430 research outputs found
Oscillatons revisited
In this paper, we study some interesting properties of a spherically
symmetric oscillating soliton star made of a real time-dependent scalar field
which is called an oscillaton. The known final configuration of an oscillaton
consists of a stationary stage in which the scalar field and the metric
coefficients oscillate in time if the scalar potential is quadratic. The
differential equations that arise in the simplest approximation, that of
coherent scalar oscillations, are presented for a quadratic scalar potential.
This allows us to take a closer look at the interesting properties of these
oscillating objects. The leading terms of the solutions considering a quartic
and a cosh scalar potentials are worked in the so called stationary limit
procedure. This procedure reveals the form in which oscillatons and boson stars
may be related and useful information about oscillatons is obtained from the
known results of boson stars. Oscillatons could compete with boson stars as
interesting astrophysical objects, since they would be predicted by scalar
field dark matter models.Comment: 10 pages REVTeX, 10 eps figures. Updated files to match version
published in Classical and Quantum Gravit
Treatment of squamous cell carcinoma of the anal canal: A new strategies with anti-EGFR therapy and immunotherapy
The incidence of squamous cell carcinoma of the anal canal (SCAC) is increasing in both sexes but the standard treatment remains that of 20 years ago. However, interesting data have recently emerged on the use of anti-epidermal growth factor receptor (EGFR) agents and immunotherapy in advanced disease. Thus, new avenues of research are opening up that will hopefully lead to more effective therapeutic strategies. We provide an overview of the latest studies published on this tumor and discuss the possible future therapeutic options for combination therapy, anti-EGFR treatment and radiotherapy
On the thermal footsteps of Neutralino relic gases
Current literature suggests that neutralinos are the dominant cold dark
matter particle species. Assuming the microcanonical definition of entropy, we
examine the local entropy per particle produced between the ``freeze out'' era
to the present. An ``entropy consistency'' criterion emerges by comparing this
entropy with the entropy per particle of actual galactic structures given in
terms of dynamical halo variables. We apply this criterion to the cases when
neutralinos are mosly b-inos and mostly higgsinos, in conjunction with the
usual ``abundance'' criterion requiring that present neutralino relic density
complies with 0.1 < \Omega_{\chic{\tilde\chi^0_1}} < 0.3 for .
The joint application of both criteria reveals that a better fitting occurs for
the b-ino channels, hence the latter seem to be favoured over the higgsino
channels. The suggested methodology can be applied to test other annihilation
channels of the neutralino, as well as other particle candidates of thermal
gases relics.Comment: LaTex AIP style, 8 pages including 1 figure. Final version to appear
in Proceedings of the Mexican School of Astrophysics (EMA), Guanajuato,
M\'exico, July 31 - August 7, 200
Hydrodynamics of galactic dark matter
We consider simple hydrodynamical models of galactic dark matter in which the
galactic halo is a self-gravitating and self-interacting gas that dominates the
dynamics of the galaxy. Modeling this halo as a sphericaly symmetric and static
perfect fluid satisfying the field equations of General Relativity, visible
barionic matter can be treated as ``test particles'' in the geometry of this
field. We show that the assumption of an empirical ``universal rotation curve''
that fits a wide variety of galaxies is compatible, under suitable
approximations, with state variables characteristic of a non-relativistic
Maxwell-Boltzmann gas that becomes an isothermal sphere in the Newtonian limit.
