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1.
Int J Sports Med ; 37(8): 619-24, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27136509

ABSTRACT

We evaluated the effectiveness of cold water immersion on recovery of performance (i. e., the ability of repetitively performing a physical test) in rugby players acutely and 12 h later. 8 male rugby union players (23±4.7 years; 176.9±4.5 cm; 87.5±8.6 kg) performed a rugby-specific exercise protocol (40 min) followed by recovery strategies: cold water immersion (8.9±0.6°C; 9 min with 1 min out of water, repeated twice) or control (players remained seated for 20 min) in a random order. The players underwent performance tests (countermovement and 30 s continuous jumps and agility T) at 4 time points: at baseline, immediately after rugby-specific exercise, post-recovery strategies and 12 h later. The performance of the agility and countermovement jump test were not different between cold water immersion and control immediately post rugby-specific exercises and 12 h thereafter. However, the 30 s continuous jump test performance decreased immediately but increased 12 h later after cold water immersion compared with control. Perception of recovery was better in the cold water immersion group compared with controls post 12 h exercise. Cold water immersion improves 30 s continuous jump performance, total quality recovery and seems to be an easy and practical tool for coaches and players, especially during congested periods of the season when fast recovery (~12 h) for the following activity is essential.


Subject(s)
Athletic Performance/physiology , Cold Temperature , Football/physiology , Adult , Athletes , Cross-Over Studies , Exercise Test , Humans , Immersion , Male , Water , Young Adult
2.
Nat Genet ; 5(2): 189-94, 1993 Oct.
Article in English | MEDLINE | ID: mdl-8252046

ABSTRACT

Charcot-Marie-Tooth disease type 1A (CMT1A) is an autosomal dominant neuropathy that can be caused by dominant point mutations in PMP22 which encodes a peripheral nerve myelin protein. Usually, CMT1A is caused by the duplication of a 1.5-megabase (Mb) region on chromosome 17p11.2-p12 containing PMP22. Deletion of a similar 1.5-Mb region is associated with hereditary neuropathy with liability to pressure palsies (HNPP), a clinically distinct neuropathy. We have identified a severely affected CMT1 patient who is a compound heterozygote for a recessive PMP22 point mutation, and a 1.5 Mb deletion in 17p11.2-p12. A son heterozygous for the PMP22 point mutation had no signs of neuropathy, while two others heterozygous for the deletion had HNPP, suggesting that point mutations in PMP22 can result in dominant and recessive alleles contributing to CMT1A.


Subject(s)
Charcot-Marie-Tooth Disease/genetics , Point Mutation , Aged , Amino Acid Sequence , Charcot-Marie-Tooth Disease/classification , Female , Gene Deletion , Genes, Recessive , Heterozygote , Humans , In Situ Hybridization, Fluorescence , Male , Molecular Sequence Data , Pedigree
3.
Nat Genet ; 1(3): 159-65, 1992 Jun.
Article in English | MEDLINE | ID: mdl-1303228

ABSTRACT

Charcot-Marie-Tooth disease type 1A (CMT1A) is an autosomal dominant peripheral neuropathy associated with a large DNA duplication on the short arm of human chromosome 17. The trembler (Tr) mouse serves as a model for CMT1A because of phenotypic similarities and because the Tr locus maps to mouse chromosome 11 in a region of conserved synteny with human chromosome 17. Recently, the peripheral myelin gene Pmp-22 was found to carry a point mutation in Tr mice. We have isolated cDNA and genomic clones for human PMP-22. The gene maps to human chromosome 17p11.2-17p12, is expressed at high levels in peripheral nervous tissue and is duplicated, but not disrupted, in CMT1A patients. Thus, we suggest that a gene dosage effect involving PMP-22 is at least partially responsible for the demyelinating neuropathy seen in CMT1A.


Subject(s)
Charcot-Marie-Tooth Disease/genetics , Myelin Proteins/genetics , Amino Acid Sequence , Animals , Base Sequence , Charcot-Marie-Tooth Disease/classification , Chromosome Mapping , Chromosomes, Human, Pair 17 , DNA/genetics , DNA Mutational Analysis , Disease Models, Animal , Female , Humans , Mice , Mice, Neurologic Mutants , Molecular Sequence Data , Multigene Family , Pedigree
4.
Environ Monit Assess ; 185(7): 6173-85, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23224644

