Representativeness of the particulate matter pollution assessed by an official monitoring station of air quality in Santiago, Chile: projection to human health.

Santiago, capital city of Chile, presents air pollution problems for decades mainly by particulate matter, which significantly affects population health, despite national authority efforts to improve air quality. Different properties of the particulate matter (PM10, PM2.5 and PM1 fractions, particle surface and number) were measured with an optical spectrometer. The sampling was done during spring 2019 at different sites within the official representative area of Independencia monitoring station (ORMS-IS). The results of this study evidence large variations in PM mass concentration at small-scale areas within the ORMS-IS representative zone, which reports the same value for the total area. Results from PM properties such as PM1, particle number and particle surface distribution show that these properties should be incorporated in regular monitoring in order to improve the understanding of the effects of these factors on human health. The use of urban-climate canopy-layer models in a portion of the sampled area around the monitoring station demonstrates the influence of street geometry, building densities and vegetation covers on wind velocity and direction. These factors, consequently, have an effect on the potential for air pollutants concentrations. The results of this study evidence the existence of hot spots of PM pollution within the area of representativeness of the ORMS-IS. This result is relevant from the point of view of human health and contributes to improve the effectiveness of emission reduction policies.

Supervivencia y factores asociados en pacientes con cáncer cervicouterino atendidas por el Seguro Popular en México.

 Objetivo. Estimar la supervivencia a cinco años por cáncer cervicouterino y sus factores asociados en pacientes mexica-nas, cuya atención fue financiada por el Fondo de Protección contra Gastos Catastróficos (FPGC) del Seguro Popular durante el periodo 2006-2014. Material y métodos. Se analizó la base de datos de las pacientes mencionadas y se vinculó con el Subsistema Epidemiológico y Estadístico de Defunciones. Se hizo un análisis de supervivencia a cinco años por etapa clínica y factores asociados, mediante el método de Kaplan-Meier y los modelos de riesgos proporcionales de Cox. Resultados. La supervivencia global por cáncer cervicouterino a los cinco años fue de 68.5%. Los factores asociados fueron la etapa clínica (locoregional [HR=2.8 IC95% HR: 2.6,3.0] y metastásica [HR=5.4 IC95% HR: 4.9,5.9]) com-parada con la etapa temprana y la edad (HR=1.003 IC95% HR:1.001,1.004). Conclusiones. Las mujeres que lograron el acceso a la atención del cáncer cervical financiadas por el FPGC tuvieron una supervivencia ligeramente superior a las reportadas en otros estudios.

Impact of Erythropoietin Production by Erythroblastic Island Macrophages on Homeostatic Murine Erythropoiesis.

Erythropoietin (EPO) is an essential hormone for erythropoiesis, protecting differentiating erythroblasts against apoptosis. EPO has been largely studied in stress or pathological conditions but its regulatory role in steady state erythropoiesis has been less documented. Herein, we report production of EPO by bone marrow-derived macrophages (BMDM) in vitro, and its further enhancement in BMDM conditioned with media from apoptotic cells. Confocal microscopy confirmed EPO production in erythroblastic island (EBI)-associated macrophages, and analysis of mice depleted of EBI macrophages by clodronate liposomes revealed drops in EPO levels in bone marrow (BM) cell lysates, and decreased percentages of EPO-responsive erythroblasts in the BM. We hypothesize that EBI macrophages are an in-situ source of EPO and sustain basal erythropoiesis in part through its secretion. To study this hypothesis, mice were injected with clodronate liposomes and were supplied with exogenous EPO (1-10 IU/mouse) to evaluate potential rescue of the deficiency in erythroid cells. Our results show that at doses of 5 and 10 IU, EPO significantly rescues BM steady state erythropoiesis in mice deficient of macrophages. We propose existence of a mechanism by which EBI macrophages secrete EPO in response to apoptotic erythroblasts, which is in turn controlled by the numbers of erythroid precursors generated.

Osteoclasts Are Required for Hematopoietic Stem and Progenitor Cell Mobilization but Not for Stress Erythropoiesis in Plasmodium chabaudi adami Murine Malaria.

