Minimum Vapor Pressure Research Articles

Broad-scale ecological niches of pathogens vectored by the ticks Ixodes scapularis and Amblyomma americanum in North America.

Environmental dimensions, such as temperature, precipitation, humidity, and vegetation type, influence the activity, survival, and geographic distribution of tick species. Ticks are vectors of various pathogens that cause disease in humans, and Ixodes scapularis and Amblyomma americanum are among the tick species that transmit pathogens to humans across the central and eastern United States. Although their potential geographic distributions have been assessed broadly via ecological niche modeling, no comprehensive study has compared ecological niche signals between ticks and tick-borne pathogens. We took advantage of National Ecological Observatory Network (NEON) data for these two tick species and associated bacteria pathogens across North America. We used two novel statistical tests that consider sampling and absence data explicitly to perform these explorations: a univariate analysis based on randomization and resampling, and a permutational multivariate analysis of variance. Based on univariate analyses, in Amblyomma americanum, three pathogens (Borrelia lonestari, Ehrlichia chaffeensis, and E. ewingii) were tested; pathogens showed nonrandom distribution in at least one environmental dimension. Based on the PERMANOVA test, the null hypothesis that the environmental position and variation of pathogen-positive samples are equivalent to those of A. americanum could not be rejected for any of the pathogens, except for the pathogen E. ewingii in maximum and minimum vapor pressure and minimum temperature. For Ixodes scapularis, six pathogens (A. phagocytophilum, Babesia microti, Borrelia burgdorferi sensu lato, B. mayonii, B. miyamotoi, and Ehrlichia muris-like) were tested; only B. miyamotoi was not distinct from null expectations in all environmental dimensions, based on univariate tests. In the PERMANOVA analyses, the pathogens departed from null expectations for B. microti and B. burgdorferi sensu lato, with smaller niches in B. microti, and larger niches in B. burgdorferi sensu lato, than the vector. More generally, this study shows the value of large-scale data resources with consistent sampling methods, and known absences of key pathogens in particular samples, for answering public health questions, such as the relationship of presence and absence of pathogens in their hosts respect to environmental conditions.

A portable audible-range acoustical approach for determining headspace vapour-phase properties

Measuring vapour-phase properties including pressure, density, concentration and molecular weight is an important step towards integrating mobile olfactory devices into smart societies for monitoring chemical processes. However, there are few portable and low-cost devices for realising dynamic headspace vapour-phase measurements, which work for various molecules. Herein, the concept of utilising audible-range sound waves, in the form of an acoustic resonator, is introduced for extracting vapour-phase properties. As different headspace molecules enter the acoustic resonator, the weight and number of molecules change, and molecular vibrations are perturbed, manifesting in modified local acoustic waves due to changing vapour density and specific heat ratio. Physical waves enable the accurate determination of vapour properties for different molecules, agreeing well with reference values. A minimum vapour pressure down to n-decane of 0.2 kPa is detectable using an audible-range acoustical approach, either by flowing N2 to force molecules into the headspace; or using a simple cap-based design, which securely fastens onto a vial without any external flow. Low-cost speaker and microphone technologies are an innovative physical approach for determining vapour characteristics, whilst simultaneously demonstrating the inherently complex dynamic fluid space over time. Audible-range acoustical techniques can easily integrate into sensor networks and may yield new alternatives in mobile olfactory technology, due to its physical nature and irrelevance to chemical affinity, which may be useful for portable devices in various applications.

West coast U.S. tree species show stronger evidence for shifts in density than range