ABSTRACT

The three-stage sequential extraction procedure for the fractionation of Cd, Cr, Cu, Ni, Pb, and Zn, proposed by the Commission of the European Communities Bureau of Reference, was applied to sediment five samples collected from the Sal estuary, Sergipe State, northeast Brazil, in September 2009. The method showed satisfactory recoveries, detection limits, and standard deviations for determinations of trace metals in the sediments. Cd and Pb were the metals most prevalent in the bioavailable fractions (carbonates, Fe and Mn oxides, organic matter, and sulfides), while Ni, Zn, Cu, and Cr showed higher percentages in the inert fraction. The order of mobility of the metals was Cd (66%) > Pb (65%) > Zn (59%) > Ni (57%) = Cr (57%) > Cu (56%). Possible toxicity related to these metals was examined using the risk assessment code, and by comparing the chemical data with sediment quality guideline ERL-ERM values. Results obtained using the two methods were in agreement, and showed low to medium risk for all metals, indicating that adverse effects on aquatic biota should rarely occur.


Subject(s)
Estuaries , Geologic Sediments/chemistry , Metals/analysis , Models, Chemical , Water Pollutants, Chemical/analysis , Brazil , Environmental Monitoring , Risk Assessment
5.
Neurologia ; 27(7): 414-20, 2012 Sep.
Article in English, Spanish | MEDLINE | ID: mdl-22093691

ABSTRACT

INTRODUCTION: Autism spectrum disorders are group of conditions characterised by qualitative impairments in social communication, interaction, and imagination, and by a restricted range of interests and typical repetitive behaviours. Frequently, there is a delay in the age of detection, and therefore in starting multidisciplinary evaluations and interventions, which may result in a poorer prognosis and reduced quality of life for both children and parents. The aim of our study was to describe clinical and epidemiological data including the age of detection and main initial complaints present in children with autism disorders referred to a paediatric neurology centre. PATIENTS AND METHODS: A total of 393 medical records of consecutive cases diagnosed with an autism spectrum disorder were reviewed. RESULTS: Autism was diagnosed in 82.1% of the cases, unspecified pervasive disorder in 9.9%, Asperger syndrome in 4.8%, and Rett syndrome in 3%. Sixty percent of autistic children presented with a language disorder as their main complaint. The average age of detection was 4 years. CONCLUSIONS: Compared with other countries, age of detection is delayed. Primary care-based screening and surveillance are required in order to improve prognosis and quality of life of children with an autism spectrum disorder.


Subject(s)
Child Development Disorders, Pervasive/psychology , Age of Onset , Asperger Syndrome/classification , Asperger Syndrome/epidemiology , Asperger Syndrome/psychology , Child , Child Development Disorders, Pervasive/classification , Child Development Disorders, Pervasive/epidemiology , Child, Preschool , Diagnostic and Statistical Manual of Mental Disorders , Female , Humans , Male , Mexico/epidemiology , Nervous System Diseases/complications , Neurologic Examination , Neuropsychological Tests , Retrospective Studies , Rett Syndrome/classification , Rett Syndrome/epidemiology , Rett Syndrome/psychology
6.
J Mol Model ; 27(5): 141, 2021 Apr 28.
Article in English | MEDLINE | ID: mdl-33909152

ABSTRACT

Structural, electronic, binding energies and magnetic properties of aluminum-doped and single vacancy blue phosphorene interacting with pollutant molecules are investigated using the density functional theory (DFT) with periodic boundary conditions. Acetylene, ozone, sulfur trioxide, hydrogen selenide, and sulfur dichloride molecules are considered to show the efficiency and enhancement of the sensing properties in comparison with the pristine blue phosphorene. Acetylene, sulfur trioxide, hydrogen selenide, and sulfur dichloride show chemisorption (> 0.5 eV/molecule) when interacting with the aluminum-doped system, but the ozone molecule dissociates in all configurations and symmetry sites. On the other hand, the acetylene, ozone, and sulfur trioxide with the single vacancy blue phosphorene exhibit chemisorption, the hydrogen selenide molecule exhibit a weak interaction energy, and the sulfur dichloride dissociates in all configurations and symmetry sites. In all the cases, the enhancement in the interaction energy was achieved when compared to other results for the same molecules. Finally, the single vacancy blue phosphorene shows a magnetic moment of ~1 µB/supercell, as induced by the vacancy.

