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1.
Sensors (Basel) ; 24(8)2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38676214

RESUMO

Passive acoustic monitoring (PAM) through acoustic recorder units (ARUs) shows promise in detecting early landscape changes linked to functional and structural patterns, including species richness, acoustic diversity, community interactions, and human-induced threats. However, current approaches primarily rely on supervised methods, which require prior knowledge of collected datasets. This reliance poses challenges due to the large volumes of ARU data. In this work, we propose a non-supervised framework using autoencoders to extract soundscape features. We applied this framework to a dataset from Colombian landscapes captured by 31 audiomoth recorders. Our method generates clusters based on autoencoder features and represents cluster information with prototype spectrograms using centroid features and the decoder part of the neural network. Our analysis provides valuable insights into the distribution and temporal patterns of various sound compositions within the study area. By utilizing autoencoders, we identify significant soundscape patterns characterized by recurring and intense sound types across multiple frequency ranges. This comprehensive understanding of the study area's soundscape allows us to pinpoint crucial sound sources and gain deeper insights into its acoustic environment. Our results encourage further exploration of unsupervised algorithms in soundscape analysis as a promising alternative path for understanding and monitoring environmental changes.

2.
Int J Biol Macromol ; 250: 126525, 2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37633567

RESUMO

Global production of the two major poultry products, meat and eggs, has increased quickly. This, in turn, indicates both the relatively low cost and the customers' desire for these secure and high-quality products. Natural feed additives have become increasingly popular to preserve and enhance the health and productivity of poultry and livestock. We consume a lot of polyphenols, which are a kind of micronutrient. These are phytochemicals with positive effects on cardiovascular, cognitive, anti-inflammatory, detoxifying, anti-tumor, anti-pathogen, a catalyst for growth, and immunomodulating functions, among extra health advantages. Furthermore, high quantities of polyphenols have unknown and occasionally unfavorable impacts on the digestive tract health, nutrient assimilation, the activity of digestive enzymes, vitamin and mineral assimilation, the performance of the laying hens, and the quality of the eggs. This review clarifies the numerous sources, categories, biological functions, potential limitations on usage, and effects of polyphenols on poultry performance, egg composition, exterior and interior quality traits.


Assuntos
Antioxidantes , Dieta , Animais , Feminino , Antioxidantes/farmacologia , Galinhas , Polifenóis/farmacologia , Ovos/análise , Ração Animal/análise , Óvulo
3.
Environ Sci Pollut Res Int ; 29(47): 70822-70831, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36066798

RESUMO

COVID-19 pandemic influenced the environment, animal health, and food security. Due to reduced human mobility, the air and water quality increased. Other environmental consequences were the personal protective types of equipment and their haphazard disposal. Atmospheric pollution could be a cofactor leading to an increased COVID-19 mortality rate. Lockdown, however, caused a reduction in air and water pollution. Noise pollution affects the health of individuals and communities in terms of cardiovascular disorders and sleeping problems. Meanwhile, the COVID-19 lockdown controls human activities that reduce noise pollution. Municipal waste affects the environment. Recycling has been reduced in some countries but not in Saudi Arabia. COVID-19 had a drastic effect on livestock production on national, regional, and global levels, affecting countries' capacities to prevent and control diseases of animals and increasing global poverty, becoming a threat to the sustainability of global food security and safety. Many lessons have been learned from the COVID-19 pandemic, so it is wise to study and analyze the previous lessons and shed some light on past pandemics such as the Spanish flu to understand the readings and earn experiences. This paper is focused on the interaction between the pandemic and environmental health from the public health concern rather than other health classifications.


Assuntos
Poluição do Ar , COVID-19 , Influenza Pandêmica, 1918-1919 , Poluição do Ar/análise , Animais , Controle de Doenças Transmissíveis , Segurança Alimentar , História do Século XX , Humanos , Pandemias , SARS-CoV-2
5.
Front Res Metr Anal ; 7: 855165, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35782366

