Adaptively weighted maximum likelihood estimation of discrete distributions

SummaryDiscrete data arise in various research fields, typically when the observations are count data.I propose a robust and efficient parametric procedure for estimation of discrete distributions. The estimation is done in two phases. First, a very robust, but possibly inefficient, estimate of the model parameters is computed and used to indentify outliers. Then the outliers are either removed from the sample or given low weights, and a weighted maximum likelihood estimate (WML) is computed.The weights are determined via an adaptive process such that if the data follow the model, then asymptotically no observation is downweighted.I prove that the final estimator inherits the breakdown point of the initial one, and that its influence function at the model is the same as the influence function of the maximum likelihood estimator, which strongly suggests that it is asymptotically fully efficient.The initial estimator is a minimum disparity estimator (MDE). MDEs can be shown to have full asymptotic efficiency, and some MDEs have very high breakdown points and very low bias under contamination. Several initial estimators are considered, and the performances of the WMLs based on each of them are studied.It results that in a great variety of situations the WML substantially improves the initial estimator, both in terms of finite sample mean square error and in terms of bias under contamination. Besides, the performances of the WML are rather stable under a change of the MDE even if the MDEs have very different behaviors.Two examples of application of the WML to real data are considered. In both of them, the necessity for a robust estimator is clear: the maximum likelihood estimator is badly corrupted by the presence of a few outliers.This procedure is particularly natural in the discrete distribution setting, but could be extended to the continuous case, for which a possible procedure is sketched.RésuméLes données discrètes sont présentes dans différents domaines de recherche, en particulier lorsque les observations sont des comptages.Je propose une méthode paramétrique robuste et efficace pour l'estimation de distributions discrètes. L'estimation est faite en deux phases. Tout d'abord, un estimateur très robuste des paramètres du modèle est calculé, et utilisé pour la détection des données aberrantes (outliers). Cet estimateur n'est pas nécessairement efficace. Ensuite, soit les outliers sont retirés de l'échantillon, soit des faibles poids leur sont attribués, et un estimateur du maximum de vraisemblance pondéré (WML) est calculé.Les poids sont déterminés via un processus adaptif, tel qu'asymptotiquement, si les données suivent le modèle, aucune observation n'est dépondérée.Je prouve que le point de rupture de l'estimateur final est au moins aussi élevé que celui de l'estimateur initial, et que sa fonction d'influence au modèle est la même que celle du maximum de vraisemblance, ce qui suggère que cet estimateur est pleinement efficace asymptotiquement.L'estimateur initial est un estimateur de disparité minimale (MDE). Les MDE sont asymptotiquement pleinement efficaces, et certains d'entre eux ont un point de rupture très élevé et un très faible biais sous contamination. J'étudie les performances du WML basé sur différents MDEs.Le résultat est que dans une grande variété de situations le WML améliore largement les performances de l'estimateur initial, autant en terme du carré moyen de l'erreur que du biais sous contamination. De plus, les performances du WML restent assez stables lorsqu'on change l'estimateur initial, même si les différents MDEs ont des comportements très différents.Je considère deux exemples d'application du WML à des données réelles, où la nécessité d'un estimateur robuste est manifeste : l'estimateur du maximum de vraisemblance est fortement corrompu par la présence de quelques outliers.La méthode proposée est particulièrement naturelle dans le cadre des distributions discrètes, mais pourrait être étendue au cas continu.

Tree line shifts in the Swiss Alps: Climate change or land abandonment?

