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We investigated how detectability and vocalization patterns of Saipan Reed Warblers (Acrocephalus hiwae) varied by time of day. We used long-duration sound recordings from 11 locations occupied by Saipan Reed Warblers to model the probability of detecting a vocalization in each hour of the day. We found that Saipan Reed Warblers sang during all daylight hours. We did not find evidence of a dawn chorus in this species. These results are useful for determining what time of day surveys of Saipan Reed Warblers should be conducted, which is particularly relevant because Saipan Reed Warblers are protected by local and U.S. Federal laws, which leads to frequent surveys for this species. Received 12 February 2024. Accepted 28 June 2024. Key words: automated recording unit, diel vocalization, endangered species, tropical bird song, Mariana Islands. (Spanish)--Investigamos como la detectabilidad y los patrones de vocalizacion de carricero Acrocephalus hiwae variaban por hora del dia. Usamos la larga duracion de sonidos de grabaciones de 11 localidades con presencia de carricero Acrocephalus hiwae para modelar la probabilidad de deteccion de vocalizaciones en cada hora del dia. Encontramos que el carricero Acrocephalus hiwae cantaba durante todas las horas del dia. No encontramos evidencias de coros crepusculares en esta especie. Estos resultados son utiles para determinar a que hora del dia deben hacerse busquedas del carricero Acrocephalus hiwae, lo que es particularmente relevante ya que el carricero Acrocephalus hiwae es protegido por leyes locales y federales en Estados Unidos de America, lo que lleva a frecuentes busquedas de esta especie. Palabras clave: canto de ave tropical, especies amenazadas, islas Mariana, unidades de grabacion automaticas, vocalizaciones diarias., The Mariana Islands are an archipelago of volcanic and uplifted limestone islands in the western Pacific Ocean ~2,300 km south-southeast of Japan, and 2,400 km east of the Philippines (Cloud [...]

The topic of this paper is the computational modeling of the gas injection process in a large-bore natural gas fueled engine. At high injection pressures, the overall gas injection and mixing process includes compressible flow features such as rarefaction waves and shock formation. The injection geometries examined in the paper include both a two-dimensional slot and an axisymmetric nozzle. The computations examine the effect of the supply pressure/cylinder stagnation pressure ratio, with ratios ranging from 3 to 80, on the velocity and pressure profiles in the near field region. Computational fluid dynamics modeling was compared with results obtained from a two-dimensional analytical method of characteristics solution and experimental results. The comparison process evaluated factors such as pressure and Math number profiles, jet boundary shape, and shock location.

Abstract Background The absence of the I allele of the angiotensin converting enzyme (ACE) gene has been associated with higher levels of circulating ACE, lower nitric oxide (NO) release and hypertension. The purposes of this study were to analyze the post-exercise salivary nitrite (NO2-) and blood pressure (BP) responses to different exercise intensities in elderly women divided according to their ACE genotype. Methods Participants (n = 30; II/ID = 20 and DD = 10) underwent three experimental sessions: incremental test - IT (15 watts workload increase/3 min) until exhaustion; 20 min exercise 90% anaerobic threshold (90% AT); and 20 min control session without exercise. Volunteers had their BP and NO2- measured before and after experimental sessions. Results Despite both intensities showed protective effect on preventing the increase of BP during post-exercise recovery compared to control, post-exercise hypotension and increased NO2- release was observed only for carriers of the I allele (p < 0.05). Conclusion Genotypes of the ACE gene may exert a role in post-exercise NO release and BP response.

This research addresses the growing need to better understand the mechanisms through which engine-out formaldehyde is formed in two-stroke cycle large bore natural gas engines. The investigation is performed using a number of different in-cylinder sampling techniques implemented on a Cooper-Bessemer GMV-4TF four-cylinder two-stroke cycle large bore natural gas engine with a 36-cm (14-in.) bore and a 36-cm (14-in.) stroke. The development and application of various in-cylinder sampling techniques is described. Three different types of valves are utilized, (1) a large sample valve for extracting a significant fraction of the cylinder mass, (2) a fast sample valve for crank angle resolution, and (3) check valves. Formaldehyde in-cylinder sampling data are presented that show formaldehyde mole fractions at different times during the engine cycle and at different locations in the engine cylinder. The test results indicate that the latter part of the expansion process is a critical time for engine-out formaldehyde formation. The data show that significant levels of formaldehyde form during piston and end-gas compression. Additionally, formaldehyde is measured during the combustion process at mole fractions five to ten times higher than engine-out formaldehyde mole fractions. Formaldehyde is nearly completely destroyed during the final part of the combustion process. The test results provide insights that advance the current understanding and help direct future work on formaldehyde formation. [DOI: 10.1115/1.1363601]

This work expands the knowledge base concerning the formation of oxides of nitrogen (NOx) in the precombustion chamber (PCC) of a four-stroke lean burn (4SLB) industrial gas engine. Two analysis methods were used to characterize specific exhaust constituent concentrations formed in the PCC. The first method extracted gas from the PCC and the overall engine exhaust to be analysed by the industry standard five gas rack (THC, NOx, O2, CO2, and CO) and a Fourier transform infrared spectrometer (FTIR) to quantify formaldehyde (CH2O), nitric oxide (NO), and nitrogen dioxide (NO2) concentrations. This paper focuses only on NOx. The engine was operated at the manufacturer's recommended conditions and at the engine's lean limit. A PCC air-fuel ratio (A/F) map was performed at each engine operating condition by varying the fuel supply pressure to the PCC. An analytical model was developed to estimate the mass flow between the PCC and main cylinder, and mass flow out of the PCC through a sample extraction apparatus. The model was applied at specific instances during the engine cycle to clarify raw emissions data obtained directly from a cylinder's PCC. The model was developed to determine the origin of the mass sampled from the PCC which, in turn, was used to correct the measured pollutant concentrations. The corrected concentrations allowed for a comparison between NOx emissions formed in the PCC and the overall engine exhaust on a mass specific basis. PCC-formed NOx were found to constitute ∼ 10 per cent while operating at the manufacturer's recommended conditions and upwards of ∼ 75 per cent when at the lean limit. The second test method utilized the high-speed chemiluminescence capabilities of a Cambustion fNOX400 analyser to measure NO concentration in gas extracted from the PCC on a half crank angle basis. The intra-cycle NO data were recorded simultaneously with pressure traces from the PCC and main cylinder by a Hi-Techniques combustion analysis system. The high-speed data acquisition system provided qualitative information on both intra-cycle NO concentrations and cycle-to-cycle variations. [ABSTRACT FROM AUTHOR]