Climate change is associated with shifts in the geographic range of trees and other taxa globally. In North America and elsewhere tree species’ ranges are expected to shift at rates of meters to kilometers annually. However, empirically detecting a shift in the range of a tree species may be difficult due to the lack of quality long-term regional or national data. Evidence of range shifts is further confounded by apparently contradictory findings from separate studies that use different methods to evaluate species responses. In this study we examine U.S. Forest Service Forest Inventory Analysis plot revisit data in the states of California, Oregon, and Washington to examine shifts in the ranges and densities of tree species relative to values of temperature, precipitation, and maximum and minimum vapor pressure deficit (VPD) using a design-based estimation technique. We also examine changes in these four climate variables for years before and between plot visits. We found that the ranges for 49 tree species seldom shifted in the 10-year period of plot remeasurements, but depending on the climate variable considered, between seven and ten out of 30 species did exhibit density shifts, generally increasing in plots that were initially cooler, drier, and had lower VPD. Overall, plots increased in temperature and VPD values between time periods while they generally experienced declines in precipitation. These changes were frequently not constant across species plots. Temperature and precipitation values were often negatively associated with first visit values (cooler and wetter plots disproportionately warmed and dried). Maximum and minimum VPD generally increased most at plots with initially higher VPD values. These results indicate that the geographical range of U.S. west coast tree species may not change as quickly as their ecological niches geographically shift, although changes in species densities within their ranges may already be underway. The results also indicate that changes in environmental conditions may differ among and within species’ ranges.

Stem growth of Amazonian species is driven by intra-annual variability in rainfall, vapor pressure and evapotranspiration

Intra-annual distribution of precipitation in central Amazonia often leads to a short mild dry season and an increase in irradiance, temperature, and vapor pressure deficit; however, the accurate effect of intra-annual microclimatic variability on stem growth is still under investigation. The objective of this study was to determine how stem growth responds to monthly variations in microclimatic factors in the central Amazon. During five years (2008-2012) we measured diameter stem growth of 109 trees (26 species) and used principal component regression to evaluate the effect of microclimatic variability on stem growth in diameter. We found that the mean stem growth in diameter across species increased in response to an increase in rainfall and reference evapotranspiration, but it decreased with a rise in mean and minimum vapor pressure deficit. A contribution of this study is to show that even when irradiance and temperature had no significant effect on stem growth, small changes in vapor pressure deficit significantly affect stem growth. If the dry season becomes longer, as predicted by models, trees currently more sensitive to microclimatic variability associated with droughts would be the most affected by climate changes.

Forecasting Multivariate time-series data using LSTM Neural Network in Mysore district, Karnataka

Advanced and precise forecasting of infectious diseases plays a critical role in planning and providing resources effectively.Time series forecasting for non-linear issues are accessible using deep learning techniques. The association betweenclimatic parameters and dengue occurrences was investigated in this work, and a forecasting model was constructedusing a deep learning approach called long short-term memory (LSTM). Univariate and multivariate LSTM time seriesforecast models were developed using meteorological and dengue incidence data from January 2006 to December 2019.For univariate data, the Pycharm/Google Colab platform was implemented, as the deep learning framework Keras,which is one of the models in the machine learning library based on Tensorflow. The Pandas Python package with builtinsupport for time series data was used for multivariate data. The final model was chosen using the mae loss and theAdam optimizer. Once the model had been fixed, predictions were made using the model. The research showed thatthe meteorological factors such as maximum temperature at lag 3, minimum temperature at lag 3, maximum vapourpressure (lag 0,1 and 2), minimum vapour pressure at lag 1, and vapour pressure daily mean at lag 0,1,4 are all significantpredictors of dengue along with RMSE value of 1.121 . The results indicated that LSTM network has higher predictionaccuracy than any other traditional forecasting methods. Timely management of seasonal diseases such as dengue alongwith meteorological parameters can predict epidemics in the future.

Seasonal and climatic variation of weighted VPD for transpiration estimation

Abstract Vapor pressure deficit (VPD) is one of the critical variables that drives evapotranspiration, and is of fundamental importance in crop physiology and modeling in the face of climate change. Unfortunately, direct records of atmospheric moisture are rarely available at short temporal scales, e.g. hourly, and country or regional scales. Most models use approximations to estimate daily transpiration-weighted VPD. Tanner and Sinclair (1983) suggested an approach to calculate weighted daily VPD as a fraction (0.75) of the difference between daily maximum and minimum vapor pressure based on estimates calculated from daily maximum and minimum temperatures, respectively. A test of the Tanner-Sinclair suggestion is reported by obtaining daily weighted VPD from hourly measurements of humidity and temperature. The objective of this study was to assess the fractional value to obtained daily weighted VPD estimations. This study was based on ten years of hourly weather data collected at thirty five stations across the wide diversity of environments that exist in France.

