Lower Critical Limit Research Articles

Application of analytical methods to identify critical limits of grain infection by Fusarium fungi

Relevance. The scientific community and agricultural producers are looking for a solution to the problem of how to protect consumers from the effects of hazardous mycotoxins in agricultural products. One of the tools, which will be considered in this article, is a screening system that allows determining the quan-titative indicators of wheat grain infection by toxin-producing fungi in a short time.Methods. The method of quantitative PCR with the detection of fungal DNA and the method of enzyme immunoassay with the detection of Fusarium antigens were used to characterize the grain infection.Results. We established the lower critical limit of DNA content which is 3955·10-4 pg/ng and the lower critical limit of Fusarium antigens which is 596 U/g based on the analyzes of grain fungi contamination in model experiments. Grain should be subjected to mycotoxins analysis upon detection of these critical lim-its. All batches of grain can be used in production without additional analyzes if their values determined by analytical methods are below that critical points. The obtained values can be quantitative benchmarks corresponding to the standard visual analysis of grain contamination currently described in GOST 31646-2012

Does temperature at local scale explain thermal biology patterns of temperate tadpoles?

Most of the literature on temperature-organism interactions rely on mean temperature (mostly air), disregarding the real complexity of this variable. There is a growing consensus about the importance of considering the temperature fluctuations as a mechanism improving organism's performance. Tadpoles are small body size ectotherm organisms that behave isothermally with their environment. As such, are good models for studying their thermal biology relative to their immediate environment. We studied six anuran tadpole species in North Patagonia, Alsodes gargola, Hylorina sylvatica, Batrachyla taeniata, Pleurodema thaul, P. bufoninum and Rhinella spinulosa, distributed in a West-East altitudinal cline with different environments and thermal conditions. We evaluated the relationship between thermal descriptors at a local scale and the thermal biology patterns of these temperate tadpoles. We estimated thermal tolerance limits and thermal sensitivity of locomotion of each species. The different aquatic environments showed important differences in local thermal conditions, associated with observed differences in the thermal traits in these tadpoles. Species exposed to lower temperature fluctuations and lower environmental mean temperatures showed lower swimming optimal temperatures and narrower thermal tolerance ranges. We found greater variability in the upper than in the lower critical limits in these Patagonian anuran tadpoles. Minimum critical temperatures were close to freezing temperature, possibly in detriment of their tolerance to high temperatures. Overall, our results suggest that these species are adapted to low temperatures. Finally, warming tolerances and predicted thermal safety margins, show that none of the studied species appear to be under thermal stress that may compromise their survival at the present time or in the near future, under a moderate climate change scenario.

The critical bond strength of orthodontic brackets bonded to dental glass–ceramics

To evaluate the critical bond strength (σ) of ceramic and metal brackets to a lithium disilicate-based glass-ceramic. Two hundred and forty ceramic specimens (IPS e-max CAD) were randomly distributed in 12 experimental groups (n = 20). Two ceramic brackets (monocrystalline, BCm; and polycrystalline, BCp) and a metal bracket (BM) were bonded to glass-ceramic specimens after one of the following surface treatments: HF-hydrofluoric acid applied for 60s; S-silane applied for 3min; HFS-HF followed by S; and MDP-application of an adhesive containing a phosphate monomer (MDP). All brackets were bonded to the treated glass-ceramic using a resin cement, stored in 37°C water for 48h before shear bond strength testing. Optical (OM) and scanning electron (SEM) microscopies were used for fractographic analysis. Data was statistically analyzed using Kruskal-Wallis and Student-Newman-Keuls (α = 0.05). BCm bonded to glass-ceramic treated with either HFS or HF showed the highest median σ values, respectively, 10.5MPa and 8.5MPa. In contrast, the BCp bonded to glass-ceramic treated with MDP showed the lowest median σ value (0.8MPa), which was not statistically different from other MDP-treated groups. The failure mode was governed by the glass-ceramic surface treatment, not by the bracket type. Quantitative (σ values) and qualitative (fracture mode) data suggested a minimum of 5MPa for brackets bonded to glass-ceramic, which is the lower critical limit bond strength for a comprehensive orthodontic treatment. Bonding brackets to glass-ceramic requires micromechanical retention.