RESUMO

Bipartite networks are pervasive in modeling real-world phenomena and play a fundamental role in graph theory. Interactive exploratory visualization of such networks is an important problem, and particularly challenging when handling large networks. In this paper we present results from an investigation on using a general multilevel method for this purpose. Multilevel methods on networks have been introduced as a general approach to increase scalability of community detection and other complex optimization algorithms. They employ graph coarsening algorithms to create a hierarchy of increasingly coarser (reduced) approximations of an original network. Multilevel coarsening has been applied, e.g., to the problem of drawing simple ("unipartite") networks. We build on previous work that extended multilevel coarsening to bipartite graphs to propose a visualization interface that uses multilevel coarsening to compute a multi-resolution hierarchical representation of an input bipartite network. From this hierarchy, interactive node-link drawings are displayed following a genuine route of the "overview first, zoom and filter, details on demand" visual information seeking mantra. Analysts may depart from the coarsest representation and select nodes or sub-graphs to be expanded and shown at greater detail. Besides intuitive navigation of large-scale networks, this solution affords great flexibility, as users are free to select different coarsening strategies in different scenarios. We illustrate its potential with case studies involving real networks on distinct domains. The experimental analysis shows our strategy is effective to reveal topological structures, such as communities and holes, that may remain hidden in a conventional node-link layout. It is also useful to highlight connectivity patterns across the bipartite layers, as illustrated in an example that emphasizes the correlation between diseases and genes in genetic disorders, and in a study of a scientific collaboration network of authors and papers.

6.
Environ Sci Pollut Res Int ; 28(33): 44833-44844, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34244934

RESUMO

Although chickens are not susceptible to SARS-CoV-2, several coronavirus disease outbreaks have been described concerning poultry processing facilities in different countries. The COVID-19 pandemic and the developed strain caused 2nd, 3rd, and recent Indian strain waves of epidemics that have led to unexpected consequences, such as forced reductions in demands for some industries, transportation systems, employment, and businesses due to public confinement. Besides, poultry processing plants' conditions exacerbate the risks due to the proximity on the line, cold, and humidity. Most workers do not have access to paid sick time or adequate health care, and because of the low wages, they have limited reserves to enable them to leave steady employment. In addition, workers in meat and poultry slaughterhouses may be infected through respiratory droplets in the air and/or from touching dirty surfaces or objects such as workstations, break room tables, or tools. Egg prices have increased dramatically during the lockdown as consumers have started to change their behaviors and habits. The COVID pandemic might also substantially impact the international poultry trade over the next several months. This review will focus on the effect of COVID-19 on poultry production, environmental sustainability, and earth systems from different process points of view.


Assuntos
COVID-19 , Pandemias , Animais , Galinhas , Controle de Doenças Transmissíveis , Humanos , Aves Domésticas , SARS-CoV-2
7.
BMC Public Health ; 21(1): 572, 2021 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-33757480

RESUMO

BACKGROUND: The Zika virus outbreak has triggered a set of local and global actions for a rapid, effective, and timely public health response. A World Health Organization (WHO) initiative, supported by the Department of Chronic Condition Diseases and Sexually Transmitted Infections (DCCI) of the Health Surveillance Secretariat (SVS), Brazil Ministry of Health (MoH) and other public health funders, resulted in the start of the "Study on the persistence of Zika virus in body fluids of patients with ZIKV infection in Brazil - ZIKABRA study". The ZIKABRA study was designed to increase understanding of how long ZIKV persists in bodily fluids and informing best measures to prevent its transmission. Data collection began in July 2017 and the last follow up visit occurred in 06/26/2020. METHODS: A framework for the ZIKABRA Cooperation initiative is provided through a description and analysis of the mechanisms, strategies and the ethos that have guided the models of international governance and technical cooperation in health for scientific exchange in the context of a public health emergency. Among the methodological strategies, we included a review of the legal documents that supported the ZIKABRA Cooperation; weekly documents produced in the meetings and working sessions; technical reports; memorandum of understanding and the research protocol. CONCLUSION: We highlight the importance of working in cooperation between different institutional actors to achieve more significant results than that obtained by each group working in isolation. In addition, we point out the advantages of training activities, ongoing supervision, the construction of local installed research capacity, training academic and non-academic human resources, improvement of laboratory equipment, knowledge transfer and the availability of the ZIKABRA study protocol for development of similar studies, favoring the collective construction of knowledge to provide public health emergency responses. Strategy harmonization; human resources and health services; timing and recruiting particularities and processing institutional clearance in the different sites can be mentioned as challenges in this type of initiative.


