Are There Topological Black Hole Solitons in String Theory?

We point out that the celebrated Hawking effect of quantum instability of black holes seems to be related to a nonperturbative effect in string theory. Studying quantum dynamics of strings in the gravitational background of black holes we find classical instability due to emission of massless string excitations. The topology of a black hole seems to play a fundamental role in developing the string theory classical instability due to the effect of sigma model instantons. We argue that string theory allows for a qualitative description of black holes with very small masses and it predicts topological solitons with quantized spectrum of masses. These solitons would not decay into string massless excitations but could be pair created and may annihilate also. Semiclassical mass quantization of topological solitons in string theory is based on the argument showing existence of nontrivial zeros of beta function of the renormalization group.Comment: 12 pages, TeX, requires phyzzx.tex, published in Gen. Rel. Grav. 19 (1987) 1173; comment added on December 18, 199

237. Nowe kompleksowe spojrzenie na wartość prognostyczną receptorów estrogenów (ER), progesteronu (PR) i czynnika wzrostu nabłonków (EGFR) zawartych w tkankach pierwotnego raka piersi

Obecność lub brak ER, PR i EGFR w pierwotnym raku piersi odzwierciedla aktualny stan receptorowy tego nowotworu. Celem naszej pracy było określenie zależności między stanem receptorowym pierwotnych raków piersi a przeżyciem chorych kobiet. Receptory w nowotworze oznaczono metodami radiokompetycyjnymi. Bezobjawowy pooperacyjny okres przeżycia chorych (DFS) i całkowite przeżycie chorych (OS) oceniono wielowariantową analizą proporcjonalnego hazardu wg Cox’a. Analizowano 8 możliwych wariantów jednoczesnej obecności lub braku ER, PR i EGFR w nowotworze oraz wybrane kliniczno-morfologiczne parametry chorych takie jak wiek, wielkość guza i stan węzłów chłonnych. Wykazano, e 4 grupy chorych o następującym stanie receptorowym: ER+PR+EGFR+; ER+PR+EGFR-; ER-PR+EGFR- i ER-PR-EGFR-miały lepsze parametry przeżycia dla DFS i OS. Względne ryzyka nawrotu choroby lub śmierci wymienionych grup chorych mieściły się w granicach 0,45–1,16. Natomiast chore ze stanami receptorowymi: ER+PR-EGFR-, ER-PR-EGFR+ i ER+PR-EGFR+ miały bardziej agresywny przebieg choroby. Względne ryzyka nawrotu choroby lub śmierci mieściły się w granicach 1,46–3,95. Wykazaliśmy, że zarówno DFS jak i OS chorych na raka piersi zależą od określonego stanu receptorowego w pierwotnym guzie. Mniej agresywny przebieg choroby wydaje się być zależny głównie od obecności PR w guzie. Obecność samego EGFR lub jego współistnienie z ER lub wyłączna obecność ER w guzie wiążą się z gorszymi parametrami przeżycia. Średnie względne ryzyka nawrotu choroby mieściły się w przedziale: 2,14–3,31. Natomiast ryzyka śmierci znajdowały się w przedziale: 2,32–3,95. Obecność EGFR w tkance raka piersi nie zawsze jest negatywnym czynnikiem prognostycznym. Łączna obecność EGFR, ER i PR wiązała się z najlepszymi parametrami przeżycia (RR = 0,45 dla DFS i RR = 0,22 dla OS). Ponadto wykazano, że wielkość guza, stan węzłów chłonnych i wiek chorych są niezależnymi wskażnikami prognostycznymi dla DFS i OS chorych

Modeling usual and unusual anisotropic spheres

In this paper, we study anisotropic spheres built from known static spherical solutions. In particular, we are interested in the physical consequences of a "small" departure from a physically sensible configuration. The obtained solutions smoothly depend on free parameters. By setting these parameters to zero, the starting seed solution is regained. We apply our procedure in detail by taking as seed solutions the Florides metrics, and the Tolman IV solution. We show that the chosen Tolman IV, and also Heint IIa Durg IV,V perfect fluid solutions, can be used to generate a class of parametric solutions where the anisotropic factor has features recalling boson stars. This is an indication that boson stars could emerge by "perturbing" appropriately a perfect fluid solution (at least for the seed metrics considered). Finally, starting with Tolman IV, Heint IIa and Durg IV,V solutions, we build anisotropic gravastar-like sources with the appropriate boundary conditions.Comment: Final version published in IJMP