Questions: Did the forest area in the Swiss Alps increase between 1985 and 1997? Does the forest expansion near the tree line represent an invasion into abandoned grasslands (ingrowth) or a true upward shift of the local tree line? What land cover / land use classes did primarily regenerate to forest, and what forest structural types did primarily regenerate? And, what are possible drivers of forest regeneration in the tree line ecotone, climate and/or land use change? Location: Swiss Alps. Methods: Forest expansion was quantified using data from the repeated Swiss land use statistics GEOSTAT. A moving window algorithm was developed to distinguish between forest ingrowth and upward shift. To test a possible climate change influence, the resulting upward shifts were compared to a potential regional tree line. Results: A significant increase of forest cover was found between 1650 to and 2450 m. Above 1650 m, 10% of the new forest areas were identified as true upward shifts whereas 90% represented ingrowth, and we identified both land use and climate change as likely drivers. Most upward shift activities were found to occur within a band of 300 m below the potential regional tree line, indicating land use as the most likely driver. Only 4% of the upward shifts were identified to rise above the potential regional tree line, thus indicating climate change. Conclusions: Land abandonment was the most dominant driver for the establishment of new forest areas, even at the tree line ecotone. However, a small fraction of upwards shift can be attributed to the recent climate warming, a fraction that is likely to increase further if climate continues to warm, and with a longer time-span between warming and measurement of forest cover.

The Effect Of Induced Intraocular Straylight (cataract Simulation) On Sensitivity Measures Of Standard Automated Perimetry, Pulsar Perimetry And Moorfields Motion Displacement Test

Purpose: To investigate the effect of incremental increases in intraocular straylight on threshold measurements made by three modern forms of perimetry: Standard Automated Perimetry (SAP) using Octopus (Dynamic, G-Pattern), Pulsar Perimetry (PP) (TOP, 66 points) and the Moorfields Motion Displacement Test (MDT) (WEBS, 32 points).Methods: Four healthy young observers were recruited (mean age 26yrs [25yrs, 28yrs]), refractive correction [+2 D, -4.25D]). Five white opacity filters (WOF), each scattering light by different amounts were used to create incremental increases in intraocular straylight (IS). Resultant IS values were measured with each WOF and at baseline (no WOF) for each subject using a C-Quant Straylight Meter (Oculus, Wetzlar, Germany). A 25 yr old has an IS value of ~0.85 log(s). An increase of 40% in IS to 1.2log(s) corresponds to the physiological value of a 70yr old. Each WOFs created an increase in IS between 10-150% from baseline, ranging from effects similar to normal aging to those found with considerable cataract. Each subject underwent 6 test sessions over a 2-week period; each session consisted of the 3 perimetric tests using one of the five WOFs and baseline (both instrument and filter were randomised).Results: The reduction in sensitivity from baseline was calculated. A two-way ANOVA on mean change in threshold (where subjects were treated as rows in the block and each increment in fog filters was treated as column) was used to examine the effect of incremental increases in straylight. Both SAP (p<0.001) and Pulsar (p<0.001) were significantly affected by increases in straylight. The MDT (p=0.35) remained comparatively robust to increases in straylight.Conclusions: The Moorfields MDT measurement of threshold is robust to effects of additional straylight as compared to SAP and PP.

Assessment of distribution and evolution of mechanical dyssynchrony in a porcine model of myocardial infarction by cardiovascular magnetic resonance.

