SUSY Enhancements in (0,4) Deformations of AdS_3/CFT_2

We discuss a marginal deformation of the SL(2,R) x SU(2) x U(1)^4 WZW model, which describes string theory on AdS_3 x S^3 x T^4, that corresponds to warping the S^3 factor. This deformation breaks part of the N=(4,4) supersymmetry of the undeformed dual CFT to N=(0,4) supersymmetry. In the spirit of work by Giveon, Kutasov, and Seiberg, we construct the asymptotic spacetime symmetry algebra from worldsheet operators and find a restoration of (4,4) supersymmetry at discrete values of the deformation parameter. We explain this result from various perspectives: the worldsheet, supergravity, and from the singular D1-D5 CFT. The supergravity analysis includes an asymptotic symmetry computation of the level of the affine SU(2) R-symmetry, which arises purely from B-field contributions.Comment: 16 pages; v2: references adde

FORECAST OF THE EXPECTED NON-EPIDEMIC MORBIDITY OF ACUTE DISEASES USING RESAMPLING METHODS

In epidemiological surveillance it is important that any unusual increase of reported cases be detected as rapidly as possible. Reliable forecasting based on a suitable time series model for an epidemiological indicator is necessary for estimating the expected non-epidemic indicator and to elaborate an alert threshold. Time series analysis of acute diseases often use Gaussian autoregressive integrated moving average models. However, these approaches could be adversely affected by departures from the true underlying distribution. The objective of this paper is to introduce a bootstrap procedure for obtaining prediction intervals in linear models in order to avoid the normality assumption. We present a Monte Carlo study comparing the finite sample properties of the bootstrap prediction intervals with those of alternative methods. Finally, we illustrate the performance of the proposed method with a meningococcal disease incidence series.

INTRODUCING MODEL UNCERTAINTY IN TIME SERIES BOOTSTRAP

It is common in parametric bootstrap to select the model from the data, and then treat it as it were the true model. Kilian (1998) have shown that ignoring the model uncertainty may seriously undermine the coverage accuracy of bootstrap confidence intervals for impulse response estimates which are closely related with multi-step-ahead prediction intervals. In this paper, we propose different ways of introducing the model selection step in the resampling algorithm. We present a Monte Carlo study comparing the finite sample properties of the proposed method with those of alternative methods in the case of prediction intervals.

Transient tunneling effects of resonance doublets in triple barrier systems

Transient tunneling effects in triple barrier systems are investigated by considering a time-dependent solution to the Schr\"{o}dinger equation with a cutoff wave initial condition. We derive a two-level formula for incidence energies $E$ near the first resonance doublet of the system. Based on that expression we find that the probability density along the internal region of the potential, is governed by three oscillation frequencies: one of them refers to the well known Bohr frequency, given in terms of the first and second resonance energies of the doublet, and the two others, represent a coupling with the incidence energy $E$. This allows to manipulate the above frequencies to control the tunneling transient behavior of the probability density in the short-time regim

Predicting Medication Adherence Patterns During the Maintenance Phase of Treatment for Pediatric Leukemia and Lymphoma: A Model of Individual- and Family-Level Factors

