Anàlisi de la gestió de fons d’inversió de renda variable en el període 2009-2013

La crisi financera que es va originar l’any 2007 va tenir uns efectes devastadors a tots els àmbits de l’economia. El mercat hipotecari es va desplomar i l’accés al crèdit es va restringir a la majoria de la població. Els efectes que va tenir la crisi sobre aquests mercats han estat analitzats i estudiats repetidament en diverses assignatures. Però el que es vol observar amb la realització d’aquest treball són els efectes que va provocar la crisi econòmica sobre un altre àmbit del mercat financer, el mercat de fons d’estalvi i més concretament, en el de fons d’inversió. Aquest treball vol analitzar si els mercats espanyol i europeu de fons d’inversió ha patit els efectes de la crisi econòmica i si ha estat així, en quin grau s’han vist afectats. Aquests mercats venen regits per experts professionals en la matèria i la rendibilitat d’aquests actius vindrà determinada per la gestió que aquests facin. Per poder mesurar si la seva gestió aconsegueix millorar els resultats que podríem obtenir invertint en el mercat, utilitzarem uns índexs financers anomenats mesures de performance. Dins el ventall disponible de fons d’inversió, ens centrarem en el mercat de renda variable ja que és el que presenta major variabilitat i està més sotmès a possibles canvis en el mercat. En concret s’analitzaran els resultats de la gestió del mercat de fons d’inversió de renda variable durant els anys posteriors a la crisi fins a l’actualitat tant al mercat espanyol com al mercat europeu per diferents categories de fons.

Energy-efficient control strategies for variable speed driven parallel pumping systems based on pump operation point monitoring with frequency converters

The pumping processes requiring wide range of flow are often equipped with parallelconnected centrifugal pumps. In parallel pumping systems, the use of variable speed control allows that the required output for the process can be delivered with a varying number of operated pump units and selected rotational speed references. However, the optimization of the parallel-connected rotational speed controlled pump units often requires adaptive modelling of both parallel pump characteristics and the surrounding system in varying operation conditions. The available information required for the system modelling in typical parallel pumping applications such as waste water treatment and various cooling and water delivery pumping tasks can be limited, and the lack of real-time operation point monitoring often sets limits for accurate energy efficiency optimization. Hence, alternatives for easily implementable control strategies which can be adopted with minimum system data are necessary. This doctoral thesis concentrates on the methods that allow the energy efficient use of variable speed controlled parallel pumps in system scenarios in which the parallel pump units consist of a centrifugal pump, an electric motor, and a frequency converter. Firstly, the suitable operation conditions for variable speed controlled parallel pumps are studied. Secondly, methods for determining the output of each parallel pump unit using characteristic curve-based operation point estimation with frequency converter are discussed. Thirdly, the implementation of the control strategy based on real-time pump operation point estimation and sub-optimization of each parallel pump unit is studied. The findings of the thesis support the idea that the energy efficiency of the pumping can be increased without the installation of new, more efficient components in the systems by simply adopting suitable control strategies. An easily implementable and adaptive control strategy for variable speed controlled parallel pumping systems can be created by utilizing the pump operation point estimation available in modern frequency converters. Hence, additional real-time flow metering, start-up measurements, and detailed system model are unnecessary, and the pumping task can be fulfilled by determining a speed reference for each parallel-pump unit which suggests the energy efficient operation of the pumping system.

Factors influencing the dissolution of phosphate rock in a range of high P-fixing soils from Cameroon

