Schedule-induced polydipsia: An artifact.

Conducted 6 experiments with 4 female rats in which they were allowed access to Noyes pellets for 1 hr/day with water freely available at all times. The food was presented either ad lib or in a lever-pressing situation on various interval schedules of reinforcement. The size of the individual reinforcements ("bites") was varied between experiments. Schedule-induced polydipsia was obtained when the S's meal consisted of a large number of very small bites. When the meal consisted of a smaller number of larger bites, polydipsia did not occur. The experiments collectively indicate that the amount of water consumed while eating is a function of the number of bites taken and independent of bite size or total food consumption. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schedule-induced polydipsia in rats: Adrenocortical and hippocampal modulation.

Onset of schedule-induced polydipsia (SIP) is related to adrenal gland weight. In 4 experiments with 43 Sprague-Dawley rats, adrenalectomy, but not demedullation, hastened the emergence of SIP, and exogenous corticosterone administration tended to reverse this effect. Hippocampal lesions were followed by a rapid and uniform release of SIP. None of the above manipulations influenced normal (home-cage) drinking. A synthesis of present findings with the literature suggests that the hippocampus and the adrenal cortex interact and that the equilibrium established within this system is reflected, for any particular rat, in its adjunctive behavior. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schedule-induced polydipsia suppresses pituitary-adrenal activity in rats.

The effects of schedule-induced polydipsia (SIP) on pituitary-adrenal activity, as indicated by plasma levels of corticosterone, were examined in 3 experiments in which a total of 52 Sprague-Dawley rats were given daily sessions on a fixed time 60-sec intermittent-feeding schedule. Half of the Ss in each experiment had water available during sessions. Ss with water available in the experimental chamber exhibited SIP. Blood samples were taken at various steps in the procedure and also after the opportunity to drink during sessions was removed. Results indicate that (a) schedule-induced drinking suppresses pituitary-adrenal activity, (b) corticoid suppression may become a conditioned response to drinking in the chamber, and (c) corticoids return to presession levels following removal of water from the chamber. In view of these findings, it is hypothesized that SIP may serve an arousal-reducing role in intermittent-feeding situations. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Specific preference for hypothalamic cooling.

Tested 2 adult male albino rats in a choice situation where they could produce hypothalamic or peripheral cooling, whichever they preferred. When the hypothalamus was warmed, Ss showed a specific preference for hypothalamic cooling. When the periphery was warmed, Ss showed a specific preference for peripheral cooling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hyperthermia following MDMA administration in rats: effects of ambient temperature, water consumption, and chronic dosing

In two experiments it was found that the hyperthermia which follows MDMA ("Ecstasy") results from an interaction of direct pharmacological effect of the drug and the prevailing environmental conditions in which it is administered. In Experiment 1, rats given fixed doses of either 2.5, 5.0 or 7.5 mg/kg MDMA or saline were injected on different days at ambient temperatures (Ta's) of 11, 24, and 30 degrees C. At each Ta drinking water was freely available following dosing on one session and temporarily unavailable on a second. The hyperthermic and hyperkinetic responses were monitored using remote biotelemetry. Experiment 2 used a between-subject design in which each group of rats received a standard 7.5 mg/kg dose of MDMA administered at only one of the three levels of Ta(24 degrees C) and at only one level of the water-availability factor. Dosing in some groups was continued for a further 13 days to test for tolerance or sensitization effects. Ambient temperature significantly affected the magnitude of the hyperthermia but not the hyperkinesis. Water deprivation during the drugged period significantly augmented the hyperthermia, but only in the high Ta (30 degrees C.) condition. Chronic dosing produced sensitization of both hyperthermic and hyperkinetic responses. The findings indicate that ambient temperature, water consumption and frequency of drug use affect the hyperthermia which follows MDMA administration.     

Voluntary control of hypothalamic temperature.

Reports 3 experiments in which 7 male Sprague-Dawley rats were given direct voluntary control of hypothalamic temperature by having their responses produce temperature changes in the water perfusing their hypothalamic thermodes. When heat stressed, Ss worked vigorously for hypothalamic cooling; brain cooling is thus a reward for a warm animal. Exp. II compared rates of responding for brain cooling and external cooling and found that, under a given set of heat-stress conditions, the rates of responding for internal and external cooling were the same. Exp. III determined whether reductions in hypothalamic temperature caused temperature changes at any other place in the body besides the one in the anterior hypothalamic-preoptic area; however, no other area was found. Results indicate that an interoceptive stimulus is a rewarding event and its effectiveness as a reward is comparable to that of an exteroceptive stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