Multiple stressors including contaminant exposure and parasite infection predict spleen mass and energy expenditure in breeding ring-billed gulls

Daily energy expenditure (DEE) in animals is influenced by many factors although the impact of stressors remains largely unknown. The objective of this study was to determine how multiple physiological stressors (parasite infection and contaminant exposure) and natural challenges (energy-demanding activities and weather conditions) may affect DEE in nesting ring-billed gulls (Larus delawarensis) exposed to high concentrations of persistent organic contaminants (POPs). Physical activity, temperature, gastrointestinal parasitic worm abundance, relative spleen mass, plasma thyroid hormone levels and liver concentrations of POPs were determined; field metabolic rate (FMR) was used as a measure of DEE. For females, FMR was best explained by the percent of time spent in nest-site attendance and exposure to temperatures below their lower critical limit (65% of variation); 32% was also explained by relative spleen mass. In males, FMR was best explained by the number of hours spent in nest site attendance and either relative spleen mass or liver concentrations of tetra-brominated diphenyl ethers (tetra-BDEs) (55% of variation). Relative spleen mass, as an important factor relating to FMR, was best explained by models with a combination of parasite abundance (Diplostomum for females and Eucoleus for males) in a negative relationship, and liver POP concentrations (p,p′-DDE for females and tetra-BDEs for males) in a positive relationship (34%, 55% of variation for females and males, respectively). This study demonstrates that immune activity may be an important factor affecting energy expenditure in ring-billed gulls, and that contaminants and parasite abundance may have both a direct and/or indirect influence on FMR.

Critical temperature in relativistic Lorentzian thermodynamics of massive bosons

The critical temperature for condensation of massive bosons in high-temperature ultra-relativistic gases is generalized to the presence of temperature anisotropy and extended to generalized-Lorentzian statistical mechanics. A lower critical limit is given for the Lorentzian κ-parameter as function of the boson mass.

The energetics of a Malagasy rodent, Macrotarsomys ingens (Nesomyinae): a test of island and zoogeographical effects on metabolism.

This study provides first insights into the energetics of the Nesomyinae, a subfamily of rodents endemic to Madagascar. The ancestral nesomyine colonized Madagascar from Africa ca. 30-15 mya at the onset of Oligocene global cooling. We tested the hypothesis that, contrary to what might be expected from Island Biogeography theory, post-colonization character displacement of thermoregulatory traits was constrained by phylogenetic inertia through climate adaptation. The study was conducted in the Parc National d'Ankarafantsika, Madagascar. We measured the basal metabolic rate (BMR) and body temperature (T b) patterns of naturally warm-acclimated, freshly captured adult long-tailed big-footed mice Macrotarsomys ingens (67.4 g). The mean ± SD BMR of M. ingens was 0.298 ± 0.032 Watts (n = 12), 31.7 % lower than that predicted by a phylogenetically independent allometric equation. Body mass was correlated with BMR. The lower critical limit of thermoneutrality (T lc) was 30.7°C. The mean ± SD T b = 36.1 ± 0.8°C (n = 12) compared well with the mean T b values for myomorph rodents from the Afrotropical zone, but was lower than those of the Neotropical and Palearctic zones. M. ingens became pathologically hypothermic when exposed to ambient temperatures lower than 18°C. The soil temperature at depths of 250 mm and deeper did not decrease below 22°C throughout the austral winter. The thermoregulatory data for M. ingens did not differ from those that characterize mainland Afrotropical rodents. However, BMR and T b were lower than those of Holarctic rodents. Thus, contrary to expectations of Island Biogeography theory that rapid character displacement often occurs in morphological and behavioural traits when mammals colonize islands, M. ingens displayed climate-related physiological traits indicative of phylogenetic inertia. Presumably the tropical conditions that prevailed on Madagascar at the time of colonisation differed very little from those of the African mainland, and hence there was no strong driving force for change. Unlike small tenrecs and lemurs that radiated on Madagascar prior to the Oligocene, traits associated with an insular existence, such as daily torpor and hibernation, were not evident in M. ingens.

Criticality in alternating layered Ising models. I. Effects of connectivity and proximity

The specific heats of exactly solvable alternating layered planar Ising models with strips of width m_{1} lattice spacings and "strong" couplings J_{1} sandwiched between strips of width m_{2} and "weak" coupling J_{2}, have been studied numerically to investigate the effects of connectivity and proximity. We find that the enhancements of the specific heats of the strong layers and of the overall or "bulk" critical temperature T_{c}(J_{1},J_{2};m_{1},m_{2}) arising from the collective effects reflect the observations of Gasparini and co-workers in experiments on confined superfluid helium. Explicitly, we demonstrate that finite-size scaling holds in the vicinity of the upper limiting critical point T_{1c} (∝J_{1}/k_{B}) and close to the corresponding lower critical limit T_{2c} (∝J_{2}/k_{B}) when m_{1} and m_{2} increase. However, the residual enhancement, defined via appropriate subtractions of leading contributions from the total specific heat, is dominated (away from T_{1c} and T_{2c}) by a decay factor 1/(m_{1}+m_{2}) arising from the seams (or boundaries) separating the strips; close to T_{1c} and T_{2c} the decay is slower by a factor lnm_{1} and lnm_{2}, respectively.

