On CPT Symmetry: Cosmological, Quantum-Gravitational and other possible violations and their phenomenology

I discuss various ways in which CPT symmetry may be violated, and their phenomenology in current or immediate future experimental facilities, both terrestrial and astrophysical. Specifically, I discuss first violations of CPT symmetry due to the impossibility of defining a scattering matrix as a consequence of the existence of microscopic or macroscopic space-time boundaries, such as Planck-scale Black-Hole (event) horizons, or cosmological horizons due to the presence of a (positive) cosmological constant in the Universe. Second, I discuss CPT violation due to breaking of Lorentz symmetry, which may characterize certain approaches to quantum gravity, and third, I describe models of CPT non invariance due to violations of locality of interactions. In each of the above categories I discuss experimental sensitivities. I argue that the majority of Lorentz-violating cases of CPT breaking, with minimal (linear) suppression by the Planck-mass scale, are already excluded by current experimental tests. There are however some (stringy) models which can evade these constraints.Comment: 27 pages latex, Conference talk Beyond the Desert 200

A supersymmetric model for triggering Supernova Ia in isolated white dwarfs

We propose a model for supernovae Ia explosions based on a phase transition to a supersymmetric state which becomes the active trigger for the deflagration starting the explosion in an isolated sub-Chandrasekhar white dwarf star. With two free parameters we fit the rate and several properties of type Ia supernovae and address the gap in the supermassive black hole mass distribution. One parameter is a critical density fit to about $3 \cdot 10^7$ g/cc while the other has the units of a space time volume and is found to be of order $0.05\,$ Gyr $R_E^3$ where $R_E$ is the earth radius. The model involves a phase transition to an exact supersymmetry in a small core of a dense star.Comment: 20 pages, 5 figures, expanded version to be published in Physical Review

A case of mistaken identification of an amber fossil male strepsipteran (Insecta: Strepsiptera)

A well preserved specimen of amber Strepsiptera was erroneously described as Stylops neotropicallis Kogan and Poinar, 2010. The taxonomic position of the species was based on a count of 6 antennomeres (typical of the Stylopidae), however, further observations showed that there are actually 7 antennomeres, which places the fossil in the family Myrmecolacidae, and it is herein re-described in the genus Palaeomyrmecolax Kulicka, 2001. Furthermore, nuclear magnetic resonance spectroscopy analysis of a sample of the amber piece containing the fossil revealed that it was Baltic rather than Dominican amber as originally thought. The fossil was compared to another specimen from Baltic amber in the Poinar collection, which shows close affinity to P. succineus Kulicka, 2001, the type species of the genus. P. neotropicallis (n.comb.) differs from that specimen and seems to differ also from the other 4 species in the genus Palaeomyrmecolax.Keywords: Palaeomyrmecolax succineus, Palaeomyrmecolax, Baltic amber, Stylops neotropicalis, Myrmecolacida

Thermal Partition Functions for S-branes

We calculate the thermal partition functions of open strings on the S-brane backgrounds (the bouncing or rolling tachyon backgrounds) both in the bosonic and superstring cases. According to hep-th/0302146, we consider the discretized temperatures compatible with the pure imaginary periodicity of tachyon profiles. The ``effective Hagedorn divergence'' is shown to appear no matter how low temperature is chosen (including zero-temperature). This feature is likely to be consistent with the large rate of open string pair production discussed in hep-th/0209090 and also emission of closed string massive modes hep-th/0303139. We also discuss the possibility to remove the divergence by considering the space-like linear dilaton backgrounds as in hep-th/0306132.Comment: 33 pages, no figure; v2 typos corrected, a reference adde

In-training assessment using direct observation of single-patient encounters: a literature review

We reviewed the literature on instruments for work-based assessment in single clinical encounters, such as the mini-clinical evaluation exercise (mini-CEX), and examined differences between these instruments in characteristics and feasibility, reliability, validity and educational effect. A PubMed search of the literature published before 8 January 2009 yielded 39 articles dealing with 18 different assessment instruments. One researcher extracted data on the characteristics of the instruments and two researchers extracted data on feasibility, reliability, validity and educational effect. Instruments are predominantly formative. Feasibility is generally deemed good and assessor training occurs sparsely but is considered crucial for successful implementation. Acceptable reliability can be achieved with 10 encounters. The validity of many instruments is not investigated, but the validity of the mini-CEX and the ‘clinical evaluation exercise’ is supported by strong and significant correlations with other valid assessment instruments. The evidence from the few studies on educational effects is not very convincing. The reports on clinical assessment instruments for single work-based encounters are generally positive, but supporting evidence is sparse. Feasibility of instruments seems to be good and reliability requires a minimum of 10 encounters, but no clear conclusions emerge on other aspects. Studies on assessor and learner training and studies examining effects beyond ‘happiness data’ are badly needed

Spontaneous rupture of renal pelvis after renal transplantation

Spontaneous rupture of the renal pelvis occurred in 4 cases following renal transplantation. The diagnosis was difficult, and all 4 patients were septic at the time of treatment. Three patients survived, but preservation of the transplant was possible in only 1 case. The cause is uncertain but may be related to functional obstruction or vascular insufficiency.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24216/1/0000475.pd

Two-Point Functions and S-Parameter in QCD-like Theories

We calculated the vector, axial-vector, scalar and pseudo-scalar two-point functions up to two-loop level in the low-energy effective field theory for three different QCD-like theories. In addition we also calculated the pseudo-scalar decay constant $G_M$. The QCD-like theories we used are those with fermions in a complex, real or pseudo-real representation with in general n flavours. These case correspond to global symmetry breaking pattern of $SU(n)_L\times SU(n)_R\to SU(n)_V$, $SU(2n)\to SO(2n)$ or $SU(2n)\to Sp(2n)$. We also estimated the S parameter for those different theories.Comment: 29 page

Simple de Sitter Solutions

We present a framework for de Sitter model building in type IIA string theory, illustrated with specific examples. We find metastable dS minima of the potential for moduli obtained from a compactification on a product of two Nil three-manifolds (which have negative scalar curvature) combined with orientifolds, branes, fractional Chern-Simons forms, and fluxes. As a discrete quantum number is taken large, the curvature, field strengths, inverse volume, and four dimensional string coupling become parametrically small, and the de Sitter Hubble scale can be tuned parametrically smaller than the scales of the moduli, KK, and winding mode masses. A subtle point in the construction is that although the curvature remains consistently weak, the circle fibers of the nilmanifolds become very small in this limit (though this is avoided in illustrative solutions at modest values of the parameters). In the simplest version of the construction, the heaviest moduli masses are parametrically of the same order as the lightest KK and winding masses. However, we provide a method for separating these marginally overlapping scales, and more generally the underlying supersymmetry of the model protects against large corrections to the low-energy moduli potential.Comment: 37 pages, harvmac big, 4 figures. v3: small correction