Generalized Strong Curvature Singularities and Cosmic Censorship

A new definition of a strong curvature singularity is proposed. This definition is motivated by the definitions given by Tipler and Krolak, but is significantly different and more general. All causal geodesics terminating at these new singularities, which we call generalized strong curvature singularities, are classified into three possible types; the classification is based on certain relations between the curvature strength of the singularities and the causal structure in their neighborhood. A cosmic censorship theorem is formulated and proved which shows that only one class of generalized strong curvature singularities, corresponding to a single type of geodesics according to our classification, can be naked. Implications of this result for the cosmic censorship hypothesis are indicated.Comment: LaTeX, 11 pages, no figures, to appear in Mod. Phys. Lett.

Influence of some physical properties of 5-fluorouracil on encapsulation efficiency in liposomes

The aim of this study is to encapsulate two drugs: 5-fluorouracil (5-FU) with the hydrophobic properties and 1-b-D-arabinofuranosylcytosine (Ara-C) with the amphiphilic properties into liposomes prepared by the modified reverse-phase evaporation method (mREV) from L-a-phosphatidylcholine dipalmitoyl (DPPC). We studied the thermotropic phase behavior of liposome entrapped 5-FU and Ara-C. It is known that the stability of liposomes depends not only on the method of chemical gradient loading, the use of membrane stabilizer such as sterols, but also on the phase transition temperature (Tc) of phospholipids, which undergoes an alteration after encapsulation of drugs to liposomes. The competition of these two drugs entrapped in liposomes was analyzed by the use of two spectroscopies: 1H NMR and UV on the basis of the analysis of the signals of each drug in the liposome- drug system. The percent of encapsulation in DPPC/Ara-C/5-FU liposome obtained by the use of UV spectroscopy amounted 93.84 and 96.05% for 5-FU and Ara-C, respectively. Phase transition temperature Tc of liposomes containing Ara-C did not significantly change while for the liposomes containing 5-FU it increased in comparison with Tc of the reference liposomes formed from DPPC

The Gamma Factory path to high-luminosity LHC with isoscalar beams

There are two main ways to increase LHC luminosity without upgrading CERN injectors: (1) modification of beam-collision optics and (2) reduction of beam transverse emittance. The former is followed in the ongoing high-luminosity upgrade of the LHC (HL-LHC), while the latter, applicable only to ion beams, is described in this contribution. The reduction of the beam emittance can be achieved by employing a laser-cooling technique to bunches of partially stripped ions at the SPS flat-top energy. In the case the isoscalar calcium beams fulfilling the presentbeam-operation constrains, the transverse beam emittance can be reduced in this way by a factor of 5 during the 8 second long cooling phase. This would allow to reach the nucleon–nucleon luminosity L_NN = 4.2 x 10^34 s^(-1)cm^(-2), which is comparable to the levelled luminosity for the HL-LHC proton–proton collisions, but with reduced pile-up background. The calcium–calcium collisions have several advantages over the proton–proton collisions for the electroweak physics, such as precision measurements of the W-boson mass and sin^2_W, clean observation of the Higgs boson decay into bbar in its photoproduction channel or BSM phenomena. If this scheme is confirmed by the future Gamma Factory proof-of-principle experiment, it could be implemented at CERN with minor infrastructure investments. This contribution is based on Ref. [1

Anatomy of Malicious Singularities

As well known, the b-boundaries of the closed Friedman world model and of Schwarzschild solution consist of a single point. We study this phenomenon in a broader context of differential and structured spaces. We show that it is an equivalence relation $\rho$, defined on the Cauchy completed total space $\bar{E}$ of the frame bundle over a given space-time, that is responsible for this pathology. A singularity is called malicious if the equivalence class $[p_0]$ related to the singularity remains in close contact with all other equivalence classes, i.e., if $p_0 \in \mathrm{cl}[p]$ for every $p \in E$. We formulate conditions for which such a situation occurs. The differential structure of any space-time with malicious singularities consists only of constant functions which means that, from the topological point of view, everything collapses to a single point. It was noncommutative geometry that was especially devised to deal with such situations. A noncommutative algebra on $\bar{E}$, which turns out to be a von Neumann algebra of random operators, allows us to study probabilistic properties (in a generalized sense) of malicious singularities. Our main result is that, in the noncommutative regime, even the strongest singularities are probabilistically irrelevant.Comment: 16 pages in LaTe

Sudden vanishing and reappearance of nonclassical effects: General occurrence of finite-time decays and periodic vanishings of nonclassicality and entanglement witnesses