Clearing of invasive alien plants under different budget scenarios: using a simulation model to test efficiency

Clearing of invasive alien plants (IAPs) is a necessary but expensive exercise. Typically, insufficient resources are available to clear all areas simultaneously. Consequently areas need to be prioritized for clearing. The financial resources available determine the extent of the area which can be cleared, while the prioritization identifies the location of the areas to be cleared. We investigate the following questions: (1) How does a change in the budget impact on the efficiency of the clearing operations over time? (2) How does this differ for different sites? (3) Can we identify pattern which make it possible for managers to determine if their budget is sufficient to achieve a management goal (e.g. clearing 95% of the area of IAPs) in a given time? (4) Can we draw general rules about how the time needed of achieving a management goal is changing when increasing the budget? We use a spatio-temporal explicit simulation model (SpreadSim) to simulate the spread of major woody IAPs over time, using a random prioritization strategy as a null model. This strategy requires no understanding or assumptions about the factors influencing spread; it is thus a reasonable baseline prioritization strategy. Our results confirm that a reduction of the budget increases the time needed to reach a management goal of 95% non-invaded areas and simultaneously increases the overall budget needed to achieve this goal. In addition, for each site, we can identify three values. Firstly, a “lower critical limit” of the budget, below which the IAP spread is only slowed down and management does not result in a reduction of the area invaded by IAPs, which is independent of the management goal. Secondly, the “critical budget”, at which we have a chance of more than 50% of achieving our management goal in a given time. Thirdly, an “upper critical limit” for the budget, above which no substantial change in the time needed to reach the management goal can be observed. For all our three sites, the “upper critical limit” is located at approximately 1.7 times the “critical budget”. The variability of the temporal trajectories of the area covered by IAPs for different simulations for the same input parameter and highly non-linear change in IAP cover over time indicate that an identification of the “critical budget” based on few years of IAP management is nearly impossible and that the use of simulation models is imperative. Nevertheless, the general pattern observed can be generalized to other prioritization strategies and provide important guidance for budget allocations.

Geographical variation in thermal tolerance within Southern Ocean marine ectotherms

Latitudinal comparisons of the Southern Ocean limpet, Nacella concinna, and clam, Laternula elliptica, acclimated to 0.0 °C, were used to assess differences in thermal response to two regimes, 0.0, 5.1 to 10.0 °C and 2.5, 7.5 to 12.5 °C, raised at 5.0 °C per week. At each temperature, tissue energy status was measured through a combination of O 2 consumption, intracellular pH, cCO 2, citrate synthase (CS) activity, organic acids (succinate, acetate, propionate), adenylates (ATP, ADP, AMP, ITP, PLA (phospho-L-arginine)) and heart rate. L. elliptica from Signy (60°S) and Rothera (67°S), which experience a similar thermal regime (− 2 to + 1 °C) had the same lethal (7.5–10.0 °C), critical (5.1–7.5 °C) and pejus (< 5.1 °C; = getting worse) limits with only small differences in biochemical response . N. concinna, which experiences a wider thermal regime (− 2 to + 15.8 °C), had higher lethal limits (10.0–12.5 °C). However, at their Northern geographic limit N. concinna, which live in a warmer environment (South Georgia, 54°S), had a lower critical limit (5.1–10.0 °C; O 2, PLA and organic acids) than Rothera and Signy N. concinna (10.0–12.5 °C). This lower limit indicates that South Georgia N. concinna have different biochemical responses to temperatures close to their thermal limit, which may make them more vulnerable to future warming trends.