Assuntos
Infecção por Zika virus , Zika virus , Brasil/epidemiologia , Surtos de Doenças/prevenção & controle , Humanos , Saúde Pública , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/prevenção & controle
8.
J Intensive Care Med ; 35(4): 347-353, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29258386

RESUMO

OBJECTIVE: Compare the mortality between critically ill patients who received urgent chemotherapy for a cancer-related life-threatening complication with matched patients (controls) who did not received it. DESIGN: Propensity score-matched retrospective study. SETTING: Adult intensive care unit in an oncological hospital. PARTICIPANTS: All adults with solid tumor or hematological malignancies who received at least 1 day of urgent intravenous chemotherapy for a cancer-related life-threatening complication. Using the propensity score method adjusted for 10 variables, patients who received urgent chemotherapy were matched to patients who did not. INTERVENTIONS: None. MAIN OUTCOMES MEASURES: Intensive care unit and hospital mortality. RESULTS: Forty-seven patients (57% with solid tumors and 43% with hematological malignancies) who received urgent chemotherapy were matched to 94 controls. At intensive care unit admission, patients were similar except that those who received urgent chemotherapy were less likely to have received chemotherapy previously (36% vs 85%; P < .01). The intensive care unit (48.9% vs 23.4%; P < .01) and hospital (76.6% vs 46.8%; P < .01) mortality of the patients who received urgent chemotherapy was higher than the controls. The subgroup analysis showed that the higher mortality was limited to patients with solid tumor. CONCLUSION: The use of urgent chemotherapy is associated with an increase in the intensive care unit and hospital mortality of unselected critically ill patients with solid tumors but not in patients with hematological malignancies.


Assuntos
Neoplasias Hematológicas/tratamento farmacológico , Mortalidade Hospitalar , Unidades de Terapia Intensiva/estatística & dados numéricos , Cuidados para Prolongar a Vida/estatística & dados numéricos , Neoplasias/tratamento farmacológico , Adulto , Antineoplásicos/administração & dosagem , Estudos de Casos e Controles , Resultados de Cuidados Críticos , Estado Terminal/mortalidade , Estado Terminal/terapia , Feminino , Neoplasias Hematológicas/complicações , Neoplasias Hematológicas/mortalidade , Humanos , Cuidados para Prolongar a Vida/métodos , Masculino , Pessoa de Meia-Idade , Neoplasias/complicações , Neoplasias/mortalidade , Pontuação de Propensão , Estudos Retrospectivos , Resultado do Tratamento
9.
Medicine (Baltimore) ; 97(47): e13309, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30461642

RESUMO

The Conscripts Survey has been conducted periodically by the Brazilian Department of Sexually Transmitted Infections (STIs), AIDS, and Viral Hepatitis (DIAHV) in collaboration with the Brazilian Ministry of Defense for over 2 decades. It aims to assess the syphilis prevalence and obtain data on knowledge regarding STIs and their risk factors among conscripts enlisted for the Brazilian Army.This cross-sectional study was conducted among conscripts across Brazil aged 17 to 22 years from August to December 2016. It included a self-reported questionnaire and blood testing for syphilis, HIV, and hepatitis B and C.In total 38,247 conscripts were enrolled; after exclusion due to a lack of information, 37,282 (93.2%) conscripts were included. The estimated syphilis prevalence rates were: 1.63%, 1.09%, and 0.62% for screened, confirmed, and active syphilis, respectively. Among those with active syphilis, 81.1% reported not having syphilis infection in their lifetime. Higher confirmed syphilis prevalence rates were observed in the South region, followed by North and Southeast regions. Independent factors associated with confirmed syphilis infection were: self-reported STIs in one's lifetime (odds ratio [OR] = 7.24; P < .001), same-sex sexual relationships (OR = 3.43; P = .001), and having the 1st sexual intercourse encounter before 15 years of age (OR = 2.62; P = .04). The proportion of conscripts who reported having sex with other men (MSM) was 4.3%, and the estimated syphilis prevalence in this group was 5.23%, 4.61%, and 3.60% for screened, confirmed, and active syphilis, respectively. The sexual behaviors most frequently associated with confirmed syphilis were: sexual relationship with casual partners in the last year (P < .001), same-sex sexual relationships (P < .001), more than 10 partners (P = .006), and having sexual intercourse before 15 years of age (P = .003). Although not significant, only 25.4% of the conscripts who had a confirmed syphilis reported the use of condoms with steady partners, 32.4% with casual partner, and 24.3% with any partner.We found that syphilis is on the rise among the young Brazilian male population. The increase in its prevalence, particularly among MSM, highlights the need for urgent public health interventions, action plans, and implementation of risk reduction strategies aimed at this population.