The anemia and inflammation concurrent with blood stage malaria trigger stress haematopoiesis and erythropoiesis. The activity of osteoclasts seems required for the mobilization of hematopoietic stem and progenitor cells (HSPC) from the bone marrow to the periphery. Knowing that BALB/c mice with acute Plasmodium chabaudi adami malaria have profound alterations in bone remodelling cells, we evaluated the extent to which osteoclasts influence their hematopoietic response to infection. For this, mice were treated with osteoclast inhibiting hormone calcitonin prior to parasite inoculation, and infection as well as hematological parameters was studied. In agreement with osteoclast-dependent HSPC mobilization, administration of calcitonin led to milder splenomegaly, reduced numbers of HSPC in the spleen, and their retention in the bone marrow. Although C-terminal telopeptide (CTX) levels, indicative of bone resorption, were lower in calcitonin-treated infected mice, they remained comparable in naive and control infected mice. Calcitonin-treated infected mice conveniently responded to anemia but generated less numbers of splenic macrophages and suffered from exacerbated infection; interestingly, calcitonin also decreased the number of macrophages generated in vitro. Globally, our results indicate that although osteoclast-dependent HSC mobilization from bone marrow to spleen is triggered in murine blood stage malaria, this activity is not essential for stress erythropoiesis.

[Construction of a development index for young people aged 14 - 26 in Medellín, Colombia]. / Construcción de un índice de desarrollo para jóvenes de 14 a 26 años, Medellín, Colombia.

OBJECTIVE: To construct and validate a Medellín youth development index (IDJM, for its Spanish acronym) covering young people aged 14 - 26 residing in the city's comunas and corregimientos, thus contributing scientific evidence for the development of intervention strategies. METHODS: A cross-sectional study of a random representative sample of 8 001 young people residing in Medellín, Colombia, was conducted, to whom a validated instrument was applied whose dimensions provide information on youth development. The Prinqual method for processing qualitative variables through optimal quantification was used. The first main component, the IDJM, was selected by means of a categorical analysis of the main components. The index was validated and disaggregated by sex, age group, and each dimension studied. RESULTS: The average IDJM score was 74.4 (SD=9.8; CI95%: 74.2 - 74.6). The 14 - 17-year-old age group had the highest score, with females exhibiting slightly higher scores than their male counterparts. The analysis likewise showed that scores increased with socioeconomic level and decreased as the age of the study population increased. Education was the dimension that contributed the most to the index, followed by Goods and Services, while Democracy and Participation and Labor contributed the least across all age groups. CONCLUSIONS: A Medellín youth development index was constructed and validated. It should prove to be a very useful tool, especially for decision-making regarding public policies that target young people. It is essential that the IDJM be updated regularly to ensure accurate assessment of the interventions' impact, especially in the dimensions that contributed lower scores.

Evaluation of gold adsorption on activated carbon from real cyanide and thiourea leachate solutions.

The recovery of gold by adsorption using activated carbon from sodium cyanide and thiourea leached solutions are reported in this study. The leached solutions were obtained under real operating conditions from the beneficiation plant "Paz Borja", Machala-Ecuador. Calgon Carbon DG-11 6X12 type, widely used in the local metallurgical industry was used as adsorbent material. The operational parameters varied during the adsorption process experiments included the concentration of leaching agent, agitation speed, dose of activated carbon and initial concentration of gold. The control parameters included density, percentage of solid, pH, temperature, and solution potential. The obtained results were adjusted to mass transfer model by diffusion through the interface and the Freundlich model for the equilibrium isotherms. The analysis of the results indicates a higher adsorption rate of the gold di-cyanide complex on activated carbon compared to gold-thiourea complexes.

An Ecological Inquiry on Young People's Suicidal Ideation at University: Individual, Relational and Cultural Factors and Their Interactions.

