Qualitative and quantitative water investigation of Erin-Ijesha (Olumirin) Waterfall, Erin-Ijesha, Nigeria.

This study focused on the assessment of water quality in Erin-Ijesha (Olumirin) Waterfall, a prominent natural attraction in southwestern Nigeria. The physiochemical parameters, heavy metal concentrations, and bacteriological characteristics were examined in the upstream, midstream, and downstream sections, to ensure the resource quality and safety from harm. The results revealed notable variations in water quality. The pH, Total Dissolved Solids, Electrical Conductivity, and Temperature were highest in the midstream while Total Hardness, Alkalinity, salinity, Chloride, sulphate, Phosphate, Nitrate, Calcium, and Magnesium were highest in the downstream section. The physicochemical parameters were within the acceptable limits of World Health Organization (WHO), United States Environmental Protection Agency (USEPA), and the Standard Organization of Nigeria (SON) standards, except the pH, temperature, and Total Hardness were higher than the acceptable limits of 6.5-8.5, <25 °C or >50 °C and 50 mg/L in all the sections. Iron was above the WHO, USEPA, and SON permissible limits of 3.0 mg/L in all the sections of the river while there was no indication of copper, lead, and cadmium. Bacterial contamination, particularly the presence of E. coli, exceeded recommended safety thresholds. The Total Bacterial Count (TBC) exceeded safety limits by 0.1 million cfu/mL in the downstream. The mean of the parameters was higher in some instances, and sometimes lower than the values in the various sections of the river. A significant relationship existed between most physical, chemical, and bacteriological parameters at p < 0.01. The appraisal of water quality in Olumirin Waterfalls emphasizes the need for proactive measures to ensure water safety, preserve ecosystems, and promote responsible water resource management.

Considerations on static pressure gradients in closed circulatory systems.

Siphons are devices that transport liquids uphill between two containers. It has been proposed that a siphon principle operates in closed circulatory systems, as best exemplified by the circulation of blood in mammals. This principle is supposed to ensure that no additional work is necessary to pump blood above the level of the heart, and that there is no gravitational static pressure gradient in the column of blood. The first statement is correct, while we demonstrate that, ignoring hydraulic resistance to blood flow, the static pressure gradient is equal to the hydrostatic gradient in a siphon model of blood circulation, although the details of the proof do not depend on the geometry of the circulatory system and the proof can be trivially extended to other models such as a vascular waterfall. This implies that the controversy over the siphon principle has no implications for the description of blood circulation, and that mechanisms such as the "baffle," which some authors have appealed to in order to obtain the expected gradient, are not necessary. In our discussion, we also discuss empirical data that appear to provide additional verification of our results, as well as several everyday occurrences that provide additional support.

Accelerating neurotechnology development using an Agile methodology.

Novel bioelectronic medical devices that target neural control of visceral organs (e.g., liver, gut, spleen) or inflammatory reflex pathways are innovative class III medical devices like implantable cardiac pacemakers that are lifesaving and life-sustaining medical devices. Bringing innovative neurotechnologies early into the market and the hands of treatment providers would benefit a large population of patients inflicted with autonomic and chronic immune disorders. Medical device manufacturers and software developers widely use the Waterfall methodology to implement design controls through verification and validation. In the Waterfall methodology, after identifying user needs, a functional unit is fabricated following the verification loop (design, build, and verify) and then validated against user needs. Considerable time can lapse in building, verifying, and validating the product because this methodology has limitations for adjusting to unanticipated changes. The time lost in device development can cause significant delays in final production, increase costs, and may even result in the abandonment of the device development. Software developers have successfully implemented an Agile methodology that overcomes these limitations in developing medical software. However, Agile methodology is not routinely used to develop medical devices with implantable hardware because of the increased regulatory burden of the need to conduct animal and human studies. Here, we provide the pros and cons of the Waterfall methodology and make a case for adopting the Agile methodology in developing medical devices with physical components. We utilize a peripheral nerve interface as an example device to illustrate the use of the Agile approach to develop neurotechnologies.

