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1.
PLoS Comput Biol ; 19(1): e1010829, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36608145

RESUMEN

When faced with navigating back somewhere we have been before we might either retrace our steps or seek a shorter path. Both choices have costs. Here, we ask whether it is possible to characterize formally the choice of navigational plans as a bounded rational process that trades off the quality of the plan (e.g., its length) and the cognitive cost required to find and implement it. We analyze the navigation strategies of two groups of people that are firstly trained to follow a "default policy" taking a route in a virtual maze and then asked to navigate to various known goal destinations, either in the way they want ("Go To Goal") or by taking novel shortcuts ("Take Shortcut"). We address these wayfinding problems using InfoRL: an information-theoretic approach that formalizes the cognitive cost of devising a navigational plan, as the informational cost to deviate from a well-learned route (the "default policy"). In InfoRL, optimality refers to finding the best trade-off between route length and the amount of control information required to find it. We report five main findings. First, the navigational strategies automatically identified by InfoRL correspond closely to different routes (optimal or suboptimal) in the virtual reality map, which were annotated by hand in previous research. Second, people deliberate more in places where the value of investing cognitive resources (i.e., relevant goal information) is greater. Third, compared to the group of people who receive the "Go To Goal" instruction, those who receive the "Take Shortcut" instruction find shorter but less optimal solutions, reflecting the intrinsic difficulty of finding optimal shortcuts. Fourth, those who receive the "Go To Goal" instruction modulate flexibly their cognitive resources, depending on the benefits of finding the shortcut. Finally, we found a surprising amount of variability in the choice of navigational strategies and resource investment across participants. Taken together, these results illustrate the benefits of using InfoRL to address navigational planning problems from a bounded rational perspective.


Asunto(s)
Navegación Espacial , Realidad Virtual , Humanos , Motivación , Aprendizaje por Laberinto , Cognición
2.
Cogn Psychol ; 147: 101614, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37837926

RESUMEN

It has long been assumed in economic theory that multi-attribute decisions involving several attributes or dimensions - such as probabilities and amounts of money to be earned during risky choices - are resolved by first combining the attributes of each option to form an overall expected value and then comparing the expected values of the alternative options, using a unique evidence accumulation process. A plausible alternative would be performing independent comparisons between the individual attributes and then integrating the results of the comparisons afterwards. Here, we devise a novel method to disambiguate between these types of models, by orthogonally manipulating the expected value of choice options and the relative salience of their attributes. Our results, based on behavioral measures and drift-diffusion models, provide evidence in favor of the framework where information about individual attributes independently impacts deliberation. This suggests that risky decisions are resolved by running in parallel multiple comparisons between the separate attributes - possibly alongside an additional comparison of expected value. This result stands in contrast with the assumption of standard economic theory that choices require a unique comparison of expected values and suggests that at the cognitive level, decision processes might be more distributed than commonly assumed. Beyond our planned analyses, we also discovered that attribute salience affects people of different risk preference type in different ways: risk-averse participants seem to focus more on probability, except when monetary amount is particularly high; risk-neutral/seeking participants, in contrast, seem to focus more on monetary amount, except when probability is particularly low.


Asunto(s)
Conducta de Elección , Toma de Decisiones , Humanos , Probabilidad
3.
Entropy (Basel) ; 23(7)2021 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-34208923

RESUMEN

In recent years, the use of psychedelic drugs to study brain dynamics has flourished due to the unique opportunity they offer to investigate the neural mechanisms of conscious perception. Unfortunately, there are many difficulties to conduct experiments on pharmacologically-induced hallucinations, especially regarding ethical and legal issues. In addition, it is difficult to isolate the neural effects of psychedelic states from other physiological effects elicited by the drug ingestion. Here, we used the DeepDream algorithm to create visual stimuli that mimic the perception of hallucinatory states. Participants were first exposed to a regular video, followed by its modified version, while recording electroencephalography (EEG). Results showed that the frontal region's activity was characterized by a higher entropy and lower complexity during the modified video, with respect to the regular one, at different time scales. Moreover, we found an increased undirected connectivity and a greater level of entropy in functional connectivity networks elicited by the modified video. These findings suggest that DeepDream and psychedelic drugs induced similar altered brain patterns and demonstrate the potential of adopting this method to study altered perceptual phenomenology in neuroimaging research.

