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Incirrate octopodes are the only cephalopods that exhibit transient epidermal structures called Kolliker's organs (KO) in the early development stages. This work describes for the first time the histological formation process of these organs during embryonic development and of the paralarva of Octopus huhbsorum Berry, 1953, as well as their morphological characteristics. Egg masses were collected in the Gulf of California and the species was identified by molecular analysis. The histological formation of KO starts when the funnel is fully developed and ends when the embryo is ready for hatching. Differences were observed compared with the only complete histological description of KO currently available. In O. huhbsorum, the basal membrane wraps the basal and lateral cells until the KO erupts, and the cell conformation of KO (binding with muscle cells) is completed when the mantle covers the ventral margin of the funnel and chromatophores are visible. The KO of O. huhbsorum are of intermediate size and show a higher density compared with other species, especially in the arms. The cellular degradation of KO is reported here for the first time; KO disappears within 48 h posthatching, contrary to observations reported for other species in which these organs last more than 30 days, even before settlement. It is concluded that in this species, KO probably facilitate hatching or are an evolutionary reminiscence, and it is ruled out that they facilitate buoyancy before settlement. KEY WORDS: cephalopods, embryo, paralarvae, epidermis, octopus, INTRODUCTION Particularly in octopuses, the external morphology of some species varies markedly during early development (embryo, paralarva, and juvenile), including the number of suckers per arm, arm length, and chromatophore [...]

In the present study, XRD, SEM/EDS, Raman, EMR/EPR spectroscopy, and vibrating sample magnetometry (VSM) were used to analyze the reduction of hematite by the carbonization products of waste activated sludge (WAS) at 500–1000 °C. The reduction process includes the following steps: α-Fe2O3 → Fe2O3 + Fe3O4 (Ttr~500 °C) → Fe3O4 (Ttr~600–700 °C) → FeO → Feamorph. (Ttr~1000 °C). The prevalence of certain phase compositions at different hematite reduction temperatures makes it possible to predict the areas viable for the application of reduced oxides: adsorbents (after Ttr~500 °C) → soft ferromagnetic materials (after Ttr~600–700 °C) → electrically engineered amorphous iron (after Ttr~1000 °C).

Introducción: El retraso del crecimiento en niños es estudiando globalmente por profesionales de enfermería de manera independiente en todos los niveles de atención, sin embargo, no existe dentro del lenguaje estandarizado una etiqueta para describirlo desde la disciplina. Objetivo: Analizar el concepto de retraso del crecimiento en niños e identificar factores etiológicos, formas de cuantificarlo, diferenciarlo y reconocerlo desde la disciplina de enfermería. Metodología: Revisión integrativa de la literatura a fin de realizar un análisis de concepto a través de la metodología de Walker y Avant. Se analizaron 46 artículos publicados en LILACS, CUIDEN, Wiley Online Library, Science Direct, EBSCO, Scielo, PudMed en inglés, español, portugués y francés entre enero a abril del 2022. Los descriptores fueron: retardo del crecimiento, niño, factores de riesgo y enfermería, explorando conceptos, atributos, antecedentes, consecuencias y referentes empíricos. Se hizo uso de ficheros de lectura crítica y evaluación de calidad metodológica mediante los criterios de la iniciativa STROBE. Los datos cuantitativos se analizaron en forma descriptiva. Resultados: Se identificaron antecedentes como patrón de alimentación inadecuado, higiene deficiente del hogar, lactancia materna inefectiva, Cuidado ineficaz parental y sus consecuentes fueron la disminución o pausa del crecimiento del niño, proponiendo el concepto: condición en la que el peso, longitud, talla, velocidad de talla cm/año, índice de masa corporal y perímetro cefálico del niño son inferiores para sexo, edad, en relación con la media poblacional. Conclusiones: La evidencia describe la complejidad multifactorial del concepto y resalta las peculiaridades del retraso y pausa de la tasa de crecimiento.