BOIN-ETC: A Bayesian optimal interval design considering efficacy and toxicity to identify the optimal dose combinations.

One of the primary objectives of a dose-finding trial for novel anti-cancer agent combination therapies, such as molecular targeted agents and immune-oncology therapies, is to identify optimal dose combinations that are tolerable and therapeutically beneficial for subjects in subsequent clinical trials. The goal differs from that of a dose-finding trial for traditional cytotoxic agents, in which the goal is to determine the maximum tolerated dose combinations. This paper proposes the new design, named 'BOIN-ETC' design, to identify optimal dose combinations based on both efficacy and toxicity outcomes using the waterfall approach. The BOIN-ETC design is model-assisted, so it is expected to be robust, and straightforward to implement in actual oncology dose-finding trials. These characteristics are quite valuable from a practical perspective. Simulation studies show that the BOIN-ETC design has advantages compared with the other approaches in the percentage of correct optimal dose combination selection and the average number of patients allocated to the optimal dose combinations across various realistic settings.

Development of a Silicone Rubber Mold with an Innovative Waterfall Cooling Channel.

A conformal cooling channel (CCC) follows the mold core or cavity profile to carry out uniform cooling in the cooling stage. However, the significant pressure drop along the cooling channels is a distinct disadvantage of the CCC. In this study, an innovative waterfall cooling channel (WCC) was proposed and implemented. The WCC cools the injected products via surface contact, replacing the conventional line contact to cool the injected products. The WCC was optimized using numerical simulation software. Silicone rubber molds with two kinds of cooling channels were designed and implemented. The cooling time of the molded part was evaluated using a low-pressure wax injection molding machine. The experimental results of the cooling time of the molded part were compared with the simulation results from numerical simulation software. The results showed that the optimal mesh element count was about 1,550,000 with a mesh size of 1 mm. The simulation software predicted the filling time of the water cup injection-molded product to be approximately 2.008 s. The cooling efficiency for a silicone rubber mold with a WCC is better than that of the silicone rubber mold with a CCC since the core and cavity cooling efficiency is close to 50%. The pressure drop of the WCC is smaller than that of the CCC, which reduces the pressure drop by about 56%. Taking a water cup with a mouth diameter of 70 mm, a height of 60 mm, and a thickness of 2 mm as an example, the experimental results confirmed that the use of the WCC can save the cooling time of the product by about 265 s compared with the CCC. This shows how a WCC can increase cooling efficiency by approximately 17.47%.

Effect of norepinephrine on the vascular waterfall and tissue perfusion in vasoplegic hypotensive patients: a prospective, observational, applied physiology study in cardiac surgery.

BACKGROUND: Norepinephrine is a commonly used drug for treating vasoplegic acute circulatory failure in ICU. The prediction of norepinephrine macro- and micro-circulatory response is complicated by its uneven receptors' distribution between the arterial and the venous structures, and by the presence of a physiological vascular waterfall (VW) that disconnects the arterial and the venous circulation in two pressure systems. The objectives of this study were to describe the VW in patients with arterial hypotension due to vasodilatory circulatory shock, and its behavior according to its response to norepinephrine infusion. METHODS: A prospective, observational, bi-centric study has included adult patients, for whom the physician decided to initiate norepinephrine during the six first hours following admission to the ICU after cardiac surgery, and unresponsive to a fluid challenge. The mean systemic pressure (MSP) and the critical closing pressure (CCP) were measured at inclusion and after norepinephrine infusion. RESULTS: Thirty patients were included. Norepinephrine increased arterial pressure and total peripheral resistances in all cohort. The cohort was dichotomized as VW responders (patients with a change of VW over the least significant change (≥ 93% increase in VW)), and as VW non-responders. In 19 (63%) of the 30 patients, VW increased from 3.47 [- 14.43;7.71] mmHg to 43.6 [25.8;48.1] mmHg, p < 0.001) with norepinephrine infusion, being classified as VW responders. The VW responders improved cardiac index (from 1.8 (0.6) L min-1 m-2 to 2.2 (0.5) L min-1 m-2, p = 0.002), capillary refill time (from to 4.2 (1.1) s to 3.1 (1) s, p = 0.006), and pCO2 gap (from 9 [7;10] mmHg to 6 [4;8] mmHg, p = 0.04). No baseline parameters were able to predict the VW response to norepinephrine. In comparison, VW non-responders did not significantly change the VW (from 5 [-5;16] mmHg to -2 [-12;15] mmHg, p = 0.17), cardiac index (from 1.6 (0.3) L min-1 m-2 to 1.8 (0.4) L min-1 m-2, p = 0.09) and capillary refill time (from 4.1 (1) s to 3.7 (1.4), p = 0.44). CONCLUSIONS: In post-cardiac surgery patients with vasoplegic arterial hypotension, the vascular waterfall is low. Norepinephrine did not systematically restore the vascular waterfall. Increase of the vascular waterfall was associated with an improvement of laboratory and clinical parameters of tissue perfusion.

