A multi-color and Fourier study of RR Lyrae variables in the globular cluster NGC 5272 (M3)

We have performed a detailed study of the pulsational and evolutionary characteristics of 133 RR Lyrae stars in the globular cluster NGC5272 (M3) using highly accurate BVI data taken on 5 separate epochs. M3 seems to contain no less than ~32% of Blazhko stars, and the occurrence and characteristics of the Blazhko effect have been analyzed in detail. We have identified a good number (~ 14%) of overluminous RR Lyrae stars that are likely in a more advanced evolutionary stage off the Zero Age Horizontal Branch (ZAHB). Physical parameters (i.e. temperature, luminosity, mass) have been derived from (B--V) colors and accurate color-temperature calibration, and compared with Horizontal Branch evolutionary models and with the requirements of stellar pulsation theory. Additional analysis by means of Fourier decomposition of the V light curves confirms, as expected, that no metallicity spread is present in M3. Evolution off the ZAHB does not affect [Fe/H] determinations, whereas Blazhko stars at low amplitude phase do affect [Fe/H] distributions as they appear more metal-rich. Absolute magnitudes derived from Fourier coefficients might provide useful average estimates for groups of stars, if applicable, but do not give reliable {\em individual} values. Intrinsic colors derived from Fourier coefficients show significant discrepancies with the observed ones, hence the resulting temperatures and temperature-related parameters are unreliable.Comment: 86 pages, 19 figures, 13 tables, in press A

The Metallicity Dependence of the Fourier Components of RR Lyrae Light Curves is the Oosterhoff/Arp/Preston Period Ratio Effect in Disguise

The correlation of particular Fourier components of the light curves of RR Lyrae variables with metallicity, discovered by Simon and later by Kovacs and his coworkers, is shown to have the same explanation as the period ratios (period shifts in log P) between RRab Lyrae variables that have the same colors, amplitudes, and light-curve shapes but different metallicities. A purpose of this paper is to demonstrate that the model which predicts the period-metallicity relations is the mediating parameters of colors, amplitudes, and light-curve shapes also explains the Simon/Kovacs et al. correlation between period, Phi_31, and metallicity. The proof is made by demonstrating that the combination of the first and third phase terms in a Fourier decomposition of RRab light curves, called Phi_31 by Simon and Lee, varies monotonically across the RR Lyrae instability strip in the same way that amplitude, color, and rise time vary with period within the strip. The premise of the model is that if horizontal branches at the RR Lyrae strip are stacked in luminosity according to the metallicity, then there necessarily must be a log period shift between RR Lyraes with different metallicities at the same Phi_31 values. However, there are exceptions to the model. (...)Comment: 17 pages, 8 figures, 1 table. Accepted for publication in The A

Left ventricular heart failure and pulmonary hypertension

In patients with left ventricular heart failure (HF), the development of pulmonary hypertension (PH) and right ventricular (RV) dysfunction are frequent and have important impact on disease progression, morbidity, and mortality, and therefore warrant clinical attention. Pulmonary hypertension related to left heart disease (LHD) by far represents the most common form of PH, accounting for 65–80% of cases. The proper distinction between pulmonary arterial hypertension and PH-LHD may be challenging, yet it has direct therapeutic consequences. Despite recent advances in the pathophysiological understanding and clinical assessment, and adjustments in the haemodynamic definitions and classification of PH-LHD, the haemodynamic interrelations in combined post- and pre-capillary PH are complex, definitions and prognostic significance of haemodynamic variables characterizing the degree of pre-capillary PH in LHD remain suboptimal, and there are currently no evidence-based recommendations for the management of PH-LHD. Here, we highlight the prevalence and significance of PH and RV dysfunction in patients with both HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF), and provide insights into the complex pathophysiology of cardiopulmonary interaction in LHD, which may lead to the evolution from a ‘left ventricular phenotype’ to a ‘right ventricular phenotype’ across the natural history of HF. Furthermore, we propose to better define the individual phenotype of PH by integrating the clinical context, non-invasive assessment, and invasive haemodynamic variables in a structured diagnostic work-up. Finally, we challenge current definitions and diagnostic short falls, and discuss gaps in evidence, therapeutic options and the necessity for future developments in this context