水温对冷轧马氏体钢板淬火冷却速度和性能的影响

冷轧马氏体钢板以其高强度特点,在汽车零部件制造中具有较大的减重潜力,逐步获得越来越多的应用.冷轧马氏体钢板一般采用具有水淬冷却功能的连续退火机组生产,水淬过程工艺参数对马氏体钢板的组织和性能影响很大.以C-Mn系冷轧马氏体钢板为研究对象,研究水温对淬火冷却速度、钢板的力学性能和组织的影响.结果表明,在室温较低的情况下,马氏体薄钢板的冷速可达近1 000 K/s.随着水温的变化,不仅平均冷却速度发生改变,而且瞬时冷却速度曲线的形状也发生较大的变化.水温提高导致冷却速度下降,从而导致马氏体钢板强度和组织的较大变化.这种变化规律,对于马氏体钢板性能稳定控制有一定的参考意义.     

冷却水和氧化铁皮对轧辊辊耗的影响

指出当前该厂轧钢生产中,轧辊作为大型工具在降低成本中的重要性。简要分析高温应力掰棍的力学原理,指出高温对轧辊寿命的影响,提出采取优化冷却水控制提高轧辊寿命的措施。并描述轧辊与坯料氧化铁皮之间磨损带来的轧辊缺陷,以及该厂BD2轧辊毛刺与氧化铁皮的关系。对冷却控制和减少氧化铁皮给出一些预防措施。     

小方坯结晶器水温水速对传热过程影响

通过建立结晶器内钢液和水的二维对流-传热耦合模型过程,研究了小方坯结晶器冷却水入口温度和流速对铜管温度和结晶器内平均热流的影响.该模型使用Fluent进行求解,模拟了钢液和冷却水的流动和传热,凝固坯壳的生长,以及热量以辐射和导热两种通过保护渣和气隙.通过将坯壳厚度和铜管温度与其他研究的结果进行对比来验证模型准确性.研究结果表明,结晶器冷却水的温度显著影响铜管的冷面温度,水温超过313 K会导致铜管冷面最高温度超过水的沸点.水流速升高0.49 m·s^-1能够消除水温升高4 K带来的不利影响.     

高炉冷却水包高精度水温差测量系统的开发与应用

针对炼铁高炉冷却水包进、出水温差小,环境温度变化大等对温差测量影响较大的不利因素,从传感器选择、测量电路实现、数据传输方式等方面进行了讨论,提出了采用就地测量方式的总线传输的高分辨率(0.01℃)水温差测量系统解决方案,应用效果良好,达到了预期目的。     

智能温度控制仪在空调冷却水温度自动控制系统中的应用

介绍了XMT-122-10HL31型温度控制仪在空调冷却水温度自动控制系统中的应用情况及其主要的性能特点.     

磁处理对循环冷却水硬度的影响

选择磁场强度、水溶液离子质量浓度、水速和水温4个因素进行正交试验,考察磁处理工艺条件对循环冷却水硬度的影响。结果表明,最佳处理工艺条件按照其影响程度由大到小顺序依次为离子浓度为900 mg/L、流速为0.8 m/s、磁场强度为0.5 T和温度为30 ℃,该条件下硬度可达2 390 mg/L;然后在其他条件均为最佳处理工艺的条件下,利用XRD和SEM分别分析离子质量浓度为900、300 mg/L的垢样,发现离子质量浓度越大,文石和球霰石结构的碳酸钙比例越大,方解石结构的碳酸钙的比例却出现相反的变化,并且其表面形貌变得相对松散,易于冲涮。     

磁处理对循环冷却水缔合程度的影响

基于L16(45)的正交试验,通过TDS、电导率以及表面张力的极差分析结果和最佳值出现差异的原因,综合研究了磁处理过程中各个因素对循环冷却水缔合程度的影响,发现在离子质量浓度为900 mg/L、温度为35 ℃、流速为0.4 m/s、磁场强度为0.5 T的情况下,TDS和电导率均达到最佳值,水分子的缔合程度和离子质量浓度也相应达到了最大值,此时磁处理的除垢效果最好。但表面张力达到最佳值时,水分子的缔合程度却出现了差异,主要表现为当其最佳值的条件不同于TDS和电导率的最佳条件时,水分子的缔合程度减弱了,结果导致磁处理的除垢效率减弱。当表面张力、TDS、电导率达到最佳值的条件一致时,磁处理是加强水分子缔合程度的,同样也增强了磁处理的阻垢效果。     

