Value of clinical factors in selecting postmenopausal women with rheumatoid arthritis for bone densitometry.

Criteria to decide which patients with rheumatoid arthritis (RA) should be examined by dual energy x ray absorptiometry (DXA) are currently not available. The rheumatologists from Amsterdam have proposed preliminary criteria based on clinical risk factors (age, disease activity, and functional status). These criteria are preliminary and not widely accepted but might be helpful in practice. The value of the proposal in a group of Spanish postmenopausal women with RA is analysed. METHODS DXA (lumbar spine and femoral neck) was performed in 128 patients recruited from a clinical setting, and the proposed criteria were applied. T and Z scores were established for a Spanish reference population. RESULTS The mean (SD) age of the patients was 61.3 (10.7) and mean duration of the postmenopausal period 14.5 (10.1) years. Mean duration of RA was 13.7 (7.7) years. Mean C reactive protein was 22 (21) mg/l; mean erythrocyte sedimentation rate 26 (18) mm/1st h; and mean Health Assessment Questionnaire score 1.25 (0.79). Ninety (70%) patients fulfilled the proposed criteria. Their sensitivity for the diagnosis of osteoporosis (T score ¿¿2.5 SD) was 86% and their specificity, 43%. Positive predictive value was 54% and negative predictive value, 79%. CONCLUSIONS The proposed criteria seem a good screening method for the selection of those patients with RA whose bone mineral density should be assessed as the sensitivity and negative predictive value are acceptable.

Point-occurrence self-similarity in crackling-noise systems and in other complex systems

It has been recently found that a number of systems displaying crackling noise also show a remarkable behavior regarding the temporal occurrence of successive events versus their size: a scaling law for the probability distributions of waiting times as a function of a minimum size is fulfilled, signaling the existence on those systems of self-similarity in time-size. This property is also present in some non-crackling systems. Here, the uncommon character of the scaling law is illustrated with simple marked renewal processes, built by definition with no correlations. Whereas processes with a finite mean waiting time do not fulfill a scaling law in general and tend towards a Poisson process in the limit of very high sizes, processes without a finite mean tend to another class of distributions, characterized by double power-law waiting-time densities. This is somehow reminiscent of the generalized central limit theorem. A model with short-range correlations is not able to escape from the attraction of those limit distributions. A discussion on open problems in the modeling of these properties is provided.

Kriging coordinates: what does that mean?

Kriging is an interpolation technique whose optimality criteria are based on normality assumptions either for observed or for transformed data. This is the case of normal, lognormal and multigaussian kriging.When kriging is applied to transformed scores, optimality of obtained estimators becomes a cumbersome concept: back-transformed optimal interpolations in transformed scores are not optimal in the original sample space, and vice-versa. This lack of compatible criteria of optimality induces a variety of problems in both point and block estimates. For instance, lognormal kriging, widely used to interpolate positivevariables, has no straightforward way to build consistent and optimal confidence intervals for estimates.These problems are ultimately linked to the assumed space structure of the data support: for instance, positive values, when modelled with lognormal distributions, are assumed to be embedded in the whole real space, with the usual real space structure and Lebesgue measure

Subsampling the mean of heavy-tailed dependent observations

We establish the validity of subsampling confidence intervals for themean of a dependent series with heavy-tailed marginal distributions.Using point process theory, we study both linear and nonlinear GARCH-liketime series models. We propose a data-dependent method for the optimalblock size selection and investigate its performance by means of asimulation study.

Duality in mean-variance frontiers with conditioning information

Portfolio and stochastic discount factor (SDF) frontiers are usually regarded as dual objects, and researchers sometimes use one to answer questions about the other. However, the introduction of conditioning information and active portfolio strategies alters this relationship. For instance, the unconditional portfolio frontier in Hansen and Richard (1987) is not dual to the unconditional SDF frontier in Gallant, Hansen and Tauchen (1990). We characterise the dual objects to those frontiers, and relate them to the frontiers generated with managed portfolios, which are commonly used in empirical work. We also study the implications of a safe asset and other special cases.

