Chasing Lambda

Recent astronomical observations of SNIa, CMB, as well as BAO in the Sloan Digital Sky Survey, suggest that the current Universe has entered a stage of an accelerated expansion with the transition redshift at $z \simeq 0.5$. While the simplest candidates to explain this fact is cosmological constant/vacuum energy, there exists a serious problem of coincidence. In theoretical cosmology we can find many possible approaches alleviating this problem by applying new physics or other conception of dark energy. We consider state of art candidates for the description of accelerating Universe in the framework of the Bayesian model selection. We point out advantages as well as troubles of this approach. We find that the combination of four data bases gives a stringent posterior probability of the $\Lambda$CDM model which is 74%. This fact is a quantitative exemplification of a turmoil in modern cosmology over the $\Lambda$ problem.Comment: Talk presented at the "A Century of Cosmology - Past, Present and Future" conference, S.Servolo(Venice), Italy, August 27-31 2007. To be published in Il Nuovo Ciment

Towards classification of simple dark energy cosmological models

We characterize a class of simple FRW models filled by both dark energy and dark matter in notion of a single potential function of the scale factor $a(t)$; $t$ is the cosmological time. It is representing potential of fictitious particle - Universe moving in 1-dimensional well $V(a)$ which the positional variable mimics the evolution of the Universe. Then the class of all dark energy models (called a multiverse) can be regarded as a Banach space naturally equipment in the structure of the Sobolev metric. In this paper we explore notion of $C^{1}$ metric introduced in the multiverse which measure distance between any two dark energy models. If we choose cold dark matter as a reference one then we can find how so far apart are different models offering explanation of present accelerating expansion phase of the Universe. We consider both models with dark energy (models with the generalized Chaplygin gas, models with variable coefficient equation of state $w_{X}=\frac{p_{X}}{\rho_{X}}$ parameterized by redshift $z$, models with phantom matter) as well as models basing on some modification of the Friedmann equation (Cardassian models, Dvali-Gabadadze-Porati brane models). We argue that because observational data still favor the $\Lambda$CDM model all reasonable dark energy models should belong to the nearby neighborhood of this model.Comment: 10 pages, 2 figures, the paper presented at 42nd Karpacz Winter School of Theoretical Physics: Ladek, Poland, 6-11 Feb 200

Testing and selection cosmological models with dark energy

It is described dynamics of a large class of accelerating cosmological models in terms of dynamical systems of the Newtonian type. The evolution of the models is reduced to the motion of a particle in a potential well parameterized by the scale factor. This potential function can be reconstructed from distant supernovae type Ia data and many cosmological models represented in terms of the potential becomes in a good agreement with current observational data. It is proposed to use the information criteria to overcome this degeneracy within a class of A) dark energy models and B) simple models basing on modification of the FRW equation. Two class of models can be recommended by the Akaike (AIC) and Schwarz (BIC) information criteria: the phantom and $\Lambda$CDM models.Comment: Talk at Albert Einstein Century International Conference at Palais de l'Unesco, Paris, France, 18-23 July 2005; to appear in the Proceedings; AIP style files included, 6 pages, 2 figure

Bayesian analysis of the backreaction models

We present the Bayesian analysis of four different types of backreation models, which are based on the Buchert equations. In this approach, one considers a solution to the Einstein equations for a general matter distribution and then an average of various observable quantities is taken. Such an approach became of considerable interest when it was shown that it could lead to agreement with observations without resorting to dark energy. In this paper we compare the LambdaCDM model and the backreation models with SNIa, BAO, and CMB data, and find that the former is favoured. However, the tested models were based on some particular assumptions about the relation between the average spatial curvature and the backreaction, as well as the relation between the curvature and curvature index. In this paper we modified the latter assumption, leaving the former unchanged. We find that, by varying the relation between the curvature and curvature index, we can obtain a better fit. Therefore, some further work is still needed -- in particular the relation between the backreaction and the curvature should be revisited in order to fully determine the feasibility of the backreaction models to mimic dark energy.Comment: Extended analysis compared to v1. Matches published version

