Showing papers by "Marche Polytechnic University published in 2003"
TL;DR: A survey of current approaches to the automated assessment of free text answers is presented and the following systems will be discussed: Project Essay Grade, Intelligent Essay Assessor (IEA), Educational Testing service I, Electronic Essay Rater, C-Rater, BETSY, IntelligentEssay Marking System, SEAR, Paperless School free text Marking Engine and Automark.
Abstract: Introduction Assessment is considered to play a central role in the educational process. The interest in the development and in use of Computer-based Assessment Systems (CbAS) has grown exponentially in the last few years, due both to the increase of the number of students attending universities and to the possibilities provided by e-learning approaches to asynchronous and ubiquitous education. According to our findings (Valenti, Cucchiarelli, & Panti., 2002) more than forty commercial CbAS are currently available on the market. Most of those tools are based on the use of the so-called objective-type questions: i.e. multiple choice, multiple answer, short answer, selection/association, hot spot and visual identification (Valenti et al., 2000). Most researchers in this field agree on the thesis that some aspects of complex achievement are difficult to measure using objective-type questions. Learning outcomes implying the ability to recall, organize and integrate ideas, the ability to express oneself in writing and the ability to supply merely than identify interpretation and application of data, require less structuring of response than that imposed by objective test items (Gronlund, 1985). It is in the measurement of such outcomes, corresponding to the higher levels of the Bloom's (1956) taxonomy (namely evaluation and synthesis) that the essay question serves its most useful purpose. One of the difficulties of grading essays is the subjectivity, or at least the perceived subjectivity, of the grading process. Many researchers claim that the subjective nature of essay assessment leads to variation in grades awarded by different human assessors, which is perceived by students as a great source of unfairness. Furthermore essay grading is a time consuming activity. According to Mason (2002), about 30% of teachers' time in Great Britain is devoted to marking. "So, if we want to free up that 30% (worth 3 billion UK Pounds/year to the taxpayer by the way) then we must find an effective way, that teacher will trust, to mark essays and short text responses." This issue may be faced through the adoption of automated assessment tools for essays. A system for automated assessment would at least be consistent in the way it scores essays, and enormous cost and time savings could be achieved if the system can be shown to grade essays within the range of those awarded by human assessor. Furthermore, according to Hearst (2000) using computers to increase our understanding of the textual features and cognitive skills involved in the creation and in the comprehension of written texts, will provide a number of benefits to the educational community. In fact "it will help us develop more effective instructional materials for improving reading, writing and other communication abilities. It will also help us develop more effective technologies such as search engines and question answering systems for providing universal access to electronic information." Purpose of this paper is to present a survey of current approaches to the automated assessment of free text answers. Thus, in the next section, the following systems will be discussed: Project Essay Grade (PEG), Intelligent Essay Assessor (IEA), Educational Testing service I, Electronic Essay Rater (E-Rater), C-Rater, BETSY, Intelligent Essay Marking System, SEAR, Paperless School free text Marking Engine and Automark. All these systems are currently available either as commercial systems or as the result of research in this field. For each system, the general structure and the performance claimed by the authors are presented. In the last section, we will try to compare these systems and to identify issues that may foster the research in the field. Current Tools for Automated Essay Grading Project Essay Grade (PEG) PEG is one of the earliest and longest-lived implementations of automated essay grading. It was developed by Page and others (Hearst, 2000; Page, 1994, 1996) and primarily relies on style analysis of surface linguistic features of a block of text. …
300 citations
Posted Content•
TL;DR: In this article, the authors discuss a scaling approach to business fluctuations and show that a simple financial fragility agent-based model based on complex interactions of heterogeneous agents is able to replicate a large number of scaling type stylized facts with a remarkable high degree of statistical precision.
Abstract: In this paper we discuss a scaling approach to business fluctuations. Our starting point consists in recognizing that concepts and methods derived from physics have allowed economists to (re)discover a set of stylized facts which have to be satisfactorily accounted for in their models. Standard macroeconomics, based on a reductionist approach centered on the representative agent, is definitely badly equipped for this task. On the contrary, we show that a simple financial fragility agent-based model, based on complex interactions of heterogeneous agents, is able to replicate a large number of scaling type stylized facts with a remarkable high degree of statistical precision.
264 citations
TL;DR: A general relationship between oxidative stress and loss of DNA integrity in juvenile eels exposed to the chemicals studied herein is suggested.
