Same-different comparison of duration

Pigeons were trained on a task in which a red light of durationt ₁ was followed by a green light of durationt ₂ and then responses to different keys were reinforced according to whether the durations of the stimuli were the same or different. For Experiment 1, duration pairs consisted of all combinations of 1, 2, 4, and 8 sec. In Experiment 2,different-duration pairs included only combinations witht ₁ >t ₂ and, in addition, 2 subjects with extended training involving lesser-greater duration comparisons were transferred to the same-different task. Two of 3 subjects learned the task in Experiment 1 and analyses suggested that choices were based on specific instances, not on a temporal same-different rule. All 5 birds acquired the discrimination in Experiment 2, where it appeared that choices were controlled by a combination of relative and absolute rules. Accuracy decreased following transfer from a lesser-greater to a same-different discrimination, but performance was above chance on the first transfer session. In both experiments, however, accuracy was below that found in earlier work with lesser-greater comparisons of duration. These findings are discussed in relation to prior research with lesser-greater comparisons of duration and same-different tasks involving nontemporal stimuli.     

Prevalence and genotype of <Emphasis Type="Italic">Chlamydia psittaci</Emphasis> in faecal samples of birds from zoos and pet markets in Kunming,Yunnan, China

Chlamydia psittaci is an important zoonotic pathogen in birds and may be transmitted to humans and result in severe respiratory disease. To assess the prevalence and genotype of C. psittaci in birds in Kunming, Yunnan, China, a total of 136 specimens of psittacine birds involving 8 species were collected from the city’s zoos (n=60) and pet markets (n=76). The frequency of C. psittaci infection was 19.9% (27/136) in the psittacine birds. The prevalence of C. psittaci was higher in pet birds (26.3%; 20/76) than in zoo birds (11.7%; 7/60) (P=0.034). In particular, among Agapornis fischeri, the C. psittaci infection (50%; 10/20) was significantly more frequent in the pet markets than in the zoos (P=0.006). In addition, the highest prevalence of 41.2% (7/17) was found in Ara ararauna. To determine the genotype of C. psittaci, 23 OmpA gene fragments (about 1.4 kb) in 27 positive samples were successfully amplified and sequenced. Phylogenetic analysis showed that all the 23 strains belonged to genotype A. Our results demonstrate the high prevalence of C. psittaci genotype A infection in psittacine birds in Yunnan Province, suggesting a potential threat to human health in this area. Therefore, it is necessary to take effective measures to prevent the spread of C. psittaci among psittacine birds, as well as among employees and customers.     

Comparing spatial memory in two species of tit: Recalling a single positive location

The performance of a food-storing species, the marsh tit(Parus palustris), was compared with that of a nonstorer, the blue tit(P. caeruleus), in a spatial memory task in which birds had to return to a site where they had previously been allowed to eat part of a piece of peanut. No differences were found between species’ overall performance, but increasing retention interval from 1 min to 24 h brought about a decrease in performance. The results are discussed in relationship to the hypothesis that food-storing birds have a specialized spatial memory capacity.     

Rate of a maintained operant as a function of temporal position within a session

McSweeney and her colleagues (e.g., McSweeney, Hatfield, & Allen, 1990) have demonstrated reliable, large magnitude rate changes in maintained operants within daily sessions under a wide variety of reinforcement schedules. The present paper examined the role of schedule of reinforcement, reinforcement rate, and total amount of food access in determining those within-session rate changes. When median rates across birds were considered, all procedures resulted in a brief period of an increasing rate, followed by a modest rate loss across the major portion of the session. However, not all individuals exhibited that pattern. When the amount of food access per session was limited by lower reinforcement rates, shorter sessions, or shorter reinforcement durations, the magnitude of the withinsession rate change was reduced from that occurring without those constraints. Additionally, under the conditions that produced strong within-session rate changes, the magnitude of the within-session rate loss was correlated with the bird’s body weight. These effects are consistent with what is typically labeledsatiation.     