Constraints on oscillating dark energy models

The oscillating scenario of route to Lambda was recently proposed by us arXiv:0704.1651 as an alternative to a cosmological constant in a explanation of the current accelerating universe. In this scenario phantom scalar field conformally coupled to gravity drives the accelerating phase of the universe. In our model $\Lambda$CDM appears as a global attractor in the phase space. In this paper we investigate observational constraints on this scenario from recent measurements of distant supernovae type Ia, CMB R shift, BAO and $H(z)$ observational data. The Bayesian methods of model selection are used in comparison the model with concordance $\Lambda$CDM one as well as with model with dynamical dark energy parametrised by linear form. We conclude that $\Lambda$CDM is favoured over FRW model with dynamical oscillating dark energy. Our analysis also demonstrate that FRW model with oscillating dark energy is favoured over FRW model with decaying dark energy parametrised in linear way.Comment: revtex4, 7 pages, 3 figures; (v2) 12 pages, 11 figures; Phys. Lett. B (in press

Polimorfizm –A162G genu PON1 jako czynnik ryzyka rozwoju sporadycznej postaci stwardnienia bocznego zanikowego

Background and purpose Sporadic amyotrophic lateral sclerosis (sALS) is a devastating neurodegenerative disease, which results from complex genetic and environmental interactions. Recent studies have reported an association between several polymorphisms of the PON1 and PON2 genes and risk of sALS. The aim of the present study was to identify an association between the – A162G polymorphism of the promoter region of the human PON1 gene and the risk of sALS in a Polish population. Material and methods We included 259 patients with a diagnosis of definite or probable sALS (76 bulbar onset, 183 limb onset) and 694 healthy controls matched for age and sex. The diagnosis of ALS was established according to El Escorial criteria. The polymorphism was studied by Single Nucleotide Polymorphism Real-Time Polymerase Chain Reaction analysis. Results No overall difference in the PONI – A162G genotype and allele distribution was seen between cases and controls (all p > 0.05). There was, however, a difference in the A allele frequency when the bulbar onset group was compared to the controls (p = 0.03), but this significance disappeared after the Bonferroni correction. Conclusions The results did not show that the – A162G polymorphism of the PON1 gene is a risk factor of sALS in a Polish population; it may affect, however, bulbar onset of the disease.Wstęp i cel pracy Sporadyczna postać stwardnienia bocznego zanikowego (sSLA) jest chorobą zwyrodnieniową układu nerwowego, w której etiopatogenezie kluczową rolę odgrywają interakcje między czynnikami genetycznymi i środowiskowymi. Dotychczasowe badania wskazują na istnienie zależności między polimorfizmami genów PON1 i PON2 a ryzykiem wystąpienia sSLA. Celem pracy było zbadanie, czy istnieje związek między polimorfizmem – A162G miejsca promotorowego genu PON1 a ryzykiem wystąpienia sSLA w populacji polskiej. Materiał i metody Badanie przeprowadzono u 259 chorych, uktórych zgodnie z kryteriami El Escorial rozpoznano pewne lub prawdopodobne SLA (76 osób z postacią opuszkową, 183 osoby z postacią kończynową) oraz u 694 zdrowych ochotników, stanowiących grupę kontrolną dobraną pod względem wieku i płci. Polimorfizm genu PON1 był badany za pomocą reakcji łańcuchowej polimerazy DNA z analizą ilości produktu w czasie rzeczywistym. Wyniki Nie stwierdzono istotnych statystycznie różnic w rozkładzie genotypów i alleli genu PON1 między grupą chorych a grupą kontrolną (p > 0,05). Stwierdzono natomiast różnice w częstości występowania allela A między grupą chorych z postacią opuszkową w porównaniu z grupą kontrolną (p = 0,03), jednak po korekcie Bonferroniego wynik ten nie był już istotny statystycznie. Wnioski Wyniki naszego badania nie wykazały, aby polimorfizm – A162G genu PON1 był czynnikiem ryzyka sSLA w populacji polskiej, jednak sugerują, że może mieć znaczenie dla wystąpienia postaci opuszkowej tej choroby