A laboratory incubation experiment was conducted to evaluate the soil factors that influence the dissolution of two phosphate rocks (PRs) of different reactivity (Gafsa, GPR, reactive PR; and Togo-Hahotoe, HPR, low reactivity PR) in seven agricultural soils from Cameroon having variable phosphorus (P)- sorption capacities, organic carbon (C) contents, and exchangeable acidities. Ground PR was mixed with the soils at a rate of 500 mg P kg 21 soil and incubated at 30 degrees C for 85 days. Dissolution of the PRs was determined at various intervals using the Delta NaOH-P method ( the difference of the amount of P extracted by 0.5 M NaOH between the PR-treated soils and the control). Between 4 and 27% of HPR and 33 and 50% of GPR were dissolved in the soils. Calcium (Ca) saturation of cation exchange sites and proton supply strongly affected PR dissolution in these soils. Acid soils with pH-(H2O), < 5 (NKL, ODJ, NSM, MTF) dissolved more phosphate rock than those with pH-(H2O) > 5 (DSC, FGT, BAF). However, the lack of a sufficient Ca sink in the former constrained the dissolution of both PRs. The dissolution of GPR in the slightly acidic soils was limited by increase in Ca saturation and that of HPR was constrained by limited supply in protons. Generally, the dissolution of GPR was higher than that of HPR for each soil. The kinetics of dissolution of PR in the soils was best described by the power function equation P At B. More efficient use of PR in these soils can be achieved by raising the soil cation exchange capacity, thereby increasing the Ca sink size. This could be done by amending such soils with organic materials.

Differences between naïve and expert observers’ vergence and accommodative responses to a range of targets

Purpose: Vergence and accommodation studies often use adult participants with experience of vision science. Reports of infant and clinical responses are generally more variable and of lower gain, with the implication that differences lie in immaturity or sub-optimal clinical characteristics but expert/naïve differences are rarely considered or quantified. Methods: Sixteen undergraduates, naïve to vision science, were individually matched by age, visual acuity, refractive error, heterophoria, stereoacuity and near point of accommodation to second- and third-year orthoptics and optometry undergraduates (‘experts’). Accommodation and vergence responses were assessed to targets moving between 33 cm, 50 cm, 1 m and 2 m using a haploscopic device incorporating a PlusoptiX SO4 autorefractor. Disparity, blur and looming cues were separately available or minimised in all combinations. Instruction set was minimal. Results: In all cases, vergence and accommodation response slopes (gain) were steeper and closer to 1.0 in the expert group (p = 0.001), with the largest expert/naïve differences for both vergence and accommodation being for near targets (p = 0.012). For vergence, the differences between expert and naïve response slopes increased with increasingly open-loop targets (linear trend p = 0.025). Although we predicted that proximal cues would drive additional response in the experts, the proximity-only cue was the only condition that showed no statistical effect of experience. Conclusions: Expert observers provide more accurate responses to near target demand than closely matched naïve observers. We suggest that attention, practice, voluntary and proprioceptive effects may enhance responses in experienced participants when compared to a more typical general population. Differences between adult reports and the developmental and clinical literature may partially reflect expert/naïve effects, as well as developmental change. If developmental and clinical studies are to be compared to adult normative data, uninstructed naïve adult data should be used.

Designs for an adaptive tuned vibration absorber with variable shape stiffness element

An adaptive tuned vibration absorber (ATVA) with a smart variable stiffness element is capable of retuning itself in response to a time-varying excitation frequency., enabling effective vibration control over a range of frequencies. This paper discusses novel methods of achieving variable stiffness in an ATVA by changing shape, as inspired by biological paradigms. It is shown that considerable variation in the tuned frequency can be achieved by actuating a shape change, provided that this is within the limits of the actuator. A feasible design for such an ATVA is one in which the device offers low resistance to the required shape change actuation while not being restricted to low values of the effective stiffness of the vibration absorber. Three such original designs are identified: (i) A pinned-pinned arch beam with fixed profile of slight curvature and variable preload through an adjustable natural curvature; (ii) a vibration absorber with a stiffness element formed from parallel curved beams of adjustable curvature vibrating longitudinally; (iii) a vibration absorber with a variable geometry linkage as stiffness element. The experimental results from demonstrators based on two of these designs show good correlation with the theory.