Estudi i implantació de programari lliure

RESUM Actualment la majoria de nosaltres sabem de l’existència de molts programes lliures, però hem tenir clar que lliure no vol dir sempre programa gratuït. Tot i que a vegades sí que pot ser-ho, es té en compte molt més que això: és una manera de pensar i entendre el programari i al llarg dels anys ha generat tot un moviment social. Considerem que un programa lliure és aquell que garanteix als usuaris la llibertat per executar, copiar, distribuir, estudiar, canviar i millorar el codi programat, com molt bé defineixen les seves llibertats bàsiques. El programari lliure el podem trobar funcionant en ordinadors personals, escoles, empreses diverses, administracions, etc. ja que la majoria de programes que utilitzen actualment, com hem vist, tenen el seu equivalent en lliure. El fet de si és viable que una empresa es passi a programari lliure, depèn ben bé del seu entorn, ja que en funció d’aquest li serà més o menys fàcil la migració. La finalitat d’aquest projecte és, primer de tot, fer un ampli estudi del món del programari lliure i del seu moviment social. S’ha fet una recerca de diferents aspectes dins del programari lliure per conèixer-lo a fons i després s’ha proposat una possible implantació d’aquest en un usuari domèstic i en una administració pública, tenint en compte tots els aspectes vistos en l’estudi, valorant si totes les idees que defensa i els beneficis que aporta són aplicables i viables en qualsevol persona i àmbit i el perquè. Com a conclusió principal en destacaria que tot i que el programa lliure disposa d’una ideologia que agrada i té uns programes tècnicament perfectes (sense que això sigui el seu objectiu principal), penso que encara hi ha molt camí per recórrer quant a una migració en grans entorns, ja que per exemple en un ajuntament una migració total és encara difícil (tot i que no impossible perquè n’hi ha que s’hi han migrat). A l’apartat d’annexos s’hi inclou un glossari amb un seguit de terminologies amb paraules que no tothom pot saber i s’ha cregut oportú incloure-les en aquest apartat. La primera vegada que apareix alguna d’aquestes paraules la podem trobar senyalitzada amb un *.

Modeling premartensitic effects in Ni2MnGa: A mean-field and Monte Carlo simulation study

ic first-order transition line ending in a critical point. This critical point is responsible for the existence of large premartensitic fluctuations which manifest as broad peaks in the specific heat, not always associated with a true phase transition. The main conclusion is that premartensitic effects result from the interplay between the softness of the anomalous phonon driving the modulation and the magnetoelastic coupling. In particular, the premartensitic transition occurs when such coupling is strong enough to freeze the involved mode phonon. The implication of the results in relation to the available experimental data is discussed.

Mean field model for spatially extended systems in the presence of multiplicative noise

We present a mean field model that describes the effect of multiplicative noise in spatially extended systems. The model can be solved analytically. For the case of the phi4 potential it predicts that the phase transition is shifted. This conclusion is supported by numerical simulations of this model in two dimensions.

Warranties used as a mean to promote commercial FOSS

From a business standpoint, this paper describes the point of view on the question of warranties of a FOSS editor doing business in a risk-averse market segment. It is based on 15-years experience of AdaCore in the safety-critical embedded industry. However, it is not only the point of view of a provider, as it also aims at demonstrating that the interests of providers and users are aligned in this area. From a legal point of view, the enforceability of these warranties will be partly covered, as well as the articulation between the license and the warranties on one hand, and the articulation between the license and the other contracts that can be created in a business relationship on the other hand.

Short communication. Persistence of point crop yield subjective estimates

En este trabajo se investiga la persistencia de las estimaciones puntuales subjetivas de rendimientos en cultivos anua- les realizadas por un amplio grupo de agricultores. La persistencia en el tiempo es una condición necesaria para la co- herencia y la confiabilidad de las estimaciones subjetivas de variables aleatorias. Los sujetos entrevistados estimaron valores puntuales de rendimientos de cultivos anuales (rendimientos medio, mayor, mínimo y más frecuente). Se han encontrado diferencias relativas poco importantes en todas las variables, excepto en los rendimientos mínimos, donde existe una alta dispersión. Los resultados son interesantes para estimar la adecuación de las técnicas de estimación de probabilidades subjetivas para ser utilizadas en los sistemas de ayuda en la toma de decisiones en agricultura.