Abstract: In this work, susceptibility to oxidative stress was analyzed under laboratory conditions in the European eel Anguilla anguilla. Eels were treated with increasing concentrations of benchmark environmental pollutants, namely, benzo[a]pyrene ([BaP], at 0, 0.1, 1, 10, and 50 mg/kg), β-naphthoflavone ([BNF], at 0, 0.1, 1, 10, and 50 mg/kg), Arochlor® 1254 (at 0, 0.1, 1, 10, and 50 mg/kg), and 2,3,7,8-tetrachlorodibenzo p-dioxin ([TCDD], at 0, 0.01, 0.1, 1, and 2 μg/kg). The integral relationships were analyzed between induction of ethoxyresorufin O-deethylase (EROD) activity, its involvement in perturbing oxyradical metabolism, and the role of cytochrome P450 and/or oxidative stress in mediating genotoxic effects. To reveal whether the oxidative status in exposed organisms was altered as a result of chemical exposure, measurements of the main endogenous antioxidant defenses were integrated with the measurement of total oxyradical scavenging capacity (TOSC) toward peroxyl radicals and hydroxyl radicals (·OH). This approach permits discriminating the resistance of a tissue toward different forms of oxyradicals, thereby indicating a differential role for specific reactive oxygen species (ROS) in perturbing the balance between prooxidant and antioxidant mechanisms. All the analyzed chemicals promoted EROD induction (reflective of CYP1A) and altered either the levels or the activities of the antioxidants studied, which might be anticipated to exert alterations in oxyradical metabolism. Analysis of TOSC suggested the prevalence of metabolic oxidative pathways leading to the more reactive ·OH on exposure to the chemicals studied. Of these chemicals, enhanced EROD activity correlated with genotoxic damage only in the cases of the nonhalogenated hydrocarbons BaP and BNF. The highest degree of genotoxic damage was consistently observed in organisms in which the capacity to absorb or scavenge ·OH was lowest. These data suggests a general relationship between oxidative stress and loss of DNA integrity in juvenile eels exposed to the chemicals studied herein.
163 citations
TL;DR: The production and characterization of monoglyceride-based supramolecular systems by a simple processing technique, avoiding time-consuming procedures, high energy input, and the use of organic solvents is described.
Abstract: This article describes the production and characterization of monoglyceride-based supramolecular systems by a simple processing technique, avoiding time-consuming procedures, high energy input, and the use of organic solvents. A preformulatory study was performed to study the influence of the experimental parameters on the production of monoglyceride-based disperse systems. In particular the effects of (1) stirring speed, (2) type and concentration of monoglyceride mixture, and (3) type and concentration of surfactant were investigated on the recovery, fraction of larger particles, mean diameter, and shape of smaller particles (so called nanosomes). Dispersions were first characterized by optical microscopy and freeze-fracture electron microscopy. The mean diameter of standard nanosomes, analyzed by photon correlation spectroscopy (PCS) after elimination of larger particles by filtration, was 193.5 nm. Cryotransmission electron microscopy studies, conducted in order to investigate the structure of dispersions, showed the coexistence of vesicles and particles characterized by a cubic organization. X-ray diffraction data revealed the coexistence of 2 different cubic phases, the first being a bicontinuous cubic phase of spatial symmetry Im3m (Q229) and the second belonging to the Pn3m spatial symmetry. A study on the stability of monoglyceride-based dispersions based on macroscopical analysis of organoleptic properties and dimensional analysis by time was performed after elimination of larger particles by filtration. Organoleptic and morphological features do not change by time, appearing free from phase-separation phenomena for almost 1 year from production. PCS studies showed that nanosomes undergo an initial increase in mean diameter within the first month following production; afterwards they generally maintain their dimensions for the next 4 months.
145 citations
TL;DR: Diversity in improved varieties grown by farmers needs to be monitored, as the introduction of transgenic technologies has led to a consolidation of the seed industry and a reduction in the diversity of the elite crop gene pool.
