Self-Navigation with Compressed Sensing for 2D Translational Motion Correction in Free-Breathing Coronary MRI: A Feasibility Study.

PURPOSE: Respiratory motion correction remains a challenge in coronary magnetic resonance imaging (MRI) and current techniques, such as navigator gating, suffer from sub-optimal scan efficiency and ease-of-use. To overcome these limitations, an image-based self-navigation technique is proposed that uses "sub-images" and compressed sensing (CS) to obtain translational motion correction in 2D. The method was preliminarily implemented as a 2D technique and tested for feasibility for targeted coronary imaging. METHODS: During a 2D segmented radial k-space data acquisition, heavily undersampled sub-images were reconstructed from the readouts collected during each cardiac cycle. These sub-images may then be used for respiratory self-navigation. Alternatively, a CS reconstruction may be used to create these sub-images, so as to partially compensate for the heavy undersampling. Both approaches were quantitatively assessed using simulations and in vivo studies, and the resulting self-navigation strategies were then compared to conventional navigator gating. RESULTS: Sub-images reconstructed using CS showed a lower artifact level than sub-images reconstructed without CS. As a result, the final image quality was significantly better when using CS-assisted self-navigation as opposed to the non-CS approach. Moreover, while both self-navigation techniques led to a 69% scan time reduction (as compared to navigator gating), there was no significant difference in image quality between the CS-assisted self-navigation technique and conventional navigator gating, despite the significant decrease in scan time. CONCLUSIONS: CS-assisted self-navigation using 2D translational motion correction demonstrated feasibility of producing coronary MRA data with image quality comparable to that obtained with conventional navigator gating, and does so without the use of additional acquisitions or motion modeling, while still allowing for 100% scan efficiency and an improved ease-of-use. In conclusion, compressed sensing may become a critical adjunct for 2D translational motion correction in free-breathing cardiac imaging with high spatial resolution. An expansion to modern 3D approaches is now warranted.

Improving anemia management with less frequently dosed erythropoiesis stimulating agents

Introduction and Aims: The process of delivering erythropoiesis stimulating agents (ESAs) to hemodialysis patients (HD) is complex. Many European countries are requiring centers to document this process. To date, there has not been any comprehensive description of the operational aspects of ESA delivery in Europe. The objective of the Mercurius study was to describe the entire process of ESA delivery in dialysis centers. In addition, we explored the benefits of less frequent dosing. Methods: A conceptual model was developed to classify the sub-processes in the pharmacy, dialysis unit, waste unit, and back office. Within each dialysis unit activities associated with dose determination, ordering procedures, receipt and storage of ESAs, and ESA administration were measured. Within the pharmacy, ordering from supplier, receiving and storing, and delivering ESA to the dialysis unit were measured. The amount of time and materials associated with waste disposal and back office activities were also observed. We also evaluated the impact of less frequent dosing on the resources required to perform anemia management for HD patients. Structured interviews with staff were used to develop a comprehensive list of processes, sub-processes, and activities that are routinely followed to order, register, administer, and dispose of waste associated with ESAs. Each activity was evaluated to determine if less frequent dosing influenced the amount of resources required. A model was developed to estimate the change in resources consumed using less frequent dosing regimens. Results: Eight centers from 5 European countries (Belgium, France, Italy, Sweden, and Switzerland) participated in the study. The number of HD patients in each center ranged from 42 to 707 (mean=175). Across all of the centers, patients received a variety of dosing regimens (eg, TIW, BIW, QW and Q2W). The mean (±SD) time spent for the pharmacy to order an ESA from the supplier was 6.1 (±8.7) minutes; time spent in the dialysis unit and pharmacy for receiving and storing ESPs was 5.3 (±5.3) and 10.0 (±10.9) minutes, respectively; and time spent administering each injection was 6.4 (±6.5) minutes. Switching from current dosing practices to Q2W could decrease the mean number of syringes used from 12,420 to 5,085 per year. We estimate a reduction in the number of disinfective tissues and liquids of 58% and 71%, respectively by switching from current practice to dosing ESAs Q2W. Conclusions: There was significant variation in the time that it takes to perform routine ESA activities. We estimate that a reduction in resources required to manage anemia can be obtained by reducing the frequency of administration from the current mix of ESAs. These resources could be redeployed for patient care.