Statistical plots in oncologic imaging, a primer for neuroradiologists.

The simplest approach to convey the results of scientific analysis, which can include complex comparisons, is typically through the use of visual items, including figures and plots. These statistical plots play a critical role in scientific studies, making data more accessible, engaging, and informative. A growing number of visual representations have been utilized recently to graphically display the results of oncologic imaging, including radiomic and radiogenomic studies. Here, we review the applications, distinct properties, benefits, and drawbacks of various statistical plots. Furthermore, we provide neuroradiologists with a comprehensive understanding of how to use these plots to effectively communicate analytical results based on imaging data.

Full-BAPose: Bottom Up Framework for Full Body Pose Estimation.

We present Full-BAPose, a novel bottom-up approach for full body pose estimation that achieves state-of-the-art results without relying on external people detectors. The Full-BAPose method addresses the broader task of full body pose estimation including hands, feet, and facial landmarks. Our deep learning architecture is end-to-end trainable based on an encoder-decoder configuration with HRNet backbone and multi-scale representations using a disentangled waterfall atrous spatial pooling module. The disentangled waterfall module leverages the efficiency of progressive filtering, while maintaining multi-scale fields-of-view comparable to spatial pyramid configurations. Additionally, it combines multi-scale features obtained from the waterfall flow with the person-detection capability of the disentangled adaptive regression and incorporates adaptive convolutions to infer keypoints more precisely in crowded scenes. Full-BAPose achieves state-of-the art performance on the challenging CrowdPose and COCO-WholeBody datasets, with AP of 72.2% and 68.4%, respectively, based on 133 keypoints. Our results demonstrate that Full-BAPose is efficient and robust when operating under a variety conditions, including multiple people, changes in scale, and occlusions.

qHTSWaterfall: 3-dimensional visualization software for quantitative high-throughput screening (qHTS) data.

High throughput screening (HTS) is widely used in drug discovery and chemical biology to identify and characterize agents having pharmacologic properties often by evaluation of large chemical libraries. Standard HTS data can be simply plotted as an x-y graph usually represented as % activity of a compound tested at a single concentration vs compound ID, whereas quantitative HTS (qHTS) data incorporates a third axis represented by concentration. By virtue of the additional data points arising from the compound titration and the incorporation of logistic fit parameters that define the concentration-response curve, such as EC50 and Hill slope, qHTS data has been challenging to display on a single graph. Here we provide a flexible solution to the rapid plotting of complete qHTS data sets to produce a 3-axis plot we call qHTS Waterfall Plots. The software described here can be generally applied to any 3-axis dataset and is available as both an R package and an R shiny application.

AdvanCE, a capsule endoscope delivery device, is effective in investigating a waterfall stomach.

AdvanCE is a useful device in patients who cannot swallow capsule endoscopes, or when these remain in the patient's stomach without passing into the duodenum. A net or snare may be used to guide the capsule endoscope into the duodenum when the capsule endoscope becomes stuck in the stomach, but it may be difficult to guide the capsule into the duodenum in some cases, particularly in those of waterfall stomach. In such cases, AdvanCE is found to be an effective guidance tool.