Abstract: Gene flow is a potential concern associated with the use of transgenic crops because it could affect genetic diversity of related landraces and wild relatives. This concern has taken on added importance with the looming introduction of transgenic crops in centers of crop domestication (Mexico, China) and those producing pharmaceutical compounds. For gene flow to take place among cultivars and their wild relatives, several steps have to be fulfilled, including the presence of cultivars or wild relatives within pollen or seed dispersal range, the ability to produce viable and fertile hybrids, at least partial overlap in flowering time, actual gene flow by pollen or seed, and the establishment of crop genes in the domesticated or wild recipient populations. In contrast with domestication genes, which often make crops less adapted to natural ecosystems, transgenes frequently represent gains of function, which might release wild relatives from constraints that limit their fitness. In most sexually reproducing organisms, the chromosomal region affected by selection of a single gene amounts to a small percentage of the total genome size. Because of gene flow, the level of genetic diversity present in the domesticated gene pool becomes a crucial factor affecting the genetic diversity of the wild gene pool. For some crops, such as cotton and maize, the introduction of transgenic technologies has led to a consolidation of the seed industry and a reduction in the diversity of the elite crop gene pool. Thus, diversity in improved varieties grown by farmers needs to be monitored. Several areas deserve further study, such as the actual magnitude of gene flow and its determinants in different agroecosystems, the long-term effects of gene flow on genetic diversity both across gene pools and within genomes, the expression of transgenes in new genetic backgrounds, and the effects of socio-economic factors on genetic diversity.
137 citations
TL;DR: It is proposed that the mitochondrial carbonic anhydrase is involved in supplying HCO3- for anaplerotic assimilation catalyzed by phosphoenolpyruvate carboxylase, which provides C skeletons for N assimilation under some circumstances.
Abstract: Previous studies of the mitochondrial carbonic anhydrase (mtCA) of Chlamydomonas reinhardtii showed that expression of the two genes encoding this enzyme activity required photosynthetically active radiation and a low CO 2 concentration. These studies suggested that the mtCA was involved in the inorganic carbon-concentrating mechanism. We have now shown that the expression of the mtCA at low CO 2 concentrations decreases when the external NH 4 + concentration decreases, to the point of being undetectable when NH 4 + supply restricts the rate of photoautotrophic growth. The expression of mtCA can also be induced at supra-atmospheric partial pressure of CO 2 by increasing the NH 4 + concentration in the growth medium. Conditions that favor mtCA expression usually also stimulate anaplerosis. We therefore propose that the mtCA is involved in supplying HCO 3 - for anaplerotic assimilation catalyzed by phospho enol pyruvate carboxylase, which provides C skeletons for N assimilation under some circumstances.
121 citations
TL;DR: While optical microscopy and X-ray diffraction suggest a chiral columnar aggregate in the LC phase, NMR and Circular Dichroism reveal the presence of a helical structures in solution.
Abstract: The cooperative effect of solvophobic interactions and hydrogen bonding has been exploited to self-assemble supramolecular helical architectures of 8-oxoguanosines in different environments. This self-assembly into helical structures is completely different from that of the parent guanosines which, in the same experimental conditions, form flat, ribbonlike structures. While optical microscopy and X-ray diffraction suggest a chiral columnar aggregate in the LC phase, NMR and Circular Dichroism reveal the presence of a helical structures in solution. Scanning Tunneling Microscopy made it possible to visualize hexagonally arranged G-quartets on graphite, which are sections of the helices packed with their long axis perpendicular to the basal plane of the substrate. Due to their rectifying electrical properties, such helices are interesting for fabricating (opto)electronic biodevices.
116 citations
TL;DR: The opportunity to perform NIRS and TCD simultaneously provides useful information about both hemodynamic and metabolic cerebral adaptive status in patients with occlusive disease in a simple, noninvasive, and reliable way.
Abstract: Background and Purpose— Cerebral hemodynamic and metabolic changes can compensate for the decrease in cerebral blood flow occurring in patients with carotid occlusive disease. At present, a complet...
99 citations
TL;DR: CAT D is suggested as a novel bioindicator of the presence of endocrine-disrupting substances in the environment, and HSP70, the Heath Shock Protein 70, was found to be affected by all the toxicant compounds employed in the study; this protein protects cells against harmful conditions by binding and refolding damaged proteins.
90 citations
TL;DR: In this article, the peak stress dependence on strain rate and temperature was analyzed by means of the conventional constitutive equation and by a modified form, where the stress was substituted by the difference between stress and a threshold stress.
88 citations
TL;DR: In this article, the authors proposed a method for small strain measurement utilizing the numerical processing of digital images, which is based on the analysis of photographic plates that are exposed twice with the image of a random speckle pattern that has been previously printed on the test piece surface.
