Consideration In Previous Studies Research Articles

Analytical model for CO2 geo-sequestration in deep saline aquifers considering the effect of heterogeneity and matrix-fracture interaction

Deep saline aquifers are considered to be the best storage option for long-term CO2 geo-sequestration because such geological formation has the largest identified storage potential that can securely trap CO2 under its low-permeability caprock layers. Many analytical models have been proposed to rapidly detect the CO2 leakage from the storage aquifers. However, the heterogeneity and matrix-fracture interaction of storage layers have not been taken into consideration in previous studies. In this paper, we develop an analytical model to determine the dimensionless leakage rate and pressure build-up due to CO2 leakage from the heterogeneous, dual-porosity and multi-layer bounded storage aquifer. Based on the model description and assumptions, the analytical solution is obtained by means of dimensionless transformation, Laplace transform and numerical inversion. Afterwards, our model is verified by comparing with existing analytical model. In order to determine the effect of heterogeneity and the matrix-fracture interaction on the dimensionless leakage rate and pressure change, we conducted sensitivity analysis taking account of the heterogeneous factors. Based on the obtained results, increasing layer number and layer thickness from the bottom layer to the upper layer will delay the CO2 leakage. Furthermore, each layer in storage aquifer with greater fluid mobility is not conductive to CO2 storage but the overall effect is not obvious. As for the matrix-fracture fluid transfer processes, when the ratio of the matrix permeability to the fracture permeability is small, the fast flow of CO2 through the fracture system without significant storage in the matrix. Obviously, the resistance along the leakage path is decreasing with the decrease of the caprock thickness, which leads to greater leakage between the two aquifers. The derived analytical solutions considering heterogeneity and dual media is practical and helpful for CO2 geo-sequestration site selection and storage risk assessment.

Steel corrosion and corrosion-induced cracking in reinforced concrete with carbonated recycled aggregate

Accelerated carbonation treatment was proposed as an environmentally friendly and promising method to strengthen the old mortar attached to the surface of recycled aggregate (RA), thereby improving the properties of recycled aggregate concrete (RAC). However, the steel corrosion and corrosion-induced cracking in concrete with the carbonated RA (CRAC), as the potential threats to the application in structural concrete, received little consideration in previous studies. In this study, RA was modified by accelerated carbonation treatment and the effects on the physical properties of RA were evaluated. Moreover, the compressive strength, resistance to steel corrosion and resistance to corrosion-induced cracking of RAC and CRAC were experimentally investigated. In addition, the pore structure test of old mortar adhered to RA and the microhardness test of interfacial transition zones (ITZs) in concrete were conducted to reveal the enhancement mechanism of accelerated carbonation treatment. The results show that the carbonated RA exhibits lower water absorption and slightly higher apparent density due to the enhancement of pore structure; CRAC exhibits higher compressive strength, better resistance to steel corrosion and less corrosion-induced cracks, which can be explained by an improvement in the microhardness of ITZ between new and old mortar in RAC.

Commercial and Instant Coffees Effectively Lower Aβ1-40 and Aβ1-42 in N2a/APPswe Cells.

BackgroundAlzheimer's disease (AD) is a multifactorial neurological disease with neurofibrillary tangles and neuritic plaques as histopathological markers. Due to this, although AD is the leading cause of dementia worldwide, clinical AD dementia cannot be certainly diagnosed until neuropathological post-mortem evaluation. Coffee has been reported to have neurologically protective factors, particularly against AD, but coffee brand and type have not been taken into consideration in previous studies. We examined the discrepancies among popular commercial and instant coffees in limiting the development and progression through Aβ1-40 and Aβ1-42 production, and hypothesized that coffee consumption, regardless of brand or type, is beneficial for stalling the progression and development of Aβ-related AD.MethodsCoffee samples from four commercial coffee brands and four instant coffees were purchased or prepared following given instructions and filtered for the study. 5, 2.5, and 1.25% concentrations of each coffee were used to treat N2a/APPswe cell lines. MTT assay was used to assess cell viability for coffee concentrations, as well as pure caffeine concentrations. Sandwich ELISA assay was used to determine Aβ concentration for Aβ1-40 and Aβ1-42 peptides of coffee-treated cells.ResultsCaffeine concentrations were significantly varied among all coffees (DC vs. MDC, PC, SB, NIN, MIN p < 0.05). There was no correlation between caffeine concentration and cell toxicity among brands and types of coffee, with no toxicity at 0.5 mg/ml caffeine and lower. Most coffees were toxic to N2a/APPswe cells at 5% (p < 0.05), but not at 2.5%. Most coffees at a 2.5% concentration reduced Aβ1-40 and Aβ1-42 production, with comparable results between commercial and instant coffees.ConclusionAll coffees tested have beneficial health effects for AD through lowering Aβ1-40 and Aβ1-42 production, with Dunkin' Donuts® medium roast coffee demonstrating the most consistent and optimal cell survival rates and Aβ concentration. On the other hand, Starbucks® coffee exhibited the highest cell toxicity rates among the tested coffees.