Consistency criteria lead to a minimal bound for particle masses in the range
and to a constraint between the central
temperature and the particles mass. The allowed mass range includes popular
supersymmetric particle candidates, such as the neutralino, axino and
gravitino, as well as lighter particles ( keV) proposed by numerical
N-body simulations associated with self-interactive CDM and WDM structure
formation theories.Comment: LaTeX article style, 16 pages including three figures. Final version
to appear in Classical and Quantum Gravit
Metformin plus chemotherapy versus chemotherapy alone in the first-line treatment of HER2-negative metastatic breast cancer. The MYME randomized, phase 2 clinical trial
Purpose: To investigate the efficacy of metformin (M) plus chemotherapy versus chemotherapy alone in metastatic breast cancer (MBC). Methods: Non-diabetic women with HER2-negative MBC were randomized to receive non-pegylated liposomal doxorubicin (NPLD) 60 mg/m2 + cyclophosphamide (C) 600 mg/m2 × 8 cycles Q21 days plus M 2000 mg/day (arm A) versus NPLD/C (arm B). The primary endpoint was progression-free survival (PFS). Results: One-hundred-twenty-two patients were evaluable for PFS. At a median follow-up of 39.6 months (interquartile range [IQR] 24.6-50.7 months), 112 PFS events and 71 deaths have been registered. Median PFS was 9.4 months (95% CI 7.8-10.4) in arm A and 9.9 (95% CI 7.4-11.5) in arm B (P = 0.651). In patients with HOMA index < 2.5, median PFS was 10.4 months (95% CI 9.6-11.7) versus 8.5 (95% CI 5.8-9.7) in those with HOMA index ≥ 2.5 (P = 0.034). Grade 3/4 neutropenia was the most common toxicity, occurring in 54.4% of arm A patients and 72.3% of the arm B group (P = 0.019). M induced diarrhea (G2) was observed in 8.8% of patients in Arm A. The effect of M was similar in patients with HOMA index < 2.5 and ≥ 2.5, for PFS and OS. Conclusions: The MYME trial failed to provide evidence in support of an anticancer activity of M in combination with first line CT in MBC. A significantly shorter PFS was observed in insulin-resistant patients (HOMA ≥ 2.5). Noteworthy, M had a significant effect on CT induced severe neutropenia. Further development of M in combination with CT in the setting of MBC is not warranted
Intercropping of tomato with antagonistic plants in the treatment of soil infested with Meloidogyne spp., under greenhouse
El intercultivo de tomate con especies antagónicas se considera una alternativa de manejo de Meloidogyne spp. El objetivo del trabajo fue evaluar el intercultivo de las especies Tagetes erecta, Tagetes minuta y Crotalaria juncea para el manejo de Meloidogyne spp., en el cultivo de tomate. Se determinó, en las plantas de tomate, el índice de agallas y el número y peso de frutos. El intercultivo de tomate con T. erecta mostro un menor índice de agallas que el resto de los tratamientos evaluados. Además, se observó en este tratamiento, y en el de T. minuta, un mayor peso y número de frutos con respecto al tratamiento con C. juncea y al testigo sin intercultivo. En las condiciones de este ensayo, el intercultivo de tomate con T. erecta mostró ser una buena alternativa de manejo de Meloidoigyne spp. Se contribuye con esta práctica a una menor utilización de fitosanitarios, con el efecto positivo que trae aparejado para con el medio ambiente, y a la obtención de un producto hortícola de mayor inocuidad para el consumo.Tomato intercropping with antagonistic species is considered a management alternative for Meloidogyne spp. The objective of the work was to evaluate the intercropping of Tagetes erecta, Tagetes minuta and Crotalaria juncea for the management of Meloidogyne spp., in tomato cultivation. The gall index and the number and weight of fruits were determined in tomato plants. Tomato intercropping with T. erecta showed a lower gall index than the rest of evaluated treatments. In addition, a higher weight and number of fruits were observed in this treatment and in the one with T. minuta, respect to the C. juncea treatment and the control without intercropping. Under the conditions of this trial, intercropping of tomato with T. erecta proved to be a good alternative for the management of Meloidoigyne spp. This practice contributes to a lesser use of phytosanitary products, with the positive effect that it has on the environment, and to the obtaining of a more innocuous horticultural product for human consumption.Fil: Comezaña, María Micaela. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Rodríguez, R. A.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Ayastuy, M. E.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Muscolino, C.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Rosetti, F.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Belladonna, D. P.. Universidad Nacional del Sur. Departamento de Agronomía; Argentin
Beyond series expansions: mathematical structures for the susceptibility of the square lattice Ising model
We first study the properties of the Fuchsian ordinary differential equations
for the three and four-particle contributions and
of the square lattice Ising model susceptibility. An analysis of some
mathematical properties of these Fuchsian differential equations is sketched.