To understand the factors related to suicidal ideation in university students, we examined individual and microsystemic variables with an ecological model organizing bidirectional influences between different dimensions. Suicidal ideation, psychological distress, multidimensional self-concept, loneliness, community social support, life satisfaction, family functioning, bullying victimization, and problematic use of virtual social networks were measured in a sample of 376 Mexican university students (67% women) from 18 to 34 years of age (M = 20.8). Data were collected in March 2020, before mandatory confinement for COVID started in Mexico. Discriminant analyses showed that psychological distress, loneliness, self-concept, life satisfaction, family functioning, internet violence/rejection, and informal social support predicted belonging to high or no suicidal ideation groups with 88% accuracy. Only psychological distress and family self-concept predicted suicidal ideation in multilinear regression analyses. There were differences by gender in multilinear regression, with family self-concept significant for women and physical self-concept, but not family self-concept for boys. Conclusions: Early Suicide prevention in universities should include periodic screening of psychological distress, loneliness, and virtual social media use to identify students that need further evaluation and intervention. University-based strategies of mental health promotion that strengthen family relationships and the sense of community, including gender-sensitive orientation, could enhance the effect of protective factors.

KLRC1 knockout overcomes HLA-E-mediated inhibition and improves NK cell antitumor activity against solid tumors.

Introduction: Natural Killer (NK) cells hold the potential to shift cell therapy from a complex autologous option to a universal off-the-shelf one. Although NK cells have demonstrated efficacy and safety in the treatment of leukemia, the limited efficacy of NK cell-based immunotherapies against solid tumors still represents a major hurdle. In the immunosuppressive tumor microenvironment (TME), inhibitory interactions between cancer and immune cells impair antitumoral immunity. KLRC1 gene encodes the NK cell inhibitory receptor NKG2A, which is a potent NK cell immune checkpoint. NKG2A specifically binds HLA-E, a non-classical HLA class I molecule frequently overexpressed in tumors, leading to the transmission of inhibitory signals that strongly impair NK cell function. Methods: To restore NK cell cytotoxicity against HLA-E+ tumors, we have targeted the NKG2A/HLA-E immune checkpoint by using a CRISPR-mediated KLRC1 gene editing. Results: KLRC1 knockout resulted in a reduction of 81% of NKG2A+ cell frequency in ex vivo expanded human NK cells post-cell sorting. In vitro, the overexpression of HLA-E by tumor cells significantly inhibited wild-type (WT) NK cell cytotoxicity with p-values ranging from 0.0071 to 0.0473 depending on tumor cell lines. In contrast, KLRC1 KO NK cells exhibited significantly higher cytotoxicity when compared to WT NK cells against four different HLA-E+ solid tumor cell lines, with p-values ranging from<0.0001 to 0.0154. Interestingly, a proportion of 43.5% to 60.2% of NKG2A- NK cells within the edited NK cell population was sufficient to reverse at its maximum the HLA-E-mediated inhibition of NK cell cytotoxicity. The expression of the activating receptor NKG2C was increased in KLRC1 KO NK cells and contributed to the improved NK cell cytotoxicity against HLA-E+ tumors. In vivo, the adoptive transfer of human KLRC1 KO NK cells significantly delayed tumor progression and increased survival in a xenogeneic mouse model of HLA-E+ metastatic breast cancer, as compared to WT NK cells (p = 0.0015). Conclusions: Our results demonstrate that KLRC1 knockout is an effective strategy to improve NK cell antitumor activity against HLA-E+ tumors and could be applied in the development of NK cell therapy for solid tumors.

Simultaneous quantification of lead, cadmium and zinc in superficial marine sediments using a carbon-fiber microelectrode modified with bismuth film.