Introducción: El ser humano que enferma, a veces necesita ser hospitalizado para establecer su homeostasis. Este proceso lo vuelve vulnerable, ya que asume el “estatus de paciente”, que afecta también aspectos psico-afectivos y puede hacerlo sentir como un objeto debido al trato de los profesionales de salud que, en ocasiones, es poco empático. Esto produce emociones negativas que generan afecciones para la salud y prolongan la recuperación, lo que a su vez eleva el costo asociado a días de hospitalización. Objetivo: Identificar factores de riesgos que vulneren la dignidad humana de pacientes hospitalizados. Metodología: Estudio descriptivo, cuantitativo. Se identifican factores de riesgo percibidos por pacientes a través del Cuestionario de Percepción de Dignidad de Paciente Hospitalizado (CuPDPH) y del diagnóstico enfermero “Riesgo de compromiso de la dignidad humana 00174” de la NANDA-I. Resultados: De la muestra de 60 pacientes (16 hombres y 44 mujeres), el ítem con mayor puntuación fue “me han llamado por mi nombre” (M = 4.73; DE = 0.84) y el menor, “en ocasiones me he sentido como un objeto” (M = 1.75; DE = 1.29). Asimismo, el factor de riesgo “comprensión inadecuada de la información de salud” fue el más presente (65 %) y “valores incongruentes con las normas culturales” el menos presente (1.7 %). Conclusión: Los factores de riesgo más percibidos por los pacientes en la unidad de salud fueron relacionados con su intimidad, integridad, comprensión de información y privacidad, por lo que es importante estudiar esta variable e intervenirla.

In this paper, a systematic review of the literature was carried out in order to identify the contributions of frugal innovation in the manufacturing sector. The above, with the objective of knowing these innovations, highlighting the relevance and its contribution to this sector within the global emerging markets. The PRISMA method was used to perform meta-analysis of the theoretical, scientific and practical contributions of goods and services resulting from the frugal philosophy in the emerging manufacturing sector. To achieve the objectives of this research, three indexed databases of high scientific quality and visibility were considered: Scopus, Ebscohost and Science Direct in the period 2010-2020, with a search equation defined by keywords and exclusion and inclusion criteria, in which a first search of 15079 articles was obtained. As a result of the final filtering process, 52 documents were obtained that allowed the identification of these innovations, their classification, description, frugal, social and economic contribution in the benefited communities. This paper provides relevant findings related to the contribution of future perspectives of similar studies and empirical evidence of frugal operational processes (products) that drive the competitiveness of manufacturing firms.

Antecedentes: La valoración de la fuerza muscular es de interés para la investigación de patologías como la fragilidad y la sarcopenia; sin embargo, el costo de algunos instrumentos necesarios para su evaluación podría ser una limitante en algunos escenarios. Objetivo: Comparar dos dinamómetros para comparar la concordancia entre las mediciones. Material y métodos: El estudio se realizó en una clínica ambulatoria de geriatría. Se evaluaron 120 participantes de 60 años y más provenientes de la comunidad. Se utilizó el dinamómetro manual hidráulico Jamar® y el dinamómetro manual digital Camry® EH101. Resultados: Se observó correlación positiva entre los dos instrumentos para la mano dominante (MD), con r de Pearson = 0.974 (p < 0.001) y ρ de Spearman = 0.973 (p < 0.001) para la mano no dominante (MND). El coeficiente de concordancia de Lin para la MD fue de 0.98 (p < 0.001) y para la MND, de 0.97 (p < 0.001) El coeficiente de correlación intraclase fue de 0.971 (IC 95 % = 0.95-0.97, p < 0.001) para MD y de 0.975 (IC 95 % = 0.96-0.98, p < 0.001) para MND. Conclusiones: El dinamómetro digital es un instrumento confiable para la medición de la fuerza de prensión en personas mayores de 60 años provenientes de la comunidad.

Este editorial del vol. 7, núm. 14 de PatryTer – Revista Latinoamericana y Caribeña de Geografía y Humanidades se enfoca la cartografía, en tanto instrumento analítico de la Geografía, y la historia del territorio, como noción sintética de una de las preocupaciones de la disciplina. Ello justifica el homenaje que este número de la revista rinde al Dr. José Omar Moncada Maya, colega mexicano que ha dedicado más de medio siglo a la Geografía Iberoamericana. Sin duda, el homenaje a un geógrafo historiador resulta pertinente en estos momentos de la historia humana en que el conocimiento está dominado por las técnicas, la fugacidad y la proyección hacia el futuro, pues no debemos olvidar, ni en la ciencia ni en ningún aspecto de la existencia humana, que en el pasado están las claves para comprender el presente y planear un futuro mejor. La obra de José Omar Moncada nos permite revisar el devenir de la geografía mexicana para entender los caminos actuales de esta disciplina y plantear los escenarios del mañana en diálogo con otras escuelas latinoamericanas.