4.
J Chem Phys ; 152(19): 194110, 2020 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-33687268

RESUMEN

The BigDFT project was started in 2005 with the aim of testing the advantages of using a Daubechies wavelet basis set for Kohn-Sham (KS) density functional theory (DFT) with pseudopotentials. This project led to the creation of the BigDFT code, which employs a computational approach with optimal features of flexibility, performance, and precision of the results. In particular, the employed formalism has enabled the implementation of an algorithm able to tackle DFT calculations of large systems, up to many thousands of atoms, with a computational effort that scales linearly with the number of atoms. In this work, we recall some of the features that have been made possible by the peculiar properties of Daubechies wavelets. In particular, we focus our attention on the usage of DFT for large-scale systems. We show how the localized description of the KS problem, emerging from the features of the basis set, is helpful in providing a simplified description of large-scale electronic structure calculations. We provide some examples on how such a simplified description can be employed, and we consider, among the case-studies, the SARS-CoV-2 main protease.

5.
Behav Res Methods ; 51(5): 2290-2301, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-30484220

RESUMEN

The race model inequality (RMI), as first introduced by Miller (Cognitive Psychology, 14, 247-279, 1982), entails an upper bound on the amount of statistical facilitation for reaction times (RTs) attainable by a race model within the redundant-signals paradigm. A violation of RMI may be considered as empirical evidence for a coactivation model rather than a race model. Here, we introduce a novel nonparametric procedure for evaluating the RMI for single participant analysis. The statistical procedure is based on a new probabilistic representation that highlights some neglected, but important distributional features of the RMI. In particular, we show how the reconstructed distribution function under maximal statistical facilitation for a race model is characterized by a specific truncated-type property. The results of two Monte Carlo simulation studies suggest that our procedure efficiently controls for type I error with reasonable power. Finally, unlike previous proposals for single participant analysis (e.g., Maris and Maris (Journal of Mathematical Psychology 47, 507-514, 2003)), our approach is also more consistent with the typical way to collect RT data in experimental works. R script functions for running the statistical analysis on single participant data are made freely available to the readers on a dedicated web server.


Asunto(s)
Factores Socioeconómicos , Humanos , Modelos Psicológicos , Tiempo de Reacción
6.
Plant Cell Environ ; 37(4): 813-826, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24127750

RESUMEN

Volatile organic compounds (VOCs) released by soil microorganisms influence plant growth and pathogen resistance. Yet, very little is known about their influence on herbivores and higher trophic levels. We studied the origin and role of a major bacterial VOC, 2,3-butanediol (2,3-BD), on plant growth, pathogen and herbivore resistance, and the attraction of natural enemies in maize. One of the major contributors to 2,3-BD in the headspace of soil-grown maize seedlings was identified as Enterobacter aerogenes, an endophytic bacterium that colonizes the plants. The production of 2,3-BD by E. aerogenes rendered maize plants more resistant against the Northern corn leaf blight fungus Setosphaeria turcica. On the contrary, E. aerogenes-inoculated plants were less resistant against the caterpillar Spodoptera littoralis. The effect of 2,3-BD on the attraction of the parasitoid Cotesia marginiventris was more variable: 2,3-BD application to the headspace of the plants had no effect on the parasitoids, but application to the soil increased parasitoid attraction. Furthermore, inoculation of seeds with E. aerogenes decreased plant attractiveness, whereas inoculation of soil with a total extract of soil microbes increased parasitoid attraction, suggesting that the effect of 2,3-BD on the parasitoid is indirect and depends on the composition of the microbial community.


Asunto(s)
Bacterias/metabolismo , Resistencia a la Enfermedad , Ecosistema , Endófitos/metabolismo , Enfermedades de las Plantas/inmunología , Compuestos Orgánicos Volátiles/metabolismo , Zea mays/microbiología , Animales , Butileno Glicoles/metabolismo , Recuento de Colonia Microbiana , Enterobacter aerogenes/crecimiento & desarrollo , Cromatografía de Gases y Espectrometría de Masas , Herbivoria , Interacciones Huésped-Patógeno/inmunología , Datos de Secuencia Molecular , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/parasitología , Plantones/microbiología , Microbiología del Suelo , Spodoptera/fisiología , Volatilización , Zea mays/crecimiento & desarrollo , Zea mays/parasitología
7.
IEEE Trans Neural Netw Learn Syst ; 34(8): 4903-4917, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34767511