Marine sediments are a useful environmental assessment matrix as they naturally trap toxic substances of anthropogenic origin and thus have higher concentrations of these than the surrounding water. Therefore, developing methods for the sensitive, accurate, and inexpensive quantification of these substances is important, as the traditional techniques have various disadvantages. The current study evaluated the effectiveness of an in situ bismuth-modified carbon-fiber microelectrode (voltamperometric sensor) to simultaneously detect Pb, Cd, and Zn in marine sediments from Puerto Jeli in El Oro Province, Ecuador. This site is representative of the contamination levels present along the coast in this province. Differential pulse anodic stripping voltammetry was applied, and the resulting linear regression for the metal quantification ranged from 12 to 50 µg mL-1, with quantification limits for Pb(II), Cd(II), and Zn(II) of 18.69, 12.55, and 19.29 µg mL-1, respectively. Thus, the quantification with the sensor was successful. According to the preliminary results, Cd and Pb values exceeded the permissible limits established by Ecuador (Texto Unificado de la Legislación Secundaria del Ministerio del Ambiente) and the US Environmental Protection Agency, respectively.

Molecular basis for antiviral activity of two pediatric neutralizing antibodies targeting SARS-CoV-2 Spike RBD.

Neutralizing antibodies (NAbs) hold great promise for clinical interventions against SARS-CoV-2 variants of concern (VOCs). Understanding NAb epitope-dependent antiviral mechanisms is crucial for developing vaccines and therapeutics against VOCs. Here we characterized two potent NAbs, EH3 and EH8, isolated from an unvaccinated pediatric patient with exceptional plasma neutralization activity. EH3 and EH8 cross-neutralize the early VOCs and mediate strong Fc-dependent effector activity in vitro. Structural analyses of EH3 and EH8 in complex with the receptor-binding domain (RBD) revealed the molecular determinants of the epitope-driven protection and VOC evasion. While EH3 represents the prevalent IGHV3-53 NAb whose epitope substantially overlaps with the ACE2 binding site, EH8 recognizes a narrow epitope exposed in both RBD-up and RBD-down conformations. When tested in vivo, a single-dose prophylactic administration of EH3 fully protected stringent K18-hACE2 mice from lethal challenge with Delta VOC. Our study demonstrates that protective NAbs responses converge in pediatric and adult SARS-CoV-2 patients.

Production of Protein Hydrolysate from Quinoa (Chenopodium quinoa Willd.): Economic and Experimental Evaluation of Two Pretreatments Using Supercritical Fluids' Extraction and Conventional Solvent Extraction.

Supercritical fluids' extraction (SFE) and conventional solvent extraction (CSE) for defatting of quinoa flour as pretreatments to produce the quinoa protein hydrolysate (QPH) were studied. The objective was to extract the oil and separate the phenolic compounds (PC) and the defatted quinoa flour for subsequent quinoa protein extraction and enzymatic hydrolysis. The oil extraction yield (OEY), total flavonoid content (TFC), and QPH yield were compared. SuperPro Designer 9.0® software was used to estimate the cost of manufacturing (COM), productivity, and net present value (NPV) on laboratory and industrial scales. SFE allows higher OEY and separation of PC. The SFE oil showed a higher OEY (99.70%), higher antioxidant activity (34.28 mg GAE/100 g), higher QPH yield (197.12%), lower COM (US$ 90.10/kg), and higher NPV (US$ 205,006,000) as compared to CSE (with 77.59%, 160.52%, US$ 109.29/kg, and US$ 28,159,000, respectively). The sensitivity analysis showed that the sale of by-products improves the economic results: at the industrial scale, no significant differences were found, and both processes are economically feasible. However, results indicate that SFE allows the recovery of an oil and QPH of better nutritional quality and a high level of purity-free organic solvents for further health and nutraceutical uses.

Effectiveness of tailored intervention with a salutogenic approach to improve adherence in adults with hypertension: a non-randomized trial.

