Within-host competition and diversification of macro-parasites

Although competitive speciation is more and more regarded as a plausible mechanism for sympatric speciation of non-parasite species, virtually no empirical or theoretical study has considered this evolutionary process to explain intra-host diversification of parasites. We expanded the theory of competitive speciation to parasite species looking at the effect of macro-parasite life history on the conditions for sympatric speciation under the so-called pleiotropic scenario. We included within-host competition in the classical Anderson and May framework assuming that individuals exploit within-host resources according to a quantitative trait. We derived the invasion fitness function of mutants considering different distributions of individuals among hosts. Although the mutant fitness depends on parameters describing the key features of macro-parasite life history, and on the relative distributions of mutant and residents in hosts, the conditions for competitive speciation of macro-parasites are exactly the same as those previously established for free-living species. As an interesting by-product, within-host competitive speciation is expected not to depend on the aggregation level of the parasites. This theoretical pattern is confirmed by comparing the speciation rate of weakly and strongly aggregated monogenean parasites.     

Energy metabolism,body composition,and urea generation rate in hemodialysis patients

Hemodialysis (HD) adequacy is currently assessed using normalized urea clearance (Kt/V), although scaling based on Watson volume (V) may disadvantage women and men with low body weight. Alternative scaling factors such as resting energy expenditure and high metabolic rate organ mass have been suggested. The relationship between such factors and uremic toxin generation has not been established. We aimed to study the relationship between body size, energy metabolism, and urea generation rate. A cross‐sectional cohort of 166 HD patients was studied. Anthropometric measurements were carried on all. Resting energy expenditure was measured by indirect calorimetry, fat‐free mass by bio‐impedance and total energy expenditure by combining resting energy expenditure with a questionnaire‐derived physical activity data. High metabolic rate organ mass was calculated using a published equation and urea generation rate using formal urea kinetic modeling. Metabolic factors including resting energy expenditure, total energy expenditure and fat‐free mass correlated better with urea generation rate than did Watson volume. Total energy expenditure and fat‐free mass (but not Watson Volume) were independent predictors of urea generation rate, the model explaining 42% of its variation. Small women (<mean V) had a significantly higher urea generation rate per kg than women with higher V. Similarly urea generation rate normalized to fat‐free mass was significantly greater in small women than in all others (significant only in comparison to larger men). Exercise‐related energy expenditure correlated significantly with urea generation rate. Energy metabolism, body composition and physical activity play important roles in small solute uremic toxin generation in HD patients and hence may impact on minimum dialysis requirements. Small women generate relatively more small solute toxins than other groups and thus may have a higher relative need for dialysis.     

Review of supplier diversification and pricing strategies under random supply and demand

Uncertainties of supply and demand are two major sources of risk in any supply chain. As a result, the companies are implementing different strategies to mitigate the effects of these risks. Supplier diversification and responsive pricing are two of the main strategies that are used to mitigate the supply and demand risks. In supplier diversification, a firm uses multiple channels of sourcing while in responsive pricing, a firm manipulates demand through pricing to mitigate supply and demand risks. In this paper, we review lot-sizing problems when supply and demand are random. We focus on studies that have considered supplier diversification or responsive pricing as a mitigation strategy. We classify the studies based on their main assumptions and summarise their major findings. Finally, we present some directions for future research. Part of what we have found is that most studies that use multiple decision makers have focused on cases where information is complete and non-cooperative. There is a need to consider more realistic situations when there is information asymmetry between the decision makers. In addition, we have found that there is a lack of studies that look at the impact of joint ordering and pricing in the existence of multiple suppliers.     

Academic tenure,risk-taking and the diversification of scientific research

We discuss two competing hypotheses linking the relative job security granted by tenure in academic employment to scientists’ choices between diversifying vs. specialising their research portfolio. To test our hypotheses, we develop a new methodology, using an algorithm of semantic analysis that partitions scientists’ publications into research themes, and we compute the Blau’s diversification index for 562 scientists observed over 15 years. The results of a Fractional Probit Model with fixed effects show that tenure is associated to more diversification of research interests. We discuss the implications for policy-makers and granting agencies wishing to incentivise explorative research.     