Los enteógenos han surgido en la investigación clínica como un tratamiento alternativo para la Depresión Resistente al Tratamiento (DRT). Tienen efectos antidepresivos rápidos y duraderos, son ansiolíticos, y mitigan la ideación suicida. Además, inducen emociones positivas y provocan experiencias místicas o espirituales, atributos que pueden contribuir a su eficacia terapéutica, dada la influencia protectora del misticismo y la religiosidad contra la depresión. Esta revisión narrativa tiene como objetivo discutir la evidencia existente sobre la utilización de enteógenos en la DRT, proporcionar una comprensión actualizada del panorama de la investigación y discutir los mecanismos de acción de compuestos como la psilocibina, DMT, LSD, ketamina, esketamina y cannabinoides. La eficacia de los enteógenos en el manejo de la depresión ha sido validada consistentemente en los ensayos clínicos. No obstante, es imperativo reconocer nuestra limitada comprensión de los posibles efectos adversos, especialmente a largo plazo, a pesar de los datos que sustentan su tolerabilidad aguda.

ObjectiveTo introduce MexOMICS, a Mexican Consortium focused on establishing electronic databases to collect, cross-reference, and share health-related and omics data on the Mexican population.MethodsSince 2019, the MexOMICS Consortium has established three electronic-based registries: the Mexican Twin Registry (TwinsMX), Mexican Lupus Registry (LupusRGMX), and the Mexican Parkinson's Research Network (MEX-PD), designed and implemented using the Research Electronic Data Capture web-based application. Participants were enrolled through voluntary participation and on-site engagement with medical specialists. We also acquired DNA samples and Magnetic Resonance Imaging scans in subsets of participants.ResultsThe registries have successfully enrolled a large number of participants from a variety of regions within Mexico: TwinsMX (n = 2,915), LupusRGMX (n = 1,761) and MEX-PD (n = 750). In addition to sociodemographic, psychosocial, and clinical data, MexOMICS has collected DNA samples to study the genetic biomarkers across the three registries. Cognitive function has been assessed with the Montreal Cognitive Assessment in a subset of 376 MEX-PD participants. Furthermore, a subset of 267 twins have participated in cognitive evaluations with the Creyos platform and in MRI sessions acquiring structural, functional, and spectroscopy brain imaging; comparable evaluations are planned for LupusRGMX and MEX-PD.ConclusionsThe MexOMICS registries offer a valuable repository of information concerning the potential interplay of genetic and environmental factors in health conditions among the Mexican population.

Abstract Cocaine/crack abstinence periods have higher risk of relapse. Abstinence as initial part of the recovery process is affected by learning and memory changes that could preserve the addictive cycle. To further understand how the interruption of cocaine/crack consumption affects neurotrophin level we performed the present systematic review and meta-analysis following the PRISMA statement (number CRD42019121643). The search formula was conducted in PubMed, Web of Science, Embase, ScienceDirect, and Google Scholar databases. The inclusion criterion was cocaine use disorder in 18 to 60-year-old people, measuring at least one neurotrophin in blood before and after a controlled abstinence period. Studies without pre-post design were excluded. Five investigations had nine different reports, four of them were subjected to a meta-analysis (n = 146). GRADE risk of bias method was followed. Individual studies reported increased peripheral brain derived neurotrophic factor (BDNF) after abstinence, evidence pooled by Hedge’s g showed no significant change in BDNF after abstinence. Relevant heterogeneity in the length of the abstinence period (12–32 days), last cocaine/crack consumption monitoring and blood processing were detected that could help to explain non-significant results. Further improved methods are suggested, and a potential BDNF augmentation hypothesis is proposed that, if true, would help to understand initial abstinence as a re-adaptation period influenced by neurotrophins such as the BDNF.

