Study on Noncommutative Representations of Galilean Generators

The representations of Galilean generators are constructed on a space where both position and momentum coordinates are noncommutating operators. A dynamical model invariant under noncommutative phase space transformations is constructed. The Dirac brackets of this model reproduce the original noncommutative algebra. Also, the generators in terms of noncommutative phase space variables are abstracted from this model in a consistent manner. Finally, the role of Jacobi identities is emphasised to produce the noncommuting structure that occurs when an electron is subjected to a constant magnetic field and Berry curvature.Comment: Title changed, new references added, published in Int. J. Mod. Phys.

Strange matter in rotating compact stars

We have constructed equations of state involving various exotic forms of matter with large strangeness fraction such as hyperon matter, Bose-Einstein condensates of antikaons and strange quark matter. First order phase transitions from hadronic to antikaon condensed and quark matter are considered here. The hadronic phase is described by the relativistic field theoretical model. Later those equations of state are exploited to investigate models of uniformly rotating compact stars. The effect of rotation on the third family branch for the equation of state involving only antikaon condensates is investigated. We also discuss the back bending phenomenon due to a first order phase transition from $K^-$ condensed to quark matter.Comment: 8 pages, 4 figures; Plenary talk delivered at Strangeness in Quark Matter (SQM) 2004 held in Cape Town, South Africa from 15-20 September; Accepted for publication in the proceedings in Journal of Physics

Density dependent hadron field theory for neutron stars with antikaon condensates

We investigate $K^-$ and $\bar K^0$ condensation in $\beta$-equilibrated hyperonic matter within a density dependent hadron field theoretical model. In this model, baryon-baryon and (anti)kaon-baryon interactions are mediated by the exchange of mesons. Density dependent meson-baryon coupling constants are obtained from microscopic Dirac Brueckner calculations using Groningen and Bonn A nucleon-nucleon potential. It is found that the threshold of antikaon condensation is not only sensitive to the equation of state but also to antikaon optical potential depth. Only for large values of antikaon optical potential depth, $K^-$ condensation sets in even in the presence of negatively charged hyperons. The threshold of $\bar K^0$ condensation is always reached after $K^-$ condensation. Antikaon condensation makes the equation of state softer thus resulting in smaller maximum mass stars compared with the case without any condensate.Comment: 20 pages, 7 figures; final version to appear in Physical Review

Color superconducting quark matter core in the third family of compact stars

We investigate first order phase transitions from $\beta$-equilibrated hadronic matter to color flavor locked quark matter in compact star interior. The hadronic phase including hyperons and Bose-Einstein condensate of $K^-$ mesons is described by the relativistic field theoretical model with density dependent meson-baryon couplings. The early appearance of hyperons and/or Bose-Einstein condensate of $K^-$ mesons delays the onset of phase transition to higher density. In the presence of hyperons and/or $K^-$ condensate, the overall equations of state become softer resulting in smaller maximum masses than the cases without hyperons and $K^-$ condensate. We find that the maximum mass neutron stars may contain a mixed phase core of hyperons, $K^-$ condensate and color superconducting quark matter. Depending on the parameter space, we also observe that there is a stable branch of superdense stars called the third family branch beyond the neutron star branch. Compact stars in the third family branch may contain pure color superconducting core and have radii smaller than those of the neutron star branch. Our results are compared with the recent observations on RX J185635-3754 and the recently measured mass-radius relationship by X-ray Multi Mirror-Newton Observatory.Comment: 24 pages, RevTex, 9 figures included; section II shortened, section III elaborated, two new curves in Fig. 9 and acknowledgements added; version to bepublished in Phys. Rev.

A Novel Enediynyl Peptide Inhibitor of Furin That Blocks Processing of proPDGF-A, B and proVEGF-C

BACKGROUND: Furin represents a crucial member of secretory mammalian subtilase, the Proprotein Convertase (PC) or Proprotein Convertase Subtilisin/Kexin (PCSK) superfamily. It has been linked to cancer, tumorgenesis, viral and bacterial pathogenesis. As a result it is considered a major target for intervention of these diseases. METHODOLOGY/PRINCIPAL FINDINGS: Herein, we report, for the first time, the synthesis and biological evaluation of a newly designed potent furin inhibitor that contains a highly reactive beta-turn inducing and radical generating "enediynyl amino acid" (Eda) moiety. "Eda" was inserted between P1 and P1' residues of hfurin(98-112) peptide, derived from the primary cleavage site of furin's own prodomain. The resulting hexadecapeptide derivative inhibited furin in vitro with IC(50) approximately 40 nM when measured against the fluorogenic substrate Boc-RVRR-MCA. It also inhibited furin-mediated cleavage of a fluorogenic peptide derived from hSARS-CoV spike protein with IC(50) approximately 193 nM. Additionally it also blocked furin-processing of growth factors proPDGF-A, B and VEGF-C that are linked to tumor genesis and cancer. Circular dichroism study showed that this inhibitor displayed a predominantly beta-turn structure while western blots confirmed its ability to protect furin protein from self degradation. CONCLUSION/SIGNIFICANCE: These findings imply its potential as a therapeutic agent for intervention of cancer and other furin-associated diseases

Compulsory High Schooling, Over-Crowding and Violent Youth Crime - Evidence from a Recent Constitutional Amendment in Brazil

The paper exploits the 2009 Constitutional Amendment in Brazil that introduced compulsory high schooling of 16-17 years olds as a natural experiment to investigate the effects of high schooling on selected violent youth crime indices. Using a unique data compiled from various official sources for over 5000 Brazilian municipalities over 2000-2013, we find the following: while the Amendment was successful to lower violent youth crime rates in the overall sample, the impact was relatively small because it worked primarily through incapacitation because of compulsory schools. There is no evidence that it boosted employment prospects or returns to schooling in the treated municipalities. More importantly the Amendment fails to lower youth crime rates in the poorer municipalities where over-crowding in classes increased after the Amendment, thus deteriorating the school’s learning environment. Unlike much of the previous literature that focused on more developed countries, a key finding of our study is that good governance and learning environment is a pre-requisite for reaping the benefits of compulsory high schooling in an emerging economy; the result has important implications for other countries beyond the Brazilian border

Compulsory High Schooling, Over-Crowding and Violent Youth Crime - Evidence from a Recent Constitutional Amendment in Brazil

Compulsory schooling laws (CSL) are often advocated for tackling youth crime. While this may work in developed countries, our study of the Brazilian municipalities over 2000-13 finds mixed evidence. Exploiting the large exogenous variation in compulsory high schooling of 15-17 year olds after the 2009 Brazilian Constitutional Amendment 59, we examine its effect on violent youth crime indices. Only about 53% sample municipalities had adopted the Amendment by 2013. Difference-indifference estimates with municipality fixed effects accounting for the endogenous adoption of the Amendment show small treatment effects for homicides, but insignificant effects for homicide rates in the full sample. In the absence of any significant increase in income/employment for this age group, the observed effects can only be attributed to the incapacitation induced by the Amendment; but this effect was weakened by sudden overcrowding in day and night schools in treated municipalities after 2009. In particular, the small beneficial effect of the Amendment vanishes when class size is greater than its sample median. The crime reduction effects of CSL thus crucially depend on whether/how CSL affects class size