BACKGROUND: We sought to investigate the relationship between infarct and dyssynchrony post- myocardial infarct (MI), in a porcine model. Mechanical dyssynchrony post-MI is associated with left ventricular (LV) remodeling and increased mortality. METHODS: Cine, gadolinium-contrast, and tagged cardiovascular magnetic resonance (CMR) were performed pre-MI, 9 ± 2 days (early post-MI), and 33 ± 10 days (late post-MI) post-MI in 6 pigs to characterize cardiac morphology, location and extent of MI, and regional mechanics. LV mechanics were assessed by circumferential strain (eC). Electro-anatomic mapping (EAM) was performed within 24 hrs of CMR and prior to sacrifice. RESULTS: Mean infarct size was 21 ± 4% of LV volume with evidence of post-MI remodeling. Global eC significantly decreased post MI (-27 ± 1.6% vs. -18 ± 2.5% (early) and -17 ± 2.7% (late), p < 0.0001) with no significant change in peri-MI and MI segments between early and late time-points. Time to peak strain (TTP) was significantly longer in MI, compared to normal and peri-MI segments, both early (440 ± 40 ms vs. 329 ± 40 ms and 332 ± 36 ms, respectively; p = 0.0002) and late post-MI (442 ± 63 ms vs. 321 ± 40 ms and 355 ± 61 ms, respectively; p = 0.012). The standard deviation of TTP in 16 segments (SD16) significantly increased post-MI: 28 ± 7 ms to 50 ± 10 ms (early, p = 0.012) to 54 ± 19 ms (late, p = 0.004), with no change between early and late post-MI time-points (p = 0.56). TTP was not related to reduction of segmental contractility. EAM revealed late electrical activation and greatly diminished conduction velocity in the infarct (5.7 ± 2.4 cm/s), when compared to peri-infarct (18.7 ± 10.3 cm/s) and remote myocardium (39 ± 20.5 cm/s). CONCLUSIONS: Mechanical dyssynchrony occurs early after MI and is the result of delayed electrical and mechanical activation in the infarct.

An alternative socio-ecological strategy? International Trade Unions' engagement with climate change

In the context of a global ecological crisis, it is an important move when trade unions turn to environmentalism. Yet, the form that this environmentalism takes is often overlooked. This is especially the case with international trade unions. Based on an empirical study of international trade unions' engagement with the climate change issue, this article argues that international trade unions follow three different (and partially conflicting) strategies. I label these strategies as 'deliberative', 'collaborative growth' and 'socialist', and I examine each in turn. I argue that such analysis is important if we want to identify the potential for transforming the social relations of production that are at the root of the current climate crisis, and for identifying an alternative socio-ecological strategy.

Droits du patient: ce que le nouveau Code civil va modifier dans les soins aux enfants [Patients' rights: what the new swiss civil code will change in the health care of children].

Recent progress in medicine allow to provide treatment, to cure or to extend the lifespan of people that would have not survived before. Doctors and healthcare providers have become indispensable actors in Western societies. This is particularly true for children's health issues. With the new information technologies, knowledge is now available to everyone, which enables patients to dialog on an equal footing with the physician. Nowadays, therapeutic choices are discussed and negotiated. The new tensions caused by this relationship between therapist and patient have created the need for new regulations. The Swiss Confederation has modified its Civil Code with the objective of a better protection of vulnerable individuals. This article summarizes the consequences of the new regulations with regard to the care and treatment provided to children.

Functional significance of first metatarso-phalangeal joint arthrodesis : FM101

Introduction: Indications for arthrodesis of the first metatarsophalangeal joint (MTP1) are commonly arthrosis (hallux rigidus), rheumatoid arthritis, failed hallux valgus surgery, severe hallux valgus, infectious arthritis, fractures and neuroarthropathies. Many reports focus on technical and radiological issues but few studies emphasize the functional outcome considering daily activities, sports and expectation of the patient. Method: We retrospectively reviewed the patients who underwent MTP1-arthrodesis from 2002 to 2005 in our institution. Clinical and radiological results were assessed but we specially focussed on the functional outcome. Scoring systems used were the SF-12, EQ-5D, PASI, FFI and AOFAS (10 points given to MTP1 mobility) scales. Results: 61 of 64 consecutive patients were evaluated. Female to male ratio was 49:15, mean age at surgery was 67 years, the average follow up was 29 month. Even if radiological consolidation was incomplete in 18 patients, all patients had a clinically stable and rigid arthrodesis. Mean AOFAS score was 87 (24-100) points at follow up. The FFI was 5.91% (0-66%). Patient satisfaction was excellent in 37 patients (60%), good in 18 (30%), fair in 5(8%) and poor in1 (2%). EQ- 5D was 0.7 (0.4-1).40 patients (66%) estimated their cosmetic result as excellent, 15 (25%) as good, 4(6%) as fair and 2 (3%)as poor. 10 patients (16%) had no shoe wear limitation , 48 (79%) had to wear comfortable shoes and 3 (5%) needed orthopaedic wearing. Professionally 34 patients (56%) had better performances, 18 (26%) had no change and 9 (18%) had aggravation of their capacities but this was due to other health reasons. In sports, 16 patients (26%) had better performances, 35 patients (57%) no change and 10 (17%) were worse as consequence of other health problems for 7. Finally, 56 patients (92%) would recommend the operation and 5 (8%) would not. Conclusion: Experience of clinical practice suggests that the idea of fusing the first MTP joint is initially frequently disregarded by the patients because they fear to be limited by a rigid forefoot. Our results show, in fact, that this procedure can be proposed for numerous pathological situations with the perspective of good to excellent outcome in terms of function and quality of life in the majority of cases.