Genotyping faeces reveals facultative kin association on capercaillie's leks

The role that kin selection might play in the evolution of lekking in birds remains controversial. Recent molecular data suggest that males displaying on leks are related. Here we investigated the genetic structure and pattern of relatedness on leks of a declining population of capercaillie (Tetrao urogallus) using microsatellite genetic markers. Since the species is highly sensitive to disturbance, we adopted a non-invasive method by using faecal samples collected in the field. Based on a dataset of 50 males distributed in 6 sub-populations, we found significant genetic structuring among sub-populations, and a significant pattern of isolation by distance among leks. Estimates of relatedness showed that males displaying on the same lek were related, even when controlling for the effects of genetical differentiation among sub-populations. In addition, the frequency distribution of relatedness values indicated that leks contain a mixture of close kin and unrelated individuals (34 and 66%, respectively). This pattern is consistent with the hypothesis that leks often contain kin associations, which might be due to very restricted dispersal of some of the males or to joint dispersal of kin. The results are discussed with respect to their implication for the conservation of endangered populations.

Hybrid PET/MRI in the assessment of cardiac viability: added value compared to PET/CT

Purpose: We evaluated the potential for hybrid PET/MRI devices to provide integrated metabolic, functional and anatomic characterisation of patients with suspected coronary artery disease.Methods and Materials: Ten patients (5 with suspected hibernating myocardium and 5 healthy volunteers) performed an imaging study using a hybrid PET/MRI (Philips). Viability assessed by 18F-FDG was performed in diseased patients along with MRI anatomic and functional study and reassessed within 30 minutes by conventional PET/CT. Non-contrast right coronary artery (RCA) targeted and whole heart 3D coronary angio-MRI using ECG-gating and respiratory navigator was performed in healthy volunteers with reconstruction performed using MPR and volume rendering. The extent of metabolic defect (MD) using PET/MRI and PET/CT was compared in patients and coronary territories (LAD, CX, RCA). Assessability of coronary lumen was judged as good, sub-optimal or non-assessable using a 16-segments coronary model.Results: Metabolic assessment was successful in all patients with MD being 19.2% vs 18.3% using PET/MRI and PET/CT, respectively (P=ns). The MD was 10.2%, 6 %, and 3 % vs 9.3%, 6 % and 3 % for LAD, CX and RCA territories, respectively (P= ns). Coronary angio-MRI was successful in all volunteers with 66 coronary segments visualised overall. The RCA was fully visualised in 4/5 volunteers and the left coronary arteries in 4/5 volunteers. Assessability in visualised segments was good, sub-optimal and non-assessable in 88 %, 2 % and 10 %, respectively.Conclusion: Hybrid PET/MRI devices may enable metabolic evaluation comparable to PET/CT with additional value owing to accurate functional and anatomical information including coronary assessment.

Acute pulmonary embolectomy.

Acute pulmonary embolism (PE) is a common condition frequently associated with a high mortality worldwide. It can be classified into non-massive, sub-massive and massive, based on the degree of haemodynamic compromise. Surgical pulmonary embolectomy, despite having been in existence for over 100 years, is generally regarded as an option of last resort, with expectedly high mortality rates. Recent advances in diagnosis and recognition of key qualitative predictors of mortality, such as right ventricular stress on echocardiography, have enabled the re-exploration of surgical pulmonary embolectomy for use in patients prior to the development of significant circulatory collapse, with promising results. We aim to review the literature and discuss the indications, perioperative workup and outcomes of surgical pulmonary embolectomy in the management of acute PE.

Optimal fiscal policy in overlapping generations models

[eng] This paper provides, from a theoretical and quantitative point of view, an explanation of why taxes on capital returns are high (around 35%) by analyzing the optimal fiscal policy in an economy with intergenerational redistribution. For this purpose, the government is modeled explicitly and can choose (and commit to) an optimal tax policy in order to maximize society's welfare. In an infinitely lived economy with heterogeneous agents, the long run optimal capital tax is zero. If heterogeneity is due to the existence of overlapping generations, this result in general is no longer true. I provide sufficient conditions for zero capital and labor taxes, and show that a general class of preferences, commonly used on the macro and public finance literature, violate these conditions. For a version of the model, calibrated to the US economy, the main results are: first, if the government is restricted to a set of instruments, the observed fiscal policy cannot be disregarded as sub optimal and capital taxes are positive and quantitatively relevant. Second, if the government can use age specific taxes for each generation, then the age profile capital tax pattern implies subsidizing asset returns of the younger generations and taxing at higher rates the asset returns of the older ones.