Spatially controlled formation of superparamagnetic (Mn,Ga)As nanocrystals in high temperature annealed (Ga,Mn)As/GaAs superlattices

The annealing-induced formation of (Mn,Ga)As nanocrystals in (Ga,Mn)As/GaAs superlattices was studied by X-ray diffraction, transmission electron microscopy and magnetometry. The superlattice structures with 50 A thick (Ga,Mn)As layers separated by 25, 50 and 100 A thick GaAs spacers were grown by molecular beam epitaxy at low temperature (250 C), and then annealed at high temperatures of: 400, 560 and 630 C. The high temperature annealing causes decomposition to GaMnAs ternary alloy and formation of (Mn,Ga)As nanocrystals inside the GaAs matrix. The nanocrystals are confined in the planes that were formerly occupied by (Ga,Mn)As layers for up to the 560 C of annealing and diffuse throughout the GaAs spacer layers at 630 C annealing. The corresponding magnetization measurements show the evolution of the magnetic properties of as-grown and annealed samples from ferromagnetic, through superparamagnetic to the combination of both.Comment: 14 pages, 3 figure

Kovacs effects in an aging molecular liquid

We study by means of molecular dynamics simulations the aging behavior of a molecular model of ortho-terphenyl. We find evidence of a a non-monotonic evolution of the volume during an isothermal-isobaric equilibration process, a phenomenon known in polymeric systems as Kovacs effect. We characterize this phenomenology in terms of landscape properties, providing evidence that, far from equilibrium, the system explores region of the potential energy landscape distinct from the one explored in thermal equilibrium. We discuss the relevance of our findings for the present understanding of the thermodynamics of the glass state.Comment: RevTeX 4, 4 pages, 5 eps figure

Design Patterns for Description-Driven Systems

In data modelling, product information has most often been handled separately from process information. The integration of product and process models in a unified data model could provide the means by which information could be shared across an enterprise throughout the system lifecycle from design through to production. Recently attempts have been made to integrate these two separate views of systems through identifying common data models. This paper relates description-driven systems to multi-layer architectures and reveals where existing design patterns facilitate the integration of product and process models and where patterns are missing or where existing patterns require enrichment for this integration. It reports on the construction of a so-called description-driven system which integrates Product Data Management (PDM) and Workflow Management (WfM) data models through a common meta-model.Comment: 14 pages, 13 figures. Presented at the 3rd Enterprise Distributed Object Computing EDOC'99 conference. Mannheim, Germany. September 199

The Reification of Patterns in the Design of Description-Driven Systems

To address the issues of reusability and evolvability in designing self- describing systems, this paper proposes a pattern-based, object-oriented, description-driven system architecture. The proposed architecture embodies four pillars - first, the adoption of a multi-layered meta-modeling architecture and reflective meta-level architecture, second, the identification of four data modeling relationships that must be made explicit such that they can be examined and modified dynamically, third, the identification of five design patterns which have emerged from practice and have proved essential in providing reusable building blocks for data management, and fourth, the encoding of the structural properties of the five design patterns by means of one pattern, the Graph pattern. The CRISTAL research project served as the basis onto which the pattern-based meta-object approach has been applied. The proposed architecture allows the realization of reusability and adaptability, and is fundamental in the specification of self-describing data management components.Comment: 10 pages 11 figure

ICRF-159 enhancement of radiation response in combined modality therapies. I. Time/dose relationships for tumour response.

The combined effect of the chemotherapeutic agent ICRF-159 and irradiation were evaluated using the Lewis lung tumour (LL). At a daily dose of 25 mg/kg, ICOF given alone prevented the progressive growth of LL. Daily pretreatment also potentiated the effects of radiation (600 rad) on tumour growth, provided the pretreatment kinetics of the tumour permitted a response to radiation alone. Single acute doses of the drug failed to alter the growth of LL, and when combined with radiation failed to enhance the radiation effect. Fractionation of the drug (25 mg/kg; 4 doses at 3h intervals) before irradiation, however, results in immediate effects on tumour growth which are more than additive. The results suggest that a low dose of ICRF-159 for extended periods is more effective in enhancing radiotherapy than a high dose provided acutely