AIMS: Hypertension (HTN) is a chronic long-term, slowly progressing disease. For HTN control, management, and prevention of associated complications, adequate adherence to treatment is required. It has been proposed that tailored interventions to individual needs are required to address the phenomenon of adherence to treatment. However, studies evaluating the effects of tailored interventions to improve adherence are still scarce. The aim of this study is to evaluate the effectiveness of a tailored intervention using a salutogenic approach, to improve adherence in patients with HTN. METHODS AND RESULTS: A non-randomized trial design was used in this study. Adult patients with HTN were allocated in two groups: tailored intervention (n = 75) and standard care (n = 78). The content of the tailored intervention was based on personal resources and elaboration of an action plan with objectives in agreement with the patients. Patient outcomes (treatment adherence, blood pressure) were assessed both at the beginning of the study and at the 4-week follow-up for the intervention group and the standard care group. The Treatment Adherence Questionnaire for Patients with Hypertension was used to measure adherence. The results of this study showed that the total score and each dimension of the adherence questionnaire (medications, diet, physical activity, weight control, stimulation, and stress relief) increased significantly in the experimental group compared with the control group (P < 0.05). For the group assigned to tailored intervention, the delta score of the total adherence score increased in the final evaluation to 9.4 (95% CI = 8.60-10.28). CONCLUSION: A tailored intervention with a salutogenic approach appears to be effective for improving adherence in patients with HTN. Randomized controlled trials are required to confirm the effect of tailored interventions in this type of population.

Total mercury determination in bivalves Anadara tuberculosa sold in open markets from Quito, Ecuador.

This study aimed to quantify the amount of total mercury in bivalves Anadara tuberculosa supplied from Esmeraldas Province and sold in markets in the Metropolitan District of Quito, Ecuador. The determined total mercury concentration was compared to the permissible limits established by the European Commission and World Health Organization-Food and Agriculture Organization and health risk subsequently assessed. Sampling was conducted in five open markets and involved collecting fifteen specimens from each market. Total mercury was measured through cold vapor atomic fluorescence spectrophotometry. Results showed that samples did not exceed the total mercury threshold value (0.5 mg kg-1). However, samples of Anadara tuberculosa from the Ofelia market, which receives fresh products from Eloy Alfaro canton, contained the highest mean levels of mercury contamination, 0.055 mg kg-1. This result could be associated to the influence of illegal mining activity in this area. In addition, methylmercury potential non-carcinogenic risk for consumers exceeded the threshold limit (>1) established by the US Environmental Protection Agency. The daily consumption rate (Rclim) was determined to be 26.61-38.50 g for a child weight of 14.5 kg, and 128.44-185.84 g for an adult weight of 70 kg. Thus, consuming a higher amount of Anadara tuberculosa could negatively affect human health.

Simultaneous quantification of Cd(II) and Pb(II) in surface marine sediments using Ag-Hg and Ag-Bi nanoalloys glassy carbon modified electrodes.

The evaluation of glassy carbon (GC) electrodes modified with a Nafion (Nf) film and doped with nanoalloys (Nys) deposits of Ag-Hg and Ag-Bi and their application to determination of Cd (II) and Pb(II) in marine sediments, is described. Deposited Ag-Hg and AgBi Nys have a size of approximately ~80 nm dispersed and embedded inside the booths of the Nf net, while other of them remained on Nf net surface. For the AgBiNysNf-GC electrode, a detection limit (DL), 3 s criterion, slightly higher than for the AgHgNysNf-GC modified electrode was obtained. Accuracy of measurements was asserted by comparison with quantification of Cd and Pb in three sets of marine sediments samples previously analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The values of the standard deviation and the coefficients of variation are very low, and also comparable between the different determinations.

Loss of years of healthy life due to road incidents of motorcyclists in the city of Medellin, 2012 to 2015.

OBJECTIVE: Determine the loss of years of healthy life due to road incidents of motorcyclists in the city of Medellin from 2012 to 2015. METHODS: Descriptive study with data on health care of injured motorcyclists and deaths adjusted with the Preston and Coale method, and OPS proportional distribution for the period 2012-2015. The years of life lost due to premature death (YLLs), years lived with disability (YLDs), and the disability-adjusted life years (DALYs) were calculated according to the new methodology designed for that purpose. RESULTS: The loss of years of healthy life due to road incidents of motorcyclists in the four-year period was 80,046 DALYs (823.8 per 100,000 inhabitants), with a higher proportion in men (81.3% and a ratio of 5 to 1 compared to women); the YLDs was 66.6% with marked differences in favor of men. There was nearly a 38% difference in the ages of 15 to 19 as well as a 19% difference from 30 to 49, compared to women. Premature death (YLLs) contributed to 33.4% of DALYs, with significant presentation in the above-mentioned age groups. CONCLUSIONS: The greatest loss of years of healthy life due to road incidents of motorcyclists in Medellin was due to non-fatal injuries and was concentrated in young men. If the trend of motorcycle road incidents continues, both local and national road safety plans will fail to accomplish the expected results, especially among motorcycle users.