Normalized lifespan inequality: disentangling the longevity\u2013lifespan variability nexus

Previous studies have documented a historically strong and negative association between countries’ life expectancy (i.e., average longevity) and length-of-life inequality (i.e., variability in ages at death). The relationship between both variables might be partially explained by life expectancy increasing at a faster pace than maximal length of life, a phenomenon that mechanically compresses the age-at-death distribution and has not been taken into consideration in previous studies. In this paper, we propose a new approach to lifespan inequality measurement that accounts for the (uncertainly) bounded nature of length-of-life. Applying the new approach to the countries of the Human Mortality Database, we observe that the decline in overall lifespan variability typically associated with increases in longevity seems to stop and even reverse at higher levels of life expectancy. This suggests the emergence of worrying ethical dilemmas, whereby higher achievements in longevity would only be possible at the expense of higher lifespan variability.

Investigating Spatial-Physical Consequences of Polygamy Phenomenon in Border Villages of Iran (Case Study: Hirmand County)

Purpose- The most common type of marriage in Iran is monogamy, however polygamy is sometimes happening. It seems that the situation of polygamy, as well as the causes and factors involved in it, is varied in different geographic regions and even within the geographical regions of Iran. Also, the phenomenon in different regions will have many physical consequences. So, the basic question is, given the particular geographical situation and ethnic diversity in the region, what are the physical consequences of polygamy on rural settlements in Hirmand County? The purpose of this study was to analyze the situation and spatial consequences of polygamy phenomenon in rural areas of Hirmand County in Sistan and Baluchistan province, Iran.Design/methodology/approach- The research is descriptive-analytical and based on, field studies and completion households’ questionnaires. The statistical population of the study consisted of 303 villages, which after the consultation with members of the councils, local experts in the study area, 30 villages with prevailing occurrence of polygamy had been selected by proportional allocation method according to their destination to the border. SPSS and ArcGIS soft wares were used for data and statistical analysis and zoning.Findings- The results of the study confirm that the less distance between the villages of Hirmand County from the border of Iran and Afghanistan, the more polygamy cases in villages within a radius of 5 km of the border is more common than other villages. In this regard, the results of Kendall test confirm the significant relationship between this lifestyle and its impact on the physical development of villages.Originality / Value- A review in the literature of research shows that this issue has not been taken into consideration in previous studies related to the field of geography. To this regard, the study, understanding the necessity and importance of this issue, sought to study and analyze the situation of polygamy as well as to analyze its physical consequences on the rural settlements in Hirmand County.

Two-Stage Robust Optimization Model for Fresh Cold Chain considering Carbon Emissions and Uncertainty

Sustainable development is an everlasting theme and lasting strategy in today’s era. Low-carbon economy is an inevitable approach to the implementation of sustainable development. Cold chain logistics has become one of the main sources of carbon emissions. However, in the research on location planning of cold chain logistics, the costs of carbon emissions have not been taken into consideration in previous studies. The two-stage stochastic optimization (TSSO) model was established based on the comprehensive consideration of transportation costs, time penalty costs, and carbon emission costs. In this case, it is extremely difficult to deal with uncertainty in TSSO model. Therefore, this paper constructs a two-stage robust optimization (TSRO) model using data-driven method and robust optimization theory and verifies the validity of this model through an actual case. The application of this method to a cold chain logistics enterprise showed that the service level of logistics cannot be guaranteed by stochastic optimization model. In the TSRO model, the costs increase by 2.18% at the price of robustness, whereas logistics service level shows an upward trend (from 85.83% to 92.75%). In the TSRO model, enterprises are forced to choose a better distribution path when carbon tax increases, which not only helps enterprises save costs but also achieves low-carbon environmental benefits.