Adherence during the maintenance phase of pediatric cancer treatment is critical to prevent relapse and ensure long-term, event-free survival. Yet, little research has been done to examine individual- and family-level factors that may relate to adherence during the maintenance phase of treatment, particularly among Latinx patients. This is surprising given findings demonstrating that children who miss more than 5% of their prescribed oral chemotherapy medicine, most commonly 6-mercaptopurine (6MP), are 2.5-2.7 times more likely to relapse than children who take 95% or more of their prescribed 6MP. Pediatric cancer patients face unique adherence challenges given the importance of family involvement in children’s care. As such, it is important to consider both individual- and family-level factors when examining adherence. Objective. Conducted a secondary data analysis to investigate individual- and family-level factors that may predict 6MP medication adherence patterns, in a multisite cohort of pediatric patients diagnosed with acute lymphoblastic leukemia (ALL) or lymphoblastic leukemia (LBL), in a sample that is 34% Latinx. Methods. Participants included 139 patients ages 7-19 years diagnosed with ALL or LBL, across six centers. Medication adherence was measured daily for 15 months using electronic monitoring of 6MP. At baseline, 6 months, and 15 months, participants reported on individual- (e.g., child depressive symptoms, caregiver depressive symptoms, child/adolescent health beliefs) and family-level (e.g., caregiver-child communication, younger children within the home) factors that might predict adherence patterns. Medical history was evaluated via standardized medical chart reviews at baseline, 6 months, 15 months, which included information on prescribed daily 6MP dose and duration of cancer diagnosis. Results. Results demonstrated characteristic differences between the adherence groups (e.g., age, dose, health beliefs). Results further indicated that developmental age group was the strongest predictor of medication adherence, such that youth in the middle-late adolescence age group were significantly more likely to be in the nonadherent group than youth in the preadolescent or early-middle adolescence age groups. Dosage and health beliefs, specifically positive outcome expectancy, also significantly predicted adherence group membership. Preliminary exploratory analyses indicate that predictors of adherence may differ between Latinx and non-Latinx, white patients. These results must be interpreted cautiously as the current study focused on outcomes rather than processes and social stratification. Furthermore, exploratory analyses indicated that adherence and quality of life were not significantly related in the current study, in either direction. Conclusions. Older adolescents may be at increased risk for nonadherence, which is an area of major concern warranting future research in this area. Findings also indicate that fostering positive outcome expectancy among youth at the start of maintenance phase may serve to enhance adherence during this phase of treatment. Future work examining adherence behaviors should continue to assess longitudinal individual, family, and medication-level factors

EXPLORING WHETHER CONTEXTUAL FACTORS RELATE TO THE HOPED-FOR AND FEARED POSSIBLE SELVES OF LATINX YOUTH

Youth’s hopes and fears for their future (i.e., hoped-for and feared possible selves) are related to their academic and health behavior outcomes. Much of the literature on possible selves focuses on African-American and European-American youth. In a sample of 132 Latinx youth, the present cross-sectional study utilized widely-used measures (i.e., Possible Selves Questionnaire, Beliefs about Education, Youth Risk Surveillance Survey) to identify the content and characteristics (e.g., strategies, balance) of their possible selves; investigate the relationship between contextual factors (e.g., sex, immigrant status) and possible selves; and, explore whether possible selves predicted youth’s beliefs about education and sexual risk behaviors. The most prevalent hoped-for selves were in the achievement and physical health domains, while the most prevalent feared selves were in the risky behavior and achievement domains. Culturally modifying balance was found to increase overall ratings of balance among youth’s selves. We also found that females reported more educational hoped-for selves and feared health selves than males, and that males reported more occupational feared selves than females. Moreover, youth in high school/GED programs reported more traditionally-coded balanced selves and more achievement and occupational hoped-for and feared possible selves than youth in middle school. Youth born outside of the U.S. (compared to youth born in the U.S.) reported more achievement feared selves and more balanced selves, when using modified coding. Finally, the total number of hoped-for possible selves positively predicted youth’s beliefs about education and traditionally-coded balance negatively predicted beliefs. Possible selves characteristics did not predict youth’s sexual risk behaviors