Local attributable burden disease to PM 2.5 ambient air pollution in Medellín, Colombia, 2010-2016.

Background: Exposure to 2.5-micron diameter air pollutants (PM 2.5) has been associated with an increased risk of illness and death worldwide; however, in Latin American health impacts assessment of this risk factor is scarce. Medellín is one of the most polluted cities in the region, with a population growth rate that is twice as high as that of other Colombian cities, which implies a growing population at risk. Methods: A descriptive study of the disease burden was carried out using the city as the unit of observation. Health events were selected based on epidemiologic evidence and the availability of the population attributable fraction associated with PM 2.5. The mortality records were taken from the module of deceased of the Single Registry of Affiliates of the Health System; the morbidity records were taken from the Individual Health Services Registries. For the estimation of the burden of disease, the current Global Burden of Disease guidelines were followed. Results: Attributable disability-adjusted life years to exposure to ambient PM 2.5 pollution (DALYs PM2.5) constituted 13.8% of total burden of the city. Males showed the greatest loss of DALYs PM2.5 due to acute events, while in women the greatest loss was due to chronic events. Ischemic heart disease, chronic diseases of the lower respiratory tract, and influenza and pneumonia were the events that contributed the most to DALYs PM2.5. 71.4% of the DALYs PM2.5 corresponded to mortality, mainly in the population over 65 years of age. Regarding attributable morbidity, acute events were more prevalent in both sexes, especially due to respiratory diseases Conclusion: Premature death among the elderly population has the greatest weight on burden of disease attributable to ambient PM 2.5 pollution, mainly due to respiratory and cardiovascular diseases, without significant differences according to gender.

[Quality of life and associated factors in women with breast cancer in Antioquia, Colombia]. / Calidad de vida y factores asociados en mujeres con cáncer de mama en Antioquia, Colombia.

OBJECTIVE: To determine the quality of life and some associated factors in women diagnosed with breast cancer enrolled in cancer treatment programs in a Colombian province. METHODS: In a cross-sectional study, the WHOQOL BREF domains related to the quality of life of 220 women with breast cancer who were in treatment were analyzed. First, a descriptive analysis was done of the sociodemographic variables included in the study. This was followed by an analysis of the quality-of-life scores of the patients in terms of their demographic, clinical, and social characteristics. Finally, some characteristics were identified that, in combination, explained the patients' quality of life. RESULTS: The quality of life was better for women with more schooling, those who were beneficiaries of the contributory health system, those who received support from family members, those from high-income groups, and those whose personal beliefs (religious and spiritual) helped them cope with the disease. Belonging to a lower-income group and having a skeptical attitude constituted risk factors for obtaining lower quality-of-life scores. CONCLUSIONS: The quality of life of breast cancer patients was poorer, both in general and in the physical, psychological, social, and environmental domains, in those who came from more humble levels of society. Psychosocial intervention, through patient-centered methods, is proposed as a strategy that can improve patients' quality of life, especially that of lower-income women. It is necessary to strengthen strategies that enable patients to cope with the disease, relying on the moral, social, and spiritual support of their environment as the main resource.

Disability-Adjusted Life Years Due to Mental Disorders and Diseases of the Nervous System in the Population of Medellin, 2006-2012. / Años de vida saludable perdidos a causa de trastornos mentales y enfermedades del sistema nervioso de la población de Medellín, 2006-2012.

