440 research outputs found

    Direct Visualization of Mechanical Beats by Means of an Oscillating Smartphone

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    [EN] The resonance phenomenon is widely known in physics courses.1 Qualitatively speaking, resonance takes place in a driven oscillating system whenever the frequency approaches the natural frequency, resulting in maximal oscillatory amplitude. Very closely related to resonance is the phenomenon of mechanical beating, which occurs when the driving and natural frequencies of the system are slightly different. The frequency of the beat is just the difference of the natural and driving frequencies. Beats are very familiar in acoustic systems. There are several works in this journal on visualizing the beats in acoustic systems.2¿4 For instance, the microphone and the speaker of two mobile devices were used in previous work2 to analyze the acoustic beats produced by two signals of close frequencies. The formation of beats can also be visualized in mechanical systems, such as a mass-spring system5 or a double-driven string.6 Here, the mechanical beats in a smartphone-spring system are directly visualized in a simple way. The frequency of the beats is measured by means of the acceleration sensor of a smartphone, which hangs from a spring attached to a mechanical driver. This laboratory experiment is suitable for both high school and first-year university physics courses.The authors would like to thank the Institute of Educational Sciences of the Universitat Politecnica de Valencia (Spain) for the support of the Teaching Innovation Groups MoMa and e-MACAFI and for the financial support through the Project PIME 2015 B18.Giménez Valentín, MH.; Salinas Marín, I.; Monsoriu Serra, JA.; Castro-Palacio, JC. (2017). Direct Visualization of Mechanical Beats by Means of an Oscillating Smartphone. The Physics Teacher. 55(7):424-425. https://doi.org/10.1119/1.5003745S42442555

    Characterization of activated carbon fiber/polyaniline materials by position-resolved microbeam small-angle X-ray scattering

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    Activated carbon fiber (ACF)/polyaniline (PANI) materials have been prepared using two different methods, viz. chemical and electrochemical polymerization. Electrochemical characterization of both materials shows that the electrodes with polyaniline have a higher capacitance than does a pristine porous carbon electrode. To analyze the distribution of PANI within the ACF, characterization by position-resolved microbeam small-angle X-ray scattering (μSAXS) has been carried out. μSAXS results obtained with a single ACF indicate that, for the experimental conditions used, a PANI coating is formed inside the micropores and that it is higher in the external regions of the ACF than in the core. Additionally, it seems that the penetration of PANI inside the fibers occurs in a larger extent for the chemical polymerization or, in other words, for the electrochemically polymerized sample there is a slightly larger accumulation of PANI in the external regions of the ACF.Fil: Salinas-Torres, D.. Universida de Alicante; EspañaFil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Lozano-Castelló, D.. Universida de Alicante; EspañaFil: Morallón, E.. Universida de Alicante; EspañaFil: Burghammer, M.. EuropeanSynchrotronRadiationFacility; FranciaFil: Riekel, C.. EuropeanSynchrotronRadiationFacility; FranciaFil: Cazorla Amorós, Diego. Universida de Alicante; Españ

    Diabetes screen during tuberculosis contact investigations highlights opportunity for new diabetes diagnosis and reveals metabolic differences between ethnic groups

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    Type 2 diabetes (T2D) is a prevalent risk factor for tuberculosis (TB), but most studies on TB-T2D have focused on TB patients, been limited to one community, and shown a variable impact of T2D on TB risk or treatment outcomes. We conducted a cross-sectional assessment of sociodemographic and metabolic factors in adult TB contacts with T2D (versus no T2D), from the Texas-Mexico border to study Hispanics, and in Cape Town to study South African Coloured ethnicities. The prevalence of T2D was 30.2% in Texas-Mexico and 17.4% in South Africa, with new diagnosis in 34.4% and 43.9%, respectively. Contacts with T2D differed between ethnicities, with higher smoking, hormonal contraceptive use and cholesterol levels in South Africa, and higher obesity in Texas-Mexico (p \u3c 0.05). PCA analysis revealed striking differences between ethnicities in the relationships between factors defining T2D and dyslipidemias. Our findings suggest that screening for new T2D in adult TB contacts is effective to identify new T2D patients at risk for TB. Furthermore, studies aimed at predicting individual TB risk in T2D patients, should take into account the heterogeneity in dyslipidemias that are likely to modify the estimates of TB risk or adverse treatment outcomes that are generally attributed to T2D alone

    Concordance between Different Criteria for Metabolic Syndrome in Peruvian Adults Undergoing Bariatric Surgery