Mathematical model estimation and prediction application of Covid-19 infection in Indonesia using Levenberg-Marquardt Algorithm based on Python.

COVID-19 was originally diagnosed in Wuhan, China, in late December 2019; it subsequently expanded internationally, affecting around 7 million people and caused 300,000 deaths by May 2020. An Application that could surveillance the Covid-19 in Indonesia is needed. Therefore, we proposed a prediction application for the COVID-19 pandemic situation in Indonesia by referring to public compliance with surveillance policies using the SPCIRD model. The Levenberg Marquardt curve fitting method was chosen because it is simple and produces a reasonably good model. According the result of questionnaire and black box testing our application performed really well. The result of our SPCIRD model with Levenberg-Marquardt optimization achieved R2 with the score -1.248 in active cases, -0.235 in recovered and -3.982 in death for 281 number of iterations. We are also achieved 93.3% that agree and very agree with the application usability to understand and to predict pattern from COVID-19. It was also had 83.3\% respondent that satisfy with the prototype.

Do zoo animals use off-exhibit areas to avoid noise? A case study exploring the influence of sound on the behavior, physiology, and space use of two pied tamarins (Saguinus bicolor).

Noise can be a known stressor but our understanding of its effects on animals living in zoo environments remains limited. Although exposure to loud, chronic noise may be expected to negatively impact welfare, providing access to quiet areas to escape loud noise may buffer these negative effects. In this study, we explored the benefits of access to quiet, off-exhibit areas for animals living in a chronically loud sound environment. Two pied tamarins (Saguinus bicolor) living near a large waterfall feature that emitted loud, chronic noise were experimentally exposed to varying sound levels during 2-week treatment conditions. Baseline conditions (waterfall feature on and access to quiet, off-exhibit areas), were followed by a Quiet sound condition (waterfall off), a Loud sound condition (waterfall on and a speaker in the off-exhibit area playing volume-matched white noise), and a final Baseline condition. During Baseline conditions, sound levels were greater than 10 dBA higher in the exhibit than in the off-exhibit area (i.e., roughly twice as loud). The number of visitor groups present during behavior observations were consistent throughout the study. Both tamarins modified their space use during treatment conditions. Under Baseline conditions, both individuals showed frequent usage of quiet, off-exhibit areas. During the Quiet and Loud conditions, where sound levels were generally consistent across spaces, both individuals used off-exhibit areas less and their use of exhibit and off-exhibit areas was not significantly different than would be expected by chance, given the size of the areas. Additional behavioral changes were minimal. No significant differences in fecal glucocorticoid metabolites were observed. Although the monkeys in this study appeared to avoid noise, the overall impact on welfare appeared to be minimal considering the limited behavioral and hormonal changes observed. This study highlights the potential benefits of off-exhibit spaces as a quiet refuge from noise in the zoo environment.

Effects of short-term waterfall forest aerosol air exposure on rat lung proteomics.

Background: Chronic exposure to airborne microparticles has been shown to increase the incidence of several chronic diseases. Previous studies have found that waterfall forest aerosols contribute to a diminished immune stress response in patients with asthma. However, the specific effects of short-term waterfall forest aerosol exposure on lung proteins have not been fully elucidated. Methods: This study used liquid chromatography-tandem mass spectrometry (LC-MS) to analyze changes in protein expression in the lungs of rats exposed to short-term waterfall forest aerosol environments. Specific protein markers were identified using bioconductivity analysis screening and validated using immunohistochemistry. Results: Waterfall forest aerosol environment exposure on day 5 downregulated the expression of the classical inflammatory pathway nuclear factor κB (NF-κB) signaling pathway. As the waterfall forest aerosol environment increased due to the duration of exposure, it was involved in oxidative phosphorylation and then hormone signaling in lung cells from the very beginning. In contrast, at day 15 of exposure, there is an effect on the regulation of the immune-related high-affinity IgE receptor pathway. In addition, iron-sulfur Rieske protein (Uqcrfs1), mitochondrial Tu translation elongation factor (Tufm) and ribosomal protein L4 (Rpl4) were identified as possible bioindicators for the evaluation of air quality. Conclusions: These results provide a comprehensive proteomic analysis that supports the positive contribution of a good air quality environment to lung health.