7.
Comput Methods Programs Biomed ; 200: 105825, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33190944

ABSTRACT

Mammographic density (MD) is conformed by a different percentage of stromal, epithelial, and adipose tissue within the breast. One of the most critical findings in mammographic patterns for establishing a diagnosis of breast cancer is high breast tissue density. There is a wide variety of works focused on the study and automatic calculation of general breast density; however, they do not provide more detailed information about the changes that may occur within the breast tissue. This work proposes to generate a breast density map based on a texture analysis to identify the internal composition and distribution of the breast tissue through the diffuse division technique of the different densities inside the breast. Therefore, it is possible to obtain a density map associated with the breast that allows us to distinguish and quantify the different types of breast densities and their distribution according to the Breast Imaging Reporting and Data System (BI-RADS Breast Density Category). The proposed methodology was tested with mammograms from the BCDR and InBreast databases, demonstrating consistency in results and reaching an accuracy of 84.2% and 81.3%, respectively. Finally, the information obtained from the density map and its analysis could be a support tool for the specialist physician to monitor changes in breast density over time, since the fuzzy classification carried out allows quantifying the degree of membership in the BI-RADS breast density classes.


Subject(s)
Breast Density , Breast Neoplasms , Breast/diagnostic imaging , Breast Neoplasms/diagnostic imaging , Humans , Mammography
8.
FEMS Microbiol Ecol ; 96(11)2020 10 24.
Article in English | MEDLINE | ID: mdl-32816009

ABSTRACT

The aim of this work was to assess the temporal patterns in the community composition of phytoplankton (PCC) and bacterioplankton (BCC) in two interconnected and hypertrophic Pampean shallow lakes in Argentina. Factors shaping their community dynamics and community temporal covariations were also analysed. We performed 4 years of seasonal samplings (2012-2016) and communities were studied by the Utermöhl approach (PCC) and Illumina MiSeq sequencing (BCC). We found marked seasonal variations in both communities and inter-annual variations with decreasing microbial community similarities during the study. We also observed covariation in community-level dynamics among PCC and BCC within and between shallow lakes. The within-lake covariations remained positive and significant, while controlling for the effects of intrinsic (environmental) and extrinsic (temporal and meteorological) factors, suggesting a community coupling mediated by intrinsic biotic interactions. Algal-bacterial associations between different taxa of phytoplankton and bacterioplankton within each lake were also found. PCC was mainly explained by pure regional extrinsic (17-21%) and intrinsic environmental (8-9%) factors, while BCC was explained by environmental (8-10%) and biotic interactions with phytoplankton (7-8%). Our results reveal that the influence of extrinsic regional factors can be channeled to bacterioplankton through both environmental (i.e. water temperature) and phytoplankton effects.


Subject(s)
Lakes , Phytoplankton , Argentina , Bacteria/genetics , Seasons
9.
PLoS One ; 14(10): e0223563, 2019.
Article in English | MEDLINE | ID: mdl-31613902

ABSTRACT

Facial expression recognition is related to the automatic identification of affective states of a subject by computational means. Facial expression recognition is used for many applications, such as security, human-computer interaction, driver safety, and health care. Although many works aim to tackle the problem of facial expression recognition, and the discriminative power may be acceptable, current solutions have limited explicative power, which is insufficient for certain applications, such as facial rehabilitation. Our aim is to alleviate the current limited explicative power by exploiting explainable fuzzy models over sequences of frontal face images. The proposed model uses appearance features to describe facial expressions in terms of facial movements, giving a detailed explanation of what movements are in the face, and why the model is making a decision. The model architecture was selected to keep the semantic meaning of the found facial movements. The proposed model can discriminate between the seven basic facial expressions, obtaining an average accuracy of 90.8±14%, with a maximum value of 92.9±28%.


Subject(s)
Facial Expression , Facial Recognition , Fuzzy Logic , Models, Theoretical , Algorithms , Databases as Topic , Emotions , Humans
10.
Nefrologia (Engl Ed) ; 39(4): 343-354, 2019.
Article in English, Spanish | MEDLINE | ID: mdl-30737117

ABSTRACT

Diet composition has long been known to influence acid-base balance by providing acid or base precursors. In general, foods rich in protein, such as meat, cheese, eggs, and others, increase the production of acid in the body, whereas fruit and vegetables increase alkalis. The capacity of acid or base production of any food is called potential renal acid load (PRAL). Diets high in PRAL induce a low-grade metabolic acidosis state, which is associated with the development of metabolic alterations such as insulin resistance, diabetes, hypertension, chronic kidney disease, bone disorders, low muscle mass and other complications. The aim of this paper is to review the available evidence which evaluates the association of the PRAL of the diet with the incidence of chronic diseases and metabolic disorders, as well as related mechanisms involved in their development.