Change in defense mechanisms and coping over the course of short-term dynamic psychotherapy for adjustment disorder.

Short-term dynamic psychotherapy (STDP) has rarely been investigated with regard to its underlying mechanisms of change, even if psychoanalytic theory informs us about several potential putative mechanisms of change in patients. Change in overall defensive functioning is one. In this study, we explored the role of overall defensive functioning, by comparing it on the process level with the neighbouring concept of overall coping functioning. A total of N=32 patients, mainly presenting adjustment disorder, were included in the study. The patients underwent STDP up to 40 sessions; three sessions per psychotherapy were transcribed and analyzed by using two observer-rating scales: Defense Mechanism Rating Scales (Perry, 1990) and Coping Action Patterns (Perry, Drapeau, Dunkley, & Blake, 2005). Hierarchical linear modeling was applied to model the change over the course of therapy and relate it to outcome. Results suggest that STDP has an effect on the target variable of overall defensive functioning, which was absent for overall coping functioning. Links with outcome confirm the importance of the effect. These results are discussed from methodological and clinical viewpoints.

La psychologie d'Aristote chez Freud : essai de psychologie comparée

VEsquisse (1895) ainsi que le chapitre VII de L'interprétation du rêve (1900) de Freud offrent un modèle psychologique - sous-jacent à toute la psychanalyse élaborée par la suite - qui présente des analogies frap¬pantes avec les conceptions aristotéliciennes sur la psyché, principalement développées dans le De l'âme et les Petits traités d'histoire naturelle. Ceci peut se comprendre entre autres par le fait que les seuls cours uni¬versitaires de psychologie et de philosophie que Freud fréquenta, parallèlement à ses études de médecine, furent ceux du théologien, psychologue et philosophe Franz Brentano, grand spécialiste d'Aristote, dont l'impact de l'enseignement sur le jeune Freud est aujourd'hui mieux connu grâce à son échange épistolaire, au début de ses études, avec son ancien ami de gymnase Eduard Silberstein. En effet, plus d'un élément du paradigme psychologique aristotélicien, qui chez cet auteur s'ancre dans la biologie, semblent trouver écho chez Freud : ainsi, la génération de diverses sortes de représentation au sein de l'appareil psychique par l'investissement des traces mnésiques, chez Freud, fait penser à la production ât phantâsmata dans l'âme, par le travail de la phantasîa sur les mouvements résiduels de la perception sensorielle, chez Aristote. De là, ce sont autant le fonctionnement mnésique, que l'explication des phénomènes du rêve et de l'hallucination, que la compréhension du désir dans sa capacité de mettre en mouvement le vivant animé (c'est-à-dire un être doté d'une âme) qui vont représenter les points d'articulation de cette comparaison. -- The Project for a Scientific Psychology (1895) as well as Chapter VII of Freud's Interpretation of Dreams (1900) offer a psychological model - underlying the entire psychoanalysis developed hereafter - which is strikingly similar to Aristotelian conceptions of the psyche in On the Soul and Little Physical Treatises. One explanation may be that the only lectures in psychology and philosophy that Freud attended at university, alongside lectures in medicine, were given by the theologist, psychologist, and philosopher Franz Brentano, who had a deep knowledge of Aristotle. Because of young Freud's correspondence with his high school friend Eduard Silberstein at the beginning of his studies, the influence of Brentano's teachings on Freud is now better known. Indeed, much of the Aristotelian psychological paradigm - rooted in biology - seems to echo in Freud's writings. Thus, the production of various sorts of representations within the psychic apparatus by means of the investment in memory traces in Freud's model evokes the phantâsmata generated in the soul by the action of phantasîa on the residual movements of the sensory perception in Aristotle's psychology. From there, this comparison will hinge as much on the operation of memory as on the explanation of the phenomena of dreams and hallucinations, as on the understanding of desire in its ability to set the animated living being (i.e. a being with a soul) in motion.