Gross primary production of dwarf bamboo, Sasa senanensis, in a mature beech forest with a substantial gap-mosaic structure.

Forest understory plays an important role in the gross primary production (GPP) of some forest ecosystems. However, differences in understory GPP caused by obviously different overstory canopy structure have not been taken into consideration in previous studies, thus potentially over- or underestimating understory GPP. To estimate the understory GPP more accurately, we separated a forest into "canopy area", with closed-overstory canopy, and "gap area", with open-overstory canopy. The study was conducted in a mature deciduous forest dominated by beech and with an understory dominated by dwarf bamboo, Sasa senanensis. We measured S. senanensis GPP at the community scale (GPPSasa-community) using a static chamber system that covered the aboveground part of the plants and then upscaled it to the ecosystem scale (GPPSasa-ecosystem) by considering the proportions of canopy and gap areas within the forest. GPPSasa-community was 192g C m-2year-1 in the canopy area and 699g C m-2year-1 in the gap area. The large difference likely occurred because the photosynthetic ability and biomass of the S. senanensis community differed strongly between the two areas. The seasonal dynamics of GPPSasa-community also differed between the areas. The 10-day cumulative GPPSasa-community peaked from July to August in the gap area, whereas there was no clear peak of GPPSasa-community in the canopy area. Multiple linear regressions showed that light intensity and biomass were significant predictors of GPPSasa-community in the canopy area, whereas air temperature and biomass were significant predictors of GPPSasa-community in the gap area. GPPSasa-ecosystem during growing season in 2019 was 3.74 t C ha-1year-1, which contributed between 16.37 and 19.85% of the entire forest ecosystem GPP. This study highlights the need to consider differences in overstory structure for the accurate estimation of understory GPP.

Combination of Genetic Algorithm and Brill Tagger Algorithm for Part of Speech Tagging Bahasa Madura

Part of speech (POS) is commonly known as word types in a sentence such as verbs, adjectives, nouns, and so on. Part of Speech (POS) Tagging is a process of marking the word class or part of speech in every word in a sentence. Part of Speech Tagging has an important role to be used as a basis for research in Natural Language Processing. That is why research on Part of Speech Tagging for Bahasa Madura as an effort to preserve and develop the use of regional languages. In this research, POS Tagging is done using the Brill Tagger Algorithm which is combined with the Genetic Algorithm. Brill Tagger is a POS Tagging Algorithm that has the best level of accuracy when implemented in other languages. Genetic Algorithms used in the contextual learner process with consideration in previous studies can increase the speed of the training process so that it is more efficient. The results of this study are then compared with the results of the previous study so that we can find out suitable algorithms used for the development of text processing in Bahasa Madura. From a series of experiments, the average accuracy obtained by using Brill Tagger is 86.4% with the highest accuracy of 86.7%, while using GA Brill Tagger shows an average accuracy of 86.5% with the highest accuracy of 86.6%. Testing by observing OOV (Out of Vocabulary) achieves an average accuracy of 67.7% for Brill Taggers and 64.6% for GA Brill Taggers. Testing by considering multiple POS with Brill Tagger produces an average accuracy of 73.3% while testing using GA Brill Tagger produces an average accuracy of 90.9%. This shows that the accuracy with GA Brill Tagger is better than Brill Tagger, especially if considering multiple POS. This is because GA Brill Tagger can generate rules for handling the existence of multiple POS more than pure Brill Tagger. Part of speech (POS) is commonly known as word types in a sentence such as verbs, adjectives, nouns, and so on. Part of Speech (POS) Tagging is a process of marking the word class or part of speech in every word in a sentence. Part of Speech Tagging has an important role to be used as a basis for research in Natural Language Processing. That is why research on Part of Speech Tagging for Bahasa Madura as an effort to preserve and develop the use of regional languages. In this research, POS Tagging is done using the Brill Tagger Algorithm which is combined with the Genetic Algorithm. Brill Tagger is a POS Tagging Algorithm that has the best level of accuracy when implemented in other languages. Genetic Algorithms used in the contextual learner process with consideration in previous studies can increase the speed of the training process so that it is more efficient. The results of this study are then compared with the results of the previous study so that we can find out suitable algorithms used for the development of text processing in Bahasa Madura. From a series of experiments, the average accuracy obtained by using Brill Tagger is 86.4% with the highest accuracy of 86.7%, while using GA Brill Tagger shows an average accuracy of 86.5% with the highest accuracy of 86.6%. Testing by observing OOV (Out of Vocabulary) achieves an average accuracy of 67.7% for Brill Taggers and 64.6% for GA Brill Taggers. Testing by considering multiple POS with Brill Tagger produces an average accuracy of 73.3% while testing using GA Brill Tagger produces an average accuracy of 90.9%. This shows that the accuracy with GA Brill Tagger is better than Brill Tagger, especially if considering multiple POS. This is because GA Brill Tagger can generate rules for handling the existence of multiple POS more than pure Brill Tagger