Specialization versus diversification in research activities: the extent,intensity and relatedness of field diversification by individual scientists

Motivated by applications in scientometrics, we study the occurrence of first significant digits in Lavalette distribution and in double Pareto distribution. We obtain modifications of Benford’s law. When the exponents are small, significant deviations to Benford’s law are observed; when the exponents are large, the two distributions conform with Benford’s law. Both analytical and numerical results are presented. Scientometric data can fairly well be described by the modifications.     

供需双重不确定下链与链竞争的博弈分析

研究了分别由1个零售商和1个供应商构成的两条供应链之间的竞争问题,讨论了供应中断风险和需求不确定对于竞争的供应链的影响。分析了协调竞争、混合竞争、非协调竞争3种供应链结构下的最优订货量和契约参数。研究发现在一定的收益共享系数范围,供应链协调竞争成立。最后通过数值计算,分析了参数对最优订货量的影响,得到了管理启示。     

标准的本质、归属与发展

通过对标准的来历、内含与发展分析,认为标准是具体与抽象结合的特殊产品,具有价值和使用价值;人类的模仿和学习能力成为标准产生与发展的实践基础,决定了标准进化与人类发展同步进行;标准源于农业,强在工业,用于各行各业.农业是标准产出最为困难的领域;农业标准分为自然型和目的型两大类,反映了农业标准化的前期认识与最终应用结果.     

Revealing mechanisms underlying variation in malaria virulence: effective propagation and host control of uninfected red blood cell supply

Malaria parasite clones with the highest transmission rates to mosquitoes also tend to induce the most severe fitness consequences (or virulence) in mammals. This is in accord with expectations from the virulence–transmission trade-off hypothesis. However, the mechanisms underlying how different clones cause virulence are not well understood. Here, using data from eight murine malaria clones, we apply recently developed statistical methods to infer differences in clone characteristics, including induction of differing host-mediated changes in red blood cell (RBC) supply. Our results indicate that the within-host mechanisms underlying similar levels of virulence are variable and that killing of uninfected RBCs by immune effectors and/or retention of RBCs in the spleen may ultimately reduce virulence. Furthermore, the correlation between clone virulence and the degree of host-induced mortality of uninfected RBCs indicates that hosts increasingly restrict their RBC supply with increasing intrinsic virulence of the clone with which they are infected. Our results demonstrate a role for self-harm in self-defence for hosts and highlight the diversity and modes of virulence of malaria.     

In hemodialysis, adiponectin, and pro-brain natriuretic peptide levels may be subjected to variations in body mass index

Adiponectin exerts cardiovascular protective actions, although some studies have shown the opposite. In hemodialysis, obese subjects display lower mortality rates despite hypoadiponectinemia, while higher adiponectin concentrations correlate with an elevated cardiovascular risk in nonobese subjects. The aim of the study is to suggest that adiponectin level variations are associated with differences in the body mass index (BMI). The interplay between adiponectin and pro-brain natriuretic peptide (Pro-BNP) levels may vary according to body fat mass. Fifty-two chronic hemodialysis patients were divided into three groups. Group A, BMI<25 (n=20); Group B, BMI 25 to 30 (n=21), and Group C, BMI>30 (n=11). Diabetics: Group A 10%; Group B 6 29%; Group C 55%, P=0.027. Determinations: Adiponectin, Pro-BNP, insulin, insulin resistance (HOMA), troponin T, nutritional status, ultrafiltration rates, C-reactive protein (CRP), vascular accesses, and echocardiography. Group A: adiponectinemia positively and significantly correlated with Pro-BNP, CRP, and troponin T. As BMI increased, adiponectin, Pro-BNP, and malnutrition significantly decreased, while insulin, HOMA, and ultrafiltration rates significantly increased. Cardiac restriction was significantly higher in obese patients. In all groups, Pro-BNP and troponin T displayed a strong positive correlation. In low-BMI subjects, high Pro-BNP and adiponectin, low myocardial restriction, and worse nutritional status were prevalent. In obesity, hypoadiponectinemia stimulates cardiac remodeling, cardiac hypertrophy, and decreased stretching, rendering Pro-BNP levels low despite high ultrafiltration rates. Thus, adiponectin correlates inversely with BMI, probably playing different cardiovascular roles as BMI changes.     

