Diseño de 1600 ML de adoquinado, ubicado en los barrios: anexo a la villa Victoria de julio, Antonio Mendoza y Rubén Ulloa; en el casco urbano de Tipitapa, municipio de Managua

El desarrollo de nuestro país se basa en elementos fundamentales, como: agricultura industria, ganadería, comercio, turismo, etc. Pero el factor determinante entre estos es el sistema nacional de transporte es decir: transporte terrestre, transporte aéreo, transporte marítimo, etc. el cual es el enlace principal para el desarrollo de la sociedad. En Nicaragua el transporte terrestre es el más utilizado por la población, y debido al aumento de la movilización de vehículos con motores más potentes por las vías, obliga a la modernización de la infraestructura vial, permitiendo un tránsito más seguro y eficiente. El incremento de la red vial está vinculado directamente con la economía de nuestro país, pues su papel es primordial en las actividades que se realizan a diario en los diferentes sectores que aportan a la economía nacional. Actualmente la construcción de nuevas vías de comunicación, rehabilitación de carreteras y mejoras de los caminos ya existentes debe ser una necesidad para los gobiernos, ya que constituyen un componente fundamental para el bienestar y desarrollo de la sociedad, además su diseño debe adoptar las condiciones necesarias para obtener una obra de calidad; cumpliéndose en el todos los principios y normas correspondientes al diseño de carreteras. El presente trabajo denominado ‘‘Diseño de 1600 ML de calle, ubicados en los barrios: Anexo la Villa Rubén Ulloa, Villa Victoria de Julio y Antonio Mendoza localizados en el casco urbano de Tipitapa, municipio de Managua’’. Muestra en su contenido los estudios, métodos y normas aplicables para elaborar: el diseño geométrico de la vía, diseño hidráulico y de la estructura de pavimento, tomando en cuenta las especificaciones correspondientes al diseño de carreteras en Nicaragua

Altered spontaneous brain activity during dobutamine challenge in healthy young adults: A resting-state functional magnetic resonance imaging study

IntroductionThere is a growing interest in exploring brain-heart interactions. However, few studies have investigated the brain-heart interactions in healthy populations, especially in healthy young adults. The aim of this study was to explore the association between cardiovascular and spontaneous brain activities during dobutamine infusion in healthy young adults.MethodsForty-eight right-handed healthy participants (43 males and 5 females, range: 22–34 years) underwent vital signs monitoring, cognitive function assessment and brain MRI scans. Cardiovascular function was evaluated using blood pressure and heart rate, while two resting-state functional magnetic resonance imaging (rs-fMRI) methods—regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF)—were used together to reflect the local neural activity of the brain. Logistic regression was used to model the association between brain and heart.ResultsResults showed that blood pressure and heart rate significantly increased after dobutamine infusion, and the performance in brain functional activity was the decrease in ReHo in the left gyrus rectus and in ALFF in the left frontal superior orbital. The results of logistic regression showed that the difference of diastolic blood pressure (DBP) had significant positive relationship with the degree of change of ReHo, while the difference of systolic blood pressure (SBP) had significant negative impact on the degree of change in ALFF.DiscussionThese findings suggest that the brain-heart interactions exist in healthy young adults under acute cardiovascular alterations, and more attention should be paid to blood pressure changes in young adults and assessment of frontal lobe function to provide them with more effective health protection management

Seasonal variation in oxygenated organic molecules in urban Beijing and their contribution to secondary organic aerosol

Oxygenated organic molecules (OOMs) are crucial for atmospheric new particle formation and secondary organic aerosol (SOA) growth. Therefore, understanding their chemical composition, temporal behavior, and sources is of great importance. Previous studies on OOMs mainly focus on environments where biogenic sources are predominant, yet studies on sites with dominant anthropogenic emissions, such as megacities, have been lacking. Here, we conducted long-term measurements of OOMs, covering four seasons of the year 2019, in urban Beijing. The OOM concentration was found to be the highest in summer (1.6 x 10(8) cm(-3)), followed by autumn (7.9 x 10(7) cm(-3)), spring (5.7 x 10(7) cm(-3)) and winter (2.3 x 10(7) cm(-3)), suggesting that enhanced photo-oxidation together with the rise in temperature promote the formation of OOMs. Most OOMs contained 5 to 10 carbon atoms and 3 to 7 effective oxygen atoms (nO(eff) = nO - 2 x nN). The average nO(eff )increased with increasing atmospheric photo-oxidation capacity, which was the highest in summer and the lowest in winter and autumn. By performing a newly developed workflow, OOMs were classified into the following four types: aromatic OOMs, aliphatic OOMs, isoprene OOMs, and monoterpene OOMs. Among them, aromatic OOMs (29 %-41 %) and aliphatic OOMs (26 %-41 %) were the main contributors in all seasons, indicating that OOMs in Beijing were dominated by anthropogenic sources. The contribution of isoprene OOMs increased significantly in summer (33 %), which is much higher than those in the other three seasons (8 %-10 %). Concentrations of isoprene (0.2-5.3 x 10(7) cm(-3)) and monoterpene (1.1-8.4 x 10(6) cm(-3)) OOMs in Beijing were lower than those reported at other sites, and they possessed lower oxygen and higher nitrogen contents due to high NO, levels (9.5-38.3 ppbv - parts per billion by volume) in Beijing. With regard to the nitrogen content of the two anthropogenic OOMs, aromatic OOMs were mainly composed of CHO and CHON species, while aliphatic OOMs were dominated by CHON and CHON2 ones. Such prominent differences suggest varying formation pathways between these two OOMs. By combining the measurements and an aerosol dynamic model, we estimated that the SOA growth rate through OOM condensation could reach 0.64, 0.61, 0.41, and 0.30 mu g m(-3) h(-1) in autumn, summer, spring, and winter, respectively. Despite the similar concentrations of aromatic and aliphatic OOMs, the former had lower volatilities and, therefore, showed higher contributions (46 %-62 %) to SOA than the latter (14 %-32 %). By contrast, monoterpene OOMs and isoprene OOMs, limited by low abundances or high volatilities, had low contributions of 8 %-12 % and 3 %-5 %, respectively. Overall, our results improve the understanding of the concentration, chemical composition, seasonal variation, and potential atmospheric impacts of OOMs, which can help formulate refined restriction policy specific to SOA control in urban areas.Peer reviewe

Imaging Features and Etiology of Acute Cerebral Infarction in Bilateral PICA Territory

Objective: To investigate the MRI features and etiology of acute cerebral infarction in bilateral PICA territory. Methods: 38 patients with bilateral PICA and 40 patients with bilateral SCA diagnosed clinically and radiographically in Beijing Friendship Hospital of Capital Medical University from January 2019 to January 2022, were retrospectively analyzed. The difference of MRI features, were compared between the two groups, according to the size of the infarction, the distribution of infarcted lesions in posterior circulation or anterior circulation. The range of acute infarction in the bilateral PICA territory and the changes of vertebrobasilar artery were analyzed. Results: The proportion of the infarction model of one side regional infarction with the other side small infarct in bilateral PICA was significantly higher than that in bilateral SCA (39.5% vs. 15%), while the model of small infarction on both sides was lower than that in bilateral SCA (44.7% vs. 72.5%). The incidence of infarction in other blood supply areas of the combined posterior circulation was significantly lower than that in bilateral SCA (21% vs. 80%). The infarction models of bilateral PICA manifested as unilateral total infarct of PICA territory combined with the other unilateral infarct of mPICA territory (44.7%) or bilateral mPICA territory (39.5%). Unilateral vertebral artery V4 segment or PICA-localized severe stenosis/occlusion were more frequently detected in acute infarcts in bilateral PICA (54.2%). Conclusions: Bilateral PICA territory infarction mainly manifested as unilateral total infarct of PICA territory combined with the other unilateral or bilateral infarct of mPICA territory, and regional infarction was quite common, which was closely related to anatomical variation

Dobutamine-induced alternations in cerebral blood flow of healthy adults: a 3D pseudocontinuous arterial spin labeling study

Abstract Background It is unclear whether dobutamine, commonly used clinically in echocardiography and short-term congestive heart failure treatment for promoting increased myocardial contractility, affects brain microcirculatory behavior. Cerebral microcirculation plays an important role in ensuring adequate oxygen transport. Therefore, we investigated the effects of dobutamine on cerebral hemodynamics. Methods Forty-eight healthy volunteers without cardiovascular or cerebrovascular disease underwent MRI to obtain cerebral blood flow (CBF) maps using 3D pseudocontinuous arterial spin labeling before and during the dobutamine stress test. Additionally, cerebrovascular morphology was obtained based on 3D-time-off-light (3D-TOF) magnetic resonance angiography (MRA). Electrocardiogram, heart rate (HR), respiration rate (RR), blood pressure, and blood oxygen were simultaneously recorded before and during dobutamine injection and during recovery (not during MRI). The anatomic features of the circle of Willis and the basilar artery (BA) diameter were assessed on MRA images by two radiologists with extensive neuroimaging experience. Binary logistic regression was used to test for the independent determinants of CBF changes. Results HR, RR, systolic (SBP), and diastolic blood pressure (DBP) significantly increased after dobutamine infusion. Blood oxygen levels remained similar. Compared to the CBF in the resting state, the CBF values exhibited significantly lower CBF levels in both grey matter and white matter. Furthermore, compared with the CBF in the resting state, that in the stress state was decreased in the anterior circulation, mainly in the frontal lobe (voxel level P < 0.001, pixel level P < 0.05). Logistic regression showed that body mass index (BMI; odds ratio [OR] 5.80, 95% confidence interval [CI] 1.60–21.01, P = 0.008], resting SBP (OR 0.64, 95% CI 0.45–0.92, P = 0.014), and BA diameter (OR 11.04, 95% CI 1.05–116.53, P = 0.046) were significantly associated with frontal lobe CBF changes. Conclusions Dobutamine-induced stress significantly decreased CBF in the frontal lobe anterior circulation. Individuals with a high BMI and low SBP during the dobutamine stress test are more likely to have a stress-induced CBF decrease. Thus, attention should be paid to blood pressure, BMI, and cerebrovascular morphology of patients undergoing dobutamine stress echocardiography or those receiving intensive care or anesthesia