Determining thresholds of low soil temperature for ecophysiological traits of black spruce and jack pine seedlings

Many studies have estimated approximately ranges of thresholds of low soil temperature in the growth and ecophysi-ological traits of trees, but difficultly determined the exact values. To resolve the problem, black spruce （Picea mariana） and jack pine （Pinus banksiana） seedlings were exposed to 5, 10, 15, 20, 25, 30 and 35℃ soil temperature in greenhouses. After 90 days of the treatment, net photosynthetic rate （A）, stomatal conductance （gs）, transpiration rate （E）, water use efficiency （WUE） and specific leaf area （SLA） were measured. This study showed that all the traits had an asymmetrical peak relationship with changing soil temperature, the relationship was well simulated using a cubic curvilinear model, and the exact thresholds could be derived from the second derivative of the model. The results revealed that the thresholds varied among ecophysiological traits and between tree species. In black spruce, the thresholds were 14.1, 14.7, 10.7, 14.4 and 16.2℃ forA, gs, E, WUE and SLA; 15.4, 10.4, 14.7, 16.9 and 10.5℃ for the corresponding traits in jack pine. The lowest thresholds of E in black spruce and gs in jack pine were an indicator representing the minimum requirement of soil temperature for the regular processes of ecophysiology. The highest thresholds of SLA in black spruce and WUE in jack pine suggest they are the most sensitive to decreasing soil temperature and may play an important role in the acclimation. The averaged thresholds were at 14.0 and 13.6℃ for black spruce and jack pine, suggesting that the sensitivity of both species to low soil temperature was quite close.

Method of temperature rising velocity and threshold control of electron beam brazing

In order to accommodate electron beam to the brazing of the joints with various curve shapes and the brazing of thermo sensitive materials, the method of electron beam scanning and brazing temperature control was developed, in which electron beam was controlled to scan according to predefined scanning track, and the actual temperature rising velocity of the brazed seam was lim- ited in an allowed scope by detecting the brazed seam temperature, calculating the temperature rising velocity and adjusting the beam current during the brazing process; in addition, through the setting of the highest allowed temperature, the actual temperature of the brazed seam could be controlled not exceeding the threshold set value, and these two methods could be employed alone or jointly. It is shown that high precision temperature control in electron beam brazing could be realized and the productivity be increased by the proposed method.

Developmental Threshold Temperature and Effective Accumulative Tem- perature of Pupae and Eggs of Holcocerus hippophaecolus

In order to understand the occurrence and the developmental regularity of seabuckthorn carpenterworm (Holcocerus hippophaecolus) and predict its population density, the developmental threshold temperature (C) and effective accumulative tem- perature (K) of the carpenterworm pupae and eggs were analyzed under the conditions of constant and variable temperatures. The results show that the values of C and K of the carpenterworm pupae are (12.1 ± 0.2) °C and (295.2 ± 4.1) day-degrees at constant temperatures, and (15.5 ± 0.4) °C and (202.4 ± 13.1) day-degrees at variable temperatures. However, the values of C and K of the eggs at variable temperatures are (16.7 ± 0.8) °C and (101.5 ± 12.6) day-degrees. The differences of developmental threshold and effective accumulative temperature under the conditions of constant and variable temperatures of the carpenterworm pupae accord with the developmental regularity of most insects in nature. By comparing five different constant temperatures, the conclusion is that the optimum developmental temperature of the pupae is 21 °C when both the pupation of the mature larvae and the eclosion of the pupae are very accordant. Moreover, the percentage of eclosion is over 90%. The average developmental durations of the carpenter- worm pupae and eggs are 31 and 16 d at variable temperatures.

Effective accumulated temperature and developmental threshold temperature for Semanotus bifasciatus(Motschulsky) in Beijing

In order to understand the occurrence and development of Semanotus bifasciatus （Motschulsky）, a borer insect of Platycladus orientalis in parts of northern and eastern China and to improve its prediction, the developmental threshold temperature （C1） and effective accumulated temperature （K） of S. bifasciatus were determined under conditions of constant and variable temperatures. The results show that under constant temperatures the value of C1 has a range of 8.90±1.77℃and the value of K lies between 95.19±13.14 degree-day for eggs; the values for larvae are C1= 13.26±3.06℃ and the number of degree-day is K 2,885.07±187.87 degree-day; for pupae the ranges are C1 = 8.93±2.49℃ and K= 131.20±25.63 degree-day. Under the condition of ambient temperatures, the values for eggs are C1= 17.33±1.24℃ and K= 70.79±8.99 degree-day. It is suggested that S. bifasciatus adults over-winter in a state of dormancy, not at a diapause. Warm winter may accelerate the life cycle ofS. bifasciatus. Equations can be used to predict an early occurrence ofS. bifasciatus.