Abstract: This paper is concerned with small strain measurement utilizing the numerical processing of digital images. The proposed method has its theoretical basis in digital signal analysis and, from a methodological point of view, it can be considered as an extension to digital images of the wellknown white light speckle photography technique. That conventional method is based on the analysis of photographic plates that are exposed twice (before and after the specimen deformation) with the image of a random speckle pattern that has been previously printed on the test piece surface. The digital speckle correlation advantages consist of requiring a very simple specimen preparation and, mainly, of allowing the strain field computation just by numerical elaboration of the acquired images. In this paper, the theoretical basis of the technique and some valuable improvements to the known analogous methodologies are presented. Finally, test results for an application of digital speckle correlation are shown and advantages and disadvantages of the technique are elaborated. In addition, further developments in this area are discussed.
TL;DR: The pathology report should include relevant clinical information as well as provide prognostically useful data derived from the evaluation of the RP specimen.
TL;DR: The present study illustrates the first case ever of a small Indo-Pacific Pomacentridae, Chrysiptera parasema, successfully reared in captivity, and a proper diet of enriched PUFA as a first food, combined with a photoperiod of 24L/0D proved essential for survival of the C. parasema larvae.
TL;DR: D'un point de vue commercial, la gelee royale (GR) est la nourriture destinee aux larves des futures reines d'abeilles âgees de quatre a cinq jours pour ses effets pretendus toniques and bio-stimulants.
Abstract: D'un point de vue commercial, la gelee royale (GR) est la nourriture destinee aux larves des futures reines d'abeilles âgees de quatre a cinq jours. Recemment la GR a acquis une place dans le commerce mondial comme supplement dietetique et dans les cosmetiques pour ses effets pretendus toniques et bio-stimulants. Le controle de la qualite de la GR est donc un sujet important qui reste mesestime. L'evaluation de la qualite de la GR implique l'etude de sa composition et des changements des composants au cours du stockage commercial et domestique afin de definir des marqueurs de qualite. Les aspects de la determination des acides amines libres (AAL) dans la GR et les modifications des AAL au cours de la duree de conservation avant la vente sont discutes dans cette etude. Le nettoyage des AAL est l'etape preliminaire a la determination et a ete faite par les techniques de chromatographie. Le but etait de reduire la presence de substances qui interferent, telles que les sucres et les acides organiques a chaine courte, qui sont d'autres composants naturels de la GR. Les principaux AAL des series L sont la proline (2,4-5,4 mg/g GR), la lysine (0,6-2,2),le glutamate (0,5-0,9), la β-alanine (0,3-0,5), la phenylalanine (0,2-0,6), l'aspartate (0,2-0,5) et la serine (0,1-0,3) (domaine de concentration moyenne). La concentration des AAL des series-D etait inferieure a la limite de detection de la methode (0,1 mg/g GR) dans tous les echantillons, ce qui montre que l'activite microbienne etait insignifiante. Les modifications de la fraction AAL ont ete analysees dans la GR immediatement congelee apres le prelevement de l'echantillon (temoin) et dans des fractions du meme echantillon conservees a deux temperatures differentes (temperature ambiante et a 4 °C) durant des periodes de 3, 6 et 10 mois. La teneur en AAL est restee constante durant tout le stockage a 4 °C. Mais a la temperature ambiante, la proline et la lysine ont d'abord augmente jusqu'a 6,8 et 3 mg/g, respectivement, durant les trois premiers mois puis ont diminue pour atteindre 2,5 et 1 mg/g apres 6 mois et 3 et 1 mg/g apres 10 mois de stockage (Tab. II). Cette etude confirme que les AAL ne sont pas des produits terminaux formes au cours de l'evolution de la GR mais des produits intermediaires impliques dans les reactions qui ont lieu a temperature ambiante, telles que le processus de brunissement (reaction de Maillard).
TL;DR: In this article, a method for controlling nonlinear dynamics and chaos in the classical Duffing oscillator is presented. But this method is focused on optimal excitations with a finite number of superharmonics.
Abstract: A method for controlling nonlinear dynamics and chaos previouslydeveloped by the authors is applied to the classical Duffing oscillator.The method, which consists in choosing the best shape of externalperiodic excitations permitting to avoid the transverse intersection ofthe stable and unstable manifolds of the hilltop saddle, is firstillustrated and then applied by using the Melnikov method foranalytically detecting homoclinic bifurcations. Attention is focused onoptimal excitations with a finite number of superharmonics, because theyare theoretically performant and easy to reproduce. Extensive numericalinvestigations aimed at confirming the theoretical predictions andchecking the effectiveness of the method are performed. In particular,the elimination of the homoclinic tangency and the regularization offractal basins of attraction are numerically verified. The reduction ofthe erosion of the basins of attraction is also investigated in detail,and the paper ends with a study of the effects of control on delayingcross-well chaotic attractors.