RESUMEN

Comparing competing mathematical models of complex processes is a shared goal among many branches of science. The Bayesian probabilistic framework offers a principled way to perform model comparison and extract useful metrics for guiding decisions. However, many interesting models are intractable with standard Bayesian methods, as they lack a closed-form likelihood function or the likelihood is computationally too expensive to evaluate. In this work, we propose a novel method for performing Bayesian model comparison using specialized deep learning architectures. Our method is purely simulation-based and circumvents the step of explicitly fitting all alternative models under consideration to each observed dataset. Moreover, it requires no hand-crafted summary statistics of the data and is designed to amortize the cost of simulation over multiple models, datasets, and dataset sizes. This makes the method especially effective in scenarios where model fit needs to be assessed for a large number of datasets, so that case-based inference is practically infeasible. Finally, we propose a novel way to measure epistemic uncertainty in model comparison problems. We demonstrate the utility of our method on toy examples and simulated data from nontrivial models from cognitive science and single-cell neuroscience. We show that our method achieves excellent results in terms of accuracy, calibration, and efficiency across the examples considered in this work. We argue that our framework can enhance and enrich model-based analysis and inference in many fields dealing with computational models of natural processes. We further argue that the proposed measure of epistemic uncertainty provides a unique proxy to quantify absolute evidence even in a framework which assumes that the true data-generating model is within a finite set of candidate models.

8.
Brain Sci ; 11(3)2021 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-33800904

RESUMEN

Being able to distinguish between safe and risky options is paramount in making functional choices. However, deliberate manipulation of decision-makers emotions can lead to risky behaviors. This study aims at understanding how affective reactions driven by normatively irrelevant affective cues can interfere with risk-taking. Good and Bad decks of the Iowa Gambling Task have been manipulated to make them unpleasant through a negative auditory manipulation. Anticipatory skin conductance response (SCR) and heart rate variability (HRV) have been investigated in line with the somatic marker hypothesis. Results showed fewer selections from Good decks when they were negatively manipulated (i.e., Incongruent condition). No effect of the manipulation was detected when Bad decks were negatively manipulated (i.e., Congruent condition). Higher anticipatory SCR was associated with Bad decks in Congruent condition. Slower heart rate was found before selections from Good decks in Control and Congruent condition and from Bad decks in Incongruent condition. Differences in heart rate between Bad and Good decks were also detected in Congruent condition. Results shed light on how normatively irrelevant affective cues can interfere with risk-taking.

9.
Plant J ; 59(2): 292-302, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19392694

RESUMEN

Plants activate local and systemic defence mechanisms upon exposure to stress. This innate immune response is partially regulated by plant hormones, and involves the accumulation of defensive metabolites. Although local defence reactions to herbivores are well studied, less is known about the impact of root herbivory on shoot defence. Here, we examined the effects of belowground infestation by the western corn rootworm Diabrotica virgifera virgifera on aboveground resistance in maize. Belowground herbivory by D. v. virgifera induced aboveground resistance against the generalist herbivore Spodoptera littoralis, and the necrotrophic pathogen Setosphaeria turcica. Furthermore, D. v. virgifera increased shoot levels of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), and primed the induction of chlorogenic acid upon subsequent infestation by S. littoralis. To gain insight into the signalling network behind this below- and aboveground defence interaction, we compiled a set of 32 defence-related genes, which can be used as transcriptional marker systems to detect activities of different hormone-response pathways. Belowground attack by D. v. virgifera triggered an ABA-inducible transcription pattern in the shoot. The quantification of defence hormones showed a local increase in the production of oxylipins after root and shoot infestation by D. v. virgifera and S. littoralis, respectively. On the other hand, ABA accumulated locally and systemically upon belowground attack by D. v. virgifera. Furthermore, D. v. virgifera reduced the aboveground water content, whereas the removal of similar quantities of root biomass had no effect. Our study shows that root herbivory by D. v. virgifera specifically alters the aboveground defence status of a maize, and suggests that ABA plays a role in the signalling network mediating this interaction.