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    Background: Metabolic Syndrome (MetS) is a clinical entity that has been linked to several non-communicable diseases. There are various consensuses to determine its presence, such as the IDF, ALAD, Harmonized, AHA/NHLBI, NCEP-ATP III or AACE criteria. However, there is currently no standardization to properly identify it. Objective: To assess the diagnostic concordance between different criteria for MetS in Peruvian adults undergoing bariatric surgery. Methods: We conducted a secondary analysis of the institutional database of a bariatric clinic located in Lima, Peru. We obtained data from adults between 18–59 years who underwent bariatric surgery (Roux-en-Y Gastric Bypass or Sleeve Gastrectomy). According to the Kappa coefficient, a heatplot was designed to analyze the concordance of the criteria. Results: An almost perfect concordance was found between all criteria except AACE. The highest kappa coefficient (κ = 0.980) was recorded between the IDF and ALAD criteria using all the sample. Similar results were obtained when we stratified by sex. Conclusions: This study shows that, excluding the AACE, different criteria for metabolic syndrome could be used in Latino adults undergoing bariatric surgery with similar results. Given the postoperative implications, we believe that IDF and ALAD would be the best options in our population.Revisión por pare

    Efficacy of robotic-assisted prostatectomy in localized prostate cancer : a systematic review of clinical trials

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    Q2Artículo de revisión1-7Background. Radical prostatectomy is an effective treatment for clinically localized prostate cancer. The three approaches in current use have been extensively compared in observational studies, which have methodological limitations. Objective. To compare the efficacy and safety of three radical prostatectomy approaches in patients with localized prostate cancer: open, laparoscopic, and robotic-assisted laparoscopic surgery. Materials and Methods. A systematic review of the literature was carried out. Databases MEDLINE, EMBASE, LILACS, and CENTRAL were searched for randomized clinical trials that directly compared two or more radical prostatectomy approaches. Selection criteria, methodological rigor, and risk of bias were evaluated by two independent researchers using Cochrane Collaboration’s tools. Results. Three trials were included. In one study, laparoscopic surgery was associated with fewer blood loss and transfusion rates than the open procedure, in spite of longer operating time. The other two trials compared laparoscopic and robotic-assisted surgery in which no differences in perioperative outcomes were detected. Nevertheless, robotic-assisted prostatectomy showed more favorable erectile function and urinary continence recovery. Conclusion. At the present time, no clear advantage can be attributed to any of the existing prostatectomy approaches in terms of oncologic outcomes. However, some differences in patient-related outcomes favor the newer methods. Larger trials are required

    Risk of Food Insecurity Reflects Health Status in Adult Relatives of PreK Children – ​ Data from the STEPS Snap-Ed Research Study​

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    Background: Past research shows a correlation between household food insecurity and chronic medical conditions such as diabetes in the general U.S. population as well as metabolic syndrome-related cardiometabolic markers in Hispanic/Latino youth. Furthermore, minority status, including Hispanic/Latino identity, shows an association with low food security and diabetes. The Hunger Vital Sign (HVS) is a validated screener designed to assess risk of food insecurity within households. This study analyzes associated factors related to the screener’s 2 questions, specifically targeting PreK 4-year-old children and their household relatives. The first question assesses concern about food running out before obtaining more due to financial constraints, while the second question evaluates instances when food did not last and there was insufficient money to purchase more. Methods: The participating preschools were primarily Hispanic/Latino and nested within schools and school districts. Data were collected through household questionnaires. The frequency of food insecurity (FI) risk was measured as an ordinal variable (never, sometimes, often) and dichotomized (never vs sometimes + often). Agreement between questions was assessed using the kappa coefficient. Mixed models were employed to predict the risk of children’s BMI and the risk of relatives developing chronic disease, adjusting for age and sex. Results: The study included 828 families, with 74% reporting never experiencing food insecurity, 22% sometimes, and 4% often. The agreement between the 2 survey questions was substantial (kappa 0.80, p \u3c 0.001). Probability of FI decreased as income level and education level of parents increased. No significant associations were found between FI and children’s age, BMI, height, or the ratio of children to adults in the household. However, a positive screen using the HVS correlated with hypertension and/or diabetes in the family. Conclusion: The HVS screens for food insecurity risk and is associated with health issues in adults rather than children\u27s body weight or height. Responses to the survey’s 2 questions can provide insights into the overall health status of a household, emphasizing the intricate relationship between food insecurity, malnutrition, and various health outcomes. The presented results support planning and resource allocation strategies to reduce food insecurity in the Hispanic/Latino population
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