TL;DR: Combining recent and new inelastic neutron scattering data for the molecular cyclic cluster Cr8 produces a deep understanding of the low lying excitations in bipartite antiferromagnetic Heisenberg rings.
Abstract: Combining recent and new inelastic neutron scattering data for the molecular cyclic cluster ${\mathrm{C}\mathrm{r}}_{8}$ produces a deep understanding of the low lying excitations in bipartite antiferromagnetic Heisenberg rings. The existence of the $L$ band, the lowest rotational band, and the $E$ band, essentially spin wave excitations, is confirmed spectroscopically. The different significance of these excitations and their physical nature is clearly established by high-energy and $Q$-dependence data.
TL;DR: BM at birth is delayed in almost half of CH patients and CH severity per se can affect DQ at the age of 1 Year irrespective of other variables related to therapy, according to retrospective evaluated infants with congenital hypothyroidism.
Abstract: Objective: To evaluate in a cohort of infants with congenital hypothyroidism (CH): (a) the frequency of bone maturation (BM) retardation at birth and (b) whether BM delay at birth may be considered as a tool to make a prognosis of psychomotor status at the age of 1 year, irrespective of other variables related to treatment. Design: BM at birth, CH severity and developmental quotient (DQ) at the age of 1 year were retrospectively evaluated in 192 CH infants selected by the following inclusion criteria: (a) gestation age ranging between 38 and 42 weeks; (b) onset of therapy within the first month of life; (c) initial thyroxine (L-T4) dosage ranging from 10 to 12mg/kg/day; (d) normalization of serum thyrotropin (TSH) levels before the age of 3 months; (e) monthly adjustments of L-T4 dose during the first year of life with serum TSH levels ranging from 0.5 to 4 mIU/l; (f) no major diseases and/or physical handicaps associated with CH; (g) availability of both thyroid scanning and knee X-rays at the time of treatment initiation; (h) availability of DQ assessment at an average age of 12 months. Methods: BM was considered normal if the distal femur bony nucleus diameter exceeded 3 mm (group A) or retarded if either this nucleus was absent (subgroup B1) or its diameter was , 3 mm (subgroup
TL;DR: It is found that this combination induces a high response rate and a long progression-free survival without significantly increasing thalidomide-related toxicity.
Abstract: Thalidomide exerts synergistic or additive effects when combined with other drugs. This study reports the toxicity and efficacy of the combination of thalidomide plus oral melphalan in 27 patients with advanced multiple myeloma. We found that this combination induces a high response rate and a long progression-free survival without significantly increasing thalidomide-related toxicity.
TL;DR: It is concluded that as vibrios do not lose adhesive properties after long-term exposure to ASW, it is important to include methods for VBNC bacteria when testing environmental and clinical samples for purposes of public health safety.
Abstract: The effect of exposure to artificial sea water (ASW) on the ability of classical Vibrio cholerae O1 cells to interact with chitin-containing substrates and human intestinal cells was studied. Incubation of vibrios in ASW at 5 degrees C and 18 degrees C resulted in two kinds of cell responses: the viable but non-culturable (VBNC) state (i.e. <0.1 colony forming unit ml-1) at 5 degrees C, and starvation (i.e. maintenance of culturability of the population) at 18 degrees C. The latter remained rod shaped and, after 40 days' incubation, presented a 47-58% reduction in the number of cells attached to chitin, a 48-53% reduction in the number of bacteria adhering to copepods, and a 48-54% reduction in the number of bacteria adhering to human cultured intestinal cells, compared to control cells not suspended in ASW. Bacteria suspended in ASW at 5 degrees C became coccoid and, after 40 days, showed 34-42% fewer cells attached to chitin, 52-55% fewer adhering to copep-ods, and 45-48% fewer cells adhering to intestinal cell monolayers, compared to controls. Sarkosyl-insoluble membrane proteins that bind chitin particles were isolated and analysed by SDS-PAGE. After 40 days incubation in ASW at both 5 degrees C and 18 degrees C vibrios expressed chitin-binding ligands similar to bacteria harvested in the stationary growth phase. It is concluded that as vibrios do not lose adhesive properties after long-term exposure to ASW, it is important to include methods for VBNC bacteria when testing environmental and clinical samples for purposes of public health safety.