Deep subsoiling of a subsurface-compacted typical hapludult under citrus orchard

Soil management practices which increase the root depth penetration of citrus are important to the longevity and yield maintenance of this plant, especially in regions where long periods of drought are common, even in soil conventionally subsoiled to a depth of 30-40 cm, when the orchard was first established. The objective of this study was to evaluate the efficiency of subsoiling on the physical and hydric properties of a Typical Hapludult and fruit yield in a 14-year-old citrus orchard located in Piracicaba, SP. The treatments consisted of: no-subsoiling (with no tilling of the soil after the orchard was planted); subsoiling on one side of the plant lines (SUB. 1); and subsoiling on both sides of the plant lines (SUB. 2). The subsoiling treatments were carried out 1.5 m from the plant lines and to a depth of 0.8 m. Soil samples were taken 120 days after this operation, at four depths, in order to determine physical and hydric properties. Fruit yield was evaluated 150 days after subsoiling. Subsoiling between the plant lines of an old established citrus orchard alters the physical and hydric properties of the soil, which is reflected in increased soil macroporosity and unsaturated hydraulic conductivity, and reduced soil bulk density, critical degree-of-compactness and penetration resistance. The improvements in the physical and hydric properties of the soil were related to an increase in fruit number and orchard yield.

Fragile-glass behavior of a short-range p-spin model

We propose a short-range generalization of the p-spin interaction spin-glass model. The model is well suited to test the idea that an entropy collapse is at the bottom line of the dynamical singularity encountered in structural glasses. The model is studied in three dimensions through Monte Carlo simulations, which put in evidence fragile glass behavior with stretched exponential relaxation and super-Arrhenius behavior of the relaxation time. Our data are in favor of a Vogel-Fulcher behavior of the relaxation time, related to an entropy collapse at the Kauzmann temperature. We, however, encounter difficulties analogous to those found in experimental systems when extrapolating thermodynamical data at low temperatures. We study the spin-glass susceptibility, investigating the behavior of the correlation length in the system. We find that the increase of the relaxation time is accompanied by a very slow growth of the correlation length. We discuss the scaling properties of off-equilibrium dynamics in the glassy regime, finding qualitative agreement with the mean-field theory.

Micronutrient Accumulation in Conilon Coffee Berries with Different Maturation Cycles

ABSTRACT The number of days between anthesis and maturation of conilon coffee berries varies according to the genotype. Thus, it is believed that periods of greater nutrient demand for fruit formation also vary according to the genotype, directly influencing fertilizer management. The goal of this study was to establish accumulation curves for the micronutrients boron, copper, iron, manganese, and zinc in conilon coffee trees with different maturation cycles. The experiment was conducted in Nova Venécia, State of Espírito Santo, Brazil, during the reproductive cycle of the 2010/2011 crop year. Four coffee genotypes with different maturation cycles (early, intermediate, late, and super-late) were studied. A completely randomized experimental design was used with five replications. The treatments correspond to the accumulation of B, Cu, Fe, Mn, and Zn in the berries every 28 days in the period from flowering to harvest. The early, intermediate, and late genotypes accumulated Fe, Cu, and Mn in a similar manner, with sigmoid curves, whereas the super-late genotype accumulated these nutrients exponentially. Zn was accumulated by all four genotypes following a sigmoid curve. The early, intermediate, and late genotypes accumulated B linearly, whereas the super-late genotype accumulated B following a sigmoid curve. The maturation cycle of the genotype must be taken into account to apply the correct rate of micronutrient fertilization in coffee plantations.

Delirium upon admission to Swiss nursing homes: a cross-sectional study.

QUESTIONS UNDER STUDY: We wished to investigate the prevalence of delirium in patients upon admission to nursing homes and whether or not the previous place of residence predicts delirium. METHODS: The Resident Assessment Instrument Minimum Data Set (RAI-MDS) and the Nursing Home Confusion Assessment Method (NHCAM) were used to determine whether the previous place of residence (community, nursing home, acute care, psychiatric, rehabilitation hospital) predicted the prevalence of sub-syndromal or full delirium in nursing home residents in three Swiss cantons (n = 11745). RESULTS: 39.7% had sub-syndromal and 6.5% had full delirium. Lower cognitive performance and increased depressive symptoms were significant predictors of higher NHCAM values independent of previous residence. Age, civil status, continence, newly introduced drugs, and basic activities of daily living were predictors in some resident groups. The variance of NHCAM scores explained varied between 25.1% and 32.3% depending on previous residence. CONCLUSIONS: Sub-syndromal and full delirium are common upon nursing home admission. Increased dependence and depression are consistently associated with higher NHCAM scores. Patients from psychiatric settings have an increased risk of delirium. Although factors associated with delirium depend on a patient's previous residence, all patients must be carefully screened for sub-syndromal and full delirium.