Asunto(s)
Benzoxazinas/metabolismo , Escarabajos/fisiología , Raíces de Plantas/metabolismo , Zea mays/metabolismo , Ácido Abscísico/metabolismo , Animales , Ascomicetos/fisiología , Ácido Clorogénico/metabolismo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Larva/fisiología , Mariposas Nocturnas/fisiología , Oxilipinas/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Raíces de Plantas/genética , Raíces de Plantas/fisiología , ARN de Planta/metabolismo , Transducción de Señal , Zea mays/genética , Zea mays/fisiología
10.
PeerJ ; 8: e10316, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33335805

RESUMEN

Adaptive behavior emerges through a dynamic interaction between cognitive agents and changing environmental demands. The investigation of information processing underlying adaptive behavior relies on controlled experimental settings in which individuals are asked to accomplish demanding tasks whereby a hidden regularity or an abstract rule has to be learned dynamically. Although performance in such tasks is considered as a proxy for measuring high-level cognitive processes, the standard approach consists in summarizing observed response patterns by simple heuristic scoring measures. With this work, we propose and validate a new computational Bayesian model accounting for individual performance in the Wisconsin Card Sorting Test (WCST), a renowned clinical tool to measure set-shifting and deficient inhibitory processes on the basis of environmental feedback. We formalize the interaction between the task's structure, the received feedback, and the agent's behavior by building a model of the information processing mechanisms used to infer the hidden rules of the task environment. Furthermore, we embed the new model within the mathematical framework of the Bayesian Brain Theory (BBT), according to which beliefs about hidden environmental states are dynamically updated following the logic of Bayesian inference. Our computational model maps distinct cognitive processes into separable, neurobiologically plausible, information-theoretic constructs underlying observed response patterns. We assess model identification and expressiveness in accounting for meaningful human performance through extensive simulation studies. We then validate the model on real behavioral data in order to highlight the utility of the proposed model in recovering cognitive dynamics at an individual level. We highlight the potentials of our model in decomposing adaptive behavior in the WCST into several information-theoretic metrics revealing the trial-by-trial unfolding of information processing by focusing on two exemplary individuals whose behavior is examined in depth. Finally, we focus on the theoretical implications of our computational model by discussing the mapping between BBT constructs and functional neuroanatomical correlates of task performance. We further discuss the empirical benefit of recovering the assumed dynamics of information processing for both clinical and research practices, such as neurological assessment and model-based neuroscience.

11.
Brain Sci ; 10(3)2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-32121566

RESUMEN

Understanding dependencies between brain functioning and cognition is a challenging task which might require more than applying standard statistical models to neural and behavioural measures to be accomplished. Recent developments in computational modelling have demonstrated the advantage to formally account for reciprocal relations between mathematical models of cognition and brain functional, or structural, characteristics to relate neural and cognitive parameters on a model-based perspective. This would allow to account for both neural and behavioural data simultaneously by providing a joint probabilistic model for the two sources of information. In the present work we proposed an architecture for jointly modelling the reciprocal relation between behavioural and neural information in the context of risky decision-making. More precisely, we offered a way to relate Diffusion Tensor Imaging data to cognitive parameters of a computational model accounting for behavioural outcomes in the popular Balloon Analogue Risk Task (BART). Results show that the proposed architecture has the potential to account for individual differences in task performances and brain structural features by letting individual-level parameters to be modelled by a joint distribution connecting both sources of information. Such a joint modelling framework can offer interesting insights in the development of computational models able to investigate correspondence between decision-making and brain structural connectivity.

12.
J Chem Theory Comput ; 16(8): 4874-4882, 2020 Aug 11.
Artículo en Inglés | MEDLINE | ID: mdl-32544327

RESUMEN

Benchmarking molecular properties with Gaussian-type orbital (GTO) basis sets can be challenging, because one has to assume that the computed property is at the complete basis set (CBS) limit, without a robust measure of the error. Multiwavelet (MW) bases can be systematically improved with a controllable error, which eliminates the need for such assumptions. In this work, we have used MWs within Kohn-Sham density functional theory to compute static polarizabilities for a set of 92 closed-shell and 32 open-shell species. The results are compared to recent benchmark calculations employing the GTO-type aug-pc4 basis set. We observe discrepancies between GTO and MW results for several species, with open-shell systems showing the largest deviations. Based on linear response calculations, we show that these discrepancies originate from artifacts caused by the field strength and that several polarizabilies from a previous study were contaminated by higher order responses (hyperpolarizabilities). Based on our MW benchmark results, we can affirm that aug-pc4 is able to provide results close to the CBS limit, as long as finite difference effects can be controlled. However, we suggest that a better approach is to use MWs, which are able to yield precise finite difference polarizabilities even with small field strengths.