TL;DR: The novel Npr1 gene 3C variant and the Npr3 gene C(−55) allele are associated with hypertensive family history and are also associated with higher systolic blood pressure and prolonged ventricular relaxation.
Abstract: ObjectiveAbnormalities in the natriuretic peptide system could play a key role in the genesis of hypertension. We evaluated the associations between a family history of hypertension, cardiovascular phenotype and allelic variants of Npr1 and Npr3, two candidate genes that codify for natriuretic pepti
TL;DR: In this article, a 3-RPC topology with 3-D.o.f. parallel mechanism is presented and the kinematics of the mechanism are studied. But the authors do not consider the problem of finding closed-form solutions for both inverse and direct position kinematic problems.
Abstract: A new three-d.o.f. parallel mechanism, with 3-RPC topology, is presented in the paper and its kinematics is studied. The proposed architecture, if proper geometrical conditions are satisfied, has an overconstrained structure which allows motions of pure translation. The simple structure of the mechanism allows finding closed-form solutions for both inverse and direct position kinematics; the differential analysis has been developed as well. by deriving a symbolic expression for the Jacobian matrix. Then, some design considerations are exposed to keep the singular points out of the working space of the mechanism and all the isotropic configurations are eventually identified.
TL;DR: MTLBL is unique variant of T-cell/histiocyte-rich diffuse LBL, characterized by primary splenic presentation and a micronodular architecture, and the prognosis was poor; seven of the 12 cases with follow-up were dead within 2 years.
Abstract: Occasionally, primary large B-cell lymphomas (LBLs) arising in the spleen present with a micronodular pattern involving the splenic white pulp but sparing the red pulp. Histologically, the nodules contain scattered large B cells in a background of numerous T cells and histiocytes. They can cause substantial difficulty in histologic diagnosis as the morphology can mimic reactive and inflammatory lesions as well as other lymphoid neoplasms. In this study, we examined the histology and immunophenotype of the micronodular T-cell/histiocyte-rich LBL (MTLBL) of the spleen with a view to establish the characteristics that may be helpful in diagnosis. Paraffin-embedded material from 17 cases of MTLBL was studied. Clinical features and histology were reviewed and immunohistochemistry was performed for immunoglobulins, CD20, CD79a, CD3, CD68, CD10, BCL6, BCL2, OCT-2, epithelial membrane antigen, CD30, CD138, and EBV markers. The median age of presentation was 56 years, and the most frequent presenting features were anemia and B symptoms. All cases showed a micronodular pattern of involvement. The tumor nodules comprised a mixture of numerous CD3+ T cells and CD68+ histiocytes and scattered large CD20+ B cells with immunoglobulin light chain restriction. They were positive for BCL6 and OCT2 but negative for CD10, CD138, and EBV markers. There was variable expression of epithelial membrane antigen, Bcl-2, and CD30. No follicle dendritic cell meshwork infrastructure underlying the nodules could be demonstrated by staining for CD21 or CD35 antigens. The prognosis was poor; seven of the 12 cases with follow-up were dead within 2 years. MTLBL is unique variant of T-cell/histiocyte-rich diffuse LBL, characterized by primary splenic presentation and a micronodular architecture. The main differential diagnoses include granulomatous inflammation, Hodgkin's lymphoma, follicular lymphoma, and peripheral T-cell lymphomas.
Journal Article•
TL;DR: It is confirmed again that symptomatic efficacy of STN stimulation is retained during the 2( second) and 3(rd) years following the implant, without any obvious decay of efficacy or need for increase of energy delivered.