Subject(s)
Acid-Base Equilibrium , Diet , Kidney/metabolism , Diet/adverse effects , Humans
11.
Acta Crystallogr D Struct Biol ; 75(Pt 10): 882-894, 2019 Oct 01.
Article in English | MEDLINE | ID: mdl-31588920

ABSTRACT

Electron microscopy of macromolecular structures is an approach that is in increasing demand in the field of structural biology. The automation of image acquisition has greatly increased the potential throughput of electron microscopy. Here, the focus is on the possibilities in Scipion to implement flexible and robust image-processing workflows that allow the electron-microscope operator and the user to monitor the quality of image acquisition, assessing very simple acquisition measures or obtaining a first estimate of the initial volume, or the data resolution and heterogeneity, without any need for programming skills. These workflows can implement intelligent automatic decisions and they can warn the user of possible acquisition failures. These concepts are illustrated by analysis of the well known 2.2 Šresolution ß-galactosidase data set.


Subject(s)
Image Processing, Computer-Assisted/methods , Microscopy, Electron/methods , Single Molecule Imaging/methods , Software , Automation , beta-Galactosidase/chemistry
12.
An Pediatr (Barc) ; 68(2): 103-9, 2008 Feb.
Article in Spanish | MEDLINE | ID: mdl-18341874

ABSTRACT

INTRODUCTION: Total white blood cell count (WBC), erythrosedimentation rate (ESR) and C-reactive protein (CRP) are frequently used by primary care physicians attending infants < 90 days old with fever without localizing signs to distinguish those with a serious bacterial infection (SBI). The main objective of this study was to obtain the diagnostic values of these parameters in infants with fever. PATIENTS AND METHODS: We analyzed previously healthy infants aged 0 to 90 days old and fever with no source of infection admitted to the emergency room and/or hospitalized. The main outcome measure was the presence or absence of a SBI (urinary tract infection, bacteremia, meningitis, pneumonia, enteritis) and diagnostic values of WBC, ESR and CRP. RESULTS: A total of 103 infants met the inclusion criteria. Of these, 22 infants (21.3%) had a SBI, the most common being urinary tract infection. Absolute neutrophil count (ANC) and WBC had an area under the ROC curve (AUC) of 0.6 (95% CI: 0.46-0.73) and 0.55 (95% CI: 0.44-0.68) respectively. An ANC>or=10,000/microl had a sensitivity and specificity of 9% (95% CI: 1-21) and 92.5% (95% CI: 86-98) respectively. A WBC>or=15,000/microl had a sensitivity and specificity of 13.6% (95% CI: 1-28) and 85% (95% CI: 77-93) respectively. CRP showed an AUC of 0.71 (95% CI: 0.55-0.86) and a best cut-off point of 2 mg/dL (sensitivity 53% [95% CI: 29-76] and specificity of 85% [95% CI: 75-94]). ESR>or=20 mm/hour had an AUC, sensitivity and specificity of 0.53 (95% CI: 0.37-0.7), 38% (95% CI: 16-62) and 75% (95% CI: 65-85) respectively. CONCLUSIONS: None of these parameters alone, commonly used by physicians, is a reliable diagnostic tool to rule out SBI in infants<90 days old with fever without source of infection.


Subject(s)
Bacterial Infections/blood , C-Reactive Protein/analysis , Fever of Unknown Origin/blood , Fever of Unknown Origin/microbiology , Algorithms , Blood Sedimentation , Female , Humans , Infant , Infant, Newborn , Leukocyte Count , Male , Retrospective Studies , Severity of Illness Index
13.
Physiol Meas ; 39(8): 084006, 2018 08 31.
Article in English | MEDLINE | ID: mdl-30074904

ABSTRACT

OBJECTIVE: This work aims at providing a new method for the automatic detection of atrial fibrillation, other arrhythmia and noise on short single-lead ECG signals, emphasizing the importance of the interpretability of the classification results. APPROACH: A morphological and rhythm description of the cardiac behavior is obtained by a knowledge-based interpretation of the signal using the Construe abductive framework. Then, a set of meaningful features are extracted for each individual heartbeat and as a summary of the full record. The feature distributions can be used to elucidate the expert criteria underlying the labeling of the 2017 PhysioNet/CinC Challenge dataset, enabling a manual partial relabeling to improve the consistency of the training set. Finally, a tree gradient boosting model and a recurrent neural network are combined using the stacking technique to provide an answer on the basis of the feature values. MAIN RESULTS: The proposal was independently validated against the hidden dataset of the Challenge, achieving a combined F 1 score of 0.83 and tying for the first place in the official stage of the Challenge. This result was even improved in the follow-up stage to 0.85 with a significant simplification of the model, attaining the highest score so far reported on the hidden dataset. SIGNIFICANCE: The obtained results demonstrate the potential of Construe to provide robust and valuable descriptions of temporal data, even with the presence of significant amounts of noise. Furthermore, the importance of consistent classification criteria in manually labeled training datasets is emphasized, and the fundamental advantages of knowledge-based approaches to formalize and validate those criteria are discussed.


