Entropy in Spin Foam Models: The Statistical Calculation

Recently an idea for computing the entropy of black holes in the spin foam formalism has been introduced. Particularly complete calculations for the three dimensional euclidean BTZ black hole were done. The whole calculation is based on observables living at the horizon of the black hole universe. Departing from this idea of observables living at the horizon, we now go further and compute the entropy of BTZ black hole in the spirit of statistical mechanics. We compare both calculations and show that they are very interrelated and equally valid. This latter behaviour is certainly due to the importance of the observables.Comment: 11 pages, 1 figur

Keratinocytes from human skin respond as typical immune cells after the stimulation with _Trichophyton rubrum_

_Trichophyton rubrum_ is the main agent causing dermatophytosis (1). Keratinocytes are
considered to be the first physical barrier of defense against pathogens (2). But not
only a physical barrier. They recognize antigens through Toll like receptors (TLR) (3).
The activation of this TLR, present on the surface of the keratinocytes, induce the
expression of different pro-inflammatory cytokines, co-stimulatory molecules and
antimicrobial peptides such as [beta]-defensins (4).
The main objective of this work is to determine if lipopolysaccharides of G – bacteria
(LPS), lipotheichoic acid from G+ bacteria (LTA), and conidias, isolated from _T. rubrum_
were able to activate the expression of TLR2 and TLR6 on the cell surface of a primary
culture of human keratinocytes through Flow cytometry. Furthermore we are looking for
the presence of [beta]-defensins 1 and 2, IL-1b and IL-8 in the supernatant, of the above
mentioned culture of cells, by Western blot.
From the flow cytometry data, the preliminary results showed an important dispersion
in terms of proliferation, increase in size and granularity of keratinocytes, from primary
cultures of skin from healthy donors, stimulated 6 hours with conidias of _T. rubrum_, and
LTA, but not when non stimulated, or stimulated with LPS (Fig 1).
When keratinocytes from primary cultures of skin from healthy donors were cultivated
48 hours, it was found dispersion in terms of proliferation, increase in size and
granularity when stimulated with conidias of _T. rubrum_, and LPS but not when non
stimulated, or stimulated with LTA (Fig 2).
The keratinocytes expressed increased levels of TLR2 and TLR6 when were
stimulated with LTA and less to _T. rubrum_, in the 6 hours cultures, but this last cells still
showed increased size (Fig 3).
The Keratinocytes expressed increased levels of TLR2 in the 48 hours cultures when
were stimulated with LPS and _T. rubrum_.(Fig 4)
Besides, [beta]-defensin-2 was detected in the supernatant of cultures of keratinocytes
stimulated with LPS (Fig 5).
It can preliminary be concluded that keratinocytes from primary cultures of human skin from healthy donors, are cells that respond as typical immune cells, after stimulation
with _T. rubrum_, LTA and LPS in different conditions, and that this mechanism may be
very important, for the protection of local environment. 

References
1.- Arenas R., Dermatofitosis en México. Rev Iberoam Micol 2002; 19: 63-67.
2.- Kupper T. and Fuhlbrigge R. Immune surveillance in the skin: mechanims and clinical consecuences.
Nat Rev Immunol 2004; 4: 211-222
3.- Kôllish G., Naderi B., Voelcker V., Wallich R., Behrendt H., Ring J., Bauer S., Jacob T., Mempel M. and
Olelrt M. Various members of the Toll-Like receptor family contribute to the innate immune response of
human epidermal keratinocytes. Immunology 2005; 114: 531-541.
4.- Akira, S. and Takeda K. 2004. Toll-like Receptor Signalling. Nature Reviews Immunology 4:499-511

Towards a spin foam model description of black hole entropy

We propose a way to describe the origin of black hole entropy in the spin foam models of quantum gravity. This stimulates a new way to study the relation of spin foam models and loop quantum gravity.Comment: 5 pages, 1 figur