Coefficients of mass transfer between a fluidized bed and the surface of a capillary-porous body

Results are presented from a theoretical determination of coefficients of mass transfer between a fluidized bed of porous particles and a capillary-porous body.Notation a particle radius - F area of contact of particles with the surface of the body - f percentage of area of surface of product in contact with the bubble phase - g acceleration due to gravity - i flow of liquid mass from a unit area of the surface - N number of fluidizations - n number of particles coming into contact with a surface of unit area per unit of time - p_p, p_b capillary potentials of particles and product - R₂, R₁ radii of narrow and broad pores inside the product - r radius of capillaries in the particles - S area of the surface being treated - T temperature of the bed - t time of treatment - u percentage content of liquid in the specimen - V volume of the product being treated - v mean square component of the fluctuation velocity of the particles in the direction normal to the surface - , * standard and corrected mass-transfer coefficients determined from (5) and (9) - _b, _b, _p porosities of product determined for all and for only the small pores and the porosity of the material of the particles - _d, _m porosity of the dense phase and the porosity of the bed in the state of minimum fluidization - _b, _p angles of wetting of the materials of the product and particles, respectively, by the liquid binder - , viscosity and density of the liquid - ₀ density of the dry product - surface tension coefficient of the liquid - characteristic time of contact of particles with the surface - Re_m Reynolds number corresponding to particle radius and minimum-bed-fluidization velocity [6] Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 40, No. 3, pp. 460–465, March, 1981.     

Numerical solution of the problem of heat and mass transfer in a moist porous body

A system of controlling equations is derived. The method of finite differences is used to obtain numerical solutions for the temperature distributions, the moisture content, and the pressure of the air-vapor mixture in a porous body during contact heating.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 3, pp. 416–423, March, 1976.     

Using metabolic energy to quantify the subjective value of physical effort

Economists have known for centuries that to understand an individual''s decisions, we must consider not only the objective value of the goal at stake, but its subjective value as well. However, achieving that goal ultimately requires expenditure of effort. Surprisingly, despite the ubiquitous role of effort in decision-making and movement, we currently do not understand how effort is subjectively valued in daily movements. Part of the difficulty arises from the lack of an objective measure of effort. Here, we use a physiological approach to address this knowledge gap. We quantified objective effort costs by measuring metabolic cost via expired gas analysis as participants performed a reaching task against increasing resistance. We then used neuroeconomic methods to quantify each individual''s subjective valuation of effort. Rather than the diminishing sensitivity observed in reward valuation, effort was valued objectively, on average. This is significantly less than the near-quadratic sensitivity to effort observed previously in force-based motor tasks. Moreover, there was significant inter-individual variability with many participants undervaluing or overvaluing effort. These findings demonstrate that in contrast with monetary decisions in which subjective value exhibits diminishing marginal returns, effort costs are valued more objectively in low-effort reaching movements common in daily life.     

Quantum metabolism explains the allometric scaling of metabolic rates

A general model explaining the origin of allometric laws of physiology is proposed based on coupled energy-transducing oscillator networks embedded in a physical d-dimensional space (d = 1, 2, 3). This approach integrates Mitchell''s theory of chemi-osmosis with the Debye model of the thermal properties of solids. We derive a scaling rule that relates the energy generated by redox reactions in cells, the dimensionality of the physical space and the mean cycle time. Two major regimes are found corresponding to classical and quantum behaviour. The classical behaviour leads to allometric isometry while the quantum regime leads to scaling laws relating metabolic rate and body size that cover a broad range of exponents that depend on dimensionality and specific parameter values. The regimes are consistent with a range of behaviours encountered in micelles, plants and animals and provide a conceptual framework for a theory of the metabolic function of living systems.     

原子质量的相对论效应和应用

应用相对论理论(Dirac)来计算C、O、S、Se、Te、Sm和Pu原子的相对论和非相对论的电子状态和能量,比较相对论和非相对论的能量差别后得到:如果以O原子的相对论和非相对论能量差为1,则S、Se、Sm和Pu原子的相对论和非相对论能量差分别为17.5、479、6 781和46 166。就钚和氧相比,质量的相对论效应增加46 166倍。Pu的相对论的和非相对论的能量的差占总能量的8.72%,所以对重元素,应用相对论的计算是很必要的。     

Sulfur Loading and Speciation Control the Hydrophobicity,Electron Transfer,Reactivity, and Selectivity of Sulfidized Nanoscale Zerovalent Iron