Assessing spatial and temporal patterns of canopy decline across a diverse montane landscape in the Klamath Mountains, CA, USA using a 30-year Landsat time series

Tree mortality is of considerable concern, but the magnitude and extent of forest canopy decline are relatively unknown in landscapes with high levels of topographic complexity, spatial heterogeneity, and species diversity. We assessed 30 years of canopy decline, including a 5-year period characterized by extreme drought, in one of North America’s most diverse landscapes in the Klamath Mountains of northern California, USA. (1) Characterize tree mortality by species, (2) Quantify temporal and spatial patterns of remotely-sensed canopy decline in relation to climate, (3) Compare canopy decline among vegetation types, topographic settings, and stand structural classes during drought. We characterized tree mortality by species with field data and quantified the role of climate on canopy decline with a 30-year Landsat time series. We assessed and compared the role of topography and stand structure on canopy decline during drought. Most tree mortality and canopy decline occurred at higher elevations in Shasta red fir (Abies magnifica var. shastensis) and subalpine forests. Annual area of canopy decline was positively correlated with summer temperature and minimum vapor pressure deficit but not precipitation. The area of canopy decline was three times greater during the drought. The magnitude of decline was greatest at higher elevations, on more exposed, southwestern slopes, and in stands with old-growth structure. Stands in valleys and low slopes experienced relatively little decline. Our study demonstrates the vulnerability of high elevation, old-growth forests to increasing temperature and suggests the potential for refugia from drought in diverse, heterogeneous landscapes.

New methodology for estimating the minimum design vapor pressure of prismatic pressure vessel for on-ship application

This paper presents a methodology for estimating the minimum design vapor pressure of prismatic pressure vessels for on-ship application. Engineering authorities guide the codes for a novel concept design such as a prismatic pressure vessel using a design by analysis (DBA). DBA methods enable high efficiency because they directly calculate the loads to avoid inherent conservativeness that exists in a design by rule (DBR). However, in DBA methods, the designer should conduct a finite element analysis (FEA) and evaluate the results iteratively to meet the design criteria. In this paper, we propose a new approach to estimating the minimum vapor pressure of a prismatic pressure vessel that follows the design philosophy of an IMO Type C independent tank. The procedure of the proposed method was demonstrated based on a case study. An FEA was also conducted for verification purposes. The results show that the proposed method can effectively estimate the required minimum shell thickness and designed vapor pressure without conducting an iterative FEA. In addition, minimization of the tank shell thickness is made possible because the proposed method directly calculates the crack propagation rate to avoid an unnecessary margin while satisfying the fatigue crack propagation criteria.

기상요인과 식중독 발병의 연관성에 대한 빅 데이터 분석

Abstract This research attempts an analysis that fuses the big data concerning weather variation and health care from January 1, 2011 to December 31, 2014; it gives the weather factor as to what kind of influence there is for the incidence of food poisoning, and also endeavors to be helpful regarding national health prevention. By using R, the Logistic and Lasso Logistic Regression were analyzed. The main factor germ generating the food poisoning was classified and the incidence was confirmed for the germ of bacteria and virus. According to the result of the analysis of Logistic Regression, we found that the incidence of bacterial food poisoning was affected by the following influences: the average temperature, amount of sunshine deviation, and deviation of temperature. Furthermore, the weather factors, having an effect on the incidence of viral food poisoning, were: the minimum vapor pressure, amount of sunshine deviation and deviation of temperature. This study confirmed the correlation of meteorological factors and incidence of food poisoning. It was also found out that even if the incidence from two causes were influenced by the same weather factor, the incidence might be oppositely affected by the characteristic of the germs.