不同环境温度下典型身管用钢磨损性能研究

通过摩擦磨损、高温硬度及相应的分析试验研究了典型身管用钢32Cr2MoVA、30SiMn2MoVA在室温、200、400以及600℃下的摩擦磨损行为与规律.结果表明:两种材料的摩擦系数在各个温度区间内的区别不大,主要受摩擦氧化物产生与否影响.32Cr2MoVA的磨损率随着温度的提高先降低再提高之后又下降,30SiMn2MoVA的磨损率随着温度的上升而先降低,然后逐渐升高,600℃达到最高.温度、身管钢在高温下的硬度和磨盘材料与滑动销的高温硬度差(H_d-H_p)共同影响磨损表面氧化物层的最终形态.室温至200℃时,身管钢磨损行为主要受表面氧化物层的影响.室温下两种身管钢磨损机理均为黏着磨损及磨粒磨损,200℃时均为氧化轻微磨损.环境温度达到400℃以上时,身管钢以及磨盘材料的基体硬度开始影响磨损行为.400℃时两种身管钢磨损机理均为氧化严重磨损.600℃时,32Cr2MoVA的H_d-H_p减小,磨损表面出现了厚度很大、致密的氧化物层,磨损机理为氧化轻微磨损;而30SiMn2MoVA的H_d-H_p显著增大,试样发生了明显的塑性挤出,为塑性挤出磨损.     

水温差在线检测技术在高炉上的应用

对水温差在线检测系统的组成和特点进行了阐述.重点阐述了水温差在线检测系统的功能以及利用水温差检测技术,分析高炉热制度、判断煤气流的分布和检查冷却壁的漏水情况.     

Primary polydipsia. Syndrome of inappropriate thirst

A patient with lifelong severe polyuria and polydipsia had normal serum antidiuretic hormone (ADH) levels and responded to water deprivation with a prompt increase in urine osmolality and maintenance of normal plasma osmolality (less than 290 mOsm/kg), despite extreme thirst. When treated with desmopressin acetate and allowed free access to water, she was able to reduce plasma osmolality below 270 mOsm/kg, and her compelling thirst disappeared. The disorder is interpreted to be the result of excessive fluid intake in response to a thirst stimulus that was not inhibited by normal plasma osmolality. This study indicates that osmoreceptor control of ADH secretion is normal. Continued administration of vasopressin has relieved the symptoms and has not resulted in water intoxication.     

Schedule-induced kinesic and taxic behavioral stereotypy in the pigeon.

Two experiments explored the functional character of 2 schedule-induced interim behaviors (pacing and retreat) and 1 terminal behavior (keypecking) that developed on fixed-time (FT) schedules of food delivery with a keylight that increased in brightness throughout the interstimulus interval. In Experiment 1, this ramp procedure was compared with a less discriminable ramp, and FT and Random Time (RT) procedures without a signal. Decreased discriminability expanded keypecking in the trial. The FT schedule eliminated only keypecking and the RT procedure eliminated keypecking and retreat while pacing remained. In Experiment 2, predictive and unpredictive ramps were added to the RT procedure. The data suggest that schedule-induced stereotypy can be divided into kinesic stereotypy (pacing), which arises from repeated reinforcer presentations, and taxic stereotypy, which is tied to an increase (keypecking) or decrease (retreat) in the momentary probability of reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

加热温度对TRIP钢连续冷却转变曲线及室温组织的影响

采用膨胀法在DIL805热膨胀仪上测定了不同加热温度下实验钢的连续冷却转变(CCT)曲线,通过光学显微镜和扫描电镜分析不同加热温度对CCT曲线和冷却试样显微组织的影响.结果表明:当加热温度由完全奥氏体化温度降低到两相区内较高温度时,CCT曲线中铁素体转变区左移;当加热温度处在两相区范围内时,随着加热温度的降低,铁素体转变被推迟,使得CCT曲线右移;新生铁素体外延生长方式和奥氏体中碳富集程度的差异是导致上述变迁的主要因素.     

Pituitary-adrenal and dopaminergic modulation of schedule-induced polydipsia: Behavioral and neurochemical evidence.

Five experiments investigated in rats the effects of increasing or decreasing plasma corticosterone levels on schedule-induced polydipsia (SIP) and dopamine efflux in the nucleus accumbens. The results indicate that the acquisition of SIP could be decreased by adrenalectomy, blockade of corticosterone synthesis, or administration of corticosterone. Performance of established SIP was also decreased by adrenalectomy. The effects of corticosterone administration on established SIP depended on the level of performance. High levels of drinking were enhanced by a high dose of corticosterone, whereas low rates of drinking were increased by a low dose. Similar injections of corticosterone also significantly increased dopamine efflux. The relative involvement of pituitary–adrenal activity and dopamine neurotransmission to the nucleus accumbens in the acquisition and performance of SIP is discussed and related to contemporary hypotheses of schedule-induced behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)