651 research outputs found
Self-similar static solutions admitting a two-space of constant curvature
A recent result by Haggag and Hajj-Boutros is reviewed within the framework
of self-similar space-times, extending, in some sense, their results and
presenting a family of metrics consisting of all the static spherically
symmetric perfect fluid solutions admitting a homothety.Comment: 6 page
A Geometry of the Generations
We propose a geometric theory of flavor based on the discrete group
, in the context of the minimal supersymmetric standard model. The
group treats three objects symmetrically, while making fundamental distinctions
between the generations. The top quark is the only heavy quark in the symmetry
limit, and the first and second generation squarks are degenerate. The
hierarchical nature of Yukawa matrices is a consequence of a sequential
breaking of .Comment: 10 pages, 1 EPS figure as uuencoded tar-compressed file, uses
psfig.st
Design of an Information System for optimizing the Programming of nursing work shifts
Health institutions operate twenty-four hours a day, seven days a week. They face a demand that fluctuates daily. Unlike jobs with fixed hours and obligatory days off, in health, operational continuity is required. The allocation for nursing shifts generates a rotation of people for health services according to legal and casuistic guidelines. Assigning and planning shifts results in a workload that takes an average of five to six extra hours. Existing applications offer a partial solution because they do not consider the news and contingencies of a health service. A web application is presented that, given a list of nurses, historical shifts and restrictions, a work shift planning is generated. This application comes to support the current shift allocation method based on electronic spreadsheets. The development consists of two modules. The first module has a shift allocation algorithm developed in C ++ and the second module has a graphical interface. As a case study, a set of health services from Chile and Colombia was used. The services have a defined number of nurses, who work different shifts according to the role and need of the institution. The results obtained are similar to a historical one. The proposed system takes less time and delivers various files and parameters that can be useful for nurses, the service and the health institutio
Testing Supergravity Grand Unification at Future Accelerator and Underground Experiments
The full parameter space of supergravity grand unified theory with
type proton decay is analysed using renormalization
group induced electroweak symmetry breaking under the restrictions that the
universal scalar mass and gluino mass are TeV (no extreme fine
tuning) and the Higgs triplet mass obeys . Future proton
decay experiments at SuperKamiokande or ICARUS can reach a sensitivity for the
mode of yr allowing a number of
predictions concerning the SUSY mass spectrum. Thus either the decay mode will be seen at these experiments or a
chargino of mass GeV will exist and hence be observable
at LEP2. Further, if yr,
then either the light Higgs has mass GeV or GeV i.e. either the light Higgs or the light chargino (or both) would be
observable at LEP2. Thus, the combination of future accelerator and future
underground experiments allow for strong experimental tests of this theory.Comment: 7 figures available upon request, CTP-TAMU-32/93, NUB-TH-3066/93 and
SSCL-Preprint-44
More on Supersymmetric Domain Walls, N Counting and Glued Potentials
Various features of domain walls in supersymmetric gluodynamics are
discussed. We give a simple field-theoretic interpretation of the phenomenon of
strings ending on the walls recently conjectured by Witten. An explanation of
this phenomenon in the framework of gauge field theory is outlined. The
phenomenon is argued to be particularly natural in supersymmetric theories
which support degenerate vacuum states with distinct physical properties. The
issue of existence (or non-existence) of the BPS saturated walls in the
theories with glued (super)potentials is addressed. The amended
Veneziano-Yankielowicz effective Lagrangian belongs to this class. The physical
origin of the cusp structure of the effective Lagrangian is revealed, and the
limitation it imposes on the calculability of the wall tension is explained.
Related problems are considered. In particular, it is shown that the so called
discrete anomaly matching, when properly implemented, does not rule out the
chirally symmetric phase of supersymmetric gluodynamics, contrary to recent
claims.Comment: 40 pages, Latex, 5 figures. Several references added, final version
to be published in Physical Review
Inverting the Supersymmetric Standard Model Spectrum: from Physical to Lagrangian Ino Parameters
We examine the possibility of recovering the supersymmetric (and soft
supersymmetry breaking) Lagrangian parameters as direct {\em analytical}
expressions of appropriate physical masses, for the unconstrained (but CP and
R-parity conserving) minimal supersymmetric standard model. We concentrate
mainly on the algebraically non-trivial "inversion" for the ino parameters, and
obtain, for given values of , simple analytical expressions for the
, and parameters in terms of three arbitrary input physical
masses, namely either two chargino and one neutralino masses, or alternatively
one chargino and two neutralino masses. We illustrate and discuss in detail the
possible occurrence of ambiguities in this reconstruction. The dependence of
the resulting ino Lagrangian parameters upon physical masses is illustrated,
and some simple generic behaviour uncovered in this way. We finally briefly
sketch generalizing such an inversion to the full set of MSSM Lagrangian
parameters.Comment: Latex, 28 pages, 6 figures, 1 table, some typos corrected, one
paragraph extended in section 4.2. Version to appear in Phys. Rev.