Colletotrichum lindemuthianum is the most frequent pathogenic fungus of the common bean Phaseolus vulgaris. This filamentous fungus employs a hemibiotrophic nutrition/infection strategy, which is characteristic of many Colletotrichum species. Due to host–pathogen coevolution, C. lindemuthianum includes pathotypes with a diversity of virulence against differential common bean varieties. In this study, we performed comparative genomic analyses on three pathotypes with different virulence levels and a non-pathogenic pathotype, isolated from different geographical areas in Mexico. Our results revealed large genomes with high transposable element contents that have undergone expansions, generating intraspecific diversity. All the pathotypes exhibited a similar number of clusters of orthologous genes (COGs) and Gene Ontology (GO) terms. TFomes contain families that are typical in fungal genomes; however, they show different contents between pathotypes, mainly in transcription factors with the fungal-specific TF and Zn2Cys6 domains. Peptidase families mainly contain abundant serine peptidases, metallopeptidases, and cysteine peptidases. In the secretomes, the number of genes differed between the pathotypes, with a high percentage of candidate effectors. Both the virulence gene and CAZyme gene content for each pathotype was abundant and diverse, and the latter was enriched in hemicellulolytic enzymes. We provide new insights into the nature of intraspecific diversity among C. lindemuthianum pathotypes and the origin of their ability to rapidly adapt to genetic changes in its host and environmental conditions.

Abstract Conservation funding is currently limited; cost‐effective conservation solutions are essential. We suggest that the thousands of field stations worldwide can play key roles at the frontline of biodiversity conservation and have high intrinsic value. We assessed field stations’ conservation return on investment and explored the impact of COVID‐19. We surveyed leaders of field stations across tropical regions that host primate research; 157 field stations in 56 countries responded. Respondents reported improved habitat quality and reduced hunting rates at over 80% of field stations and lower operational costs per km2 than protected areas, yet half of those surveyed have less funding now than in 2019. Spatial analyses support field station presence as reducing deforestation. These “earth observatories” provide a high return on investment; we advocate for increased support of field station programs and for governments to support their vital conservation efforts by investing accordingly.

Abstract According to WHO statistics, breast cancer (BC) disease represents about 2.3 million diagnosed and 685,000 deaths globally. Regarding histological classification of BC, the Estrogen (ER) and Progesterone (PR) receptors negative-expression cancer, named Triple-Negative BC (TNBC), represents the most aggressive type of this disease, making it a challenge for drug discovery. In this context, our research group, applying a well-established Virtual Screening (VS) protocol, in addition to docking and molecular dynamics simulations studies, yielded two ligands identified as 6 and 37 which were chemically synthesized and evaluated on MCF-7 and MDA-MB-231 cancer cell lines. Strikingly, 37 assayed on MDA-MB-231 (a TNBC cell model) depicted an outstanding value of 18.66 μM much lower than 65.67 μM yielded by Gossypol Bcl-2 inhibitor whose main disadvantage is to produce multiple toxic effects. Highlighted above, enforce the premise of the computational tools to find new therapeutic options against the most aggressive forms of breast cancer, as the results herein showed.

Abstract Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection induces a spectrum of clinical manifestations that depend on the immune response of the patient, i.e., from an asymptomatic form to an inflammatory response with multiorgan deterioration. In some cases, severe cases of SARS-CoV-2 are characterized by an excessive, persistent release of inflammatory mediators known as a cytokine storm. This phenomenon arises from an ineffective T helper (Th)-1 response, which is unable to control the infection and leads to a reinforcement of innate immunity, causing tissue damage. The evolution of the disease produced by SARS-CoV2, known as COVID-19, has been of interest in several research fields. Asthma patients have been reported to present highly variable outcomes due to the heterogeneity of the disease. For example, the Th2 response in patients with allergic asthma is capable of decreasing Th1 activation in COVID-19, preventing the onset of a cytokine storm; additionally, IL-33 released by damaged epithelium in the context of COVID-19 potentiates either Th1 or T2-high responses, a process that contributes to poor outcomes. IL-13, a T2-high inflammatory cytokine, decreases the expression of angiotensin converting enzyme-2 (ACE2) receptor, hindering SARS-CoV-2 entry; finally, poor outcomes have been observed in COVID-19 patients with severe neutrophilic asthma. In other contexts, the COVID-19 lockdown has had interesting effects on asthma epidemiology. The incidence of asthma in the most populated states in Mexico, including Tamaulipas, which has the highest asthma incidence in the country, showed similar tendencies independent of how strict the lockdown measures were in each state. As described worldwide for various diseases, a decrease in asthma cases was observed during the COVID-19 lockdown. This decrease was associated with a drop in acute respiratory infection cases. The drop in cases of various diseases, such as diabetes, hypertension or depression, observed in 2020 was restored in 2022, but not for asthma and acute respiratory infections. There were slight increases in asthma cases when in-person classes resumed. In conclusion, although many factors were involved in asthma outcomes during the pandemic, it seems that acute respiratory infection is intimately linked to asthma cases. Social distancing during remote learning, particularly school lockdown, appears to be an important cause of the decrease in cases.