Damage behavior of the multiple ITZs in recycled aggregate concrete subjected to aggressive ion environment

Recycled aggregate concrete (RAC) is inevitably subjected to various aggressive environments; however, the damage behavior of multiple interfacial transition zones (ITZs) in RAC under such environments has received little consideration in previous studies. Therefore, this paper was developed to quantify the influence of sulfate and chloride attack on the properties of multiple ITZs in RAC. A modeled RAC sample that contained multiple ITZs was first prepared, and the micro-hardness and micro-structure of multiple ITZs undergoing sulfate and chloride attack were determined. The results showed that the ITZOA-NM between old aggregate and new mortar was the weak point of RAC when the new concrete strength was lower than the old concrete strength; however, the ITZOA-OM between old aggregate and old mortar was the weakness of RAC when the new concrete strength was higher than the old concrete strength. A binomial relationship between ITZs properties and sulfate attack duration was observed, and the micro-hardness of multiple ITZs decreased linearly with increasing chloride attack duration. The degradation model for the micro-hardness of multiple ITZs was similar to that for the compressive strength of RAC subjected to an aggressive ion environment. The properties of ITZOA-NM were more sensitive to aggressive ion attack compared with that of other ITZs. Increasing the strength of new concrete is an effective method of improving the properties of multiple ITZs in RAC.

The star formation timescale of elliptical galaxies

The alpha element to iron peak element ratio, for example [Mg/Fe], is a commonly applied indicator of the galaxy star formation timescale (SFT) since the two groups of elements are mainly produced by different types of supernovae that explode over different timescales. However, it is insufficient to consider only [Mg/Fe] when estimating the SFT. The [Mg/Fe] yield of a stellar population depends on its metallicity. Therefore, it is possible for galaxies with different SFTs and at the same time different total metallicity to have the same [Mg/Fe]. This effect has not been properly taken into consideration in previous studies. In this study, we assume the galaxy-wide stellar initial mass function (gwIMF) to be canonical and invariant. We demonstrate that our computation code reproduces the SFT estimations of previous studies, where only the [Mg/Fe] observational constraint is applied. We then demonstrate that once both metallicity and [Mg/Fe] observations are considered, a more severe “downsizing relation” is required. This means that either low-mass ellipticals have longer SFTs (&gt; 4 Gyr for galaxies with mass below 1010 M⊙) or massive ellipticals have shorter SFTs (≈200 Myr for galaxies more massive than 1011 M⊙) than previously thought. This modification increases the difficulty in reconciling such SFTs with other observational constraints. We show that applying different stellar yield modifications does not relieve this formation timescale problem. The quite unrealistically short SFT required by [Mg/Fe] and total metallicity would be prolonged if a variable stellar gwIMF were assumed. Since a systematically varying gwIMF has been suggested by various observations this could present a natural solution to this problem.

The influence of particle morphology on microbially induced CaCO3 clogging in granular media

