Simulations of cosmic reionization

In this thesis we investigate numerically how ionizing photons emitted by stars in galaxies cause the reionization of the Universe, the transition during which most of the gas in the Universe from a mostly neutral, to a highly ionised state it is in today. To this end, we discuss and improve two techniques for the transport of ionising radiation across cosmological volumes, analyse the sources of ionising photons at high redshifts predicted by a semi-analytical galaxy formation model (GALFORM), and combine these to make consistent model of how reionization proceeds. Our improvements to the hybrid characteristics (HC) radiative transport scheme are significant, making the code faster and more accurate, as demonstrated by our contribution to a code comparison paper (Iliev et al., 2009). Our improvements to the SimpleX radiative transport scheme allow for accurate and significantly better numerically converged calculations of the speeds of ionization fronts of cosmological HII regions. This is accomplished by a much more thorough analysis of how to properly model the density field on the unstructured density field in SimpleX. The dependence of the ionizing emissivity of GALFORM galaxies on various parameters of the model is examined. We show that massive stars formed in abundance because of the assumed top-heavy stellar initial mass function during starbursts in the Baugh et al. (2005) model, triggered by galaxy mergers, are the dominant source of ionizing photons. We show that the luminosity functions predicted by this model are in good agreement with the most recent Hubble Space Telescope results at z \gtrsim 8. The model also demonstrates that most photons are produced in faint galaxies which are not yet seen in the current data. We then combine the sources predicted by GALFORM with the SimpleX RT scheme to model inhomogeneous reionization including the effects of source suppression. We investigate how the morphology of reionization depends on the model for the sources, which may be crucial for future observations of this cosmic epoch

Mangan-superoksid-dismutaza (MnSOD) katalizuje NO-zavisno nitrovanje ostatka tirozina

The peroxynitrite-induced nitration of manganese superoxide dismutase (MnSOD) tyrosine residue, which causes enzyme inactivation, is well established, This led to suggestions that MnSOD nitration and inactivation in vivo, detected in various diseases associated with oxidative stress and overproduction of nitric monoxide (NO), conditions which favor peroxynitrite formation, is also caused by peroxynitrite. However, our previous ill vitro study demonstrated that exposure of MnSOD to NO led to NO conversion into nitrosonium (NO+) and nitroxyl (NO-) species, which caused enzyme modifications and inactivation. Here it is reported that MnSOD is tyrosine nitrated upon exposure to NO, as well as that MnSOD nitration contributes to inactivation of the enzyme. Collectively, these observations provide a compelling argument supporting the generation of nitrating species in MnSOD exposed to NO and shed a new light on MnSOD tyrosine nitration and inactivation ill vivo. This may represent a novel mechanism by which MnSOD protects cell from deleterious effects associated with overproduction of NO. However, extensive MnSOD modification and inactivation associated with prolonged exposure to NO will amplify the toxic effects caused by increased cell superoxide and NO levels.Dobro je poznato da peroksinitrit izaziva nitrovanje ostataka tirozina u mangan-superoksid- dismutazi (MnSOD) što dovodi do inaktivacije enzima. Pokazano je da nitrovanje i inaktivacija MnSOD-a nastaje u raznim bolestima za koje je karakteristič an oksidativni stres i povećana produkcija azot-monoksida (NO). Pošto se pri ovim uslovima očekuje nastajanje peroksinitrita predloženo je da peroksinitrit izaziva nitrovanje i inaktivaciju MnSOD in vivo. U našem prethodnom radu pokazali smo da MnSOD katalizuje transformaciju NO u nitrozonijum (NO+) i nitroksil (NO–) reaktivne vrste, te identifikovali neke od modifikacija molekula enzima koje pri tome nastaju izazivajući njegovu inaktivaciju. U ovom radu je pokazano da pri izlaganju MnSOD azot-monoksidu dolazi i do nitrovanja ostatka tirozina u molekulu enzima, što doprinosi njegovoj inaktivaciji. Ovi rezultati ukazuju da pri interakciji MnSOD sa NO dolazi do nastajanja nitrujućih vrsta, što baca novo svetlo na proces nitrovanja ostataka tirozina i inaktivaciju MnSOD in vivo. Ovo može da predstavlja novi mehanizam kojim MnSOD štiti ćeliju odštetnih efekata izazvanih hiperprodukcijom azot-monoksida. Međutim ekstenzivne modifikacije i inaktivacija MnSOD do kojih dolazi pri produženom izlaganju enzima NO, uvećaće toksične efekte izazvane povećanim koncentracijama superoksida i NO u ćeliji