Seed populations for large solar particle events of cycle 23

Using high-resolution mass spectrometers on board the Advanced Composition Explorer (ACE), we surveyed the event-averaged ~0.1-60 MeV/nuc heavy ion elemental composition in 64 large solar energetic particle (LSEP) events of cycle 23. Our results show the following: (1) The rare isotope ^3He is greatly enhanced over the corona or the solar wind values in 46% of the events. (2) The Fe/O ratio decreases with increasing energy up to ~10 MeV/nuc in ~92% of the events and up to ~60 MeV/nuc in ~64% of the events. (3) Heavy ion abundances from C-Fe exhibit systematic M/g-dependent enhancements that are remarkably similar to those seen in ^3He-rich SEP events and CME-driven interplanetary (IP) shock events. Taken together, these results confirm the role of shocks in energizing particles up to ~60 MeV/nuc in the majority of large SEP events of cycle 23, but also show that the seed population is not dominated by ions originating from the ambient corona or the thermal solar wind, as previously believed. Rather, it appears that the source material for CME-associated large SEP events originates predominantly from a suprathermal population with a heavy ion enrichment pattern that is organized according to the ion's mass-per-charge ratio. These new results indicate that current LSEP models must include the routine production of this dynamic suprathermal seed population as a critical pre-cursor to the CME shock acceleration process

Paramagnetism of Cu3RE2W4O18 semiconductors (RE = Gd, Dy-Er)

Cu3RE2W4O18 tungstates (RE = Gd, Dy Er) are paramagnets in the temperature range 4.2 300 K visible also in the absence of the energy losses in the curve of the imaginary part of magnetic susceptibility, 00. The negative values of the paramagnetic Curie Weiss temperature, , may suggest the weak antiferromagnetic coupling below 4.2 K. The temperature independent component of magnetic susceptibility has a positive value indicating a domination of the Van Vleck contribution. Calculations of the e ective number of the Bohr magnetons revealed that the orbital contribution to the magnetic moment comes mainly from the RE3+ ions

Cosmological Dark Energy: Prospects for a Dynamical Theory

We present an approach to the problem of vacuum energy in cosmology, based on dynamical screening of Lambda on the horizon scale. We review first the physical basis of vacuum energy as a phenomenon connected with macroscopic boundary conditions, and the origin of the idea of its screening by particle creation and vacuum polarization effects. We discuss next the relevance of the quantum trace anomaly to this issue. The trace anomaly implies additional terms in the low energy effective theory of gravity, which amounts to a non-trivial modification of the classical Einstein theory, fully consistent with the Equivalence Principle. We show that the new dynamical degrees of freedom the anomaly contains provide a natural mechanism for relaxing Lambda to zero on cosmological scales. We consider possible signatures of the restoration of conformal invariance predicted by the fluctuations of these new scalar degrees of freedom on the spectrum and statistics of the CMB, in light of the latest bounds from WMAP. Finally we assess the prospects for a new cosmological model in which the dark energy adjusts itself dynamically to the cosmological horizon boundary, and therefore remains naturally of order H^2 at all times without fine tuning.Comment: 50 pages, Invited Contribution to New Journal of Physics Focus Issue on Dark Energ

Gravity a la Born-Infeld

A simple technique for the construction of gravity theories in Born-Infeld style is presented, and the properties of some of these novel theories are investigated. They regularize the positive energy Schwarzschild singularity, and a large class of models allows for the cancellation of ghosts. The possible correspondence to low energy string theory is discussed. By including curvature corrections to all orders in alpha', the new theories nicely illustrate a mechanism that string theory might use to regularize gravitational singularities.Comment: 21 pages, 2 figures, new appendix B with corrigendum: Class. Quantum Grav. 21 (2004) 529