Jackfruit, primarily cultivated in Nayarit, Mexico, has four notable genotypes: “Agüitada”, “Rumina”, “Licenciada”, and “Karlita”, which require thorough characterization. This study aimed to provide a comprehensive characterization of these genotypes through an integration of morphological, physiological, physicochemical, phytochemical, and DNA fingerprinting analyses. Measurements were taken from physiological maturity to senescence. SSR and SRAP markers were employed for DNA fingerprinting, and a complete randomized design followed by multivariate analysis was used to observe variable relationships. The results revealed that “Rumina” had the largest leaf size, while “Karlita” had the largest fruit size and the highest respiration rate (117.27 mL of CO2·kg−1·h−1). “Licenciada” showed the highest ethylene production (265.45 µL·kg−1·h−1). “Agüitada” and “Licenciada” were associated with orange bulbs, whereas “Rumina” and “Karlita” were associated with yellow ones. Additionally, “Agüitada” demonstrated higher levels of soluble phenols and carotenoids, indicating greater antioxidant capacity. The Jaccard index suggested moderate genetic diversity among the genotypes, and the dendrogram revealed two genetic clusters. “Licenciada” emerged as a promising genotype, combining high genetic diversity with desirable physicochemical traits. This study highlights the need to broaden future genetic analyses to include a wider range of jackfruit genotypes from various regions, offering a more comprehensive understanding of genetic diversity.

In this study, the theoretical welding parameters influencing porosity formation were examined with the aim of reducing or minimizing porosity levels. An experimental design was implemented using the Taguchi methodology for data analysis, resulting in an L9 orthogonal array matrix of experiments. The welding variables considered in the orthogonal array were peak current, peak time, and frequency. Nine lap welds were performed on CP780 steel using the gas metal arc welding process with pulsed arc (GMAW-P), employing an ER70S-3 electrode as filler metal. The percentage of porosity was determined as a response variable, and the actual heat input was treated as a covariable, thereby identifying the welding parameters with the predicted values. Three repetitions were conducted with the optimal welding parameters to validate the Taguchi prediction. The quality of the welds was assessed through radiographic inspection, and metallographic preparation was performed, revealing the microstructure with 5% Nital for 12 s. The samples were analyzed using an optical microscope, and images were obtained with the collage technique. The results showed that the welding parameters predicted by the Taguchi statistics were favorable for all three predicted welded joints. The maximum percentage of porosity obtained was 19%, which was reduced to 1% using the Taguchi methodology, demonstrating the effectiveness of this statistical tool for process optimization. It was observed that for heat input values of 230 to 250 J/mm, the presence of porosities is dramatically reduced, finding a very small window that allows the gases generated by the burning of zinc to be expelled to the surface.

Colletotrichum lindemuthianum is a phytopathogenic fungus that causes anthracnose in common beans (Phaseolus vulgaris) and presents a great diversity of pathotypes with different levels of virulence against bean varieties worldwide. The purpose of this study was to establish whether pathotypic diversity is associated with differences in the mycelial growth and secretion of plant-cell-wall-degrading enzymes (PCWDEs). We evaluated growth, hemicellulase and cellulase activity, and PCWDE secretion in four pathotypes of C. lindemuthianum in cultures with glucose, bean hypocotyls and green beans of P. vulgaris, and water hyacinth (Eichhornia crassipes). The results showed differences in the mycelial growth, hemicellulolytic activity, and PCWDE secretion among the pathotypes. Glucose was not the preferred carbon source for the best mycelial growth in all pathotypes, each of which showed a unique PCWDE secretion profile, indicating different levels of carbon catabolite regulation (CCR). The pathotypes showed a high differential hemicellulolytic capacity to degrade host and water hyacinth tissues, suggesting CCR by pentoses and that there are differences in the absorption and metabolism of different monosaccharides and/or disaccharides. We propose that different levels of CCR could optimize growth in different host tissues and could allow for consortium behavior in interactions with bean crops.

