stars producing pair-instability supernovae is smaller at Z = 0.0004 than at Z = 0.002. We find that during the main sequence (MS) phase, the ratio between nitrogen and carbon abundances (N/C) remains unchanged for nonrotating models. However, N/C increases by factors of 10–20 in rotating models at the end of the MS. Cepheids coming from stars with Mini >  4 − 6 M⊙ are beyond the core helium burning phase and spend little time in the instability strip. Since they would evolve towards cooler effective temperatures, these Cepheids should show an increase of the pulsation period as a function of age

DNA Dynamics Is Likely to Be a Factor in the Genomic Nucleotide Repeats Expansions Related to Diseases

Trinucleotide repeats sequences (TRS) represent a common type of genomic DNA motif whose expansion is associated with a large number of human diseases. The driving molecular mechanisms of the TRS ongoing dynamic expansion across generations and within tissues and its influence on genomic DNA functions are not well understood. Here we report results for a novel and notable collective breathing behavior of genomic DNA of tandem TRS, leading to propensity for large local DNA transient openings at physiological temperature. Our Langevin molecular dynamics (LMD) and Markov Chain Monte Carlo (MCMC) simulations demonstrate that the patterns of openings of various TRSs depend specifically on their length. The collective propensity for DNA strand separation of repeated sequences serves as a precursor for outsized intermediate bubble states independently of the G/C-content. We report that repeats have the potential to interfere with the binding of transcription factors to their consensus sequence by altered DNA breathing dynamics in proximity of the binding sites. These observations might influence ongoing attempts to use LMD and MCMC simulations for TRS–related modeling of genomic DNA functionality in elucidating the common denominators of the dynamic TRS expansion mutation with potential therapeutic applications

Mammalian Stem Cells Reprogramming in Response to Terahertz Radiation

We report that extended exposure to broad-spectrum terahertz radiation results in specific changes in cellular functions that are closely related to DNA-directed gene transcription. Our gene chip survey of gene expression shows that whereas 89% of the protein coding genes in mouse stem cells do not respond to the applied terahertz radiation, certain genes are activated, while other are repressed. RT-PCR experiments with selected gene probes corresponding to transcripts in the three groups of genes detail the gene specific effect. The response was not only gene specific but also irradiation conditions dependent. Our findings suggest that the applied terahertz irradiation accelerates cell differentiation toward adipose phenotype by activating the transcription factor peroxisome proliferator-activated receptor gamma (PPARG). Finally, our molecular dynamics computer simulations indicate that the local breathing dynamics of the PPARG promoter DNA coincides with the gene specific response to the THz radiation. We propose that THz radiation is a potential tool for cellular reprogramming