Koncentracija metala u vodi i sedimentu reke Dunav

Voda je osnov opstanka živog sveta koji je u njoj i nastao. Dve trećine zemljine površine je pod vodom. Bez obzira na značaj vode na opstanak živog sveta ljudska vrsta prema vodi nema odgovarajući odnos. O tome govore podaci o zagađenju okeana, mora, vodotokova (reke, potoci) i jezera. Antropogeno zagađenje vode, dakle, poreklom od čoveka, javlja se kao posledica direktnog ili indirektnog ispuštanja zagađivača u vodu, bez adekvatnog postupka sa štetnim i opasnim jedinjenjima. Najčešći zagađivači vode posledica su otpadnih voda i voda koje dolaze sa površina zemlje (naročito obradivih površina). Zagađenost vode je blisko povezana za povećanim potrebama stanovništva za vodenim resursima. Povećane potrebe rastu sa porastom stanovništva, razvoja privrede i tehnologije. Veća potrošnja vode znači i veću količinu otpadnih voda. Dospevanjem u reke otpadne vode menjaju fizička (boja, miris, ukus, providnost), hemijska (sastav) i biološka svojstva (živi svet reka). Naša zemlja nema odgovarajuće propise za procenu kvaliteta sedimenta pa se, zbog toga, koriste standardi kvaliteta prema kanadskom zakonodavstvu, preporuke ICPDR-a (International Commission for the Protection of the Danube River ), a pojedini parametri se procenjuju korišćenjem holandske metodologije. Prema kanadskom zakonodavstvu definisane su dve vrednosti: niža vrednost ISQGs (Interim Sediment Quality Guideline) predstavlja privremene preporuke koje su dobijene teorijskim putem i iznad kojih je moguć uticaj na akvatične organizme, dok je druga, viša, vrednost PEL (Probable Effect Level), vrednost iznad koje je uticaj na akvatične organizme verovatan. Poređenjem sa kanadskim preporukama, sadržaj žive je prekoračen na skoro svim ispitanim lokalitetima, prema ISQG vrednosti. Viša PEL vrednost ukazuje na verovatno prisutne negativne toksične efekte na akvatične organizme i sedimente u dva ispitivana profila u Dunavu (profil A i profil B). Pojava žive u sedimentu je posledica ispuštanja industrijskih otpadnih voda (naročito iz pogona za proizvodnju hlora), upotrebe živinih pesticida za zaštitu semena, upotrebe živinih jedinjenja u upaljačima eksplozivnih sredstava (posledice ratnog konflikta 1999.godine) i upotreba žive u mernim uređajima (u toku razaranja industrijskih postrojenja za vreme konflikta 1999. godine uništen je deo ove merne opreme). Arsen je poznat po negativnim ekotoksičnim efektima, a negov sadržaj u sedimentu reke Dunav nije bio iznad ICPDR vrednosti. Sadržaj drugih teških metala, cinka, bakra, kadmijuma i olova (profil B) je bio u ispod vrednosti propisane ICPDR. Kako se sam proces zagađivanja vode teško može sprečiti, zaštita voda, prvenstveno, je usmerena na smanjenje uticaja, a u najboljem slučaju, potpuno uklanjanjanje uticaja teških metala. To se postiže kroz opšte ekološke (radne akcije, ekološki aktivizam) kao i specifične mere (obrazovanje, sredstva javnog informisanja). Najvažnije je utvrđivanje kvaliteta vode i mogućnosti vodotoka da primi otpadne vode, registovanje svih mogućih zagađivača (njihova lokacije i stepen zagađivanja), obavljanje stalnih kontrola otpadnih voda u blizini vodotokova, prečišćavanje otpadnih voda i izmeštanje industrije na mesta na kojima će zagađivanje biti minimalno

