Scaling and self-averaging in the three-dimensional random-field Ising model

We investigate, by means of extensive Monte Carlo simulations, the magnetic critical behavior of the three-dimensional bimodal random-field Ising model at the strong disorder regime. We present results in favor of the two-exponent scaling scenario, $\bar{\eta}=2\eta$, where $\eta$ and $\bar{\eta}$ are the critical exponents describing the power-law decay of the connected and disconnected correlation functions and we illustrate, using various finite-size measures and properly defined noise to signal ratios, the strong violation of self-averaging of the model in the ordered phase.Comment: 8 pages, 6 figures, to be published in Eur. Phys. J.

Electronic symptom monitoring in pediatric patients hospitalized for chemotherapy

Background: Using patient-reported outcomes for symptom monitoring in oncology has resulted in significant benefits for adult patients with cancer. The feasibility of this approach has not been established in the routine care of children with cancer. Methods: The Pediatric Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (Ped-PRO-CTCAE) is an item library that enables children and caregivers to self-report symptoms. Ten symptom items from the Ped-PRO-CTCAE were uploaded to an online platform. Patients at least 7 years old and their caregivers were prompted by text/email message to electronically self-report daily during a planned hospitalization for chemotherapy administration. Symptom reports were emailed to the clinical team caring for the patient, but no instructions were given regarding the use of this information. Rates of patient participation and clinician responses to reports were systematically tracked. Results: The median age of the participating patients (n = 52) was 11 years (range, 7-18 years). All patients and caregivers completed an initial login, with 92% of dyads completing at least 1 additional symptom assessment during hospitalization (median, 3 assessments; range, 0-40). Eighty-one percent of participating dyads submitted symptom reports on at least half of hospital days, and 54% submitted reports on all hospital days. Clinical actions were taken in response to symptom reports 21% of the time. Most patients felt that the system was easy (73%) and important (79%). Most clinicians found symptom reports easy to understand and useful (97%). Conclusions: Symptom monitoring using patient-reported outcome measures for hospitalized pediatric oncology patients is feasible and generates data valued by clinicians and patients

Full reduction of large finite random Ising systems by RSRG

We describe how to evaluate approximately various physical interesting quantities in random Ising systems by direct renormalization of a finite system. The renormalization procedure is used to reduce the number of degrees of freedom to a number that is small enough, enabling direct summing over the surviving spins. This procedure can be used to obtain averages of functions of the surviving spins. We show how to evaluate averages that involve spins that do not survive the renormalization procedure. We show, for the random field Ising model, how to obtain the "connected" 2-spin correlation function and the "disconnected" 2-spin correlation function. Consequently, we show how to obtain the average susceptibility and the average energy. For an Ising system with random bonds and random fields we show how to obtain the average specific heat. We conclude by presenting our numerical results for the average susceptibility and the "connected" 2-spin correlation function along one of the principal axes. (We believe this to be the first time, where the full three dimensional correlation is calculated and not just parameters like Nu or Eta.) The results for the average susceptibility are used to extract the critical temperature and critical exponents of the 3D random field Ising system.Comment: 30 pages, 17 figure

Alfv\'en Reflection and Reverberation in the Solar Atmosphere

Magneto-atmospheres with Alfv\'en speed [a] that increases monotonically with height are often used to model the solar atmosphere, at least out to several solar radii. A common example involves uniform vertical or inclined magnetic field in an isothermal atmosphere, for which the Alfv\'en speed is exponential. We address the issue of internal reflection in such atmospheres, both for time-harmonic and for transient waves. It is found that a mathematical boundary condition may be devised that corresponds to perfect absorption at infinity, and, using this, that many atmospheres where a(x) is analytic and unbounded present no internal reflection of harmonic Alfv\'en waves. However, except for certain special cases, such solutions are accompanied by a wake, which may be thought of as a kind of reflection. For the initial-value problem where a harmonic source is suddenly switched on (and optionally off), there is also an associated transient that normally decays with time as O(t-1) or O(t-1 ln t), depending on the phase of the driver. Unlike the steady-state harmonic solutions, the transient does reflect weakly. Alfv\'en waves in the solar corona driven by a finite-duration train of p-modes are expected to leave such transients.Comment: Accepted by Solar Physic

Rare charm meson decays D->Pl^+l^- and c->ul^+l^- in SM and MSSM

We study the nine possible rare charm meson decays D->Pl^+l^- (P=pi,K,eta,eta') using the Heavy Meson Chiral Lagrangians and find them to be dominated by the long distance contributions. The decay D^+ -> pi^+l^+l^- with the branching ratio 1*10^(-6) is expected to have the best chances for an early experimental discovery. The short distance contribution in the five Cabibbo suppressed channels arises via the c->ul^+l^- transition; we find that this contribution is detectable only in the D->pi l^+l^- decay, where it dominates the differential spectrum at high-q^2. The general Minimal Supersymmetric Standard Model can enhance the c->ul^+l^- rate by up to an order of magnitude; its effect on the D->Pl^+l^- rates is small since the c->ul^+l^- enhancement is sizable in low-q^2 region, which is inhibited in the hadronic decay.Comment: 17 page

Alterações psiquiátricas e qualidade de vida em pacientes com homocistinúria clássica