Fecal microbiota in patients receiving enteral feeding are highly variable and may be altered in those who develop diarrhea

Background: The pathogenesis of diarrhea in patients receiving enteral feeding includes colonic water secretion, antibiotic prescription, and enteropathogenic colonization, each of which involves an interaction with the gastrointestinal microbiota. Objective: The objective was to investigate temporal changes in the concentrations of fecal microbiota and short-chain fatty acids (SCFAs) in patients starting 14-d of enteral feeding and to compare these changes between patients who do and do not develop diarrhea. Design: Twenty patients starting exclusive nasogastric enteral feeding were monitored for 14 d. Fecal samples were collected at the start, middle, and end of this period and were analyzed for major bacterial groups by using culture independent fluorescence in situ hybridization and for SCFAs by using gas-liquid chromatography. Results: Although no significant changes in fecal microbiota or SCFAs were observed during enteral feeding, stark alterations occurred within individual patients. Ten patients (50%) developed diarrhea, and these patients had significantly higher concentrations of clostridia (P = 0.026) and lower concentrations (P = 0.069) and proportions (P = 0.029) of bifidobacteria. Patients with and without diarrhea had differences in the proportion of bifidobacteria (median: 0.4% and 3.7%; interquartile range: 0.8 compared with 4.3; P = 0.035) and clostridia (median: 10.4% and 3.7%; interquartile range: 14.7 compared with 7.0; P = 0.063), respectively, even at the start of enteral feeding. Patients who developed diarrhea had higher concentrations of total fecal SCFAs (P = 0.044), acetate (P = 0.029), and butyrate (P = 0.055). Conclusion: Intestinal dysbiosis occurs in patients who develop diarrhea during enteral feeding and may be involved in its pathogenesis. Am J Clin Nutr 2009; 89: 240-7.

The effect of Parkinson's disease on time estimation as a function of stimulus duration range and modality

The present research sought to investigate the role of the basal ganglia in timing of sub- and supra-second intervals via an examination of the ability of people with Parkinson's disease (PD) to make temporal judgments in two ranges, 100-500 ms, and 1-5 s. Eighteen nondemented medicated patients with PD were compared with 14 matched controls on a duration-bisection task in which participants were required to discriminate auditory and visual signal durations within each time range. Results showed that patients with PD exhibited more variable duration judgments across both signal modality and duration range than controls, although closer analyses confirmed a timing deficit in the longer duration range only. The findings presented here suggest the bisection procedure may be a useful tool in identifying timing impairments in PD and, more generally, reaffirm the hypothesised role of the basal ganglia in temporal perception at the level of the attentionally mediated internal clock as well as memory retrieval and/or decision-making processes. (c) 2007 Elsevier Inc. All rights reserved.

Impact of variable atmospheric and oceanic form drag on simulations of Arctic sea ice

Over Arctic sea ice, pressure ridges and floe andmelt pond edges all introduce discrete obstructions to the flow of air or water past the ice and are a source of form drag. In current climate models form drag is only accounted for by tuning the air–ice and ice–ocean drag coefficients, that is, by effectively altering the roughness length in a surface drag parameterization. The existing approach of the skin drag parameter tuning is poorly constrained by observations and fails to describe correctly the physics associated with the air–ice and ocean–ice drag. Here, the authors combine recent theoretical developments to deduce the total neutral form drag coefficients from properties of the ice cover such as ice concentration, vertical extent and area of the ridges, freeboard and floe draft, and the size of floes and melt ponds. The drag coefficients are incorporated into the Los Alamos Sea Ice Model (CICE) and show the influence of the new drag parameterization on the motion and state of the ice cover, with the most noticeable being a depletion of sea ice over the west boundary of the Arctic Ocean and over the Beaufort Sea. The new parameterization allows the drag coefficients to be coupled to the sea ice state and therefore to evolve spatially and temporally. It is found that the range of values predicted for the drag coefficients agree with the range of values measured in several regions of the Arctic. Finally, the implications of the new form drag formulation for the spinup or spindown of the Arctic Ocean are discussed.

The chaotic frequency hopping signals for MIMO radar

In multiple-input multiple-output (MIMO) radar systems, the transmitters emit orthogonal waveforms to increase the spatial resolution. New frequency hopping (FH) codes based on chaotic sequences are proposed. The chaotic sequences have the characteristics of good encryption, anti-jamming properties and anti-intercept capabilities. The main idea of chaotic FH is based on queuing theory. According to the sensitivity to initial condition, these sequences can achieve good Hamming auto-correlation while also preserving good average correlation. Simulation results show that the proposed FH signals can achieve lower autocorrelation side lobe level and peak cross-correlation level with the increasing of iterations. Compared to the LFM signals, this sequence has higher range-doppler resolution.