Optimal fiscal policy in overlapping generations models

[eng] This paper provides, from a theoretical and quantitative point of view, an explanation of why taxes on capital returns are high (around 35%) by analyzing the optimal fiscal policy in an economy with intergenerational redistribution. For this purpose, the government is modeled explicitly and can choose (and commit to) an optimal tax policy in order to maximize society's welfare. In an infinitely lived economy with heterogeneous agents, the long run optimal capital tax is zero. If heterogeneity is due to the existence of overlapping generations, this result in general is no longer true. I provide sufficient conditions for zero capital and labor taxes, and show that a general class of preferences, commonly used on the macro and public finance literature, violate these conditions. For a version of the model, calibrated to the US economy, the main results are: first, if the government is restricted to a set of instruments, the observed fiscal policy cannot be disregarded as sub optimal and capital taxes are positive and quantitatively relevant. Second, if the government can use age specific taxes for each generation, then the age profile capital tax pattern implies subsidizing asset returns of the younger generations and taxing at higher rates the asset returns of the older ones.

Learning wind fields with multiple kernels

This paper presents multiple kernel learning (MKL) regression as an exploratory spatial data analysis and modelling tool. The MKL approach is introduced as an extension of support vector regression, where MKL uses dedicated kernels to divide a given task into sub-problems and to treat them separately in an effective way. It provides better interpretability to non-linear robust kernel regression at the cost of a more complex numerical optimization. In particular, we investigate the use of MKL as a tool that allows us to avoid using ad-hoc topographic indices as covariables in statistical models in complex terrains. Instead, MKL learns these relationships from the data in a non-parametric fashion. A study on data simulated from real terrain features confirms the ability of MKL to enhance the interpretability of data-driven models and to aid feature selection without degrading predictive performances. Here we examine the stability of the MKL algorithm with respect to the number of training data samples and to the presence of noise. The results of a real case study are also presented, where MKL is able to exploit a large set of terrain features computed at multiple spatial scales, when predicting mean wind speed in an Alpine region.

Voimalaitoksen ylläpitosuunnitelma

Tässä diplomityössä on tehtyylläpitosuunnitelma Oulun Energian Toppila 1 - voimalaitokselle, jota on tavoitteena käyttää vuoteen 2015. Työssä on tarkasteltu aluksi voimalaitoksen tulevaisuuden käytön näkymiä ja tärkeimpien järjestelmien käyttökuntoa. Kattilalaitoksenkriittisille komponenteille on suoritettu ylläpito- ja epäkäytettävyyskustannusten vertailu sekä pyritty selvittämään komponenteille paras ylläpitomalli. Turbiinille on analysoitu erilaisia revisio- ja tarkastusmahdollisuuksia, ja vertailtu niistä muodostuvia kustannuksia. Tulosten perusteella voidaan sanoa, että tehostetut ylläpitotoimenpiteet ovat jatkossa kriittisille komponenteille taloudellisin ylläpitomalli, koska riittävällä määrällä tarkastuksia jakorjauksia voidaan hallita ongelmallisimpien komponenttien vaurioitumiskäyttäytymistä. Jos voimalaitosta käytetään vuoteen 2015, saattavat uusia investointeja olla eko I, eko II ja tertiääritulistin. Tämän työn perusteella investointeja eikannata tehdä, mutta komponenttien kuntoa sen sijaan on syytä arvioida vuosittain. Turbiinin kriittiset komponentit vaikuttaisivat olevan suhteellisen hyvässä kunnossa. Suurimmat vaurioitumismahdollisuudet liittyvät juoksusiipien väsymisvaurioihin.

Usages de l'eau à Gaya (Niger) : entre fortes potentialités et contraintes majeures