Abstract: AIM: High frequency stimulation of the subthalamic nucleus (STN) is gaining recognition as a new symptomatic treatment for Parkinson's disease (PD). The first available long-term observations show the stability of the efficacy of this procedure in time. METHODS: Quadripolar leads were implanted bilaterally under stereotactic conditions in the STN of patients with advanced PD. High frequency stimulation was applied for 24 hours a day. Following implant, antiparkinsonian medication was reduced as much as possible and stimulation was gradually increased. The patients were evaluated in the practically defined "off" condition and in the "on" condition using the unified PD rating scale (UPDRS) and the Schwab & England scale. Neuropsychological testing was performed before and after the implant. Thirty-three patients were followed up for at least 3 months and 13 among them until 36 months. RESULTS: The patients had a mean age of 56.8+/-7.1 years and a mean disease duration of 13.8+/-5.5 years; they were followed-up for an average of 25.7+/-13.5 months. At the time of the last available visit, the stimulation amplitude was 2.47+/-0.40 V (the total energy delivered averaged 1.57+/-0.8 microW). The levodopa-equivalent daily dose was reduced by 56.2% (p <0.001). Parkinsonian features were improved in all patients, the greatest changes were seen for tremor, gait, bradykinesia and postural stability, then rigidity and limb akinesia. Compared with the pre-implant conditions, the UPDRS motor score in the "off" condition was improved by 51.6% at the time of the last visit (p <0.001), the UPDRS activities of daily living score was improved by 68.5% (p <0.001), the Schwab & England scale was improved by 196.8% (p <0.001). The neuropsychological data did not show significant changes. Night sleep improved in all patients, due to increased mobility at night. In almost all patients insomnia was resolved. All patients gained weight after surgery with an increase of 11.1% (p <0.001) compared to their pre-implant weight. The most common permanent side effects consisted in hypophonia and dysarthria, transient side effects were increased sexuality and mania, the most common side effects related to stimulation were ballic or choreic dyskinesias. The most common adverse event related to the surgical procedure was transient psychosis; unexplained switching-off of the stimulator was the most common device-related effect. CONCLUSION: This study extends our recently published 3-years FU series. It confirms again that symptomatic efficacy of STN stimulation is retained during the 2(nd) and 3(rd) years following the implant, without any obvious decay of efficacy or need for increase of energy delivered. Improvement of dyskinesias also persists and the procedure is well tolerated. Side effects and adverse events are sometimes severe, but can be managed in most cases. The improvement of daily living activities outweighs by far the motor benefit, indicating that the use of this procedure significantly improves the patients' lifestyle
TL;DR: The presence of apoptotic cells at 1 day after surgery could support the hypothesis that highly damaged peripheral lymphocytes are committed to undergo programmed cell death if the damage is not repaired, and contribute to the understanding of the regulation of DNA damage/repair and cell death.
Abstract: Anaesthetics have gained a lot of attention for their potential mutagenic/carcinogenic effects. In the present study we have investigated the genotoxicity of the inhalation anaesthetic sevoflurane on DNA of lymphocytes isolated from 20 patients undergoing orthopaedic surgery. The genotoxicity of the anaesthetic was studied by assaying DNA damage, apoptosis, DNA repair enzyme activity and GSH content in peripheral lymphocytes before, 15 min after anaesthesia and 24 h after surgery. Lymphocytes isolated 15 min after anaesthesia showed an increase in oxidized purine and pyrimidine bases without DNA strand break formation. DNA strand breaks occurred on the first post-operative day, associated with an enhancement of DNA repair activity and a decrease in GSH. Formation of strand breaks could be the consequence of DNA repair activity. In fact, at 24 h after surgery most of the oxidized DNA bases were repaired. When DNA damage was not repaired, activation of the cell cycle checkpoint protein p53 could lead to apoptosis. An altered redox status may contribute to lymphocytopenia due to an apoptotic event as a consequence of surgical trauma. The presence of apoptotic cells at 1 day after surgery could support the hypothesis that highly damaged peripheral lymphocytes are committed to undergo programmed cell death if the damage is not repaired. In conclusion, the actual risk from anaesthesia is presumably extremely small. However, these findings contribute to our understanding of the regulation of DNA damage/repair and cell death.
TL;DR: A neural networks approach to the solution of the tracking problem for mobile robots and the proposed solutions are implemented on a PC-based control architecture for the real-time control of the LabMate mobile base and are compared with classical kinematic control schemes.
Abstract: The paper proposes a neural networks approach to the solution of the tracking problem for mobile robots. Neural networks based controllers are investigated in order to exploit the nonlinear approximation capabilities of the nets for modeling the kinematic behavior of the vehicle and for reducing unmodeled tracking errors contributions. The training of the nets and the control performances analysis have been done in a real experimental setup. The proposed solutions are implemented on a PC-based control architecture for the real-time control of the LabMate mobile base and are compared with classical kinematic control schemes. Experimental results are satisfactory in terms of tracking errors and computational efforts. © 2003 Wiley Periodicals, Inc.
TL;DR: The results demonstrate that HDL exert a protective role against lipid peroxidation, and could be related to the ability of HDL to bind metal ions at the lipoprotein surface and/or to a stimulation of the efflux of lipid hydroperoxides from cell membranes as demonstrated in other cell types.
TL;DR: The need for a reinterpretation of Hicks' contribution in the light of a more careful mathematical investigation is shown, it will be shown that only one bound is needed to have non explosive outcome if the equilibrium point is an unstable focus.