Assuntos
Militares/estatística & dados numéricos , Comportamento Sexual/estatística & dados numéricos , Sífilis/epidemiologia , Adolescente , Brasil/epidemiologia , Estudos Transversais , Homossexualidade Masculina/estatística & dados numéricos , Humanos , Masculino , Prevalência , Fatores de Risco , Inquéritos e Questionários , Adulto Jovem
10.
ACS Sens ; 3(8): 1433-1438, 2018 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-30004210

RESUMO

In this paper, we discuss the relevance of sensing and biosensing for the ongoing revolution in science and technology as a product of the merging of machine learning and Big Data into affordable technologies and accessible everyday products. Possible scenarios for the next decades are described with examples of intelligent systems for various areas, most of which will rely on ubiquitous sensing. The technological and societal challenges for developing the full potential of such intelligent systems are also addressed.


Assuntos
Nanotecnologia , Big Data , Técnicas Biossensoriais/métodos , Internet , Aprendizado de Máquina
11.
J Pediatr (Rio J) ; 92(2): 197-205, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26632247

RESUMO

OBJECTIVE: To evaluate the nutritional status of children with persistent cholestasis and to compare the anthropometric indices between children with and without liver cirrhosis and children with and without jaundice. METHODS: Children with persistent cholestasis, i.e. increased direct bilirrubin or changes in the canalicular enzyme gamma-glutamyl transferase (GGT), were included. The anthropometric measures were weight (W), height or length (H), arm circumference (AC), triceps skinfold thickness (TST), arm muscle circumference (AMC), and body mass index (BMI). RESULTS: Ninety-one children with cholestasis, with current median age of 12 months, were evaluated. W/age (A) and H/A indices below -2 Z-scores were observed in 33% and 30.8% of patients, respectively. Concerning the W/H index and BMI, only 12% and 16% of patients, respectively, were below -2 Z-scores. Regarding AC, 43.8% of 89 evaluated patients had some depletion. Observing the TST, 64% of patients had depletion, and 71.1% of the 45 evaluated patients had some degree of depletion regarding the ACM index. CONCLUSION: Evaluation using weight in patients with chronic liver diseases may overestimate the nutritional status due to visceromegaly, subclinical edema, or ascites. Indices that correlate weight and height, such as W/H and BMI, may also not show depletion because of the chronic condition in which there are depletion of both weight and height. TST, AC, and ACM are parameters that better estimate nutritional status and should be part of the management of patients with liver diseases and cholestasis.


Assuntos
Transtornos da Nutrição Infantil/fisiopatologia , Colestase/fisiopatologia , Icterícia/fisiopatologia , Cirrose Hepática/fisiopatologia , Estatura , Índice de Massa Corporal , Peso Corporal , Criança , Transtornos da Nutrição Infantil/etiologia , Pré-Escolar , Colestase/complicações , Doença Crônica , Feminino , Humanos , Lactente , Icterícia/complicações , Cirrose Hepática/complicações , Masculino , Avaliação Nutricional , Dobras Cutâneas
12.
IEEE Trans Vis Comput Graph ; 21(1): 81-94, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26357023