Sporosarcina pasteurii (ATCC 11859) is a nitrogen-circulating bacterium capable of precipitating calcium carbonate given a calcium source and urea. This microbially induced carbonate precipitation (MICP) is able to infill inter-granular porosity and act as a biological clogging agent, thus having a wide potential application in strengthening coastal foundations, preventing erosion by seas and rivers and in reducing sand liquefaction potential in coastal areas. A successful MICP application requires the understanding of the primary parameters that influence the microbially mediated process to achieve its engineering goals, such as injection scheme, chemical concentrations, retention times, and injection rates. However, the granular morphology has generally been oversimplified to ideal shape without enough consideration in previous studies. The following explores the critical micro-scale influence of particle morphology on mechanisms of microbially induced clogging. Spherical, non-spherical and angular particles were used as granular aggregates in permeating column experiments with the resulting permeability and calcium carbonate content of the treated aggregates examined. Microscopic examination (SEM) defines the features of the distribution of microbially precipitated calcium carbonate and the forms of clogging. The results show: (1) given a fixed duration of treatment, the calcium carbonate content for the spherical particle aggregate is significantly higher than that for near-spherical and angular particle aggregates; (2) for identical durations of treatment, the maximum permeability reduction occurs for angular particles (rather than for spherical particles with the highest carbonate content). This suggests that the microscopic distribution of calcium carbonate is significantly influenced by particle morphology, exerting a critical control in the effectiveness of clogging. SEM images indicate that the microbial calcium carbonate precipitates encapsulate the spherical particles as a near-uniform shell and occlude the pore space only by increasing the shell thickness. In contrast, the near-spherical and angular particles are only partially coated by a calcium carbonate film with scattered crystals of vaterite and calcite further clogging the void space. The polyhedral nature of the non-spherical particles tends to result in a slot-shaped pore structure which critically defines the hydraulic conductivity of the ensemble medium. As the microbial vaterite and calcite continue to accumulate on the particle surface, these slot-shaped pore structures become increasingly more tortuous – resulting in a noticeable reduction of permeability at a lower calcium carbonate content.

Geochemical characteristics of the Paleogene-Neogene coals and black shales from Malaysia: Implications for their origin and hydrocarbon potential

Paleogene-Neogene coals are widespread in Malaysia, cover a wide age spectrum and are considered the source rock of hydrocarbons in Malaysia. However, they have not been studied systematically up to now. Moreover, the black shales associated with these coals were not taken into consideration in previous studies. Therefore, this study presents systematic inorganic and Rock-Eval analyses of the Paleogene-Neogene coals and their associated black shales to examine their origin, depositional environment and hydrocarbon potential.With the exception of coals from the Tanjong Formation, Sabah, the Paleogene-Neogene coals are characterized by very low ash yields and low concentrations of trace and rare earth elements including hazardous trace elements. The black shales are composed of quartz, illite, kaolinite and traces of pyrite in some samples. Al2O3/TiO2 ratios in the coals (6–62) and black shales (16–34) suggest a mixture of felsic and intermediate igneous rocks as sources for their detrital fractions, which is supported by the Zr-Ti binary plot. V/(V+Ni) ratios average between 0.8 and 0.7, V/Ni between 13.5 and 3, and Ni/Co between 1.7 and 3.8 for coal and black shale samples; respectively, indicating suboxic to anoxic depositional conditions for both groups of samples. Rock-Eval analysis indicates that coal and black shale samples contain mixed Type II–III kerogens, which suggest similar organic input from terrestrial high plants. The samples also contain immature to mature organic matter and can produce gas and oil. These characteristics along with the high TOC contents (very good to excellent) indicate that the Paleogene-Neogene coals and black shales are potential source rocks for oil and gas fields in Malaysia. The coals and black shales from different ages and localities were shown to have similar source area composition, climate conditions during their deposition, terrestrial organic input as well as suboxic to anoxic depositional conditions. However, coals and black shales from the early-middle Miocene Tanjong Formation exhibit higher Al2O3/SiO2 ratios than the rest of coals and black shales suggesting a prevalence of wetter climatic conditions during formation. In addition, coals and black shales from the early-middle Miocene Tanjong Formation and upper Pliocene Liang Formation show higher values for redox proxies such as V/(V+Ni), V/Ni, Ni/Co and Ce* compared with other formations, indicating the dominance of reducing conditions during the deposition of these formations.

Vehicle-Following Model Using Virtual Piecewise Spline Tow Bar

AbstractVehicle following has always been a hotspot of research in the transportation system. It can be used in many applications, such as unmanned ground vehicle (UGV) queue marching, traffic congestion relief, automatic driving systems, etc. Trajectory tracking has been the main consideration in previous studies, but the research about following distance is rare. In this paper, a novel vehicle-following model is proposed for independent vehicle following. In the proposed model, multisensor information is fused to promote the detection accuracy. Moreover, a virtual piecewise spline tow-bar is built between the leader vehicle and the follower vehicle. According to the state of virtual tow-bar, the following speed and heading can be well controlled, to keep a reasonable gap between two vehicles. The proposed vehicle-following model is designed for low speed and minor vehicle spacing case. By using the proposed vehicle-following model, the performance of multple-vehicle automatic cruise can be improved, res...