Application evaluation of critical value fists data

Objective Analyze the historical data of critical values lists,providing scientific evidence for continuous improvement of critical value systems.Methods Screen out critical value lists data of 2006 from laboratory information system,after pretreatment and transformation of data,calculate the percentage of critical value,and its daily distribution,weekly distribution and department distribution, evaluate the range and turnaround time for critical value.Results The rate of critical value was 1.67%.It was mainly concentrated from 8 to 13 O'clock.Monday and Thursday have more critical value than other days.From the perspective of department,the majority critical value was from hematology department and transplantation department.After the evaluation of distribution diagram of critical value range,the lower critical value limit of blood potassium was adjusted from 3.0 mmol/L to 2.8 mmol/L,the blood platelet and leukocyte counts for parlents with hematology disease were a(Ijusted from 20×109/L,1.5×109/L to 10×1O9/L,1.0×109/L respectively.The laboratory turnaround time for 76.2% critical value was less than 1 hour.Conclusion Review and analyze critical value lists data regularly can improve the work efficiency and quality for the laboratory and clinic department and better meet patients' safety needs. Key words: Critical values reporting; Patient safety; Laboratory management; Data mine

Grain boundary relaxation of hydrogen precharged mild and Cr steels

Internal friction was applied to trace the formation and propagation of the hydrogen-induced degradation of commercial mild and 5% Cr steels. Hydrogen charged and then degassed specimens were subjected to internal friction measurements at the grain boundary relaxation temperature range and the irreversible effects of hydrogen precharging on the grain and phase boundary relaxation processes were studied. From the comparison of the internal friction and the hydrogen permeation data, the critical limits of hydrogen pretreatment corresponding to the different state of the grain boundary degradation were evaluated. At lower critical limit (associated with the minimum of hydrogen apparent diffusivity), the formation of near grain boundary dislocations and the grain boundary decohesion occurred. At critical hydrogen precharging causing the formation of microvoids, annihilation of dislocations and vacancies within the grain boundary voids led to the recovery of internal friction and hydrogen diffusivity. The obtained results agreed with the earlier observed effects of hydrogen precharging on pure iron and low alloy steel, despite the apparent difference in the grain boundary structure and chemistry of those materials.

Presence—Absence Sequential Decision Plans for Tetranychus urticae (Acari: Tetranychidae) in Garden-seed Beans., Phaseolus vulgaris

A sequential decision plan was developed for assessing economic status of twospotted spider mites, Tetranychus urticae Koch, in garden-seed beans, Phaseolus vulgaris L. Precision and cost analyses showed that sample units should consist of single trifoliolate leaves picked from the bottom third of the plant canopy. Provisional economic thresholds were established for two preharvest intervals in terms of proportion of leaves infested with ≥5 mites and ≥10 mites per leaf. Upper and lower critical limits of the sequential decision plan were defined by the confidence interval: Ci = ( P1)(n ) ± ( t)(n )[[[P1(l − P1)]/ n ]14], where Pt is the economic threshold, n is number of leaves examined, and t is the Student’s t statistic for the acceptable error level.

Magnetic properties of the spin glass Pd1-yFeyHx: hyperfine and susceptibility studies in a magnetic field

Mossbauer hyperfine and magnetometer measurements have been made on different compositions of the spin-glass system Pd1-yFeyHx. It is found that in the spin-glass phase the hyperfine field HHF below the ordering temperature T0 shows a distribution P(HHF) which is zero for HHF less than a lower critical limit HHF0. Satisfactory numerical agreement is found with the calculations of Palmer and Pond (1979) and of Sommers (1978, 1979) for the equivalent limiting molecular field. The effect of a magnetic field on the spin orientation (T T0, strong relaxation effects have been discovered in the Mossbauer spectra in the presence of an external magnetic field. Macroscopic susceptibility and magnetisation measurements have been used to verify the presence of ferromagnetic clusters. One result is that for T>T0, the effective Curie-Weiss temperature value strongly depends on external field, caused by the very wide spectrum of interactions in a spin glass.

A comparison of hydrogen embrittlement and stress corrosion cracking in high-strength steels

The purpose of this study was to compare the known behavior of hydrogen embrittled highstrength steel to the characteristics of environmentally induced failure where hydrogen is continuously generated at the specimen surface. The incubation time for the initiation of slow crack growth was accelerated by prestressing for a fixed time below the lower critical limit. These results obtained on high-strength steel in a stress corrosion environment were directly comparable to behavior of hydrogenated specimens. These data along with hydrogen diffusivity measurements and the insensitivity of the incubation time and crack growth rate to specimen thickness indicated that the stress corrosion process was controlled by the distilled water-metal surface reaction.