Anomalies in field theories with extra dimensions
We give an overview of the issue of anomalies in field theories with extra
dimensions. We start by reviewing in a pedagogical way the computation of the
standard perturbative gauge and gravitational anomalies on non-compact spaces,
using Fujikawa's approach and functional integral methods, and discuss the
available mechanisms for their cancellation. We then generalize these analyses
to the case of orbifold field theories with compact internal dimensions,
emphasizing the new aspects related to the presence of orbifold singularities
and discrete Wilson lines, and the new cancellation mechanisms that are
becoming available. We conclude with a very brief discussion on global and
parity anomalies.Comment: Review article written for Int.J.Mod.Phys. A, 63 pages; v2: mistake
in subsection 4.3 corrected, some comments and references added, a few
misprints fixe
b-tau Unification and neutrino masses in SU(5) extensions of the MSSM with radiative electroweak symmetry breaking
We make a complete analysis of the Yukawa coupling unification in SU(5)
extensions of the MSSM in the framework of the radiative symmetry breaking
scenario. Both logarithmic and finite threshold corrections of sparticles have
been included in the determination of the gauge and Yukawa couplings at M_Z.
The effect of the heavy masses of each model in the renormalization group
equations is also included. We find that in the minimal SU(5) model b-tau
Yukawa unification can be achieved for too large a value of alpha_s. On the
other hand the Peccei-Quinn version of the Missing Doublet model, with the
effect of the right handed neutrino also included, exhibits b-tau unification
in excellent agreement with all low energy experimental data. Unification of
all Yukawa couplings is also discussed.Comment: 20 pages, LaTeX2e,uses psfig,5 figures,full postscript file available
at http://artemis.cc.uoi.gr/~adedes/new97.ps.g
Breast treatments with Axxent equipment.Comparison with Mammosite for skin, lung and heart dose
Poster Session [EP-1314]
Purpose or Objective We have treated 250 patients at our center from May 2015 to September 2017 for breast cancer with Axxent (Xoft Inc.) intraoperativ e radiotherapy (IORT) following the inclusion parameters of the TARGIT study, in this work we compare the doses in the skin of the first 150 patients treated with the 50 kVp source with the skin doses they would have received using the Mammosite kit using an Ir192 source. Material and Methods To the 250 patients treated in our center after removing the tumor, the appropriate balloon size is chosen to cover the tumor area with a dose of 20 Gy on the ball oon surface, the sizes used range fro m 30-65 cm3, after which it is verified that the distance to skin from the 3 closest points of the balloon i s less than 10 mm and then the treatment is carried out with an average duration of 10.3 minutes being the volumes of 30 and 35 cm3 the most used due to the inclusion criteria of the procedure. Treatment plans are previously per formed in a Brachyvision treatment planning system (TPS) (Varian Inc.) for each of the possible volumes. In tur n, another plan is calculated with the Mammosite applicator and Ir192 source, from which the skin dose of each control point is estimated, compared to our results. We present also the cases of acute dermatitis seen for these first 150 patients in a time less than 6 months after the surgical act and irradiation. Results The differences in maximum skin dose for bot h types of treatment are 8.1 Ā± 1.2 Gy for the case of Mammosite and 5.7 Ā± 1.5 Gy for patients treated with electronic source, due to the difference in the depht dos e percentage of both types of treatment (Image 1). This, in turn, explains the very few cases of acute dermatitis at 6 months (8 cases of grade 2 and 2 cases of grade 3) (Image 2) with no recurrence to date.We also show the mean and maximum doses (expressed as percentage of prescribed dose) for the left lung and heart in cases of left breast tumor for the volumes of 30 and 35 cm3, which are the most common volumes in our hospital (70% of cases):
LEFT LUNG (Left Breast tratment) AXXENT MAMMOSITE
Maximun Dose (%PD) 20.4% 29.9%
Mean Dose (%PD) 1.0% 3.9%
HEART (Left Breast tratment) AXXENT MAMMOSITE
Maximun Dose (%PD) 4.1% 10.4%
Mean Dose (%PD) 0.8% 3.3%
Conclusion It is concluded that the IORT treatments performed with the Axxent equipment with electronic source are a good alternative to those performed with Ir192 and our 250 patients treated to date to the good results presented by other centers are joined.In additi on to the low skin toxicity, there is no recurrence in patients treated so far, which makes us very optimistic about the results
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