Analyses of phenomena exhibiting finite-time decay of quantum entanglement have recently attracted considerable attention. Such decay is often referred to as sudden vanishing (or sudden death) of entanglement, which can be followed by its sudden reappearance (or sudden rebirth). We analyze various finite-time decays (for dissipative systems) and analogous periodic vanishings (for unitary systems) of nonclassical correlations as described by violations of classical inequalities and the corresponding nonclassicality witnesses (or quantumness witnesses), which are not necessarily entanglement witnesses. We show that these sudden vanishings are universal phenomena and can be observed: (i) not only for two- or multi-mode but also for single-mode nonclassical fields, (ii) not solely for dissipative systems, and (iii) at evolution times which are usually different from those of sudden vanishings and reappearances of quantum entanglement.Comment: 10 pages, 3 figure

Witnesses of Quantum Chaos and Nonlinear Kerr-Like Oscillator Model

Here, we present a brief insight into some current methods allowing for the detection of quantum chaos phenomena. In particular, we show examples of proposals of the parameters which could be applied as indicators of quantum-chaotic behavior and already were presented in the literature. We concentrate here on the quantum fidelity and the fidelity-like functions, defined for the wave functions describing system’s evolution. The definition of the fidelity-like parameter also involves the operator of the mean number of photons/phonons. Discussing such parameter, we show here how it is possible to take into account in the discussion of quantum-chaotic systems simultaneously the behavior of the divergence of wave functions and the energy of the system represented by the mean number of photons/phonons. Next, we discuss entropy-type parameter which can also be a good candidate for the indicators of quantum chaos’ phenomena. We show the ability of all considered here parameters to be witnesses of quantum-chaotic behavior for the systems of the quantum nonlinear Kerr-like oscillator—the classical counterpart of such system can exhibit chaotic evolution in its canonical form

Interference contrast in multi-source few photon optics

Many recent experiments employ several parametric down conversion (PDC) sources to get multiphoton interference. Such interference has applications in quantum information. We study here how effects due to photon statistics, misalignment, and partial distinguishability of the PDC pairs originating from different sources may lower the interference contrast in the multiphoton experiments.Comment: 23 pages, 9 figures, journal versio

A proof of uniqueness of the Gurarii space

We present a short and elementary proof of isometric uniqueness of the Gurarii space.Comment: 6 pages, some improvements incorporate

Representations of (2,n)(2,n)-semigroups by multiplace functions

We describe the representations of $(2,n)$-semigroups, i.e. groupoids with $n$ binary associative operations, by partial $n$-place functions and prove that any such representation is a union of some family of representations induced by Schein's determining pairs.Comment: 17 page

Mobilizacja krwiotwórczych komórek macierzystych — wczoraj i dziś

The method of hematopoietic stem cells (HSC) mobilization to peripheral blood enabled theirefficient collection from peripheral blood instead of bone marrow, for the purpose of autologousor allogeneic transplantation. Depending on the activity of the disease and on the need ofchemotherapeutic treatment, the current protocols of mobilization consist of granulocyte-colonystimulating factor (G-CSF) alone, or in combination with chemotherapy. The mobilizationsthat use these protocols are usually efficient, as it has been documented for the last 15 years oftheir use. Recently, the new mobilization strategy arose based on the discovery of plerixafor —a specific antagonist of the CXCR4 receptor. The numerous studies revealed its high efficacy ofHSC mobilization, especially when used in combination with G-CSF, and eventually chemotherapy.The current review presents the historical perspective of HSC mobilization, focusingon the last observations regarding the use of plerixafor.Metoda mobilizacji krwiotwórczych komórek macierzystych (HSC) do krwi obwodowej umożliwiłaich efektywne pobieranie z krwi, zamiast ze szpiku, w celu autologicznego lub allogenicznegoprzeszczepienia. Zależnie od aktywności choroby, a także od potrzeby stosowania leczeniachemioterapeutycznego, obecnie stosuje się protokoły mobilizacji oparte na podawaniu czynnikastymulującego wzrost kolonii granulocytów (G-CSF) — samego lub w skojarzeniu z chemioterapią.Mobilizacje według tych protokołów są na ogół skuteczne, co udowodniono w ciąguostatnich 15 lat. Ostatnio pojawiła się kolejna możliwość terapeutyczna, wynikająca z zastosowaniapleryksaforu — swoistego antagonisty receptora chemokinowego CXCR4. Wyniki licznychbadań wykazały jego wysoką skuteczność w mobilizacji HSC, szczególnie jeśli jest stosowanyw skojarzeniu z G-CSF, a niekiedy także z chemioterapią. W niniejszym artykuleprzedstawiono rys historyczny strategii mobilizacji HSC oraz najnowsze obserwacje dotyczącezastosowania pleryksaforu