Technology Adoption: an Interaction Perspective

The success of a new technology depends on how well it is accepted by its intended users. Many technologies face the problem of low adoption rate, despite the benefits. An understanding of what makes people accept or reject a new technology can help speed up the adoption rate. This paper presents a framework for technology adoption based on an interactive perspective, resulting from a literature study on technology adoption. In studying technology adoption, it is necessary to consider the interactions among elements involved in the system, for these interactions may generate new characteristics or new relationships. The interactions among elements in a system adoption have not received sufficient consideration in previous studies of technology adoption. Based on the proposed interaction perspective, technology adoption is elaborated by examining interactions among the individual (i.e. the user or prospective user), the technology, the task and the environment. The framework is formulated by adopting several theories, including Perceived Characteristics of Innovating, Diffusion of Innovation Theory, Technology Acceptance Model, Task-Technology Fit and usability theory. The proposed framework is illustrated in the context of mobile banking adoption. It is aimed to offer a better understanding of determinants of technology adoption in various contexts, including technology in manufacturing systems.

Temperature requirements differ for the two stages of seed dormancy break in Aegopodium podagraria (Apiaceae), a species with deep complex morphophysiological dormancy

Only a few studies have considered the possibility that low temperature requirements may vary among stages of dormancy break in seeds with morphophysiological dormancy (MPD). We show that this lack of consideration in previous studies on seed dormancy and germination of Aegopodium podagraria might explain the low germination percentages and/or the relatively long periods of incubation needed for germination. Under natural temperatures, embryos began to grow in September and were fully elongated by late December; most growth occurred when the average daily mean temperature was about 10°C. Radicles emerged under snow in late winter, and cotyledons emerged after snowmelt in early spring. In laboratory experiments, 100% of the embryos grew to full length at both 0 and 5°C, whereas 0°C was much more effective than 5°C in overcoming the physiological dormancy in seeds after embryos were fully elongated. Following radicle emergence, cotyledons emerged readily in a wide range of temperatures ≥5°C. GA(3) did not substitute for the low temperature requirement for dormancy break. Seed dormancy in A. podagraria fits Nikolaeva's formula for deep complex MPD, i.e., C(3)B-C(3). Better germination of seeds pretreated at 0° than at 5°C has practical implications for cultivating this species.

Inflammation and outcome in end-stage renal failure: Does female gender constitute a survival advantage?

Elevated C-reactive protein (CRP) is a strong predictor of cardiovascular events and all-cause mortality in end-stage renal disease (ESRD) patients. However, although sex hormones may influence serum levels of inflammatory proteins, gender has not been taken into consideration in previous studies of inflammation and outcome in ESRD patients. We included 663 (374 males) ESRD patients (59 +/- 1 year) from three European renal centers (Sweden, Germany and Italy) in which CRP levels and outcome data (follow-up 33 +/- 1 months) were available. The relation between outcome and serum levels of the soluble intercellular adhesion molecule (sICAM-1) was evaluated in 312 of the patients. The present study shows that elevated CRP is a strong predictor of outcome, but whereas no difference in all-cause mortality was observed between non-inflamed (CRP <or=3.4 mg/L) males and females, inflamed males had a significantly (log rank 6.1; P = 0.01) higher mortality rate than inflamed females. A strong positive correlation between CRP and sICAM-1 was found in the combined patient material (rho = 0.37; P < 0.0001) as well as in the male (rho = 0.25; P < 0.01) and female (rho = 0.52; P < 0.0001) subgroups. The Cox proportional hazard model showed that whereas both elevated sICAM-1 and log CRP predicted outcome in males, neither predicted outcome significantly in females. As inflamed female patients have a better outcome that inflamed males the present observation suggests that sex hormones may have important cardioprotective effects that limit the effect of inflammation on vascular injury in female ESRD patients.

Effect of water fraction in selection of optimal TI value for STIR sequences.