The Climatology of Blowfly Myiasis

The relationship of oviposition to weather, with a standard stimulus (4 per cent. ammonium carbonate), has been tested by a series of 134 exposures of a group of three sheep for one hour. 190 egg clusters were obtained, of which 169 were identified. With the exception of one cluster of L. caesar all were L. sericata.There was a fairly close correlation (0·586) of oviposition with air-temperature. When the possible effect of other factors was eliminated, the correlation was little affected, showing that temperature was in itself responsible for the variations in oviposition. The lower critical limit of temperature was in the neighbourhood of 56°–58°F.Solar radiation and oviposition had an apparent correlation, but this was found to be spurious, the effect being due to related air-moisture changes. At temperatures near the lower critical limit, insolation did not increase the oviposition rate, or lower its temperature threshold.Humidity had an apparent inverse correlation with oviposition, but this also was an indirect effect, due to related temperature changes. Humidity showed a closer correlation when expressed as saturation deficiency than as relative humidity. Evaporation rate from a white atmometer sphere had only a low correlation with oviposition.It is shown that the partial correlations of both saturation deficit and insolation with temperature effects eliminated, are insignificant, i.e. their apparent effects are due to related temperature changes. The multiple correlation coefficient for temperature humidity and insolation is practically identical with that for temperature.Independent variations of insolation, i.e. variations not simultaneous with related temperature changes, had a significant effect on oviposition; for a given temperature, a high intensity of insolation was less favourable than a low, and this appeared to be a true insolation effect, and not due to associated humidity changes.Independent variations of humidity had a suggestive but statistically insignificant effect, humidity tending to be inversely related to oviposition.The regression of log oviposition on temperature, within the limits of this experiment, i.e. at temperatures up to 72°F., was linear. The slope was not significantly affected by the insolation and humidity factors, the total coefficient being 0·, and the partial coefficient 0·0428. These coefficients are the increase of the log number of egg clusters (plus one) for 1 degree F. increase, i.e. the oviposition rate increased in geometric progression for unit increase of temperature, the value (N+l) for egg clusters doubling itself for 7° increase.

The oxidation of sulphur at low pressures

The reaction between sulphur vapour and oxygen has been examined by Norrish and Rideal* for pressures of oxygen from 0·1 to 1 atmosphere at temperatures from 200° to 400° C. Between the temperatures of 235° and 305° C., they found that the reaction was confined to the sulphur surface and the walls of the vessel, while below 200° C. there was no appreciable reaction. Several investigators')* have found that the oxidation of sulphur is accompanied by phosphorescence. Emeleus studied the phosphorescent combustion in order to examine the reaction products, which he found consisted of sulphur dioxide and a small amount of the trioxide. During the course of the investi­gation he found that sulphur dioxide and certain organic vapours inhibit the glow, and he concluded that the oxidation is a chain reaction similar to the phosphorescent oxidation of phosphorus. Semenoff and Rjabinin§ have investigated the reaction between sulphur vapour and oxygen at fairly low pressures of oxygen and have obtained very interesting results. Their reaction vessel, which contained the solid sulphur, was maintained at a temperature between 80° and 120° C. and oxygen was introduced to a pressure of 20 mm. of mercury, or less. Any SO 2 or SO 3 formed was immediately condensed in a side tube which dipped into liquid air. Under these conditions they observed in general no reaction between sulphur vapour and oxygen. If, however, an electric discharge were passed through the vessel a reaction started which continued after the removal of the discharge. This reaction was accompanied by a luminescence, and its rate was practically independent of the pressure of oxygen when this was below 1 mm., until an oxygen pressure of about 0·2 mm. was reached, when the reaction ceased. It was found that the residual oxygen pressure varied with the temperature of the reaction vessel, but was not changed by addition of inert gas or by changing the diameter of the vessel as is the case with the residual oxygen pressure in the oxidation of phosphorus As the investigation* of the oxidation of phosphorus below the lower critical limit had proved interesting, it was decided to carry out a further examination of the sulphur oxidation. Experimental. To find if it were possible to obtain a stable chain oxidation of the sulphur vapour, the apparatus shown in fig. 1 was used. R is the reaction vessel, which is divided by the ground joint J, so that various filaments can be easily placed in the vessel. Borated copper wire passes through a pinch seal in the upper part of joint J, and is soldered to degassed nickel wire, which serves as a support for the various filaments. The vessel is enclosed in an electric oven H 1 , so that the temperature can be maintained at about 120° C. The small tube S contains solid sulphur, and is enclosed in a small electric oven H 3 . M is a sulphuric acid manometer which is read by means of a microscope with an eyepiece scale (1 division of the eyepiece scale corresponds to 0·024 mm. Hg). T 2 is a small “tap-pipette” to allow small quantities of oxygen to be transferred from the oxygen reservoir O into the reaction vessel. A is a reservoir for gases other than oxygen. C is a side tube which is placed in liquid air, and thus serves as a condenser for any SO 2 and SO 3 formed.