Los proyectos se definen al día de hoy como un conjunto de esfuerzos temporales encaminados a la materialización de los objetivos de una empresa. El ciclo de vida de estos se encuentra dado por etapas, lo que posibilita el desglose del trabajo y aumenta el control de los mismos desde su fase de inicio, hasta el cierre. En el sector de la construcción es común evidenciar ciertas deficiencias relacionadas a los sobrecostos y a los retrasos en materia tiempo, generalmente derivadas por la inaplicabilidad de metodologías de control y seguimiento adecuadas y por el poco uso de herramientas de gestión de proyectos fundamentadas en estándares innovadores. El objetivo principal del presente trabajo es analizar la evolución en la forma en que se han gestionado los proyectos de construcción durante la última década, teniendo en cuenta dos enfoques: el estándar PMI (Project Management Institute) y las metodologías ágiles. Para la realización del presente trabajo se examinan casos de estudio y se presentan ejemplos de organizaciones que han adoptado esta combinación de enfoques con éxito. Además, se discuten los desafíos y las consideraciones clave al implementar una combinación de estándar PMI y metodologías ágiles en proyectos de construcción.

Abstract Background Colonoscopy is a useful as a cancer screening test. However, in countries with limited medical resources, there are restrictions on the widespread use of endoscopy. Non-invasive screening methods to determine whether a patient requires a colonoscopy are thus desired. Here, we investigated whether artificial intelligence (AI) can predict colorectal neoplasia. Methods We used data from physical exams and blood analyses to determine the incidence of colorectal polyp. However, these features exhibit highly overlapping classes. The use of a kernel density estimator (KDE)-based transformation improved the separability of both classes. Results Along with an adequate polyp size threshold, the optimal machine learning (ML) models’ performance provided 0.37 and 0.39 Matthews correlation coefficient (MCC) for the datasets of men and women, respectively. The models exhibit a higher discrimination than fecal occult blood test with 0.047 and 0.074 MCC for men and women, respectively. Conclusion The ML model can be chosen according to the desired polyp size discrimination threshold, may suggest further colorectal screening, and possible adenoma size. The KDE feature transformation could serve to score each biomarker and background factors (health lifestyles) to suggest measures to be taken against colorectal adenoma growth. All the information that the AI model provides can lower the workload for healthcare providers and be implemented in health care systems with scarce resources. Furthermore, risk stratification may help us to optimize the efficiency of resources for screening colonoscopy.

Objective. This study aimed to perform a histological evaluation of teeth diagnosed with internal root resorption. Materials and Methods. A descriptive study involved the examination of 50 human teeth extracted due to an unfavorable prognosis for retention in the oral cavity. Teeth were preserved in 10% buffered formalin and subsequently subjected to the decalcification process. Masson–Goldner staining was applied for comprehensive histological assessment. Results. In all the 50 teeth examined, resorption gaps within the dentin tissue were identified, accompanied by the presence of reparative cells in the vicinity of these cavities. Marked structural loss and dentin fragmentation were evident, with regions exhibiting fissures and an absence of dentinal tubules. Conclusions. The histological evaluation of 50 teeth diagnosed with internal dental resorption revealed significant structural alterations, including resorption lacunae, the presence of multinucleated osteoclast-like cells, and reparative connective tissue. These findings highlight the complex and multifaceted nature of internal dental resorption. These histological insights provide a deeper understanding of the pathological processes involved in internal dental resorption and underscore the necessity for early detection and intervention to mitigate tooth loss and preserve dental health.

The research seeks to establish the use of social networks in companies in the tourism sector, especially to identify the most popular networks, their type and the role they play in these companies. The problem was approached through a systematic literature review, focused on the use of social networks in tourism companies. The Scopus database was consulted, initially finding 179 articles, using the keywords: social media, tourism and hotels. After applying the exclusion criteria, 15 articles were identified. The findings indicate that the Tripadvisor network, specialized in the tourism sector, is the most used, followed by Facebook and Twitter, which are generalist networks. It is concluded that social networks have transformed the way in which users in the hotel sector interact, research and make decisions about their accommodations, consulting the opinions and previous experiences of other users.