13.
J Chem Ecol ; 35(9): 999-1008, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19779759

RESUMEN

Plants infested with herbivorous arthropods emit complex blends of volatile compounds, which are used by several natural enemies as foraging cues. Despite detailed knowledge on the composition and amount of the emitted volatiles in many plant-herbivore systems, it remains largely unknown which compounds are essential for the attraction of natural enemies. In this study, we used a combination of different fractionation methods and olfactometer bioassays in order to examine the attractiveness of different compositions of volatile blends to females of the parasitoid Cotesia marginiventris. In a first step, we passed a volatile blend emitted by Spodoptera littoralis infested maize seedlings over a silica-containing filter tube and subsequently desorbed the volatiles that were retained by the silica filter (silica extract). The volatiles that broke through the silica filter were collected on and subsequently desorbed from a SuperQ filter (breakthrough). The silica extract was highly attractive to the wasps, whereas the breakthrough volatiles were not attractive. The silica extract was even more attractive than the extract that contained all herbivore-induced maize volatiles. Subsequently, we fractioned the silica extract by preparative gas-chromatography (GC) and by separating more polar from less polar compounds. In general, C. marginiventris preferred polar over non-polar compounds, but several fractions were attractive to the wasp, including one that contained compounds emitted in quantities below the detection threshold of the GC analysis. These results imply that the attractiveness of the volatile blend emitted by Spodoptera-infested maize seedlings to C. marginiventris females is determined by a specific combination of attractive and repellent/masking compounds, including some that are emitted in very small amounts. Manipulating the emission of such minor compounds has the potential to greatly improve the attraction of certain parasitoids and enhance biological control of specific insect pests.


Asunto(s)
Compuestos Orgánicos Volátiles/química , Avispas/fisiología , Zea mays/química , Animales , Cromatografía de Gases , Femenino , Interacciones Huésped-Parásitos , Plantones/química , Dióxido de Silicio/química , Compuestos Orgánicos Volátiles/aislamiento & purificación , Zea mays/parasitología
14.
Tumori ; 95(6): 675-82, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-20210228

RESUMEN

AIMS: To retrospectively evaluate 5-year local control, disease-free survival, cancer-specific survival and overall survival rates in patients with UICC stages II and III rectal cancer treated with adjuvant therapy and especially to analyze the impact of some prognostic factors on clinical outcome at univariate and multivariate analyses. METHODS AND MATERIALS: We retrospectively reviewed 306 patients treated with postoperative 5-fluorouracil-based chemoradiation (278 patients) or radiotherapy alone (28 patients) after curative surgery. The following prognostic factors were considered at univariate and multivariate analyses: age, sex, tumor location, surgery procedure, pathological stage, histology, tumor grade, surgical margins and radiotherapy technique. RESULTS: The 5-year actuarial rates for local control, disease-free survival, cancer-specific survival and overall survival were respectively 89.7%, 59.7%, 68.6% and 61.4% for the 278 patients (91%) treated with postoperative chemoradiation. Univariate analysis showed that abdominal-perineal resection impacted disease-free survival and that the T4 variable had an impact on cancer-specific survival and disease-free survival. Instead, age > or = 70, N2, IIIB (p T3 p N1) and IIIC (p T3 p N2) stage impacted cancer-specific survival, disease-free survival and rate of distant metastases. Multivariate analysis showed as significant variables age > or = 70 years, pN1 and pN2 and extraperitoneal tumor location. CONCLUSIONS: Our retrospective study showed a good 5-year local control. Factors such as individual pT4, pN1, pN2, age > or = 70 years, abdominal-perineal resection, stages IIIB-IIIC versus II-IIIA and extraperitoneal tumor location negatively influenced disease-free survival, distant metastases and cancer-specific survival. Differences exist between stages II and III rectal cancer and treatment modulation and intensification are required in order to offer the most appropriate and effective adjuvant treatment and to improve survival of rectal cancer patients.