RESUMO

Similarity-based layouts generated by multidimensional projections or other dimension reduction techniques are commonly used to visualize high-dimensional data. Many projection techniques have been recently proposed addressing different objectives and application domains. Nonetheless, very little is known about the effectiveness of the generated layouts from a user's perspective, how distinct layouts from the same data compare regarding the typical visualization tasks they support, or how domain-specific issues affect the outcome of the techniques. Learning more about projection usage is an important step towards both consolidating their role in high-dimensional data analysis and taking informed decisions when choosing techniques. This work provides a contribution towards this goal. We describe the results of an investigation on the performance of layouts generated by projection techniques as perceived by their users. We conducted a controlled user study to test against the following hypotheses: (1) projection performance is task-dependent; (2) certain projections perform better on certain types of tasks; (3) projection performance depends on the nature of the data; and (4) subjects prefer projections with good segregation capability. We generated layouts of high-dimensional data with five techniques representative of different projection approaches. As application domains we investigated image and document data. We identified eight typical tasks, three of them related to segregation capability of the projection, three related to projection precision, and two related to incurred visual cluttering. Answers to questions were compared for correctness against `ground truth' computed directly from the data. We also looked at subject confidence and task completion times. Statistical analysis of the collected data resulted in Hypotheses 1 and 3 being confirmed, Hypothesis 2 being confirmed partially and Hypotheses 4 could not be confirmed. We discuss our findings in comparison with some numerical measures of projection layout quality. Our results offer interesting insight on the use of projection layouts in data visualization tasks and provide a departing point for further systematic investigations.

13.
PLoS One ; 9(1): e86402, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24475115

RESUMO

Rhythms produced by the endogenous circadian clock play a critical role in allowing plants to respond and adapt to the environment. While there is a well-established regulatory link between the circadian clock and responses to abiotic stress in model plants, little is known of the circadian system in crop species like soybean. This study examines how drought impacts diurnal oscillation of both drought responsive and circadian clock genes in soybean. Drought stress induced marked changes in gene expression of several circadian clock-like components, such as LCL1-, GmELF4- and PRR-like genes, which had reduced expression in stressed plants. The same conditions produced a phase advance of expression for the GmTOC1-like, GmLUX-like and GmPRR7-like genes. Similarly, the rhythmic expression pattern of the soybean drought-responsive genes DREB-, bZIP-, GOLS-, RAB18- and Remorin-like changed significantly after plant exposure to drought. In silico analysis of promoter regions of these genes revealed the presence of cis-elements associated both with stress and circadian clock regulation. Furthermore, some soybean genes with upstream ABRE elements were responsive to abscisic acid treatment. Our results indicate that some connection between the drought response and the circadian clock may exist in soybean since (i) drought stress affects gene expression of circadian clock components and (ii) several stress responsive genes display diurnal oscillation in soybeans.


Assuntos
Adaptação Fisiológica/genética , Relógios Circadianos/genética , Ritmo Circadiano/fisiologia , Secas , Regulação da Expressão Gênica de Plantas/fisiologia , Glycine max/genética , Glycine max/fisiologia , Ácido Abscísico , Análise de Variância , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Reação em Cadeia da Polimerase em Tempo Real , Análise de Sequência de RNA
14.
IEEE Trans Vis Comput Graph ; 20(3): 457-70, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24434226

RESUMO

Internet users are very familiar with the results of a search query displayed as a ranked list of snippets. Each textual snippet shows a content summary of the referred document (or webpage) and a link to it. This display has many advantages, for example, it affords easy navigation and is straightforward to interpret. Nonetheless, any user of search engines could possibly report some experience of disappointment with this metaphor. Indeed, it has limitations in particular situations, as it fails to provide an overview of the document collection retrieved. Moreover, depending on the nature of the query--for example, it may be too general, or ambiguous, or ill expressed--the desired information may be poorly ranked, or results may contemplate varied topics. Several search tasks would be easier if users were shown an overview of the returned documents, organized so as to reflect how related they are, content wise. We propose a visualization technique to display the results of web queries aimed at overcoming such limitations. It combines the neighborhood preservation capability of multidimensional projections with the familiar snippet-based representation by employing a multidimensional projection to derive two-dimensional layouts of the query search results that preserve text similarity relations, or neighborhoods. Similarity is computed by applying the cosine similarity over a "bag-of-words" vector representation of collection built from the snippets. If the snippets are displayed directly according to the derived layout, they will overlap considerably, producing a poor visualization. We overcome this problem by defining an energy functional that considers both the overlapping among snippets and the preservation of the neighborhood structure as given in the projected layout. Minimizing this energy functional provides a neighborhood preserving two-dimensional arrangement of the textual snippets with minimum overlap. The resulting visualization conveys both a global view of the query results and visual groupings that reflect related results, as illustrated in several examples shown.