THE DISTRIBUTION REGION AND THE DISTRIBUTIVE TEMPERATURE AND HUMIDITY THRESHOLD OF OSIER WEEVIL IN CHINA

A distribution map of osier weevil (Crytorrynchus lapathi L.) was drown up based on widely collecting information and field survey. The results showed that Osier weevil has a widespread in China, stretching from 33°21' to 51°42' N latitude and 83°00' to 132°58' E longitude, and distributes in forms of big or small patches or sports uncontinously. According to the analysis of meteorological data, the temperature and humidity threshold for osier weevil's distribution were determined by methods of PCA (Principle Component Analysis) and RA(Relativity Analysis): January temperature is -30~ 0℃. Annual temperature -4~13℃, Annual precipitation from 411~ 1,136 min.The areas with January temperature under 0℃, annual temperature above 0℃ and annual precipitation of 400~ 800 mm are the optimum distributing places for osier weevil in China.

Developmental Threshold Temperature and Effective Accumulated Temperature of Potosia brevitarsis Lewis

[ Objective] The paper was to study the relationship between temperature and development of Potosia brevitarsis Lewis. [ Methods] Six constant tem- peratures （21, 24, 27, 30, 33 and 36 ℃ ） were set in the laboratory to study developmental threshold temperature and effective accumulated temperature of P. brevitarsis. [ Result] The developmental durations of various states of P. brevitarsis were shortened with the increasing temperature ranged from 21 ℃ to 36 ℃ ; the developmental rates were accelerated with the increasing temperature. The developmental threshold temperatures of egg, larva, pupa and pre-ovipesition of adult were estimated to be 12.79, 9.15, 14.86 and 13.80 ℃, respectively; the effective accumulated temperature were 136.25, 3 031.31,308.92 and 98.35 d · ℃, respectively. The developmental threshold temperature and effective amcumulated temperature for one complete generation were 9.96 ℃ and 3 628.73 d · ℃, re- spectively. Combined with meteorological data, the theoretical generation number of P. brevitarsis occurred in Shihezi was presumed to be one per year, which was basically coincided with actual occurrence generations in fields. [ Conclusion] The paper provided theoretical basis for effective control against P. brevitarsis.

Effects of temperatures on the development and reproduction of the armyworm, Mythimna roseilinea: Analysis using an age-stage, two-sex life table

The armyworm Mythimna roseilinea（Walker） is a major pest of grain crops in South China. So far little is known about its basic biology and ecology, making prediction of population dynamics difficult. This study examined the relationships of individual development and population growth with temperature based on an age-stage, two-sex life table of M. roseilinea reared on maize in the laboratory at 18, 21, 24, 27 and 30℃. The highest values of net reproductive rate（R_0） and fecundity were observed at 21 and 24℃, respectively. Both the intrinsic rate of increase（r） and finite rate of increase（λ） increased significantly and mean generation time（T） decreased significantly with increasing temperature. M. roseilinea was able to develop, survive and lay eggs at all temperature regimes tested. Development rates of the egg, larval, pupal, as well as the whole pre-oviposition stages had a positive linear relationship with temperature. The calculated development threshold temperatures of egg, larval, pupal, pre-oviposition and total pre-oviposition stages were 13.29, 8.39, 14.35, 7.42, and 12.24℃, respectively, and their effective accumulated temperatures were 63.59, 445.00, 211.11, 89.02, and 698.95 degree-days, respectively. These results provide insight into temperature-based phenology and population ecology of this insect pest and will allow population prediction and management available in the field.

A 0.6 μm CMOS bandgap voltage reference circuit

On the basis of mutual compensation of mobility and threshold voltage temperature effects, a stable CMOS band-gap voltage reference circuit was designed and fabricated in CSMC-HJ 0.6 μm CMOS technology. Operating from 0 to 85 ℃ under a supply voltage ranging from 4.5 to 5.5 V, the voltage reference circuit offers an output reference voltage ranging from 1.122 to 1.176 V and a voltage variation less than ±3.70%. The chip size including bonding pads is only 0.4 mm×0.4 mm and the power dissipation falls inside the scope of 28.3 to 48.8 mW operating at a supply voltage of 4.5 to 5.5 V.