TL;DR: The results indicate that hemolymph-soluble factors are involved in interactions between hemocytes and mannose-sensitive adhesins in Vibrio cholerae O1 El Tor interactions with Hemolymph of the mussel Mytilus galloprovincialis.
Abstract: The role of mannose-sensitive hemagglutinin (MSHA) in Vibrio cholerae O1 El Tor interactions with hemolymph of the mussel Mytilus galloprovincialis was studied. Bacterial adherence to and association with hemocytes were evaluated at 4 and 18°C, respectively. In hemolymph serum, the wild-type strain N16961 adhered to and associated with hemocytes about twofold more efficiently than its mutant lacking MSHA. In artificial seawater (ASW), no significant differences between the two strains were observed. N16961 was also more sensitive to hemocyte bactericidal activity than its MSHA mutant; in fact, the percentages of killed bacteria after 120 min of incubation were 60 and 34%, respectively. The addition of d-mannose abolished the serum-mediated increase in adherence, association, and sensitivity to killing of the wild-type strain without affecting the interactions of the mutant. A similar increase in N16961 adherence to hemocytes was observed when serum was adsorbed with MSHA-deficient bacteria. In contrast, serum adsorbed with either wild-type V. cholerae El Tor or wild-type Escherichia coli carrying type 1 fimbriae was no longer able to increase adherence of N16961 to hemocytes. The results indicate that hemolymph-soluble factors are involved in interactions between hemocytes and mannose-sensitive adhesins.
TL;DR: The results indicated that a single mutation might affect the structural properties of a protein, including its propensity to aggregate at high temperatures, and indicated a possible application of Fourier-transform IR spectroscopy for assessing molten globule-like states in small proteins.
Abstract: The structure of thioredoxin from Alicyclobacillus acidocaldarius (previously named Bacillus acidocaldarius ) (BacTrx) and from Escherichia coli ( E. coli Trx) was studied by Fourier-transform IR spectroscopy. Two mutants of BacTrx [Lys(18)-->Gly (K18G) and Arg(82)-->Glu (R82E)] were also analysed. The data revealed similar secondary structures in all proteins, but BacTrx and its mutants showed a more compact structure than E. coli Trx. In BacTrx and its mutants, the compactness was p(2)H-dependent. All proteins revealed the existence of a molten globule-like state. At p(2)H 5.8, the temperature at which this state was detected was higher in BacTrx and decreased in the different proteins in the following order: BacTrx>R82E>K18G> E. coli Trx. At neutral or basic p(2)H, the molten globule-like state was detected at the same temperature in both BacTrx and R82E, whereas it was found at the same temperature in all p(2)Hs tested for E. coli Trx. The thermal stability of the proteins was in the following order at all p(2)Hs tested: BacTrx>R82E>K18G> E. coli Trx, and was lower for each protein at p(2)H 8.4 than at neutral or acidic p(2)Hs. The formation of protein aggregates, brought about by thermal denaturation, were observed for BacTrx and K18G at all p(2)Hs tested, whereas they were present in R82E and E. coli Trx samples only at p(2)H 5.8. The results indicated that a single mutation might affect the structural properties of a protein, including its propensity to aggregate at high temperatures. The data also indicated a possible application of Fourier-transform IR spectroscopy for assessing molten globule-like states in small proteins.
TL;DR: In this article, the effects of mixing of magnetic states in a molecular ring were investigated by torque magnetometry and heat capacity measurements and the results were interpreted within the framework of the spin Hamiltonian approach allowing us to fit the pattern of energy levels derived by neutron spectroscopy.
Abstract: Effects of mixing of magnetic states in a molecular ${\mathrm{Cr}}_{8}$ ring were investigated by torque magnetometry and heat capacity measurements. Results are interpreted within the framework of the spin Hamiltonian approach allowing us to fit the pattern of energy levels derived by neutron spectroscopy. The torque signal gives evidence of mixing of states with the same parity while the Schottky anomaly vanishes at ${B}_{c1}=6.9\mathrm{T}$ and ${B}_{c2}=14.0\mathrm{T},$ the fields at which the $S=|0,0〉$ state crosses $S=|1,\ensuremath{-}1〉$ and $S=|1,\ensuremath{-}1〉$ crosses $S=|2,\ensuremath{-}2〉,$ respectively, showing no repulsion between states with different parity, in contrast to what was observed on ferric wheels.