Subject(s)
Algorithms , Atrial Fibrillation/diagnosis , Electrocardiography , Signal Processing, Computer-Assisted , Atrial Fibrillation/physiopathology , Heart Rate , Humans
15.
Braz J Med Biol Res ; 40(9): 1221-30, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17713645

ABSTRACT

In the late 1980's child malnutrition was still prevalent in Brazil, and child obesity was beginning to rise in the richest regions of the country. To assess the extent of the nutritional transition during the period and the influence of birth weight and maternal smoking on the nutritional condition of schoolchildren, we estimated the prevalence of excess weight and malnutrition in a cohort of Brazilian schoolchildren from 1987 to 1989. We calculated the body mass index (BMI) of 8- to 10-year-old schoolchildren born in Ribeirão Preto in 1978/79. We considered children with a BMI <5th percentile (P5) to be malnourished, children with P5 > or = BMI or = P85 to be overweight. We evaluated the association of these nutritional disorders with birth factors (infant weight, sex, preterm delivery, number of pregnancies, maternal smoking during pregnancy, marital status, and schooling) and type of school using nominal logistic regression. A total of 2797 schoolchildren were evaluated. There was a significant prevalence of malnutrition (9.5%) and excess weight already tended to increase (15.7%), while 6.4% of the children were obese. Excess weight was more prevalent among children attending private schools (odds ratio, OR = 2.27) and firstborn children (OR = 1.69). Maternal smoking during pregnancy protected against malnutrition (OR = 0.56), while children with lower birth weight were at higher risk for malnutrition (OR = 4.23). We conclude that a nutritional transition was under way while malnutrition was still present, but excess weight and related factors were already emerging.


Subject(s)
Birth Weight , Child Nutrition Disorders/epidemiology , Overweight/epidemiology , Prenatal Exposure Delayed Effects/epidemiology , Smoking , Body Mass Index , Brazil/epidemiology , Child , Child Nutrition Disorders/etiology , Cohort Studies , Female , Humans , Infant, Low Birth Weight , Infant, Newborn , Male , Overweight/etiology , Pregnancy , Prevalence , Risk Factors , Socioeconomic Factors , Urban Population
17.
Hum Immunol ; 67(1-2): 85-93, 2006.
Article in English | MEDLINE | ID: mdl-16698429

ABSTRACT

Killer cell immunoglobulin-like receptors are characterized by their great diversity of genes and alleles. Population studies have identified the presence of a broad variety of genotypes. In Mexico, there are diverse ethnic groups representing 9% of the total population and the rest is composed of Mestizos with a more varied biology. For the purpose of this study, genotyping was performed in Mestizos, in Mexico City inhabitants, and in three ethnic groups. The frequencies of genes KIR2DL2, 2DL5, 2DS1-3, 2DS5, and 3DS1 showed a greater variability in the groups studied. A total of 12 different genotypes were identified, the higher number for the Mestizos and the lower number for the Tarahumaras. Genotype 1 was found at a greater frequency in all the groups, except for the Tarahumaras, in which genotype 4 was more frequent. The frequency of genotypes 4 and 8 in Mexicans was higher than that for other populations analyzed. By subtyping of KIR3DL1, 3DL2, 2DL1, and 2DL3, two B haplotypes were identified in families; both were absent in Caucasian families. Our results indicated a greater diversity of genes in the Mestizos group than in the ethnic groups.