Sulfidized nanoscale zerovalent iron (SNZVI) is a promising material for groundwater remediation. However, the relationships between sulfur content and speciation and the properties of SNZVI materials are unknown, preventing rational design. Here, the effects of sulfur on the crystalline structure, hydrophobicity, sulfur speciation, corrosion potential, and electron transfer resistance are determined. Sulfur incorporation extended the nano-Fe⁰ BCC lattice parameter, reduced the Fe local vacancies, and lowered the resistance to electron transfer. Impacts of the main sulfur species (FeS and FeS₂) on hydrophobicity (water contact angles) are consistent with density functional theory calculations for these FeS_x phases. These properties well explain the reactivity and selectivity of SNZVI during the reductive dechlorination of trichloroethylene (TCE), a hydrophobic groundwater contaminant. Controlling the amount and speciation of sulfur in the SNZVI made it highly reactive (up to 0.41 L m⁻² d⁻¹) and selective for TCE degradation over water (up to 240 moles TCE per mole H₂O), with an electron efficiency of up to 70%, and these values are 54-fold, 98-fold, and 160-fold higher than for NZVI, respectively. These findings can guide the rational design of robust SNZVI with properties tailored for specific application scenarios.     

An investigation into the heat and mass transfer of a liquid evaporating from a capillary-porous body

A theoretical analysis is presented for the process of heat and mass transfer in the case of a liquid evaporating from a capillary-porous body into an approaching gas stream. The method of the experimental investigation into this process is described. The excellent agreement between the experimental and theoretical data makes it possible to use the resulting quantitative relationships to calculate the heattransfer coefficients in the case of intermittent cooling.     

Study of the characteristics of heat and mass transfer in a gas-solid body system at low temperatures

An experimental apparatus — a universal vacuum spectrophotometer — is described. It is used for studying the kinetic characteristics of gas-solid phase transitions at low temperatures as well as the spectral reflectances of typical optical surfaces coated with layers of cryocondensates of different gases. A method is proposed for determining the indices of refraction of the cryocondensates, the growth rates of the condensates, and the spectral reflectances.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 61, No. 6, pp. 986–992, December, 1991.     

An electrochemical study of heat and mass transfer in the vibrational motion of a medium and a body

An experimental test is reported for the effects of low-frequency oscillations on the mass transfer between a sphere and a medium at large Prandtl numbers.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 1, pp. 5–8, July, 1970.     

Effects of obstacle height on the control of the body center of mass motion during obstructed gait

Abstract

Tripping over obstacles has been reported as one of the most frequent causes of falls in the elderly. Since a successful crossing requires the stability of the body through the control of the motion of the body center of mass (COM), the purpose of this study was to investigate the COM motion when crossing obstacles of different heights. Ten young healthy adults walked and crossed obstacles of heights of 10%, 20% and 30% of their leg lengths in a gait laboratory. The COM motions were calculated using data measured from a motion analysis system. It was found that vertical motions of the COM, including position, velocity and acceleration, were all modulated to successfully cross obstacles of different height. All acceleration components of the COM were changed with increased obstacle height, suggesting that different forces from muscle contractions were needed to control COM stability when facing different obstacle heights. These findings may help shed light on further investigation of the motor control strategies of the central nervous system for obstacle crossing and serve as baseline data in the evaluation of the elderly and patients.     

Scaling and mechanics of carnivoran footpads reveal the principles of footpad design

In most mammals, footpads are what first strike ground with each stride. Their mechanical properties therefore inevitably affect functioning of the legs; yet interspecific studies of the scaling of locomotor mechanics have all but neglected the feet and their soft tissues. Here we determine how contact area and stiffness of footpads in digitigrade carnivorans scale with body mass in order to show how footpads’ mechanical properties and size covary to maintain their functional integrity. As body mass increases across several orders of magnitude, we find the following: (i) foot contact area does not keep pace with increasing body mass; therefore pressure increases, placing footpad tissue of larger animals potentially at greater risk of damage; (ii) but stiffness of the pads also increases, so the tissues of larger animals must experience less strain; and (iii) total energy stored in hindpads increases slightly more than that in the forepads, allowing additional elastic energy to be returned for greater propulsive efficiency. Moreover, pad stiffness appears to be tuned across the size range to maintain loading regimes in the limbs that are favourable for long-bone remodelling. Thus, the structural properties of footpads, unlike other biological support-structures, scale interspecifically through changes in both geometry and material properties, rather than geometric proportions alone, and do so with consequences for both maintenance and operation of other components of the locomotor system.