This article describes the effect of the water fraction in the selection of the optimal TI value in a STIR sequence. This effect has been given little consideration in previous studies. Therefore, using both STIR combined with the Dixon method (opposed-phase STIR) and conventional STIR (in-phase STIR), we have investigated the effect of the water fraction in the selection of an optimal TI value for the STIR sequence. Our findings have indicated that the water protons rather than the olefinic protons (-CH = CH-) play a major role in the opposed-phase effect in vivo. Thus, it has been concluded that the most effective fat suppression can be achieved when the intravoxel phase cancellation effect between the water and lipid protons is maximal, rather than when the longitudinal magnetization of the lipid protons is minimal.

Increase of myocardial oxygen consumption due to active diastolic wall tension.

A marked increase in left ventricular diastolic pressure ( PLVD ) relative to volume is regularly observed during angina pectoris and may contribute to further deteriorations of myocardial perfusion in the ischemic myocardium and to pulmonary congestion as well. A possible simultaneous increase in myocardial oxygen consumption (MVO2) due to a reversible diastolic tone during transient ischemia has not been taken into consideration in previous studies on alterations in ventricular diastolic properties. 13 closed-chest experiments were carried out in clinical catheterization technique with situations of high PLVD (18-50 mm Hg) relative to volume induced by right ventricular pacing (n = 19; 172 +/- 5 beats/min) and catecholamine-induced reversible diastolic tone (n = 17) in moderate hypothermia (31 degrees C). MVO2 was directly measured and indirectly calculated from its hemodynamic determinants using Bretschneider's equation (Et) that does not consider ventricular diastolic pressure. In addition, an energy demand for maintenance of active diastolic wall tension (E5) was calculated from PLVD , mean ventricular diastolic volume estimated from endsystolic and stroke volume, diastolic time and heart rate in ml O2/min X 100 g. During pacing tachycardia with high PLVD (27.4 +/- 1.8 mm Hg) the MVO2 (12.49 +/- 0.50 ml O2/min X 100 g) exceeds Et (10.11 +/- 0.25 ml O2/min X 100 g) (p less than 0.001), partly due to neglect of E5 (1.39 +/- 0.11 ml O2/min X 100 g). During catecholamine-induced high PLVD (31.1 +/- 2.5 mm Hg) the MVO2 (12.29 +/- 0.83 ml O2/min X 100 g) increases significantly (p less than 0.001) over Et (10.43 +/- 0.81 ml O2/min X 100 g). Addition of E5 (1.76 +/- 0.14 ml O2/min X 100g) to Et abolishes the differences between MVO2 and Et yielding non-significantly different values. Results indicate by means of indirect energetic evidence the occurrence of a diastolic tone of the heart under unphysiologic conditions. Acute increases in PLVD during angina pectoris are supposed to increase MVO2 markedly due to an additional energy demand for maintenance of reversible active diastolic wall tension.

High Altitude Hypoxia, Culture, and Human Fecundity/Fertility: A Comparative Study

This paper presents new demographic findings for a high altitude Himalayan population residing in Ladakh, India, and reviews problematic issues regarding the hypothesized relationship between fertility/fecundity and altitude in the Himalayas in light of these findings. It concludes that the low completed fertility ratio reported for the Sherpas of Khumbu, Nepal, is not caused by hypoxia‐induced low fecundity, but is the product of cultural factors affecting the exposure of females to the risk of intercourse, a critical confounding factor that has not received adequate consideration in previous studies. Contrary to earlier reports, the present study demonstrates that all high altitude Himalayan populations for which published data exist exhibit moderately high fertility and fecundity, and do not differ significantly in their fertility levels. Furthermore, it argues that the claims for a statistically significant difference in fertility between high, moderate, and low altitude Himalayan populations are groundless, and suggests that a parallel reevaluation of Andean findings is required. [fertility, fecundity, hypoxia, Himalayas, Andes]

Optimal Plastic Design for Bending and Shear

In optimizing flexural systems (such as beams, frames, and grillages) of continuously varying cross section, most authors assume that the specific cost of the member is a function of the bending moment only. However, the Prager-Shield theory of plastic optimal design and its extensions to multiload and multicomponent systems, partially preassigned geometry, and nonconvex cost functions can be applied readily to problems in which the specific cost depends on both bending and shear. In this note, a generalization of Heyman's method is considered but the same technique can be used for an improved optimization of grillages for which only flexure was taken into consideration in previous studies.