Role of the range of the dipole function in the classical dynamics of molecular dissociation

The dissociation dynamics of heteronuclear diatomic molecules induced by infrared laser pulses is investigated within the framework of the classical driven Morse oscillator. The interaction between the molecule and the laser field described in the dipole formulation is given by the product of a time-dependent external field with a position-dependent permanent dipole function. The effects of changing the spatial range of the dipole function in the classical dissociation dynamics of large ensembles of trajectories are studied. Numerical calculations have been performed for distinct amplitudes and carrier frequencies of the external pulses and also for ensembles with different initial energies. It is found that there exist a set of values of the dipole range for which the dissociation probability can be completely suppressed. The dependence of the dissociation on the dipole range is explained through the examination of the Fourier series coefficients of the dipole function in the angle variable of the free system. In particular, the suppression of dissociation corresponds to dipole ranges for which the Fourier coefficients associated with nonlinear resonances are null and the chaotic region in the phase space is reduced to thin layers. In this context, it is shown that the suppression of dissociation of heteronuclear molecules for certain frequencies of the external field is a consequence of the finite range of the corresponding permanent dipole. © 2013 American Physical Society.

Hopping-tunneling model to describe electric charge injection at metal/organic semiconductor heterojunctions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variable impact on mortality of AIDS-defining events diagnosed during combination antiretroviral therapy: not all AIDS-defining conditions are created equal

BACKGROUND: The extent to which mortality differs following individual acquired immunodeficiency syndrome (AIDS)-defining events (ADEs) has not been assessed among patients initiating combination antiretroviral therapy. METHODS: We analyzed data from 31,620 patients with no prior ADEs who started combination antiretroviral therapy. Cox proportional hazards models were used to estimate mortality hazard ratios for each ADE that occurred in >50 patients, after stratification by cohort and adjustment for sex, HIV transmission group, number of antiretroviral drugs initiated, regimen, age, date of starting combination antiretroviral therapy, and CD4+ cell count and HIV RNA load at initiation of combination antiretroviral therapy. ADEs that occurred in <50 patients were grouped together to form a "rare ADEs" category. RESULTS: During a median follow-up period of 43 months (interquartile range, 19-70 months), 2880 ADEs were diagnosed in 2262 patients; 1146 patients died. The most common ADEs were esophageal candidiasis (in 360 patients), Pneumocystis jiroveci pneumonia (320 patients), and Kaposi sarcoma (308 patients). The greatest mortality hazard ratio was associated with non-Hodgkin's lymphoma (hazard ratio, 17.59; 95% confidence interval, 13.84-22.35) and progressive multifocal leukoencephalopathy (hazard ratio, 10.0; 95% confidence interval, 6.70-14.92). Three groups of ADEs were identified on the basis of the ranked hazard ratios with bootstrapped confidence intervals: severe (non-Hodgkin's lymphoma and progressive multifocal leukoencephalopathy [hazard ratio, 7.26; 95% confidence interval, 5.55-9.48]), moderate (cryptococcosis, cerebral toxoplasmosis, AIDS dementia complex, disseminated Mycobacterium avium complex, and rare ADEs [hazard ratio, 2.35; 95% confidence interval, 1.76-3.13]), and mild (all other ADEs [hazard ratio, 1.47; 95% confidence interval, 1.08-2.00]). CONCLUSIONS: In the combination antiretroviral therapy era, mortality rates subsequent to an ADE depend on the specific diagnosis. The proposed classification of ADEs may be useful in clinical end point trials, prognostic studies, and patient management.

A Combinatorial Approach to the Variable Selection in Multiple Linear Regression: Analysis of Selwood et al Data set -A Case Study.