Precipitation Type Estimation and Validation in China

The results from three methods aimed at improving precipitation type （e.g., rain, sleet, and snow） estimation are presented and compared in this paper. The methods include the threshold air temperature （AT）, threshold wet bulb temperature （WBT） and Koistinen and Saltikoff （KSS） methods. Dot graphs are plotted to acquire the threshold air temperature or the threshold wet bulb temperature using daily averaged air temperature, wet bulb temperature and precipitation data at 643 stations from 1961 to 1979 （precipitation types are not labeled in the database from 1980 to present） in China. The results indicate that the threshold AT or WBT methods are not able to differentiate rain, sleet and snow in the most regions in China; sleet is difficult to differentiate from other precipitation types based on the two threshold methods. Therefore, one threshold AT and WBT method was used in this study to differentiate rain and snow. Based on Gaussian- Kriging interpolation of threshold air temperature （To） and wet bulb temperature （Tw）, the To and Tw contour lines and contour surfaces are calculated for China. Finally, a comparison between the KSS, AT and WBT methods are provided in which the KSS method is calculated based on air temperature and relative humidity. The results suggest that the KSS method is more appropriate for water phase estimation than are the other methods; the maximum precision for rain and snow is 99% and 94%, respectively. The AT method performs better than the WBT method when the critical air temperature is 2℃.

Changes of Essential Substance Contents in Exorista civilis Rondani during Diapause Stage

[ Objective ] The paper was to study the occurrence regularity of Lysiphlebus testaceipes Cresson. [ Method ] With Aphis craccivora Koch as the breeding host, developmental duration, development threshold temperature and effective accumulative temperatme of L. testaceipes Cresson were studied at six constant tem- peratures of 12, 16, 20, 24, 28 and 32℃ in the laboratory, respectively. [ Result] The developmental durations of each growth stage of L. testaceipes Cresson were shortened with the increasing temperature ranged from 12 to 32℃, and the growth rate was significantly accelerated with the increasing temperature. However, when the temperature was up to 32℃, the growth and development from mummy to adult was suppressed, and the developmental duration was extended for 0.45 d than that at 28℃. The developmental durations from egg to adult at 12, 16, 20, 24, 28 and 32℃ were 38.50, 21.25, 14.11, 12.17, 10.28 and 9.01 d, respectively. The developmental threshold temperatures of egg-mummy, mummy-adult and egg-adult were estimated to be 6.5, 6.25 and 5.36℃, respectively; and the effective accumulated temperatures were 136.28, 75.74 and 227.23 d·℃, respectively. [ Conclusion] Forecast formula of developmental duration and Logistic models were established according to effective accumulated temperature and developmental threshold temperature.

Temperature-dependent development of Neoseiulus barked （Acari： Phytoseiidae） on Tetranychus urticae （Acari： Tetranychidae） at seven constant temperatures

The effect of seven constant temperatures of 15, 20, 25, 27, 30, 35 and 37℃ on developmental time ofNeoseiulus barkeri Hughes were determined in laboratory conditions under 65% - 5% RH and a photoperiod of 12 ： 12 （L ： D） h on nymphal stages of Tetranychus urticae Koch. Total developmental time of females （from egg to adult emergence） at the above-mentioned temperatures was 26.59, 14.43, 6.32, 5.64, 4.59, 3.98 and 4.67 days, respectively. Developmental rate of the N. barkeri increased as temperature increased from 15 to 35℃, but declined at 37℃. A linear and two nonlinear models were fitted to developmental rate of immature stages ofN. barkeri to predict the developmental rate as a function of temperature, as well as to estimate the thermal constant （K） and critical temperatures （i.e., Tmin, Topt and Tmax）. The estimated values of the Tmin and K for total developmental time using the linear model were 12.07℃ and 86.20 degree-days （DD）, respectively. The Trnin and Tmax estimated by the Sharpe-Schoolfield-Ikemoto （SSI） model were 11.90℃ and 37.41℃, respectively. The estimated Topt for overall immature stage development ofN. barkeri by the Lactin and SSI models were 33.89℃ and 24.51℃, respectively. Based on the biological criteria of model evaluation, the linear and SSI models were found to be the best models for describing the developmental rate of overall immature stages of N. barkeri and estimating the temperature thresholds.

A process-insensitive thermal protection circuit

A novel process-insensitive thermal protection structure has been developed.This circuit contains several sub-circuits such as band-gap reference,reference output buffer,resistance voltage divider branch,and hysteresis circuit.By using reference buffer,the precise reference voltage from band-gap reference is delivered to resistance voltage divider branch and is divided precisely.Then the threshold temperatures of this protection circuit can be set by this precise voltage,unaffected by process variation and mismatch.A hysteresis circuit is also used here to prevent thermal oscillation.This circuit is fabricated in TSMC 0.18μm CMOS technology,and occupies about 3×10;μm;chip area.