Résumé: Le département de Gaya, cadre de notre étude, est situé au sud-ouest de la république du Niger. Il dispose d'un important potentiel hydrique composé des eaux de surface (une centaine de mares permanentes, le fleuve Niger sur 106 km) et de sept aquifères superposés comprenant des nappes de subsurface (affleurantes par endroit) et des nappes artésiennes. L'étude sur les usages de l'eau à Gaya a été menée à travers plusieurs axes centrés sur l'estimation et la répartition spatiale des ressources en eau, le cadre juridique et institutionnel régulant leur mise en valeur, les différents secteurs d'utilisation de l'eau ainsi que les contraintes affectant cette utilisation. L'usage de la cartographie à travers les SIG dans le traitement et l'analyse des données, couplée à notre expérience d'une dizaine d'année de travaux dans la région, a permis de dresser des synthèses richement illustrées permettant de mieux comprendre tous les enjeux liés à la problématique des usages de l'eau dans cette partie du Niger. Contrairement à la vision que l'on a traditionnellement du Sahel où le manque d'eau constitue une des contraintes majeures au développement, ici des conditions locales particulières contredisent ce cliché et transposent le débat sur un autre plan. Il s'agit de la maîtrise de l'eau au niveau local à travers l'élaboration d'une politique appropriée qui tienne compte non seulement des spécificités locales de la ressource, mais aussi des différents types d'usages. La politique de l'eau au Niger, définie selon le Schéma directeur de mise en valeur et de gestion des ressources en eau, à travers la mise en place d'un important arsenal juridique et institutionnel, a eu le mérite de tracer un canevas sur la question, mais a montré ses limites au niveau pratique après dix ans d'essai. En effet au niveau de Gaya, ni l'Etat ni les partenaires au développement (bailleurs de fonds extérieurs) n'ont tenu compte des caractéristiques locales de la ressource ou du contexte socioéconomique particulier de la région. Ce qui a entraîné la réalisation d'infrastructures inadaptées aux réalités hydrogéologiques locales ainsi que des choix inappropriés au niveau de certains aménagements. En dépit de l'abondance de la ressource, son accès tant au niveau quantitatif que qualitatif, reste difficile pour une grande partie des acteurs ruraux. Les différents handicaps rencontrés dans la mise en valeur des ressources en eau résultent de cette incohérence de la politique nationale de l'eau, mais aussi de la difficulté de son application sur le terrain où persiste un pluralisme juridique caractérisé par la cohabitation de deux systèmes de régulation à savoir les droits coutumiers et la législation moderne. Ces différents éléments mis en évidence dans cette étude sur la zone de Gaya pourraient servir de base pour un meilleur aménagement des ressources en eau dans le cadre plus large d'une politique d'aménagement du territoire prenant en compte tous les facteurs tant physiques que socioéconomiques de la région. Abstract: The department of Gaya, in which this study was done, is located in the SW area of the Republic of Niger. It has an important hydrological potential composed of surface water (approximately 100 permanent ponds, 106 km of the Niger River) and 7 bodies of underground water sources including sub-surface and artresan wells. This study of the exploitation of wtaer in Gaya has been carried out employing several parameters based on: the estimation and spacial distribution of water ressources, the juridic and institutional rules governing their utilisation and the various constraints affecting this exploitation. The use of mapping when treating and analysing data, coupled with ten years personel field experience, resulted in a richly illustrated synthesis of this data. This, in turn, led to a better comprehension of all the factors related to problems of water utilisation in this particular region of Niger. Contrary to the generally accepted view that the lack of water ressources is a major contributing factor to the lack of development in the Sahel, in Gaya the local conditions contradict this statement. In this region, and at the local level, the proper use of water is based on the elaboration of an appropriate policy which takes into account not only the local specifics of water ressources but the various types of water utilsation as well. Local use of water and water ressources are dependant on established rules. Water policy in Niger is defined by the General Schema based on an important institutional and judicary arsenal of rules and regulations. However, after a ten-year trial period, this system was shown to have its limitations. In Gaya, neither the State nor the development agencies took into consideration local characteristics nor the socio-economic context of the region. This, in turn, resulted in putting in place infrastructures that were not adapted to local hydrogeological realities as well as inappropriate choices in land planning and development. In spite of the abundance of water ressources, access to them remains difficult for most of the rural population. The various difficulties encountered are the result of incoherent water policies on a national level as well as the lack of practical application in this area. This is due to a double judicary system where two regulatory systems co-exist:traditional laws and modern legislation. the different elements brought out by this study could serve as a basis for a better utilisation of water ressources on a larger scale in which land planning and development policies would take into consideration all the physcial as well as the socio-economical factors of this region.

Improving Information Problem Solving skills in Secondary Education through embedded instruction

This empirical study consists in an investigation of the effects, on the development of Information Problem Solving (IPS) skills, of a long-term embedded, structured and supported instruction in Secondary Education. Forty secondary students of 7th and 8th grades (13–15 years old) participated in the 2-year IPS instruction designed in this study. Twenty of them participated in the IPS instruction, and the remaining twenty were the control group. All the students were pre- and post-tested in their regular classrooms, and their IPS process and performance were logged by means of screen capture software, to warrant their ecological validity. The IPS constituent skills, the web search sub-skills and the answers given by each participant were analyzed. The main findings of our study suggested that experimental students showed a more expert pattern than the control students regarding the constituent skill ‘defining the problem’ and the following two web search sub-skills: ‘search terms’ typed in a search engine, and ‘selected results’ from a SERP. In addition, scores of task performance were statistically better in experimental students than in control group students. The paper contributes to the discussion of how well-designed and well-embedded scaffolds could be designed in instructional programs in order to guarantee the development and efficiency of the students’ IPS skills by using net information better and participating fully in the global knowledge society.