Mechanism of the Huangguoshu waterfall forest environment's promotive effect on human health in Guizhou, China.

Background: The aim of this study was to investigate the specific mechanisms underlying the human health-promoting effects of the forest environment at Huangguoshu Falls, Guizhou, China. Methods: Ninety-five participants were recruited and an eye tracker was used to record fixation and sweep indices. A questionnaire was also used to evaluate the effects of different subject environments on human emotions, perceived recovery and preferences. Thereafter, 24 participants with chronic fatigue syndrome (CFS) were recruited and the participants' fatigue and stress-related scale indices and inflammatory factor levels were examined. Serum metabolites of the participants under different time waterfall forest interventions were detected by ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-Q/TOF-MS). Results: Eye tracking paradigm analysis showed that the "waterfall" element was the most interesting element for participants and that the "charm" of the waterfall forest environment could be well perceived by participants. Scores on the Fatigue Scale, Anxiety Scale and Depression Scale decreased as the duration of treatment in the waterfall forest environment increased. Levels of inflammatory factors decreased after treatment in the waterfall forest environment. At the same time the level of antioxidants, represented by L-ascorbic acid, increased significantly. Conclusions: The charm of the Huangguoshu waterfall scenery could be perceived by the participants and have a positive modulating effect on mood and cognitive function. In addition, the unique mixture of negative oxygen ions in this environment can increase the content of endogenous antioxidants and balance the metabolism of choline and amino acids.

Diabetes mellitus y salud visual como referentes esenciales en la práctica médica / Diabetes mellitus and visual health as essential references in medical practice

Introducción: La diabetes mellitus, requiere atención médica multifactorial y multisectorial. La oftalmopatía diabética demanda sistemas de salud integrados que faciliten la prevención, detección y tratamiento de las complicaciones en los niveles de atención primaria, secundaria y terciaria. Objetivo: Exponer los conceptos teóricos, prácticos y las tendencias actuales sobre diabetes mellitus y salud visual. Métodos: Se realizó una revisión bibliografía y documental sobre diabetes mellitus y salud visual, estudios y documentos publicados por instituciones nacionales e internacionales, temas vinculados a la diabetes mellitus y la salud visual, se accedió a artículos desde diferentes fuentes, revistas indexadas, metaanálisis y fuentes primarias no publicadas, tesis de maestría, y doctorados. Resultados: Para conservar la salud visual es necesario llevar a cabo medidas que conlleven a prevenir la pérdida de la visión por catarata, glaucoma, retinopatia y edema macular diabético, que incluyen no sólo un buen control de los parámetros metabólicos y las revisiones periódicas al oftalmólogo, sino también el cumplimiento de la educación diabetológica por un equipo multidisciplinario y actualización sobre este tema de los prestadores de salud. La disminución visual que provoca la catarata y otras enfermedades oculares puede conducir a padecer discapacidades como, pérdida de autonomía para administrarse los medicamentos, limitar las actividades de la vida cotidiana e incapacidad laboral y social, con la consiguiente afectación de la calidad de vida Conclusiones: Acudir al oftalmólogo con frecuencia, mantener el control glucémico, del colesterol y presión arterial representan el pilar fundamental para preservar la salud visual en el paciente diabético(AU)