Kernel-based methods for change detection in remote sensing images

Nowadays, the joint exploitation of images acquired daily by remote sensing instruments and of images available from archives allows a detailed monitoring of the transitions occurring at the surface of the Earth. These modifications of the land cover generate spectral discrepancies that can be detected via the analysis of remote sensing images. Independently from the origin of the images and of type of surface change, a correct processing of such data implies the adoption of flexible, robust and possibly nonlinear method, to correctly account for the complex statistical relationships characterizing the pixels of the images. This Thesis deals with the development and the application of advanced statistical methods for multi-temporal optical remote sensing image processing tasks. Three different families of machine learning models have been explored and fundamental solutions for change detection problems are provided. In the first part, change detection with user supervision has been considered. In a first application, a nonlinear classifier has been applied with the intent of precisely delineating flooded regions from a pair of images. In a second case study, the spatial context of each pixel has been injected into another nonlinear classifier to obtain a precise mapping of new urban structures. In both cases, the user provides the classifier with examples of what he believes has changed or not. In the second part, a completely automatic and unsupervised method for precise binary detection of changes has been proposed. The technique allows a very accurate mapping without any user intervention, resulting particularly useful when readiness and reaction times of the system are a crucial constraint. In the third, the problem of statistical distributions shifting between acquisitions is studied. Two approaches to transform the couple of bi-temporal images and reduce their differences unrelated to changes in land cover are studied. The methods align the distributions of the images, so that the pixel-wise comparison could be carried out with higher accuracy. Furthermore, the second method can deal with images from different sensors, no matter the dimensionality of the data nor the spectral information content. This opens the doors to possible solutions for a crucial problem in the field: detecting changes when the images have been acquired by two different sensors.

Proteomic analysis of mononuclear cells of patients with minimal-change nephrotic syndrome of childhood.

Background/Aims. Recently, peripheral blood mononuclear cell transcriptome analysis has identified genes that are upregulated in relapsing minimal-change nephrotic syndrome (MCNS). In order to investigate protein expression in peripheral blood mononuclear cells (PBMC) from relapsing MCNS patients, we performed proteomic comparisons of PBMC from patients with MCNS in relapse and controls. METHODS: PBMC from a total of 20 patients were analysed. PBMC were taken from five patients with relapsing MCNS, four in remission, five patients with other glomerular diseases and six controls. Two dimensional electrophoresis was performed and proteome patterns were compared. RESULTS: Automatic heuristic clustering analysis allowed us to pool correctly the gels from the MCNS patients in the relapse and in the control groups. Using hierarchical population matching, nine spots were found to be increased in PBMC from MCNS patients in relapse. Four spots were identified by mass spectrometry. Three of the four proteins identified (L-plastin, alpha-tropomyosin and annexin III) were cytoskeletal-associated proteins. Using western blot and immunochemistry, L-plastin and alpha-tropomyosin 3 concentrations were found to be enhanced in PBMC from MCNS patients in relapse. Conclusions. These data indicate that a specific proteomic profile characterizes PBMC from MCNS patients in relapse. Proteins involved in PBMC cytoskeletal rearrangement are increased in relapsing MCNS. We hypothesize that T-cell cytoskeletal rearrangement may play a role in the pathogenesis of MCNS by altering the expression of cell surface receptors and by modifying the interaction of these cells with glomerular cells.

