Choice in free-ranging wild pigeons

A flock of free-ranging wild pigeons were trained to peck at buttons which, when operated, allowed brief access to grain. Although only one bird at a time could have access to the buttons, the pecks of the group were treated as an aggregate. When they chose between two buttons, each of which could occasionally produce grain, the ratios of pecks at the buttons approximately equaled the ratios of the grain presentations obtained from them. This accords with a relation well substantiated in the laboratory, the matching law. It suggests that the matching law may apply to the behavior of higher organisms in natural environments.     

Stimulus control in pigeons based on proprioceptive stimuli from floor inclination

Two groups of pigeons trained to peck a dimly illuminated disc in an otherwise dark experimental chamber with the floor horizontal (0 degrees tilt) or inclined 30 degrees to the left, respectively, show decremental generalization gradients of response rate when the floor inclination is varied from its training position. Discrimination training in which food reinforcement is available under one floor tilt condition but not under another steepens the slope of such gradients. In a secondv experiment, pigeons reinforced for pecking when the floor was tilted 10 degrees or 20 degrees and not reinforced under the alternative condition showed steep gradients with maximal responding displaced from the reinforced stimulus.     

Stimulus generalization of a positive conditioned reinforcer

Stimulus generalization has been observed for discriminative, eliciting, and emotional functions of stimuli. In our study, in order to investigate the generalization of the reinforcing function of stimuli, pigeons were trained in a Skinner box to peck at an unlighted key to obtain aperiodic, brief exposures of light at a wavelength of 550 mmicro, the positive conditioned reinforcer, which was immediately followed by food reward. Testing in extinction, we obtained generalization gradients for the number of responses and the time the pigeons expended to produce exposures on the unlighted key of 550 mmicro, 530 mmicro) 510 mmicro, or no light. This finding suggests that stimulus generalization occurs with all functions of stimuli.     

Learning by following a food source

Hungry pigeons first learned to eat grain from the experimenter's hand. When the hand approached and "pecked" a small disk to produce grain in a food hopper, the pigeons followed the hand rapidly learned to peck the disk. Birds given operant conditioning training took significantly longer to learn the same response. Under natural conditions, young animals may learn to behave like their parents simply by following parental sources of food.     

Pavlovian conditioning with heat reinforcement produces stimulus-directed pecking in chicks

In a cooled chamber, chicks approached and pecked a small disk whose illumination preceded heat lamp activation, even when pecks prevented heat lamp onset. These behaviors did not occur when the disk and heat stimuli were randomly presented. Approach and contact of conditioned stimuli may develop even though these behaviors are not (i) evoked by the reinforcing stimulus, (ii) necessary for reinforcer reception, or (iii) ever followed by the reinforcer.     

Errorless discrimination, autoshaping, and conditioned inhibition

Pigeons were exposed to a discriminated autoshaping procedure in which brief presentation of a green light on a key was always followed by food whereas presentation of a vertical white line on the key was never followed by food. Pigeons acquired an errorless discrimination by pecking reliably in the presence of the green light but never in the presence of the line. The line inhibited pecking in later tests: when the white line was paired with food, key peck acquisition was retarded; and when the white line was superimposed on the green background, responding was suppressed.     

Training and maintenance of keypecking in the pigeon by negative reinforcement

Pigeons were trained to peck a key to escape a pulsing shock of linearly increasing intensity. As the rate of increase was varied from 0.0374 milliamperes per minute to 37.4 milliamperes per minute, the intensity at which most pecking occurred varied from 2.2 to 5.0 milliamperes.     

Activity and responsivity in rats after magnesium pemoline injections

Rats injected intraperitoneally with magnesium pemoline avoided a buzzing sound (conditioned stimulus) associated with an electric shock to the feet (unconditioned stimulus) more frequently than controls. Drug-injected rats did not avoid the foot shock more frequently than controls, although the experi mental rats did have shorter response latencies fn the active avoidance task. In sub sequent experiments which measured activity changes and response to the buzzing sound alone, it was found that magnesium pemoline caused a lesser decrease in activity level and a more sustained responsivity to the buzzer's. sound than did control injections of tragacanth. This may account for the latency differences observed in the avoidance task.     