Introduction: Diabetes mellitus requires multifactorial and multisectoral medical attention. Diabetic ophthalmopathy demands integrated health systems that facilitate the prevention, detection and treatment of complications at the primary, secondary and tertiary care levels. Objective: To show the theoretical and practical concepts and current trends on diabetes mellitus and visual health. Methods: A bibliographic and documentary review on diabetes mellitus and visual health was carried out. Studies and documents published by local and international institutions, articles, topics related to diabetes mellitus and visual health were retrieved from different sources, indexed journals, meta-analysis and unpublished primary sources, research degree and master's, theses. Results: To preserve visual health, it is necessary to carry out reading that lead to preventing vision loss due to cataract, glaucoma, retinopathy and diabetic macular edema, which include not only good control of metabolic parameters and regular check-ups with the ophthalmologist , but also compliance with diabetes education by a multidisciplinary team and updating the health providers on this subject. The visual decrease caused by cataract and other eye diseases can lead to disabilities such as loss of autonomy to manage medications, limit activities of daily life and work and social incapacity, with the consequent impact on quality of life. Conclusions: Frequently going to the ophthalmologist, maintaining glycemic, cholesterol and blood pressure control represent the fundamental pillar to preserve visual health in diabetic patients(AU)

Current Genetic Status of Nagaremon-charr, a Threatened Morphotype of Salvelinus leucomaenis in the Ane River, Lake Biwa System, Central Japan, With Comments on Its Conservation.

Stream-dwelling white-spotted charr, Salvelinus leucomaenis, populations tend to have unique color and spot patterns in different regions and may even display stream-specific patterns. An extreme edge of such diversity, found in individuals with atypical body color patterns (so-called nagaremon-type charr, a rare morphotype of Salvelinus leucomaenis [hereafter termed nagaremon-charr]), sympatrically occurring with normal-charr, has been reported from only six small isolated populations in Japan. Based on morphological and ecological perspectives, nagaremon-charr has been considered as an intraspecific color variant of white-spotted charr, although the genetic status of nagaremon-charr has not been determined. In this study, genetic diversity and population structure of the nagaremon-charr in a tributary of the Ane River (Lake Biwa system) were investigated through microsatellite and mtDNA analyses. Nagaremon-charr and sympatric normal-charr in the tributary shared the mtDNA haplotypes and were assigned to the same cluster in the STRUCTURE analysis and discriminant analysis of principal components (DAPC). These results suggested that nagaremon-charr in the Ane River is an intra-populational specific color variant of white-spotted charr. Above a waterfall, nagaremon-charr specimens exhibited extremely reduced genetic diversity, indicating that genetic drift may account for the fixation of the nagaremon-morphotype. Normal-charr below the waterfall clustered separately from hatchery-reared charr, indicative of native status of the former. Thus, both nagaremon-charr and normal-charr in the entire Ane River tributary should be conserved.

Esmolol response in septic shock patients in relation to vascular waterfall phenomenon measured by critical closure pressure and mean systemic filling pressure: a prospective observational study.

BACKGROUND: Bedside measurements of critical closure pressure (Pcc) and mean systemic circulation filling pressure (Pmsf) were utilized to evaluate the response to esmolol in septic shock patients, in relation to the vascular waterfall phenomenon and body oxygen supply and demand. METHODS: This prospective observational self-controlled study included patients with septic shock, newly admitted to the intensive care unit, between August 2019 and January 2021. Pcc and Pmsf, along with the heart rate and other hemodynamic indicators were observed and compared before and 1 h after esmolol IV infusion. RESULTS: After 24 h of initial hemodynamic optimization, 56 patients were finally enrolled. After start of esmolol infusion, patients had a significant decrease in cardiac index (CI) (4.0 vs. 3.3 L/min/m2, P < 0.001), a significant increase in stroke index (SI) (34.1 vs. 36.6 mL/m2, P < 0.01), and a significant decrease in heart rate (HR) (116.8 vs. 90.6 beats/min, P < 0.001). After 1 h of treatment with esmolol, patients had a significant increase in Pcc (31.4 vs. 36.7 mmHg, P < 0.01). The difference between Pcc and Pmsf before and after treatment was statistically different (4.0 vs. 10.0 mmHg, P < 0.01). After heart rate control with esmolol, the patients had a significant increase in the body circulation vascular resistance indices (RIs) (15.14 vs. 18.25 mmHg/min/m2/L, P < 0.001). There was an increase in ScvO2 in patients after treatment with esmolol, but the difference was not statistically significant (68.4% vs. 69.8%, P > 0.05), while Pcv-aCO2 was significantly lower (6.3 vs. 4.9 mmHg, P < 0.001) and patients had a significant decrease in blood lactate levels (4.0 vs. 3.6 mmol/L, P < 0.05). CONCLUSION: Patients with septic shock whose heart rate is greater than 95 beats/min after hemodynamic optimization were treated with esmolol, which could effectively control heart rate and reduce CI, as well as improve Pcc and increase the difference between Pcc and Pmsf (known as "vascular waterfall" phenomenon), without affecting MAP, CVP, Pmsf and arteriovenous vascular resistance, and improve the balance of oxygen supply and demand in the body.