Liver, Gastrointestinal, and Cardiac Toxicity in Intermediate Hepatocellular Carcinoma Treated With PRECISION TACE With Drug-Eluting Beads: Results From the PRECISION V Randomized Trial.

OBJECTIVE. The purpose of our study was to evaluate hepatic, gastrointestinal, and cardiac toxicity after PRECISION transarterial chemoembolization (TACE) with drug-eluting beads (DEB) versus conventional TACE with doxorubicin in the treatment of intermediate-stage hepatocellular carcinoma (HCC).SUBJECTS AND METHODS. Two hundred twelve patients (185 men and 27 women; mean age, 67 years) were randomized to TACE with DEB or conventional TACE. The majority of patients (67% in both groups) presented in a more advanced stage. Safety was measured by rate of adverse events (Southwest Oncology Group criteria) and changes in laboratory parameters. Cardiotoxicity was assessed with left ventricular ejection fraction (LVEF) mainly on MRI or echocardiography.RESULTS. The mean maximum postchemoembolization alanine transaminase increase in the DEB group was 50% less than in the conventional TACE group (p < 0.001) and 41% less in respect to aspartate transaminase (p < 0.001). End-of-study values returned to approximately baseline levels but with greater variability in conventional TACE patients. Treatment-emergent adverse events in the hepatobiliary system organ class occurred in 16.1% of DEB group patients compared with 25% of conventional TACE patients. There were fewer liver toxicity events in the DEB group. There was a small but statistically significant difference in mean change from baseline in LVEF between the two groups of 4 percentage points for the conventional TACE group (95% CI, 0.71-7.3; p = 0.018).CONCLUSION. PRECISION TACE with DEB loaded with doxorubicin offers a safe therapy option for intermediate-stage HCC, even in patients with more advanced liver disease.

Change in biased thinking in a 10-session treatment for borderline personality disorder: Further evidence of the motive-oriented therapeutic relationship.

Abstract Borderline Personality Disorder (BPD) is characterized by both maladaptive thinking and problematic schemas. Kramer and colleagues (2011) showed that using the motive-oriented therapeutic relationship (MOTR), based on the individualized understanding of the patient according to Plan Analysis (Caspar, 2007), can improve treatment outcomes for BPD. The present process-outcome pilot study aimed to examine the effects of the motive-oriented therapeutic relationship on the cognitive biases of patients with BPD. Change in biased cognitions in N=10 patients who were subject to MOTR was compared to that of N=10 patients who received psychiatric-psychodynamic treatment (Gunderson & Links, 2008). Results show a greater decrease in over-generalizations in patients who received MOTR, compared to the patients who received the psychiatric-psychodynamic treatment. These changes were related to outcome in various ways. These findings underline the importance of an individualized case formulation method in bringing about therapeutic change.

Transitions in partnership and parental status, gender, and political and civic participation

Participation research has documented the effect of partner and parenthood status, thereby ignoring the dynamic aspect of status changes. Based on theoretical insights on changes in political resources and interest, this study looks at partnership and parenthood as dynamic characteristics. Using data from the Swiss Household Panel (SHP), it examines to what extent important life-cycle transitions in partnership and parental status influence various forms of political and civic participation and whether they affect men and women's participation differently. Our regression analyses reveal that particularly the entry into separation or divorce is a main key point driving change in political and civic participation. Its effect is also highly gendered. Following separation, women participate less in voting, whereas men's participation rates are not affected in a negative way. Separation even increases men's level of anticipated activism. Children entering or leaving the household do not seem to represent key points of change in political and civic participation of the couple. Yet, the transition to having school-aged children significantly increases some types of participation, at least for women.