Asunto(s)
Neoplasias del Recto/patología , Neoplasias del Recto/terapia , Anciano , Análisis de Varianza , Quimioterapia Adyuvante , Supervivencia sin Enfermedad , Femenino , Humanos , Masculino , Estadificación de Neoplasias , Valor Predictivo de las Pruebas , Pronóstico , Radioterapia Adyuvante , Neoplasias del Recto/tratamiento farmacológico , Neoplasias del Recto/radioterapia , Neoplasias del Recto/cirugía , Estudios Retrospectivos , Factores de Riesgo , Análisis de Supervivencia , Factores de Tiempo , Resultado del Tratamiento
15.
Behav Sci (Basel) ; 9(7)2019 Jul 18.
Artículo en Inglés | MEDLINE | ID: mdl-31323856

RESUMEN

Higher-order cognitive functions can be seen as a class of cognitive processes which are crucial in situations requiring a flexible adjustment of behaviour in response to changing demands of the environment. The cognitive assessment of these functions often relies on tasks which admit a dynamic, or longitudinal, component requiring participants to flexibly adapt their behaviour during the unfolding of the task. An intriguing feature of such experimental protocols is that they allow the performance of an individual to change as the task unfolds. In this work, we propose a Latent Markov Model approach to capture some dynamic aspects of observed response patterns of both healthy and substance dependent individuals in a set-shifting task. In particular, data from a Wisconsin Card Sorting Test were analysed in order to represent performance trends in terms of latent cognitive states dynamics. The results highlighted how a dynamic modelling approach can considerably improve the amount of information a researcher, or a clinician, can obtain from the analysis of a set-shifting task.

16.
Front Psychol ; 10: 2716, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31920788

RESUMEN

Mouse-tracking recording techniques are becoming very attractive in experimental psychology. They provide an effective means of enhancing the measurement of some real-time cognitive processes involved in categorization, decision-making, and lexical decision tasks. Mouse-tracking data are commonly analyzed using a two-step procedure which first summarizes individuals' hand trajectories with independent measures, and then applies standard statistical models on them. However, this approach can be problematic in many cases. In particular, it does not provide a direct way to capitalize the richness of hand movement variability within a consistent and unified representation. In this article we present a novel, unified framework for mouse-tracking data. Unlike standard approaches to mouse-tracking, our proposal uses stochastic state-space modeling to represent the observed trajectories in terms of both individual movement dynamics and experimental variables. The model is estimated via a Metropolis-Hastings algorithm coupled with a non-linear recursive filter. The characteristics and potentials of the proposed approach are illustrated using a lexical decision case study. The results highlighted how dynamic modeling of mouse-tracking data can considerably improve the analysis of mouse-tracking tasks and the conclusions researchers can draw from them.

17.
J Biophotonics ; 9(6): 619-25, 2016 06.
Artículo en Inglés | MEDLINE | ID: mdl-26375607

RESUMEN

A novel hyperspectral confocal microscopy method to separate different cell populations in a co-culture model is presented here. The described methodological and instrumental approach allows discrimination of different cell types using a non-invasive, label free method with good accuracy with a single cell resolution. In particular, melanoma cells are discriminated from HaCaT cells by hyperspectral confocal imaging, principal component analysis and optical frequencies signing, as confirmed by fluorescence labelling cross check. The identification seems to be quite robust to be insensitive to the cellular shape within the studied samples, enabling to separate cells according to their cytotype down to a single cell sensitivity. Set of hyperspectral images of melanoma-keratinocytes co-culture model (left), score plot of principal component analysis and spectral analysis of principal components coefficients (center), label-free spectral identification of cell populations (right).


Asunto(s)
Técnicas de Cocultivo , Queratinocitos/citología , Melanoma/patología , Microscopía Confocal , Línea Celular , Humanos , Análisis de Componente Principal
18.
PLoS One ; 8(4): e60376, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23565236

