Consistent Off-Shell Tree String Amplitudes

We give a construction of off-shell tree bosonic string amplitudes, based on the operatorial formalism of the $N$-string Vertex, with three external massless states both for open and closed strings by requiring their being projective invariant. In particular our prescription leads, in the low-energy limit, to the three-gluon amplitude in the usual covariant gauge.Comment: 12 pages. Introductory and final parts modified in order to make them more clear. Cosmetic changes in formulae (13) and (14). Some misprints correcte

Marijuana Decriminalization: What does it mean in the United States?

It is well known in the drug policy field that eleven states reduced the criminal sanctions associated with possession of small amounts of marijuana. In this paper we review the eleven original decriminalization statutes, documenting key dimensions of these laws and identifying their common denominator. We then examine state laws in effect as of December 31, 1999, along the same key dimensions and show that it is impossible to uniquely identify the so-called decriminalized states. We show the extent to which non-decriminalized states have also reduced penalties associated with possession of small amounts of marijuana as early as 1989, calling into question the interpretation of studies evaluating this policy during the past decade. We conclude by showing that the inclusion of legal dimensions of the policy does not diminish the association identified between decriminalization and recent use, raising questions about how researchers should interpret such findings.

Prescriptions for Off-Shell Bosonic String Amplitudes

We give, in the framework of the bosonic string theory, simple prescriptions for computing, at tree and one-loop levels, off-shell string amplitudes for open and closed string massless states. In particular we obtain a tree amplitude for three open strings that in the field theory limit coincides with the three-gluon vertex in the usual covariant gauge and two-string one-loop amplitudes satisfying the property of transversality.Comment: 11 pages, LaTeX, to appear in the proceedings of the workshop "Quantum Aspects of Gauge Theories, Supersymmetry and Unification", Corfu (Greece), 20-26 September 1998. Eq. (12) and numerical factors in eqs. (13) and (16) corrected; some minor changes and references adde

Expected performances of a Laue lens made with bent crystals

In the context of the LAUE project devoted to build a Laue lens prototype for focusing celestial hard X-/soft gamma-rays, a Laue lens made of bent crystal tiles, with 20 m focal length, is simulated. The focusing energy passband is assumed to be 90--600 keV. The distortion of the image produced by the lens on the focal plane, due to effects of crystal tile misalignment and radial distortion of the crystal curvature, is investigated. The corresponding effective area of the lens, its point spread function and sensitivity are calculated and compared with those exhibited by a nominal Laue lens with no misalignment and/or distortion. Such analysis is crucial to estimate the optical properties of a real lens, in which the investigated shortcomings could be present.Comment: 20 pages, 14 figure

Brane-Inspired Orientifold Field Theories

In this paper we consider the gauge theory living on the world-volume of a stack of N D3-branes of Type 0B/\Omega' I_6(-1)^{F_{L}} and of its orbifolds C^2/Z_2 and C^3/(Z_2 x Z_2). The gauge theories obtained in the three cases are a brane realization of ``orientifold field theories'' having the bosonic sector common with N=4,2,1 super Yang-Mills respectively. In these non-supersymmetric theories, we investigate the possibility of keeping the gauge/gravity correspondence that has revealed itself so successful in the case of supersymmetric theories. In the open string framework we compute the coefficient of the gauge kinetic term showing that the perturbative behaviour of the orientifold field theory can be obtained from the closed string channel in the large N limit, where the theory exhibits Bose-Fermi degeneracy.Comment: 27 pages, LaTe

Kaehler Metrics: String vs Field Theoretical Approach

We use both a string and a field theoretical approach in order to determine respectively the Kaehler metrics of untwisted and twisted open strings attached to magnetized D9 branes in toroidal compactifications.Comment: 11 pages, LaTex file. Contribution to the proceedings of the 4th RTN workshop "Forces Universe", Varna, September 200

Hard x-ray broad band Laue lenses (80 - 600 keV): building methods and performances

We present the status of the laue project devoted to develop a technology for building a 20 meter long focal length Laue lens for hard x-/soft gamma-ray astronomy (80 - 600 keV). The Laue lens is composed of bent crystals of Gallium Arsenide (GaAs, 220) and Germanium (Ge, 111), and, for the first time, the focusing property of bent crystals has been exploited for this field of applications. We show the preliminary results concerning the adhesive employed to fix the crystal tiles over the lens support, the positioning accuracy obtained and possible further improvements. The Laue lens petal that will be completed in a few months has a pass band of 80 - 300 keV and is a fraction of an entire Laue lens capable of focusing X-rays up to 600 keV, possibly extendable down to 20 - 30 keV with suitable low absorption crystal materials and focal length. The final goal is to develop a focusing optics that can improve the sensitivity over current telescopes in this energy band by 2 orders of magnitude

The LAUE project for broadband gamma-ray focusing lenses

We present the LAUE project devoted to develop an advanced technology for building a high focal length Laue lens for soft gamma--ray astronomy (80-600 keV). The final goal is to develop a focusing optics that can improve the current sensitivity in the above energy band by 2 orders of magnitude.Comment: 7 pages, 6 figures, presented at the SPIE conference on "Optics for EUV, X-ray, and Gamma-ray Astronomy". To be published in the Proceedings of SPIE, vol.8147, 201

Identification and molecular characterization of a novel mutation in MSH2 gene in a lynch syndrome family

Background and aim of the work: The Lynch Syndrome (LS) is associated with germline mutations in one of the MisMatch Repair (MMR) genes, including MLH1, MSH2, MSH6, PMS2, MLH3 and MSH3. The molecular characterization of mutations in these MMR genes facilitates the pre-symptomatic diagnosis of subjects at risk to develop a colon cancer or a cancer LS-related. Methods: DHPLC and direct sequencing were performed for the mutation detection analysis. Results: In this study, we identified a novel frame shift mutation, the named is c.170delT in MSH2 gene that determined a premature stop codon and consequently, the formation of a truncated protein (p. Val56Glyfs*7). This is a novel mutation, as it has not been reported before in the international scientific literature. This mutation was found in two subjects (father and son) belonging to a LS family. However, they showed a different phenotype disease. Conclusion: In this study, we identified and characterized a novel MSH2 mutation; moreover, this study reaffirmed the importance of genetic testing in Lynch syndrome

Classical gauge instantons from open strings

We study the D3/D(-1) brane system and show how to compute instanton corrections to correlation functions of gauge theories in four dimensions using open string techniques. In particular we show that the disks with mixed boundary conditions that are typical of the D3/D(-1) system are the sources for the classical instanton solution. This can then be recovered from simple calculations of open string scattering amplitudes in the presence of D-instantons. Exploiting this fact we also relate this stringy description to the standard instanton calculus of field theory