15.
Transgenic Res ; 23(1): 75-87, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23807320

RESUMO

The development of drought tolerant plants is a high priority because the area suffering from drought is expected to increase in the future due to global warming. One strategy for the development of drought tolerance is to genetically engineer plants with transcription factors (TFs) that regulate the expression of several genes related to abiotic stress defense responses. This work assessed the performance of soybean plants overexpressing the TF DREB1A under drought conditions in the field and in the greenhouse. Drought was simulated in the greenhouse by progressively drying the soil of pot cultures of the P58 and P1142 lines. In the field, the performance of the P58 line and of 09D-0077, a cross between the cultivars BR16 and P58, was evaluated under four different water regimes: irrigation, natural drought (no irrigation) and water stress created using rain-out shelters in the vegetative or reproductive stages. Although the dehydration-responsive element-binding protein (DREB) plants did not outperform the cultivar BR16 in terms of yield, some yield components were increased when drought was introduced during the vegetative stage, such as the number of seeds, the number of pods with seeds and the total number of pods. The greenhouse data suggest that the higher survival rates of DREB plants are because of lower water use due to lower transpiration rates under well watered conditions. Further studies are needed to better characterize the soil and atmospheric conditions under which these plants may outperform the non-transformed parental plants.


Assuntos
Proteínas de Arabidopsis/genética , Secas , Glycine max/genética , Fatores de Transcrição/genética , Adaptação Fisiológica/genética , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas , Sementes/genética , Sementes/crescimento & desenvolvimento , Glycine max/crescimento & desenvolvimento , Água/metabolismo
16.
Langmuir ; 29(24): 7542-50, 2013 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-23356548

RESUMO

The control of molecular architectures has been exploited in layer-by-layer (LbL) films deposited on Au interdigitated electrodes, thus forming an electronic tongue (e-tongue) system that reached an unprecedented high sensitivity (down to 10(-12) M) in detecting catechol. Such high sensitivity was made possible upon using units containing the enzyme tyrosinase, which interacted specifically with catechol, and by processing impedance spectroscopy data with information visualization methods. These latter methods, including the parallel coordinates technique, were also useful for identifying the major contributors to the high distinguishing ability toward catechol. Among several film architectures tested, the most efficient had a tyrosinase layer deposited atop LbL films of alternating layers of dioctadecyldimethylammonium bromide (DODAB) and 1,2-dipalmitoyl-sn-3-glycero-fosfo-rac-(1-glycerol) (DPPG), viz., (DODAB/DPPG)5/DODAB/Tyr. The latter represents a more suitable medium for immobilizing tyrosinase when compared to conventional polyelectrolytes. Furthermore, the distinction was more effective at low frequencies where double-layer effects on the film/liquid sample dominate the electrical response. Because the optimization of film architectures based on information visualization is completely generic, the approach presented here may be extended to designing architectures for other types of applications in addition to sensing and biosensing.

17.
Biointerphases ; 7(1-4): 53, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22911268

RESUMO

An overview is provided of the various methods for analyzing biosensing data, with emphasis on information visualization approaches such as multidimensional projection techniques. Emphasis is placed on the importance of data analysis methods, with a description of traditional techniques, including the advantages and limitations of linear and non-linear methods to generate layouts that emphasize similarity/dissimilarity relationships among data instances. Particularly important are recent methods that allow processing high-dimensional data, thus taking full advantage of the capabilities of modern equipment. In this area, now referred to as e-science, the choice of appropriate data analysis methods is crucial to enhance the sensitivity and selectivity of sensors and biosensors. Two types of systems deserving attention in this context are electronic noses and electronic tongues, which are made of sensor arrays whose electrical or electrochemical responses are combined to provide "finger print" information for aromas and tastes. Examples will also be given of unprecedented detection of tropical diseases, made possible with the use of multidimensional projection techniques. Furthermore, ways of using these techniques along with other information visualization methods to optimize biosensors will be discussed.