Caracterizar o quadro psiquiátrico e a qualidade de vida (QoL) em uma coorte de pacientes com Homocistinúria Clássica (HCU). Métodos: estudo transversal, através da aplicação das escalas BPRS, Escala de Ansiedade de Beck, Escala de Depressão de Hamilton e Escala de Depressão de Beck (BDI) em 8 pacientes não responsivos à piridoxina e estudo retrospectivo avaliando qualidade de vida por meio da aplicação do questionário WHOQOL-Brief em 11 pacientes com HCU. Resultados: 5 pacientes avaliados apresentaram sintomas de depressão mínimos, 2 pacientes apresentaram sintomas leves, e 1 paciente sintomas moderados a graves. Para ansiedade, 5 pacientes apresentaram sintomas mínimos, 1 paciente apresentou sintomas leves e 2 pacientes apresentaram sintomas moderados. Cinco pacientes apresentaram algum sintoma relacionado à esquizofrenia. Em relação a QoL, todos pacientes apresentaram diagnóstico tardio e apenas 2 tinham QI>70 (Teste WASI). Os pacientes responsivos à piridoxina foram comparados com os não responsivos à piridoxina mostrando melhor pontuação nos aspectos psicológicos e sociais no primeiro grupo. Os 2 pacientes com tratamento foram comparados com os 9 sem tratamento mostrando um melhor escore no aspecto psicológico no primeiro grupo. Conclusão: este é o primeiro estudo que descreve QoL em pacientes HCU, mostrando uma diferença no aspecto psicológico e social, conforme o tipo de tratamentoFil: Donis, Karina C. Universidade Federal do Rio Grande do Sul (Brasil).Fil: Kalil, Marco A.B. Universidade Federal do Rio Grande do Sul (Brasil).Fil: Perrone, Solanger G. Universidade Federal do Rio Grande do Sul (Brasil).Fil: Teruya, Kátia. Universidade Federal do Rio Grande do Sul (Brasil).Fil: Vanz, Ana P. Universidade Federal do Rio Grande do Sul (Brasil).Fil: Vairo, Filippo P. Universidade Federal do Rio Grande do Sul (Brasil).Fil: Schwartz, Ida V.D. Universidade Federal do Rio Grande do Sul (Brasil)

Fuzzy cluster validation using the partition negentropy criterion

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-04277-5_24Proceedings of the 19th International Conference, Limassol, Cyprus, September 14-17, 2009We introduce the Partition Negentropy Criterion (PNC) for cluster validation. It is a cluster validity index that rewards the average normality of the clusters, measured by means of the negentropy, and penalizes the overlap, measured by the partition entropy. The PNC is aimed at finding well separated clusters whose shape is approximately Gaussian. We use the new index to validate fuzzy partitions in a set of synthetic clustering problems, and compare the results to those obtained by the AIC, BIC and ICL criteria. The partitions are obtained by fitting a Gaussian Mixture Model to the data using the EM algorithm. We show that, when the real clusters are normally distributed, all the criteria are able to correctly assess the number of components, with AIC and BIC allowing a higher cluster overlap. However, when the real cluster distributions are not Gaussian (i.e. the distribution assumed by the mixture model) the PNC outperforms the other indices, being able to correctly evaluate the number of clusters while the other criteria (specially AIC and BIC) tend to overestimate it.This work has been partially supported with funds from MEC BFU2006-07902/BFI, CAM S-SEM-0255-2006 and CAM/UAM project CCG08-UAM/TIC-442

Branching Fractions for D0 -> K+K- and D0 -> pi+pi-, and a Search for CP Violation in D0 Decays

Using the large hadroproduced charm sample collected in experiment E791 at Fermilab, we have measured ratios of branching fractions for the two-body singly-Cabibbo-suppressed charged decays of the D0: (D0 -> KK)/(D0 -> Kpi) = 0.109 +- 0.003 +- 0.003, (D0 -> pipi)/(D0 -> Kpi) = 0.040 +- 0.002 +- 0.003, and (D0 -> KK)/(D0 -> pipi) = 2.75 +- 0.15 +- 0.16. We have looked for differences in the decay rates of D0 and D0bar to the CP eigenstates K+K- and pi+pi-, and have measured the CP asymmetry parameters A_CP(K+K-) = -0.010 +- 0.049 +- 0.012 and A_CP(pi+pi-) = -0.049 +- 0.078 +- 0.030, both consistent with zero.Comment: 10 Postscript pages, including 2 figures. Submitted to Phys. Lett.

Asymmetries between the production of D+ and D- mesons from 500 GeV/c pi- nucleon interactions as a function of xF and pt**2

We present asymmetries between the production of D+ and D- mesons in Fermilab experiment E791 as a function of xF and pt**2. The data used here consist of 74,000 fully-reconstructed charmed mesons produced by a 500 GeV/c pi- beam on C and Pt foils. The measurements are compared to results of models which predict differences between the production of heavy-quark mesons that have a light quark in common with the beam (leading particles) and those that do not (non-leading particles). While the default models do not agree with our data, we can reach agreement with one of them, PYTHIA, by making a limited number of changes to parameters used

Search for CP Violation in Charged D Meson Decays

We report results of a search for CP violation in the singly Cabibbo-suppressed decays D+ -> K- K+ pi+, phi pi+, K*(892)0 K+, and pi- pi+ pi+ based on data from the charm hadroproduction experiment E791 at Fermilab. We search for a difference in the D+ and D- decay rates for each of the final states. No evidence for a difference is seen. The decay rate asymmetry parameters A(CP), defined as the difference in the D+ and D- decay rates divided by the sum of the decay rates, are measured to be: A(CP)(K K pi) = -0.014 +/- 0.029, A(CP)(phi pi) = -0.028 +/- 0.036, A(CP)(K*(892) K) = -0.010 +/- 0.050, and A(CP)(pi pi pi) = -0.017 +/- 0.042.Comment: 13 pages, 5 figures, 1 table; Elsevier LaTe