From model dynamics to oscillating dark energy parameterisation

We develop here a relatively simple description of dark energy based on the dynamics of non-minimally coupled to gravity phantom scalar field which, in limit, corresponds to cosmological constant. The dark energy equation of state, obtained directly from the dynamics of the model, turns out to be an oscillatory function of the scale factor. This parameterisation is compared to other possible dark energy parameterisations, among them, the most popular one, linear in the scale factor. We use the Bayesian framework for model selection and make a comparison in the light of SN Ia, CMB shift parameter, BAO A parameter, observational H(z) and growth rate function data. We find that there is evidence to favour a parameterisation with oscillations over {\it a priori} assumed linear one.Comment: 16 pages, 6 figs, extended analysis, refs. added, PLB (in press

Observational hints on the Big Bounce

In this paper we study possible observational consequences of the bouncing cosmology. We consider a model where a phase of inflation is preceded by a cosmic bounce. While we consider in this paper only that the bounce is due to loop quantum gravity, most of the results presented here can be applied for different bouncing cosmologies. We concentrate on the scenario where the scalar field, as the result of contraction of the universe, is driven from the bottom of the potential well. The field is amplified, and finally the phase of the standard slow-roll inflation is realized. Such an evolution modifies the standard inflationary spectrum of perturbations by the additional oscillations and damping on the large scales. We extract the parameters of the model from the observations of the cosmic microwave background radiation. In particular, the value of inflaton mass is equal to $m=(2.6 \pm 0.6) \cdot 10^{13}$ GeV. In our considerations we base on the seven years of observations made by the WMAP satellite. We propose the new observational consistency check for the phase of slow-roll inflation. We investigate the conditions which have to be fulfilled to make the observations of the Big Bounce effects possible. We translate them to the requirements on the parameters of the model and then put the observational constraints on the model. Based on assumption usually made in loop quantum cosmology, the Barbero-Immirzi parameter was shown to be constrained by $\gamma<1100$ from the cosmological observations. We have compared the Big Bounce model with the standard Big Bang scenario and showed that the present observational data is not informative enough to distinguish these models.Comment: 25 pages, 8 figures, JHEP3.cl

Biodiversity of bacteriophages: morphological and biological properties of a large group of phages isolated from urban sewage

A large scale analysis presented in this article focuses on biological and physiological variety of bacteriophages. A collection of 83 bacteriophages, isolated from urban sewage and able to propagate in cells of different bacterial hosts, has been obtained (60 infecting Escherichia coli, 10 infecting Pseudomonas aeruginosa, 4 infecting Salmonella enterica, 3 infecting Staphylococcus sciuri, and 6 infecting Enterococcus faecalis). High biological diversity of the collection is indicated by its characteristics, both morphological (electron microscopic analyses) and biological (host range, plaque size and morphology, growth at various temperatures, thermal inactivation, sensitivity to low and high pH, sensitivity to osmotic stress, survivability upon treatment with organic solvents and detergents), and further supported by hierarchical cluster analysis. By the end of the research no larger collection of phages from a single environmental source investigated by these means had been found. The finding was confirmed by whole genome analysis of 7 selected bacteriophages. Moreover, particular bacteriophages revealed unusual biological features, like the ability to form plaques at low temperature (4 °C), resist high temperature (62 °C or 95 °C) or survive in the presence of an organic solvents (ethanol, acetone, DMSO, chloroform) or detergent (SDS, CTAB, sarkosyl) making them potentially interesting in the context of biotechnological applications

Różnicowanie autoimmunologicznego uszkodzenia i makrogruczolaka przysadki mózgowej w trakcie terapii niwolumabem u chorej na niedrobnokomórkowego raka płuca — opis przypadku

W pracy przedstawiono opis przypadku chorej na niedrobnokomórkowego raka płuca z ekspresją PD-L1 na 1% komórek nowotworowych, leczonej za pomocą chemioterapii oraz radioterapii, a w momencie progresji choroby — immunoterapii niwolumabem. W trakcie stosowania immunoterapii u chorej rozwinęły się objawy wieloosiowej niedoczynności przysadki. W badaniach obrazowych przysadki uwidoczniono makrogruczolaka. W rozpoznaniu różnicowym brano pod uwagę autoimmunologiczne zapalenie przysadki w przebiegu terapii niwolumabem. Po wyrównaniu zaburzeń hormonalnych kontynuowano immunoterapię, uzyskując remisję choroby, utrzymującą się przez następne 2 lata