OBJECTIVE: To determine the healthy life years (HLY) lost as a result of mental disorders and nervous system diseases in Medellin from 2006 to 2012. METHODS: Descriptive study using a secondary information source according to the Global Burden of Disease (GBD) framework. To calculate the years of potential life lost (YPLL), we used vital statistics data; to calculate disability-adjusted life years (DALY), we used morbidity data from individual records managed by health service providers, outpatient clinics and other research studies. HLY are the sum of YPLL and DALY. RESULTS: In Medellin, from 2006 to 2012, out of 1,242,407 HLY related to mental disorders and nervous system diseases, the vast majority (99.39%) were due to disability. Most HLY were found in females (70.22%) and 81% were found in people aged 15 to 59. The disorders representing the greatest burden were unipolar depressive disorder (81%), Alzheimer's disease and other types of dementia (4.82%), schizophrenia (3.5%) and drug use disorders (2.78%). CONCLUSIONS: Our results indicate a significant increase in the disease burden due to mental disorders and nervous system diseases. Public policy decision-makers in the city of Medellin should take note, as health problems of this type can result in a substantial rise in healthcare costs.

[Completeness of mortality reports in the vital statistics system in the Colombian Orinoquia, 2017]. / Completitud de los reportes de mortalidad en el sistema de estadísticas vitales en la Orinoquía colombiana, 2017.

OBJECTIVE: Estimate the integrity, in terms of completeness, of the mortality records in the vital statistics information system of the Orinoquia and its departments. METHODOLOGY: A descriptive study was carried out, with a secondary source of information, from the records of non-fetal deaths reported in the vital statistics systems of each department, using methods of distribution of the mortality of Brass, Preston-Coale, Hill and Bennet-Hourichi to estimate the integrity of the records. RESULTS: Completeness was found in the mortality records of women and men (≥95%) in Meta, and in the men of Orinoquia and Arauca (≥95%), in contrast to the records of the rest of the territorial units, where under-registration is presented. CONCLUSIONS: Both demographic dynamics and migration influenced the results obtained from the integrity of the mortality records, therefore, also in the selection of the most appropriate method to estimate integrity; when the population is neither stable nor closed, methods based on two censuses with specific growth rates and migration adjustment should be applied; if there is no information on migration, the Hill method is recommended.

OBJETIVO: Estimar la integridad, en términos de completitud, de los registros de mortalidad en el sistema de información de estadísticas vitales de la Orinoquía colombiana y sus departamentos. METODOLOGÍA: Se realizó un estudio descriptivo, con fuente de información secundaria, procedente de los registros de defunciones no fetales reportados en los sistemas de estadísticas vitales de cada departamento. Se usaron métodos de distribución de la mortalidad de Brass, de Preston Coale, de Hill y de Bennet-Hourichi para estimar la integridad de los registros. RESULTADOS: Se encontró completitud en los registros de mortalidad de mujeres y hombres (≥95%) en Meta, y en los hombres de la Orinoquía y Arauca (≥95%), en contraste con los registros del resto de unidades territoriales, donde se presenta subregistro. CONCLUSIONES: Tanto la dinámica demográfica como la migración influyeron en los resultados obtenidos en la integridad de los registros de mortalidad y, por ende, también en la selección del método más adecuado para estimar la integridad; cuando la población no es estable, ni cerrada, se deben aplicar métodos basados en dos censos con tasas de crecimiento específica y ajuste por migración; si no existe información sobre migración, es recomendable el método de Hill.

Adsorption of ammonia on graphene.

We report on experimental studies of NH3 adsorption/desorption on graphene surfaces. The study employs bottom-gated graphene field effect transistors supported on Si/SiO2 substrates. Detection of NH3 occurs through the shift of the source-drain resistance maximum ('Dirac peak') with the gate voltage. The observed shift of the Dirac peak toward negative gate voltages in response to NH3 exposure is consistent with a small charge transfer (f approximately 0.068 +/- 0.004 electrons per molecule at pristine sites) from NH3 to graphene. The desorption kinetics involves a very rapid loss of NH3 from the top surface and a much slower removal from the bottom surface at the interface with the SiO2 that we identify with a Fickian diffusion process.