A combinatorial protocol (CP) is introduced here to interface it with the multiple linear regression (MLR) for variable selection. The efficiency of CP-MLR is primarily based on the restriction of entry of correlated variables to the model development stage. It has been used for the analysis of Selwood et al data set [16], and the obtained models are compared with those reported from GFA [8] and MUSEUM [9] approaches. For this data set CP-MLR could identify three highly independent models (27, 28 and 31) with Q2 value in the range of 0.632-0.518. Also, these models are divergent and unique. Even though, the present study does not share any models with GFA [8], and MUSEUM [9] results, there are several descriptors common to all these studies, including the present one. Also a simulation is carried out on the same data set to explain the model formation in CP-MLR. The results demonstrate that the proposed method should be able to offer solutions to data sets with 50 to 60 descriptors in reasonable time frame. By carefully selecting the inter-parameter correlation cutoff values in CP-MLR one can identify divergent models and handle data sets larger than the present one without involving excessive computer time.

Expression Analysis of the Theileria parva Subtelomere-Encoded Variable Secreted Protein Gene Family

Background The intracellular protozoan parasite Theileria parva transforms bovine lymphocytes inducing uncontrolled proliferation. Proteins released from the parasite are assumed to contribute to phenotypic changes of the host cell and parasite persistence. With 85 members, genes encoding subtelomeric variable secreted proteins (SVSPs) form the largest gene family in T. parva. The majority of SVSPs contain predicted signal peptides, suggesting secretion into the host cell cytoplasm. Methodology/Principal Findings We analysed SVSP expression in T. parva-transformed cell lines established in vitro by infection of T or B lymphocytes with cloned T. parva parasites. Microarray and quantitative real-time PCR analysis revealed mRNA expression for a wide range of SVSP genes. The pattern of mRNA expression was largely defined by the parasite genotype and not by host background or cell type, and found to be relatively stable in vitro over a period of two months. Interestingly, immunofluorescence analysis carried out on cell lines established from a cloned parasite showed that expression of a single SVSP encoded by TP03_0882 is limited to only a small percentage of parasites. Epitope-tagged TP03_0882 expressed in mammalian cells was found to translocate into the nucleus, a process that could be attributed to two different nuclear localisation signals. Conclusions Our analysis reveals a complex pattern of Theileria SVSP mRNA expression, which depends on the parasite genotype. Whereas in cell lines established from a cloned parasite transcripts can be found corresponding to a wide range of SVSP genes, only a minority of parasites appear to express a particular SVSP protein. The fact that a number of SVSPs contain functional nuclear localisation signals suggests that proteins released from the parasite could contribute to phenotypic changes of the host cell. This initial characterisation will facilitate future studies on the regulation of SVSP gene expression and the potential biological role of these enigmatic proteins.

Elucidating the internal structure of psychophysical timing performance in the sub-second and second range by utilizing confirmatory factor analysis

The most influential theoretical account in time psychophysics assumes the existence of a unitary internal clock based on neural counting. The distinct timing hypothesis, on the other hand, suggests an automatic timing mechanism for processing of durations in the sub-second range and a cognitively controlled timing mechanism for processing of durations in the range of seconds. Although several psychophysical approaches can be applied for identifying the internal structure of interval timing in the second and sub-second range, the existing data provide a puzzling picture of rather inconsistent results. In the present chapter, we introduce confirmatory factor analysis (CFA) to further elucidate the internal structure of interval timing performance in the sub-second and second range. More specifically, we investigated whether CFA would rather support the notion of a unitary timing mechanism or of distinct timing mechanisms underlying interval timing in the sub-second and second range, respectively. The assumption of two distinct timing mechanisms which are completely independent of each other was not supported by our data. The model assuming a unitary timing mechanism underlying interval timing in both the sub-second and second range fitted the empirical data much better. Eventually, we also tested a third model assuming two distinct, but functionally related mechanisms. The correlation between the two latent variables representing the hypothesized timing mechanisms was rather high and comparison of fit indices indicated that the assumption of two associated timing mechanisms described the observed data better than only one latent variable. Models are discussed in the light of the existing psychophysical and neurophysiological data.