Contribución al conocimiento de la vegetación de las montañas marroquíes

Different types of plant communities, till now undetected in Morocco, are here described using the phytosociological method. The following new subassociations and associations are proposed: Anthyllido polycephalae-Stachydetum fontqueri subass. quercetosum rotundifoliae is a machia from the Northern Rif Mountains; Genisto anglicae-Ericetum ciliaris subsass. pinguiculetosum lusitanicae is a heathland from the Bou Hassim range in the Western Rif; Cephalario maroccanae-Inuletum maletii is a megaphorbic community from the Middle Atlas; Bellis caerulescendis-Heracletum sphondyllii is a megaphorbic community from the High Atlas; Arenario armerinae-Sideritetum matris-fillae is a high mountain grassland from the Tichchoukt range in the Middle Atlas. New data are given for the syntaxa already described but with the distribution, variability and ecology not well known. This is the case of the following associations: Polysticho setiferi-Prunetum lusitanicae, a riverine woodland from the W Rif Mountains; Primulo acaulis-Betuletum celtibericae, a birch woodland from the C Rif and Astragaletum numidico-maroccani a high mediterranean mountain plant community from the Western Rif. As a conclusion, the vegetation of the peculiar habitats that occur in reduced areas is only partially known.Se describe con la metodología fitosociológica diferentes tipos de comunidades vegetales, no detectadas hasta el presente en Marruecos. Se proponen las siguientes nuevas asociaciones y subasociaciones: Anthyllido polycephalae-Stachydetum fontqueri subass. quercetosum rotundifoliae corresponde a una maquia de las montañas septentrionales del Rif; Genisto anglicae-Ericetum ciliaris subsass. pinguiculetosum lusitanicae es un brezal del macizo de Bou Hassim en el Rif occidental; Cephalario maroccanae- Inuletum maletii es una formación de megaforbios del Atlas Medio; Bellis caerulescendis-Heracletum sphondyllii es una formación de megaforbios del Gran Atlas; Arenario armerinae-Sideritetum matris-filiae es un pastizal de alta montaña mediterránea del macizo de Tichchoukt en el Atlas Medio. Se aportan nuevos datos para otros sintáxones ya descritos pero con la distribución, variabilidad y ecología poco conocidas. Este es el caso de las asociaciones siguientes: Polysticho setiferi-Prunetum lusitanicae, bosquecillo ripario de las montañas del Rif occidental y central; Primulo acaulis-Betuletum celtibericae, corresponde a un bosque de abedules del Rif central, y Astragaletum numidico-maroccani es una comunidad de caméfitos de alta montaña mediterránea conocida hasta el presente del Rif occidental. Como conclusión se puede aseverar que la vegetación de los hábitats que ocupan áreas reducidas en las montañas marroquíes es conocida de forma parcial

Stereodivergent, Diels-Alder-initiated organocascades employing α,β-unsaturated acylammonium salts: scope, mechanism, and application.

Chiral α,β-unsaturated acylammonium salts are novel dienophiles enabling enantioselective Diels-Alder-lactonization (DAL) organocascades leading to cis- and trans-fused, bicyclic γ- and δ-lactones from readily prepared dienes, commodity acid chlorides, and a chiral isothiourea organocatalyst under mild conditions. We describe extensions of stereodivergent DAL organocascades to other racemic dienes bearing pendant secondary and tertiary alcohols, and application to a formal synthesis of (+)-dihydrocompactin is described. A combined experimental and computational investigation of unsaturated acylammonium salt formation and the entire DAL organocascade pathway provide a rationalization of the effect of Brønsted base additives and enabled a controllable, diastereodivergent DAL process leading to a full complement of possible stereoisomeric products. Evaluation of free energy and enthalpy barriers in conjunction with experimentally observed temperature effects revealed that the DAL is a rare case of an entropy-controlled diastereoselective process. NMR analysis of diene alcohol-Brønsted base interactions and computational studies provide a plausible explanation of observed stabilization of exo transition-state structures through hydrogen-bonding effects

Characterization of bathtub distributions via percentile residual life functions

In reliability theory and survival analysis, many set of data are generated by distributions with bathtub shaped hazard rate functions. Launer (1993) established several relations between the behaviour of the hazard rate function and the percentile residual life function. In particular, necessary conditions were given for a special type of bathtub distributions in terms of percentile residual life functions. The purpose of this paper is to complete the study initiated by Launer (1993) and to characterize (necessary and sufficient conditions) all types of bathtub distributions.Percentile residual life, Bathtub hazard rate, Aging notions,