Review: Fuel Volatility Standards and Spark-Ignition Vehicle Driveability

Spark-ignition engine fuel standards have been put in place to ensure acceptable hot and cold weather driveability (HWD and CWD). Vehicle manufacturers and fuel suppliers have developed systems that meet our driveability requirements so effectively that drivers overwhelmingly find that their vehicles reliably start up and operate smoothly and consistently throughout the year. For HWD, fuels that are too volatile perform more poorly than those that are less volatile. Vapor lock is the apparent cause of poor HWD, but there is conflicting evidence in the literature as to where in the fuel system it occurs. Most studies have found a correlation between degraded driveability and higher dry vapor pressure equivalent or lower TV/L = 20, and less consistently with a minimum T50. For CWD, fuels with inadequate volatility can cause difficulty in starting and rough operation during engine warmup. The Driveability Index (DI)-a function of T10, T50, and T90-is well correlated with CWD in hydrocarbon fuels. For ethanol-containing fuels, a correction factor to the DI equation improves the correlation with CWD, although the best value for that factor has still not been determined. Ethanol increases the heat of vaporization. However, this is likely insignificant for E15 and lower concentration fuels.more » The impact of ethanol on driveability is likely due to its direct effect on vapor pressure at cold temperatures. For E51-E83 or flex-fuel blends, ASTM sets a minimum vapor pressure; however, published data suggest that a correction for the amount of ethanol in the fuel is needed to accurately predict CWD, possibly because ethanol has a higher lower-flammability limit.« less

Topoclimatological case-study of Alpine pastures near the Albula Pass in the eastern Swiss Alps

Abstract. Alpine grasslands are an important source of fodder for the cattle of Alpine farmers. Only during the short summer season can these pastures be used for grazing. With the anticipated climate change, it is likely that plant production – and thus the fodder basis for the cattle – will be influenced. Investigating the dependence of biomass production on topoclimatic factors will allow us to better understand how anticipated climate change may influence this traditional Alpine farming system. Because small-scale topoclimatological variations of the main meteorological variables: temperature, humidity, precipitation, shortwave incoming radiation and wind speed are not easily derived from available long-term climate stations in mountainous terrain, it was our goal to investigate the topoclimatic variations over the pastures belonging to the Alp Weissenstein research station north of the Albula Pass in the eastern Swiss Alps. We present a basic assessment of current topoclimatic conditions as a site characterization for ongoing ecological climate change studies. To be able to link short-term studies with long-term climate records, we related agrometeorological measurements with those of surrounding long-term sites run by MeteoSwiss, both on valley bottoms (Davos, Samedan), and on mountain tops (Weissfluhjoch, Piz Corvatsch). We found that the Davos climate station north of the study area is most closely correlated with the local climate of Alp Weissenstein, although a much closer site (Samedan) exists on the other side of the Albula Pass. Mountain top stations, however, did not provide a convincing approximation for the climate at Alp Weissenstein. Direct comparisons of near-surface measurements from a set of 11 small weather stations distributed over the domain where cattle and sheep are grazed indicate that nocturnal minimum air temperature and minimum vapor pressure deficit are mostly governed by the altitudinal gradient, whereas daily maxima – including also wind speed – are more strongly depending on vegetation cover and less on the altitude.

The incidence of heat casualties in sprint triathlon: The tale of two Melbourne race events

Triathlon is a popular participation sport combining swimming, cycling and running into a single event. The Triathlon Australia medical policy advocates the use of wet bulb globe temperature as the criterion for altering race distance and an ambient temperature of 35 degrees C as a criterion for consideration of cancellation of an event, but there is little empirical evidence detailing the effectiveness of this policy. Nor has the impact of environmental thermal stress on triathletes in shorter duration events been determined. During an injury surveillance investigation of a triathlon race series over the 2006/2007 seasons, two events with similar environmental conditions were completed. One thousand eight hundred and eighty-four participants competed in event 1 (December 2006) and 2000 competed in event 2 (February 2007). Maximum dry bulb (DBT), minimum vapour pressure (VP) and minimum relative humidity (RH) for event 1 were 37 degrees C DBT, 0.56 kPa VP and 9% RH measured by the Bureau of Meteorology. Fifty-three participants presented for medical aid, 15 due to heat-related collapse. The conditions measured for event 2 were 33 degrees C DBT, 1.16 kPa VP and 24% RH and there were no heat illness presentations despite 38 individuals presenting for medical aid. These observations suggest that the risk of heat-related collapse is greatest when high-environmental temperatures occur early in the competitive season when participants may be inadequately prepared and have not yet acquired natural acclimatisation to heat. Any Triathlon Australia policy revision could place stronger emphasis on the use of ambient temperature as a limiting criterion for race organisers.