Endosseous dental implant fractures an analysis of 21 cases

Implant fracture is an infrequent cause of implant failure. The present study evaluates 21 fractured implants, with an analysis of patient age and sex, the type, length and diameter of the implant, positioning in the dental arch, the type of prosthetic rehabilitation involved, the number of abutments and pontics, the presence or absence of distal extensions or cantilevers, and loading time to fracture. Implant fracture was more common in males than in females (15:4), and the mean patient age was 56.9 years. Most cases (n = 19) corresponded to implant-supported fixed prostheses - 16 with cantilevers of different lengths- while only two fractured implants were supporting overdentures instead of fixed prostheses. The great majority of fractured implants (80.9%) were located in the molar and premolar regions, and most fractured within 3-4 years after loading. It is important to know and apply the measures required to prevent implant fracture, and to seek the best individualized solution for each case - though complete implant removal is usually the treatment of choice

Traumatic bone cyst: a retrospective study of 21 cases

Objective: To describe the clinical and radiological characteristics, and surgical findings of traumatic bone cysts. Study Design: A retrospective observational study was made of 21 traumatic bone cysts. The diagnosis was based on the anamnesis, clinical examination, and complementary tests. Panoramic and periapical X-rays were obtained in all cases, together with computed tomography as decided by the surgeon. A descriptive statistical analysis was made of the study variables using the SPSS v12.0 for Windows. Results: There was a clear female predominance (14:7). The mean age was 26.5 years (range 8-45 years). The cysts in all cases constituted casual findings during routine radiological exploration. In those cases where computed tomographic images were available, preservation of the vestibular and lingual cortical layers was observed. Five of the 21 patients (23.8%) reported a clear antecedent of traumatism in the affected zone. All the lesions were subjected to surgery, and the cavities were found to be vacant in 90.5% of the cases. In only two patients were vascular contents seen within the cavity. Two of the patients presented postoperative paresthesia of the inferior dental nerve that subsided within two weeks. The 19 patients in whom adequate postoperative follow-up proved possible all showed complete bone healing. Conclusions: Traumatic bone cysts were a casual finding. During the surgery, most cases showed to be vacant cavity without an ephitelial lining. Careful curettage of the lesion favors progressive bone regeneration, offering a good prognosis and an almost negligible relapse rate. Other treatment options only would be justified in cases of relapse.

Estudi i implantació de programari lliure

Actualment la majoria de nosaltres sabem de l’existència de molts programes lliures, però hem tenir clar que lliure no vol dir sempre programa gratuït. Tot i que a vegades sí que pot ser-ho, es té en compte molt més que això: és una manera de pensar i entendre el programari i al llarg dels anys ha generat tot un moviment social. Considerem que un programa lliure és aquell que garanteix als usuaris la llibertat per executar, copiar, distribuir, estudiar, canviar i millorar el codi programat, com molt bé defineixen les seves llibertats bàsiques. El programari lliure el podem trobar funcionant en ordinadors personals, escoles, empreses diverses, administracions, etc. ja que la majoria de programes que utilitzenactualment, com hem vist, tenen el seu equivalent en lliure. El fet de si és viable que una empresa es passi a programari lliure, depèn ben bé del seu entorn, ja que en funció d’aquest li serà més o menys fàcil la migració. La finalitat d’aquest projecte és, primer de tot, fer un ampli estudi del món del programari lliure i del seu moviment social. S’ha fet una recerca de diferents aspectes dins del programari lliure per conèixer-lo a fons i després s’ha proposat una possible implantació d’aquest en un usuari domèstic i en una administració pública, tenint en compte tots els aspectes vistos en l’estudi, valorant si totes les idees que defensa i els beneficis que aporta són aplicables i viables en qualsevol persona i àmbit i el perquè. Com a conclusió principal en destacaria que tot i que el programa lliure disposa d’una ideologia que agrada i té uns programes tècnicament perfectes (sense que això sigui el seu objectiu principal), penso que encara hi ha molt camí per recórrer quant a una migració en grans entorns, ja que per exemple en un ajuntament una migració total és encara difícil (tot i que no impossible perquè n’hi ha que s’hi han migrat). A l’apartat d’annexos s’hi inclou un glossari amb un seguit de terminologies amb paraules que no tothom pot saber i s’ha cregut oportú incloure-les en aquest apartat. La primera vegada que apareix alguna d’aquestes paraules la podem trobar senyalitzada amb un *.