Lateralized cognitive processes and lateralized task control in the human brain

The principles underlying human hemispheric specialization are poorly understood. We used functional magnetic resonance imaging of letter and visuospatial decision tasks with identical word stimuli to address two unresolved problems. First, hemispheric specialization depended on the nature of the task rather than on the nature of the stimulus. Second, analysis of frontal candidate regions for cognitive control showed increased coupling between left anterior cingulate cortex (ACC) and left inferior frontal gyrus during letter decisions, whereas right ACC showed enhanced coupling with right parietal areas during visuospatial decisions. Cognitive control is thus localized in the same hemisphere as task execution.     

Social status and mating activity in elephant seals

Individually marked male elephant seals, Mirounga angustirostris, observed on an island off central California participate in a social hierarchy resembling the peck order of domestic chickens. Individuals achieve status by fighting and maintain it by stereotyped threat displays. The higher the status of a male, the more readily he approaches and copulates with females. Four percent of the males inseminated 85 percent of the females.     

Behavioral response rates in pigeons: effect of alpha-methyl-m-tyrosine

An intramuscular injection of alpha-methyl-m-tyrosine ( 100 mg/ kg), which differentially depletes serotonin and norepinephrine in both brain and heart, was given to two groups of pigeons trained to peck at a key for food. The first group received an injection 12 hours before the daily session and showed no behavioral effect. Response rates of birds in the second group, which were injected 30 minutes after the start of the daily session, decreased and returned to normal within 9 hours after injection. Preliminary data on brain serotonin of pigeons indicate that the disruption of the behavior follows the same time course as the change in serotonin.     

Fairness in alternative food networks: an exploration with midwestern social entrepreneurs

The notion of fairness is frequently invoked in the context of food and agriculture, whether in terms of a fair marketplace, fair treatment of workers, or fair prices for consumers. In 2009, the Kellogg Foundation named fairness as one of four key characteristics of a “good” food system. The concept of fairness, however, is difficult to define and measure. The purpose of this study is to explore the notion of fairness, particularly as it is understood within alternative food dialogues. Specifically, we wanted to answer the question of how alternative food entrepreneurs who are working to actualize fairness within local food networks understand this abstract notion. Using a multiple case study approach, the research for this project draws on semi-structured interviews that were conducted with key stakeholders in four alternative food businesses throughout the Midwest.     

Fairness in irrigation development

There is in much of contemporary irrigation development a large paradox. Irrigation development, while contributing to productivity, frequently thwarts social justice—it either introduces incipient inequalities in access or it reinforces those that exist. More progressive irrigation development policies are being developed and tested in several countries. These new approaches give more attention to the role of local groups in governing irrigation systems while reducing the heavy-handed involvement of state agencies. These new approaches are seen as both consistent with achieving greater fairness in irrigation development as well as with the new fiscal realities of governments nearly everywhere. Supporting these new approaches are a set of institutions and individuals with nonengineering expertise who traditionally have not been defined as central to irrigation development.     

Cold Resistance and Injury in Woody Plants: Knowledge of hardy plant adaptations to freezing stress may help us to reduce winter damage

It is interesting that plants can eventually acclimate fully in response to low temperatures in the absence of inductive photoperiods (67). This suggests that there is more than one route to resistance or more than one ignition key to start the machinery. In either case, the ability of plants to acclimate in response to more than one environmental stimulus provides adaptive flexibility which enhances survival potential.     

Auditory evoked potentials during speech perception

Neural responses evoked by the same binaural speech signal were recorded from ten right-handed subjects during two auditory identification tasks. One task required analysis of acoustic parameters important for making a linguistic distinction, while the other task required analysis of an acoustic parameter which provides no linguistic information at the phoneme level. In the time interval between stimulus onset and the subjects' identification responses, evoked potentials from the two tasks were significantly different over the left hemisphere but identical over the right hemisphere. These results indicate that different neural events occur in the left hemisphere during analysis of linguistic versus nonlinguistic parameters of the same acoustic signal.     