RESUMEN

BACKGROUND: The E200K mutation of the prion protein gene (PRNP) is the most frequent amino acid substitution in genetic Creutzfeldt-Jakob disease and is the only one responsible for the appearance of clustered cases in the world. In the Israel and Slovakian clusters, age of disease onset was reduced in successive generations but the absence of a clear molecular basis raised the possibility that this event was an observational bias. The aim of the present study was to investigate possible selection biases or confounding factors related to anticipation in E200K CJD patients belonging to a cluster in Southern Italy. METHODS: Clinical and demographical data of 41 parent-offspring pairs from 19 pedigrees of the Italian cluster of E200K patients were collected. Age at death of parents was compared with age at death of E200K CJD offspring. Subgroup analyses were performed for controlling possible selection biases, confounding factors, or both. RESULTS: The mean age at death/last follow-up of the parent generation was 71.4 years while that of CJD offspring was 59.3 years with an estimated anticipation of 12.1 years. When the same analysis was performed including only parents with CJD or carrying the E200K mutation (n = 26), the difference between offspring and parents increased to 14.8 years. CONCLUSIONS: These results show that early age at death occurs in offspring of families carrying the E200K PRNP mutation and that this event is not linked to observational biases. Although molecular or environmental bases for this occurrence remain unsettled, this information is important for improving the accuracy of information to give to mutated carriers.


Asunto(s)
Síndrome de Creutzfeldt-Jakob/genética , Priones/genética , Factores de Edad , Anciano , Síndrome de Creutzfeldt-Jakob/mortalidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Mutación , Proteínas Priónicas
19.
Front Plant Sci ; 4: 209, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23825475

RESUMEN

Plants under herbivore attack emit volatile organic compounds (VOCs) that can serve as foraging cues for natural enemies. Adult females of Lepidoptera, when foraging for host plants to deposit eggs, are commonly repelled by herbivore-induced VOCs, probably to avoid competition and natural enemies. Their larval stages, on the other hand, have been shown to be attracted to inducible VOCs. We speculate that this contradicting behavior of lepidopteran larvae is due to a need to quickly find a new suitable host plant if they have fallen to the ground. However, once they are on a plant they might avoid the sites with fresh damage to limit competition and risk of cannibalism by conspecifics, as well as exposure to natural enemies. To test this we studied the effect of herbivore-induced VOCs on the attraction of larvae of the moth Spodoptera littoralis and on their feeding behavior. The experiments further considered the importance of previous feeding experience on the responses of the larvae. It was confirmed that herbivore-induced VOCs emitted by maize plants are attractive to the larvae, but exposure to the volatiles decreased the growth rate of caterpillars at early developmental stages. Larvae that had fed on maize previously were more attracted by VOCs of induced maize than larvae that had fed on artificial diet. At relatively high concentrations synthetic green leaf volatiles, indicative of fresh damage, also negatively affected the growth rate of caterpillars, but not at low concentrations. In all cases, feeding by the later stages of the larvae was not affected by the VOCs. The results are discussed in the context of larval foraging behavior under natural conditions, where there may be a trade-off between using available host plant signals and avoiding competitors and natural enemies.

20.
Environ Int ; 48: 121-32, 2012 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-22903025

RESUMEN

Large scale (e.g. regional or national) assessments of contaminated sites may be very costly in terms of investigation and methodological (i.e. risk assessment procedures) requirements and may produce a quantity of information that usually discourages examination by decision-makers. Moreover, most of the existing tools effectively support local environmental risk assessment and management, but lack the capabilities of larger scale analysis, not mentioning the absence of the relevant component of socio-economic prioritization. To respond to the concerns and the management needs of experts and decision makers, the Spatial decision support sYstem for Regional rIsk Assessment of Degraded land (SYRIADE DSS) was developed and is presented according to its three modules: Regional Risk Assessment, Socio-economic Assessment and Integrated Assessment, respectively. The system allows to rank potentially contaminated sites for priority of investigation, when no information on characterization and risk by site specific methodologies is available. This GIS-based system embeds an innovative spatial and relative risk assessment procedure, and proposes the integrated analysis of different data (environmental and socio-economic) for the concerned sites, eliciting when necessary experts' knowledge and stakeholders' values (through Multi Criteria Decision Analysis, MCDA, methodologies). The application to a Polish case-study shows the performance and the flexibility of the system in investigating and mapping (potentially) contaminated sites at the regional scale.


Asunto(s)
Técnicas de Apoyo para la Decisión , Monitoreo del Ambiente/métodos , Toma de Decisiones , Sistemas Especialistas , Sistemas de Información Geográfica , Medición de Riesgo/métodos , Programas Informáticos , Análisis Espacial
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