Neuro-Behçet - Clinical and radiological findings in a Patient of Sub-saharan African origin.

Behçet's disease is a rare, systemic variable vessel vasculitis mostly seen in patients from the Middle East, Northern Africa and Central Asia. Neuro-Behçet disease (NBD) is often diagnosed in patients with known Behçet's disease who present with neurological symptoms and radiological features of central nervous system involvement. There are very few cases with neuro-Behçet reported from Sub-Saharan Africa in the literature. We report a case of severe parenchymal neuro-Behçet with pseudo-tumoral brainstem lesions in a young male patient of South African origin.

Estimating the recreational use value of Tis-Abay Waterfall in the upstream of the Blue Nile River, North-West Ethiopia.

Tis-Abay Waterfall is a famous tourist destination in northern Ethiopia, attracting both domestic and international visitors. Although the site's recreation and tourism potential are enormous, the value of the waterfall remains underestimated; an application of economic valuation methods can provide information to better utilize the resource. This study estimates the recreational value of Tis-Abay Waterfall and analyzes the consumer characteristics associated with recreational demand. Drawing on data from 1044 on-site surveys, the study uses the Individual Travel Cost Method (ITCM) with a Zero-Truncated Poisson (ZTP) regression model. Results of the ZTP regression suggest that visitors' age, monthly income, and interest in alternative recreation sites like Lake Tana and Gondar Fasiledes Royal Castle are variables significantly and positively related with recreational demand for the Tis-Abay Waterfall. However, visitors' recreational demand is negatively associated with respondents' distance from the site, leisure time, and total cost of site access. The appraisal suggests that the Tis-Abay Waterfall has a significant annual recreational value of $9.5 million. But it also shows that the waterfall's value would increase significantly, up to $17.3 million, with hypothetical quality improvements in the waterfall settings. The value attachment suggests that estimating the recreation value for Tis-Abay Waterfall is a central component in the sustainable use and management of the resource. However, the presence of unfavorable trade-offs with the electric power plant and the inadequate infrastructure and services for reaching the site are major concerns that require immediate attention to make better use of Tis-Abay Waterfall's recreational services.

Physiological and Psychological Responses of Viewing a Waterfall Image: A Crossover Study.

Growing interest in the relaxation effect of nature has elicited demands for scientific verification of the various natural elements. This study investigated the physiological and psychological responses of 27 females in their 20 s to viewing a waterfall and urban images (control) presented via a large, high-resolution display for 90 s. High-frequency [HF] for parasympathetic nervous activity and the ratio of low-frequency (LF)/[LF + HF] for sympathetic nervous activity by heart rate variability and heart rate were recorded. Simultaneous changes in oxyhemoglobin concentration in the prefrontal cortex were recorded by near-infrared time-resolved spectroscopy. The modified semantic differential method and Profile of Mood States Second Edition were used to assess the psychological effects on the participants after viewing each image. The results showed that viewing the waterfall image, compared with viewing the urban image, (1) increased sympathetic nervous activity; (2) provided comfortable, relaxed, and natural impressions; (3) improved mood states. In conclusion, visual contact with a waterfall image physiologically activated sympathetic nervous activity and psychologically evoked positive moods and feelings.