The resilience of long and short food chains: a case study of flooding in Queensland,Australia

This paper provides new insights into the food security performance of long and short food chains, through an analysis of the resilience of such chains during the severe weather events that occurred in the Australian State of Queensland in early 2011. Widespread flooding cut roads and highways, isolated towns, and resulted in the deaths of people and animals. Farmlands were inundated and there were food shortages in many towns. We found clear evidence that the supermarket-based (long) food chain delivery system experienced significant difficulties in supplying food to flood-affected towns. In contrast, more localized (short) food supply chains—which relied upon supply from growers in peri-urban areas and community-based food initiatives—remained largely intact, and provided food at a time when the supermarkets were limited in their ability to respond to consumer demand. However, on closer examination of food distribution during flooding in the regional city of Rockhampton and in the State capital, Brisbane, the demarcation of success between “long” and “short” food chains became blurred. Both types of food supply chains shared some key resilience characteristics in responding to crisis but diverged in other important ways. We argue that conceptualizing food chains in terms of key elements of resilience—scale, diversity, flexibility and cohesion—may be more fruitful than the short-long dichotomy alone. This approach is particularly useful when prioritizing food security as the basis for evaluating food system sustainability in a context of predicted increases in extreme weather events and future climate change.     

外来入侵生物福寿螺的防控及利用研究

2010、2011年通过采取捡螺摘卵、科学管水、养鸭食螺、科学施药等综合措施进行福寿螺防控,总体灭螺效果可达89.61％～92.52％,保苗率达到59.59％～80.39％,挽回经济损失8298.15元/hm2.通过杀螺活性植物的筛选,马桑叶乙醇提取物对福寿螺杀灭作用显著,质量浓度为5 mg/mL的乙醇提取物溶液中,成螺和幼螺12 h死亡率均为100％.提取福寿螺消化酶制作酶制剂及利用福寿螺蛋白质作饲料等方面均取得了较好的成效.另外,用福寿螺饲料喂养的土鸡,所产鸡蛋的长径、短径和重量均分别超过对照组鸡蛋5.91％、3.62％和16.52％.     

Impact of food and predation on the snowshoe hare cycle

Snowshoe hare populations in the boreal forests of North America go through 10-year cycles. Supplemental food and mammalian predator abundance were manipulated in a factorial design on 1-square-kilometer areas for 8 years in the Yukon. Two blocks of forest were fertilized to test for nutrient effects. Predator exclosure doubled and food addition tripled hare density during the cyclic peak and decline. Predator exclosure combined with food addition increased density 11-fold. Added nutrients increased plant growth but not hare density. Food and predation together had a more than additive effect, which suggests that a three-trophic-level interaction generates hare cycles.     

高职学生实习期间人身伤害现状及防范措施研究

顶岗实习是高职院校强化学生技能训练的一个关键环节。然而在企业顶岗实习过程中，实习学生受到的人身伤害事件频繁发生。以几个典型案例为代表，对高职学生实习期间人身伤害现状及防范措施进行了初步探讨。     

气候变暖对我国水稻生产的综合影响及其应对策略

气候变暖已是不争的事实,预计到21世纪末全球地表平均气温仍将上升1.5℃以上。水稻是我国最重要的口粮作物,全国80%以上的人口以稻米为主食,探明气候变暖对我国“口粮绝对安全”的潜在影响意义重大。作者依据多年的田间增温试验及长期观察,并结合国内外现有研究,阐明了我国粮食主产区气候变暖的基本态势,总结发现温度升高1.5℃对我国水稻生产的潜在影响正负参半,并取决于具体的稻作季节和地区。但是,随着水稻种植制度调整,尤其是南方双季稻种植面积下降,温度升高对我国水稻生产的负面影响将逐步递增。最后,作者提出了应对气候变暖的气候智慧型稻作技术创新建议,并展望了该研究领域的重点内容和方向。