Assuntos
Técnicas Biossensoriais/métodos , Processamento Eletrônico de Dados/métodos , Sensibilidade e Especificidade
18.
Langmuir ; 28(1): 1029-40, 2012 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-22103862

RESUMO

The wide variety of molecular architectures used in sensors and biosensors and the large amount of data generated with some principles of detection have motivated the use of computational methods, such as information visualization techniques, not only to handle the data but also to optimize sensing performance. In this study, we combine projection techniques with micro-Raman scattering and atomic force microscopy (AFM) to address critical issues related to practical applications of electronic tongues (e-tongues) based on impedance spectroscopy. Experimentally, we used sensing units made with thin films of a perylene derivative (AzoPTCD acronym), coating Pt interdigitated electrodes, to detect CuCl(2) (Cu(2+)), methylene blue (MB), and saccharose in aqueous solutions, which were selected due to their distinct molecular sizes and ionic character in solution. The AzoPTCD films were deposited from monolayers to 120 nm via Langmuir-Blodgett (LB) and physical vapor deposition (PVD) techniques. Because the main aspects investigated were how the interdigitated electrodes are coated by thin films (architecture on e-tongue) and the film thickness, we decided to employ the same material for all sensing units. The capacitance data were projected into a 2D plot using the force scheme method, from which we could infer that at low analyte concentrations the electrical response of the units was determined by the film thickness. Concentrations at 10 µM or higher could be distinguished with thinner films--tens of nanometers at most--which could withstand the impedance measurements, and without causing significant changes in the Raman signal for the AzoPTCD film-forming molecules. The sensitivity to the analytes appears to be related to adsorption on the film surface, as inferred from Raman spectroscopy data using MB as analyte and from the multidimensional projections. The analysis of the results presented may serve as a new route to select materials and molecular architectures for novel sensors and biosensors, in addition to suggesting ways to unravel the mechanisms behind the high sensitivity obtained in various sensors.


Assuntos
Serviços de Informação , Perileno/análogos & derivados , Microscopia de Força Atômica , Perileno/química
19.
Analyst ; 136(7): 1344-50, 2011 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-21283854

RESUMO

The development of new methods and concepts to visualize massive amounts of data holds the promise to revolutionize the way scientific results are analyzed, especially when tasks such as classification and clustering are involved, as in the case of sensing and biosensing. In this paper we employ a suite of software tools, referred to as PEx-Sensors, through which projection techniques are used to analyze electrical impedance spectroscopy data in electronic tongues and related sensors. The possibility of treating high dimension datasets with PEx-Sensors is advantageous because the whole impedance vs. frequency curves obtained with various sensing units and for a variety of samples can be analyzed at once. It will be shown that non-linear projection techniques such as Sammon's Mapping or IDMAP provide higher distinction ability than linear methods for sensor arrays containing units capable of molecular recognition, apparently because these techniques are able to capture the cooperative response owing to specific interactions between the sensing unit material and the analyte. In addition to allowing for a higher sensitivity and selectivity, the use of PEx-Sensors permits the identification of the major contributors for the distinguishing ability of sensing units and of the optimized frequency range. The latter will be illustrated with sensing units made with layer-by-layer (LbL) films to detect phytic acid, whose capacitance data were visualized with Parallel Coordinates. Significantly, the implementation of PEx-Sensors was conceived so as to handle any type of sensor based on any type of principle of detection, representing therefore a generic platform for treating large amounts of data for sensors and biosensors.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Biossensoriais/instrumentação , Espectroscopia Dielétrica/métodos , Eletrônica , Software
20.
Med Hypotheses ; 75(3): 324-7, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20392572

RESUMO

The development of an effective vaccine for hepatitis C is of paramount importance, given the global disease burden and its public health impact. We simulated a theoretical vaccine with 98% efficacy and coverage of 95% of the susceptible population, an achievable program. The simulated period of vaccination varied from 0 to 70 years and we calculated, through a mathematical model, the reduction in the number of liver transplantations carried out each year. The program is entirely inefficient until 20 years of vaccination and its impact rises linearly with time, reaching a maximum of 40% reduction. The model assumes that approximately 50% of all the liver transplantation carried out in our population are due to HCV infection. Therefore, the maximum reduction in the number of transplantation attained after 70 years is 10% less of the theoretical optimum. This is due to the 2% of primary vaccination failure plus the 5% in the coverage failure, which leaves a small proportion of susceptible individuals who will catch the infection and evolve to liver failure. In conclusion, the advent of a hepatitis C vaccine is welcome however, decision makers should be prepared for a very long time living with this scourge.


Assuntos
Hepacivirus , Hepatite C/prevenção & controle , Transplante de Fígado/estatística & dados numéricos , Modelos Teóricos , Vacinas contra Hepatite Viral , Simulação por Computador , Humanos
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