For instance, we study the factorization properties of the corresponding linear
differential operators, and consider the singularities of the three and
four-particle contributions and , versus the
singularities of the associated Fuchsian ordinary differential equations, which
actually exhibit new ``Landau-like'' singularities. We sketch the analysis of
the corresponding differential Galois groups. In particular we provide a
simple, but efficient, method to calculate the so-called ``connection
matrices'' (between two neighboring singularities) and deduce the singular
behaviors of and . We provide a set of comments and
speculations on the Fuchsian ordinary differential equations associated with
the -particle contributions and address the problem of the
apparent discrepancy between such a holonomic approach and some scaling results
deduced from a Painlev\'e oriented approach.Comment: 21 pages Proceedings of the Counting Complexity conferenc
When Does an Episode of Care for Cancer Begin?
Little is known about the medical care resources devoted to diagnosing and treating cancer-related symptoms prior to a definitive cancer diagnosis. Previous research using SEER-Medicare data to measure incremental costs and utilization associated with cancer started with the date of diagnosis. We hypothesized that health care use increases prior to diagnosis of a new primary cancer
New measurement of neutron capture resonances of 209Bi
The neutron capture cross section of Bi209 has been measured at the CERN n
TOF facility by employing the pulse-height-weighting technique. Improvements
over previous measurements are mainly because of an optimized detection system,
which led to a practically negligible neutron sensitivity. Additional
experimental sources of systematic error, such as the electronic threshold in
the detectors, summing of gamma-rays, internal electron conversion, and the
isomeric state in bismuth, have been taken into account. Gamma-ray absorption
effects inside the sample have been corrected by employing a nonpolynomial
weighting function. Because Bi209 is the last stable isotope in the reaction
path of the stellar s-process, the Maxwellian averaged capture cross section is
important for the recycling of the reaction flow by alpha-decays. In the
relevant stellar range of thermal energies between kT=5 and 8 keV our new
capture rate is about 16% higher than the presently accepted value used for
nucleosynthesis calculations. At this low temperature an important part of the
heavy Pb-Bi isotopes are supposed to be synthesized by the s-process in the He
shells of low mass, thermally pulsing asymptotic giant branch stars. With the
improved set of cross sections we obtain an s-process fraction of 19(3)% of the
solar bismuth abundance, resulting in an r-process residual of 81(3)%. The
present (n,gamma) cross-section measurement is also of relevance for the design
of accelerator driven systems based on a liquid metal Pb/Bi spallation target.Comment: 10 pages, 5figures, recently published in Phys. Rev.
Measurement of the neutron capture cross section of the s-only isotope 204Pb from 1 eV to 440 keV
The neutron capture cross section of 204Pb has been measured at the CERN
n_TOF installation with high resolution in the energy range from 1 eV to 440
keV. An R-matrix analysis of the resolved resonance region, between 1 eV and
100 keV, was carried out using the SAMMY code. In the interval between 100 keV
and 440 keV we report the average capture cross section. The background in the
entire neutron energy range could be reliably determined from the measurement
of a 208Pb sample. Other systematic effects in this measurement could be
investigated and precisely corrected by means of detailed Monte Carlo
simulations. We obtain a Maxwellian average capture cross section for 204Pb at
kT=30 keV of 79(3) mb, in agreement with previous experiments. However our
cross section at kT=5 keV is about 35% larger than the values reported so far.
The implications of the new cross section for the s-process abundance
contributions in the Pb/Bi region are discussed.Comment: 8 pages, 3 figures, article submitted to Phys. Rev.
- …