Double heavy baryons and dimesons

We critically examine the question whether the cc\bar{q}\bar{q} dimeson is bound or not.Comment: Talk presented at the Fourth Int. Conf. on Perspectives in Hadronic Physics, ICTP - Trieste; May 12-16, 2003; to be published in European Journal of Physics A; 6 pages LaTe

The Tcc = DD* molecular state

We show that the molecule-like configuration of DD^* enables weak binding with two realistic potential models (Bhaduri and Grenoble AL1). Three-body forces may increase the binding and strengthen the cc diquark configuration. As a signature we propose the branching ratio between radiative and pionic decay.Comment: 19 pages, 18 figures, revised version, to be published in Few-Body System

Possibilities of hyperlink application in spatial research

The main aim of the paper is to show the selected ways of analysing, the possible interpretations and expectations concerning the analyses of hyperlinks in spatial research. The connections existing in cyberspace for selected self-government websites of Lower Silesia were shown to illustrate the issue. The analyses were conducted for selected websites of self-government units at all levels functioning in Lower Silesia. The paper presents two approaches to the analysis of hyperlinks: analysis of outlinks and inlinks. The presented results allow us to identify some regularities regarding the functioning of connections in cyberspace versus the connections in the real world. From the perspective of self-government websites it can be concluded that the connections in cyberspace reflect the real connections. In the majority of the analysed cases there is a clear connection with the actual scope of activity. The remaining relationships with administrative cities reflect the significance of these cities for the functioning of self-government units in the social, economic, legal, and administrative conditions. Based on the conducted analyses it can be concluded that the study of hyperlinks may be useful in understanding the relationships between geographical space and cyberspace. They may form a new, interesting field of spatial research. We also found some challenges in the study of hyperlinks' spatial aspects: the identification of consistent criteria for determining the websites' ‘location in space’, the possibility of interpreting the research results and the dynamics of the Internet

Production and detection of doubly charmed tetraquarks

The feasibility of tetraquark detection is studied. For the cc\bar{u}\bar{d} tetraquark we show that in present (SELEX, Tevatron, RHIC) and future facilities (LHCb, ALICE) the production rate is promising and we propose some detectable decay channels.Comment: 6 pages, 5 figure

Are there compact heavy four-quark bound states?

We present an exact method to study four-quark systems based on the hyperspherical harmonics formalism. We apply it to several physical systems of interest containing two heavy and two light quarks using different quark-quark potentials. Our conclusions mark the boundaries for the possible existence of compact, non-molecular, four-quark bound states. While $QQ\bar n \bar n$ states may be stable in nature, the stability of $Q\bar Qn \bar n$ states would imply the existence of quark correlations not taken into account by simple quark dynamical modelsComment: 10 pages, 1 figure. Accepted for publication in Phys. Rev.

The free radical scavenger Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, and improves hypoxia tolerance in a mouse model of Rett syndrome

Rett syndrome (RS) causes severe cognitive impairment, loss of speech, epilepsy, and breathing disturbances with intermittent hypoxia. Also mitochondria are affected; a subunit of respiratory complex III is dysregulated, the inner mitochondrial membrane is leaking protons, and brain ATP levels seem reduced. Our recent assessment of mitochondrial function in MeCP2 (methyl-CpG-binding protein 2)-deficient mouse (Mecp2(-)(/y)) hippocampus confirmed early metabolic alterations, an increased oxidative burden, and a more vulnerable cellular redox balance. As these changes may contribute to the manifestation of symptoms and disease progression, we now evaluated whether free radical scavengers are capable of improving neuronal and mitochondrial function in RS. Acute hippocampal slices of adult mice were incubated with the vitamin E derivative Trolox for 3–5 h. In Mecp2(-)(/y) slices this treatment dampened neuronal hyperexcitability, improved synaptic short-term plasticity, and fully restored synaptic long-term potentiation (LTP). Furthermore, Trolox specifically attenuated the increased hypoxia susceptibility of Mecp2(-)(/y) slices. Also, the anticonvulsive effects of Trolox were assessed, but the severity of 4-aminopyridine provoked seizure-like discharges was not significantly affected. Adverse side effects of Trolox on mitochondria can be excluded, but clear indications for an improvement of mitochondrial function were not found. Since several ion-channels and neurotransmitter receptors are redox modulated, the mitochondrial alterations and the associated oxidative burden may contribute to the neuronal dysfunction in RS. We confirmed in Mecp2(-)(/y) hippocampus that Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, and improves the hypoxia tolerance. Therefore, radical scavengers are promising compounds for the treatment of neuronal dysfunction in RS and deserve further detailed evaluation

Wyszukiwarka internetowa w poznaniu przestrzeni cyfrowej

Today we notice the growing importance of digital space – more and more human interactions, their activity are moving, partly or entirely, to this space. As a result, new problems have occurred in science, including geography, and new ways of research are being developed. The aim of paper is to show methods of World Wide Web exploration in relation to the Internet search engines. Internet search engines are one of the most popular an easy to use tool for digital space exploration. The paper shows two methods of data acquisition and consequently analyses: manual entry of queries and use of services provided by search engine operators. We also discussed the pros and cons of the presented approach to digital space analysis.Obserwujemy obecnie wzrost znaczenia przestrzeni cyfrowej – coraz więcej interakcji pomiędzy ludźmi, ich aktywności przenosi się w całości lub częściowo do tej przestrzeni. W rezultacie w nauce, w tym w geografii, pojawiły się nowe problemy oraz powstają i rozwijane są nowe sposoby badań. Uwzględniając to celem opracowania jest przybliżenie sposobów eksploracji sieci WWW w odniesieniu do wyszukiwarek internetowych. Wyszukiwarki są bowiem jednym z popularniejszych i łatwych do wykorzystani narzędzi eksploracji przestrzeni cyfrowej. Przedstawiono dwa sposoby pozyskania danych, a w konsekwencji analiz: manualne wpisywanie zapytań lub korzystanie ze skryptów oraz korzystanie ze specjalnych usług dostarczanych przez operatorów wyszukiwarki. Podjęto również rozważania dotyczące zalet i wad prezentowanego podejścia do analizy przestrzeni cyfrowej