Subject(s)
American Indian or Alaska Native/genetics , Ethnicity/genetics , Receptors, Immunologic/genetics , Gene Frequency , Genetic Variation , Genotype , Haplotypes , Humans , Linkage Disequilibrium , Mexico/ethnology , Population/genetics , Receptors, KIR , Receptors, KIR2DL1 , Receptors, KIR2DL2 , Receptors, KIR2DL3 , Receptors, KIR3DL1 , Receptors, KIR3DL2 , Receptors, KIR3DS1
18.
Occup Environ Med ; 63(10): 694-9, 2006 Oct.
Article in English | MEDLINE | ID: mdl-16728501

ABSTRACT

OBJECTIVES: To investigate the prevalence and predictors of work related asthma in young adults from the general population. METHODS: A total of 1922 subjects randomly selected from a birth cohort 1978/79 in Brazil, aged 23-25 years, completed a respiratory symptoms questionnaire based on the European Community Respiratory Health Survey, and underwent spirometry, bronchial challenge test with methacholine, and skin prick test. For subjects presenting with bronchial hyperresponsiveness, workplace exposure and its relationship with symptoms were assessed by a specific questionnaire and individualised job description to define cases of work related asthma. RESULTS: The prevalence of work related asthma was 4.2% (81 cases): 1.5% (29 cases) were classified as aggravated asthma and 2.7% (52 cases) as occupational asthma. Work related asthma was associated with atopy and education. Lower educational level (1-8 years of schooling) was associated with work related asthma (odds ratio 7.06, 95% CI 3.25 to 15.33). There was no association between work related asthma and smoking, gender, or symptoms of rhinitis. CONCLUSION: The prevalence of work related asthma was high (4.2%), and was associated with low schooling, probably because of low socioeconomic level. The disease may therefore be a consequence of poverty.


Subject(s)
Asthma/epidemiology , Occupational Diseases/epidemiology , Adult , Asthma/diagnosis , Brazil/epidemiology , Bronchial Provocation Tests , Cohort Studies , Cross-Sectional Studies , Female , Forced Expiratory Volume , Humans , Hypersensitivity, Immediate/diagnosis , Male , Methacholine Chloride , Occupational Diseases/diagnosis , Odds Ratio , Prevalence , Risk Factors , Skin Tests
19.
Bull Soc Belge Ophtalmol ; (302): 231-44, 2006.
Article in English | MEDLINE | ID: mdl-17265801

ABSTRACT

By compensating for the aberrations in the eye that cause blur, the adaptive optics scanning laser ophthalmoscope (AOSLO) yields high-magnification, high-resolution, real-time images of the living human retina. Features as small as single cone photoreceptors can be resolved, single leukocytes are recorded in real time as they pass through the smallest retinal capillaries, and the optical sectioning capability can be used to visualize independent layers of the retinal tissue ranging from the nerve fiber layer, through the blood vessels to the photoreceptors. The use of AO technology not only enhances the breadth of applications of conventional SLOs, but it facilitates a host of new applications. Here we provide an overview of AOSLO performance and its applications, including two clinical examples. Finally, we preview two novel applications; one where the AOSLO is used to present AO-corrected stimuli directly onto the retina while simultaneously recording their exact retinal position, and a second application where AOSLO videos are used to provide very precise, high-frequency measures of eye movements.


Subject(s)
Diabetic Retinopathy/diagnosis , Eye Burns/diagnosis , Image Enhancement/methods , Ophthalmoscopes , Optics and Photonics/instrumentation , Adult , Diagnostic Imaging/instrumentation , Diagnostic Imaging/methods , Equipment Design , Humans , Male , Retina/injuries , Sunlight
20.
Appl Netw Sci ; 1(1): 3, 2016.
Article in English | MEDLINE | ID: mdl-30533495

ABSTRACT

One of the most significant current challenges in large-scale online social networks, is to establish a concise and coherent method aimed to collect and summarize data. Sampling the content of an Online Social Network (OSN) plays an important role as a knowledge discovery tool. It is becoming increasingly difficult to ignore the fact that current sampling methods must cope with a lack of a full sampling frame i.e., there is an imposed condition determined by a limited data access. In addition, another key aspect to take into account is the huge amount of data generated by users of social networking services such as Twitter, which is perhaps the most influential microblogging service producing approximately 500 million tweets per day. In this context, due to the size of Twitter, which is problematic to be measured, the analysis of the entire network is infeasible and sampling is unavoidable. In addition, we strongly believe that there is a clear need to develop a new methodology to collect information on social networks (social mining). In this regard, we think that this paper introduces a set of random strategies that could be considered as a reliable alternative to gather global trends on Twitter. It is important to note that this research pretends to show some initial ideas in how convenient are random walks to extract information or global trends. The main purpose of this study, is to propose a suitable methodology to carry out an efficient collecting process via three random strategies: Brownian, Illusion and Reservoir. These random strategies will be applied through a Metropolis-Hastings Random Walk (MHRW). We show that interesting insights can be obtained by sampling emerging global trends on Twitter. The study also offers some important insights providing descriptive statistics and graphical description from the preliminary experiments.

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