A laser photoionization method for the study of the CdS evaporation kinetics

The evaporation rates and saturation vapor pressures of cadmium sulfide and pure metallic cadmium are measured in the temperature ranges 585–950 K and 350–535 K, respectively, using laser resonance multistep photoionization. It is shown that CdS thermally dissociates into Cd atoms and S2 molecules. The study is carried out in the framework of a scheme proposed earlier for photoionization of cadmium atoms. The measured minimum vapor pressure of pure cadmium is 10−11 Torr.

The annual cycle of stratospheric water vapor in a general circulation model

The application of general circulation models (GCMs) to stratospheric chemistry and transport both permits and requires a thorough investigation of stratospheric water vapor. The National Center for Atmospheric Research has redesigned its GCM, the Community Climate Model (CCM2), to enable studies of the chemistry and transport of tracers including water vapor; the importance of water vapor to the climate and chemistry of the stratosphere requires that it be better understood in the atmosphere and well represented in the model. In this study, methane is carried as a tracer and converted to water; this simple chemistry provides an adequate representation of the upper stratospheric water vapor source. The cold temperature bias in the winter polar stratosphere, which the CCM2 shares with other GCMs, produces excessive dehydration in the southern hemisphere, but this dry bias can be ameliorated by setting a minimum vapor pressure. The CCM2's water vapor distribution and seasonality compare favorably with observations in many respects, though seasonal variations including the upper stratospheric semiannual oscillation are generally too small. Southern polar dehydration affects midlatitude water vapor mixing ratios by a few tenths of a part per million, mostly after the demise of the vortex. The annual cycle of water vapor in the tropical and northern midlatitude lower stratosphere is dominated by drying at the tropical tropopause. Water vapor has a longer adjustment time than methane and had not reached equilibrium at the end of the 9 years simulated here.

Low-cycle corrosion fatigue of Zircaloy-2 in iodine atmospheres

Low-cycle fatigue tests have been performed on Zircaloy-2 by a reversed-bending method in inert and iodine atmospheres at 623 K. Fatigue lives in both atmospheres followed the Coffin-Manson law. Cracks propagated by a transgranular shear mode, and the propagation was the process controlling fatigue life in an inert atmosphere. Fatigue life in a high concentration of iodine vapour was significantly shorter than in an inert atmosphere. The iodine vapour caused brittle fracture of a specimen mainly by the transgranular cleavage mode, and an accelerated crack propagation rate. The minimum vapour pressure of iodine to cause brittle fracture under fatigue conditions was about 27 Pa.

Arcing at Electrical Contacts on Closure. Part IV. Activation of Contacts by Organic Vapor

The activation of electrical contacts by decomposition products from organic vapors depends upon an adequate surface layer of adsorbed molecules. In earlier work minimum vapor pressures were given for activation by a number of organic compounds. From new experiments reported here the time available for adsorption between successive arcs is equally important, so that the minimum vapor pressure for activation to occur is inversely proportional to the time available for adsorption, or directly proportional to the rate of operation. The effective contact area and the energy are important also and, although quantitative data have not been obtained, it is reasonable to guess that these variables are connected by a relation not far from p/n=KE/A, where n is the minimum rate for activation to occur for the pressure p on the effective contact area A with the available energy E. Quantitative experiments have been made only upon the activation of palladium contacts by vapor of the organic compound known as fluorene, and only the proportionality between p and n has been established.

X. Observations on mixtures with maximum or minimum vapour-pressure

(1902). X. Observations on mixtures with maximum or minimum vapour-pressure. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 4, No. 19, pp. 116-132.