Opis przypadku — występujący rodzinnie wewnątrzczaszkowo germinoma

Background. Intracranial germinomas (ICG) are uncommon brain neoplasms with extremely rare familial occurance. Since ICG invades hypothalamus and/or pituitary, the endocrine dysfunction is one of the common determinants of these tumors. We presented two brothers with the history of ICG. Patient 1 is a 25-year-old male who had been suffering from the weakness of the right half of his body at the age of 18. Cranial MRI revealed mass lesion in the left thalamus. He underwent neurosurgery, tumor was removed completely. Histopathological (HP) and immunohistochemical analyses verified the diagnosis of pure germinoma. He experienced complete remission of the tumor after a radiation therapy. At the age of 22 the diagnosis of isolated growth hormone deficiency (IGHD) was established and GH replacement was initiated. Patient 2 is a 20-year old boy who was presented with diabetes insipidus at the age of 12. MRI detected tumor in the third ventricle and pineal region. After the endoscopic tumor biopsy the HP diagnosis was pure germinoma. He received chemotherapy followed by radiotherapy, and treated with GH during childhood. At the age of 18 GH replacement was reintroduced. A six month follow-up during the next two years in both brothers demonstrated the IGF1 normalization with no MRI signs of tumor recurrence. Conclusion. To the best of our knowledge so far, only six reports have been published related to familial ICG. The presented two brothers are the first report of familial ICG case outside of Japan. They are treated successfully with GH therapy in adult period. Wstęp: Rozrodczaki wewnątrzczaszkowe (intracranial germinomas, ICG) to rzadkie nowotwory mózgu, a szczególnie rzadko stwierdza się ich występowanie rodzinne. W związku z tym, że ICG zajmuje podwzgórze i/lub przysadkę mózgową, zaburzenia endokrynologiczne są jednym z najczęstszych wyznaczników obecności tych guzów. W pracy przedstawiono dwóch braci z ICG. Pacjent 1 to 25-letni mężczyzna, u którego w wieku 18 lat wystąpiło osłabienie mięśni po lewej stronie ciała. Badanie metodą rezonansu magnetycznego (MRI) czaszki ujawniło masę w lewym wzgórzu. Chorego poddano zabiegowi neurochirurgicznemu, podczas którego guz został całkowicie usunięty. Badania histopatologiczne i immunohistochemiczne potwierdziły rozpoznanie czystej postaci rozrodczaka. Po radioterapii nastąpiła całkowita remisja guza. W wieku 22 lat u chorego zdia­gnozowano izolowany niedobór hormonu wzrostu (isolated growth hormone deficiency, IGHD) i wdrożono terapię zastępczą hormonem wzrostu (growth hormone, GH). Genetyczna analiza molekularna tkanki guza wykazała mutację w eksonie 2 w genie KRAS. Pacjent 2 to 20-letni mężczyzna, u którego w wieku 12 lat stwierdzono moczówkę prostą. W badaniu MRI wykryto guz w okolicy trzeciej komory i szyszynki. Po ocenie histopatologicznej materiału pobranego za pomocą biopsji endoskopowej postawiono diagnozę czystego rozrod­czaka. U chorego zastosowano chemioterapię, a następnie radioterapię, a także podawano GH w okresie dzieciństwa. W wieku 18 lat u chorego wznowiono terapię GH. Sześciomiesięczna obserwacja obu braci w następnych 2 latach wykazała normalizację IGF1 przy braku objawów nawrotu guza w badaniu MRI. Wnioski: Według najlepszej wiedzy autorów dotychczas opublikowano 6 doniesień na temat rodzinnego występowania ICG. Przed­stawieni w niniejszej pracy bracia są pierwszym opisanym przypadkiem rodzinnego ICG poza Japonią. W okresie dorosłym chorzy są leczeni GH z dobrym skutkiem

Cosmological radiative transfer comparison project - II. The radiation-hydrodynamic tests

The development of radiation hydrodynamical methods that are able to follow gas dynamics and radiative transfer (RT) self-consistently is key to the solution of many problems in numerical astrophysics. Such fluid flows are highly complex, rarely allowing even for approximate analytical solutions against which numerical codes can be tested. An alternative validation procedure is to compare different methods against each other on common problems, in order to assess the robustness of the results and establish a range of validity for the methods. Previously, we presented such a comparison for a set of pure RT tests (i.e. for fixed, non-evolving density fields). This is the second paper of the Cosmological Radiative Transfer Comparison Project, in which we compare nine independent RT codes directly coupled to gas dynamics on three relatively simple astrophysical hydrodynamics problems: (i) the expansion of an H ii region in a uniform medium, (ii) an ionization front in a 1/r2 density profile with a flat core and (iii) the photoevaporation of a uniform dense clump. Results show a broad agreement between the different methods and no big failures, indicating that the participating codes have reached a certain level of maturity and reliability. However, many details still do differ, and virtually every code has showed some shortcomings and has disagreed, in one respect or another, with the majority of the results. This underscores the fact that no method is universal and all require careful testing of the particular features which are most relevant to the specific problem at han

A decade of sulfite control in Serbian meat industry and the effect of HACCP

In total 7,351 meat preparations and fresh processed meat products were analyzed from 555 different Serbian meat producers over a 10 year period, 4½ years before and 5½ years after mandatory HACCP implementation. From the obtained results, it could be concluded that HACCP has contributed to a better alignment of practices with the legal provisions. The share of non-compliant samples dropped from 18.6% before HACCP to 8.3% after its mandatory implementation. Average sulfite concentrations for all categories of meat preparations and fresh processed meat products decreased by 43%, declining from 33.6 mg kg-1 to 19.3 mg kg-1. Typical misuse and frequent abuse of sulfites was independent of a season. Application of HACCP principles in the Serbian meat industry raised awareness about the misuse of sulfites and contributed to a better control, minimizing exposure to sulfites

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe