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The impending scarcity of the radio frequency (RF) spectrum has led to a boom in the development of complementary technologies such as visible light communication (VLC). Hybrid systems that complement both technologies have demonstrated numerous advantages in terms of data rate, bandwidth, and security. However, the successful operation of a hybrid VLC/RF network is highly dependent on the network selection process. In this paper, three network selection algorithms are proposed for hybrid VLC/RF systems in an indoor Internet of things (IoT)-home scenario. The proposed algorithms consider the signal-to-noise ratio (SNR), the available capacity of each network, the number of devices connected to each network, and the users’ location within the scenario. Each algorithm analyzes the data load requirements of each mobile terminal and IoT device according to these metrics. Based on this evaluation, the network that offers the best benefit in terms of signal quality, capacity, and throughput is selected. The numerical results show that the VLC network presents higher SNR values, especially for users near its access points. In addition, a higher bandwidth, a higher connection capacity, and an improvement in the quality of service are perceived from these positions. The three proposed selection algorithms presented good overall performance of the hybrid system, with the Analytical Algorithm offering the best performance for connected users, superior to the Sequential Algorithm by an average of 15.9%. The network selection algorithms efficiently allocated the maximum number of users for the VLC network, improving overall system performance and reducing the RF network data load.

Radiation plays an essential role in the establishment and proliferation of biota in natural environments. The photosynthetic process determines the existence of all life forms, since it supplies the energy that this photobiological process needs for the reaction, it is carried out by absorbing photons in the visible and infrared bands of the electromagnetic spectrum, while ultraviolet (UV) photons and ionizing radiation tends to inhibit it (decreasing, by various mechanisms, its quantum yield). The speed of photosynthesis, measured by the amount of O2 released in the unit of time (or CO2 absorbed) depends on the intensity of the incident light, in the last three decades this radiation has been increased by the decrease of stratospheric ozone in the South latitudes of our planet, for this reason the UV values in the aquatic ecosystems of Chile have been high as well as a considerable increase in the surface temperature of the bodies of water, having possible implications in the primary biological productivity of the ecosystems lakes, especially in Andean lakes. This increase in radiation could be related to the abundance of the different algal groups and the seasonal variability of them, creating favorable conditions for those dominant species considered invasive of these ecosystems. This paper shows the direct relationship between the concentration of ozone (O3) and ultraviolet radiation and how it influences the vertical distribution of the phytoplankton groups in the water column. For the first time it was found in this lake the appearance of a bloom of toxic cyanobacteria.

It is reviewed the potential influence of solar and geomagnetic storms on terrestrial photosynthesis. Then it is presented a modification of a physical-mathematical model of photosynthesis published by some of us, which allows quantifying the influence of particulate ionizing radiation on this biological process. Some guidelines to obtain this new model from first principles are mentioned and it is applied to some case studies including atmospheric and geomagnetic perturbation due to solar storms.

Background: Because hypertension and depression share common pathways, it is possible that each disease has an impact on the natural history of the other., Objective: To determinate whether depression influences blood pressure control in hypertensive patients., Methods: Forty hypertensive patients undergoing antihypertensive treatment, excluding beta-blockers and central-acting agents, self-measured their blood pressure several times a day for three days using a validated, commercially available device. All patients also completed the Zung Self-rating Depression Scale survey for depression. Associations between the results of the blood pressure and depression tests were determined using the Spearman correlation coefficient; RR was also measured., Results: Of the 40 patients, 23 were depressed, and 21 of these 23 had poor control of their blood pressure. The RR for uncontrolled hypertension in depressed patients was 15.5. A significant correlation between systolic (r=0.713) and diastolic (r=0.52) blood pressure values and depression was found., Conclusion: Depression is common in patients with uncontrolled hypertension and may interfere with blood pressure control. Screening for depression in hypertensive patients is a simple and cost-effective tool that may improve outcomes.

Endothelial dysfunction is a common feature in type-2 diabetic patients and in hypertension, and is associated with inflammation, increased levels of circulating soluble adhesion molecules, and atherosclerosis. The aim of this study was to evaluate the relationship between the levels of circulating soluble adhesion molecules and the degree of atherosclerosis in hypertensive type-2 diabetic patients. We studied 30 hypertensive type-2 diabetic patients in whom VCAM-1, ICAM-1, and E-selectin were measured by ELISA. Additionally, the intimal-medial thickness of both the common and internal carotid arteries was measured (B-mode ultrasound). The levels of circulating adhesion molecules and maximal carotid artery intimal-medial thicknesses were correlated using the Spearman correlation coefficient test. Statistical analysis was performed with ANOVA. We found significant correlations between ICAM-1 (r = 0.5) levels and maximal carotid artery intimal-medial thickness these patients. No correlation was observed with E-selectin and VCAM-1. Our results suggest that ICAM-1 is associated and correlated with the degree of atherosclerosis in type-2 diabetic hypertensive patients.

Background and Aim: Endothelial dysfunction in hypertensive type-2 diabetic patients is associated with increased levels of circulating soluble adhesion molecules (SAM). SAM participate in the development of diabetic macroangiopathy and microangiopathy. The aim of this study was to compare the effect of trandolapril (T) and its fixed-dose combination with verapamil (FDTV) on SAM levels in hypertensive type-2 diabetic patients., Methods: Forty type-2 diabetic patients with never-treated hypertension were randomly assigned to two groups. One group (FDTV) received 2/180 mg once a day; the other group received T 2 mg once a day. Study drugs were administered for three months in both groups. VCAM-1, ICAM, and E-selectin were measured by ELISA at the beginning and end of the study. Patients were evaluated monthly for blood pressure, fasting serum glucose, and adverse events. Statistical analysis was performed with ANOVA., Results: Both therapeutics regimens reduced significantly the levels of the SAM tested. When both groups were compared, we did not find a significant difference in ICAM and E-selectin reduction. However, VCAM-1 presented a significantly greater reduction (p = 0.022) in the trandolapril-verapamil group. No patient suffered adverse events., Conclusion: Our results show that FDTV produces a greater reduction of VCAM-1 circulating levels than trandolapril alone. This may explain some of the beneficial effects of this fixed dosed combination that are non-related to its antihypertensive effects.