Development of object permanence in the New Zealand parakeet (Cyanoramphus auriceps)

Eleven young kakarikis (Cyanoramphus auriceps) were tested on 15 object-permanence tasks in a standardized scale that has been used to assess the development of human infants, some nonhuman primates, and other mammals. The birds successfully completed all tasks in this scale, and many aspects of their testing were similar to human results, such as evidencing the A-not-B error. However, the birds differed slightly but significantly from human subjects in that some of the “invisible displacements” of the later tasks were performed before the earlier visible displacement tasks. These results may relate to common ecological activities of this species. Six of the birds were parent-raised; 5 were hand-raised. The hand-raised birds achieved criteria more quickly than did the parent-raised birds possibly because the former were more accustomed to the investigator and less distractible in the test situation.     

Some relationships between outcome expectancies and sample stimuli in pigeons’ delayed matching

Two sets of experiments examined how differential outcomes affect conditional stimulus control by the samples in delayed matching-to-sample. Pigeons were initially trained on symbolic delayed matching with reinforcing outcomes that were either differential or nondiffereatial with respect to the samples. In one set of experiments, the outcome manipulation involved different (p = 1.0 vs. 0.2) versus the same (p = 0.6) probabilities of food; in the other, food and no-food outcomes were used. Following initial acquisition and mixed-delay tests, the matching procedure in each study was discontinued while the samples were nondifferentially reinforced with the same probability of food, or with food and no food, respectively. When later retested on delayed matching with those nondifferential outcomes, birds initially trained with different reinforcement probabilities matched at the same levels of accuracy as those trained with the same probability. By contrast, birds initially trained with food versus no-food outcomes showed lower levels of matching accuracy than their nondifferential controls. Subsequent transfer tests showed that matching performances by the differential birds in both studies had been originally cued in part by differential outcome expectancies. Apparently, the expectancies based upon different probabilities of food provided a source of conditional stimulus control that did not compete with the samples. By contrast, the expectation of food versus no food reduced (overshadowed) sample-stimulus control.     

脯氨酸作用下硫化镉量子点的合成及其可见光催化活性研究

以脯氨酸为添加剂,通过简单的方法合成了较为稳定、分散性良好的硫化镉量子点,其粒径在6.21 nm左右.研究显示该硫化镉量子点在200~600 nm波长范围内具有良好的光吸收性能.在可见光照射条件下,该量子点可以有效降解水中的有机染料罗丹明B,反应120 min的降解效率高达99%,并对其光催化降解机理进行了初步研究.同时该量子点具有良好的循环使用稳定性,循环使用5次后的降解效率仍高达92.7%,表明其在可见光催化降解有毒有机污染物处理方面具有良好的应用潜力.     

Contextual control of pavlovian feature-positive and feature-negative discriminations

Three pigeons were trained with a Pavlovian serial feature-positive (F-P) discrimination task in a light context, in which the houselight was on, and with a Pavlovian serial feature-negative (F-N) discrimination task in a dark context, in which the houselight was off. Three other pigeons were trained with the F-P task in the dark context and the F-N task in the light context. These two contextual conditions were changed randomly trial by trial. The former birds learned the tasks within 60 sessions, by responding exclusively to the target keylight after the feature tone in the light context and by responding exclusively to the target not preceded by the feature in the dark context. Two of the latter birds required separate training of the F-P and the F-N tasks to acquire the discrimination: responding exclusively to the target after the feature in the dark context and responding exclusively to the target not preceded by the feature in the light context. The third bird, however, failed to learn the discrimination even with separate training. These results indicate that the four-term contingency (the context-feature-target-food relationship) controlled the birds’ behavior in the Pavlovian setting. The insertion of a temporal gap between the feature and the target impaired the F-N discrimination, although it had little effect on the F-P discrimination.     

The perception of time relations in auditory tempo discrimination

European starlings (Sturnuis vulgaris) were trained to discriminate between pulses of sound presented at rates (tempos), for different birds, of 4/sec and 8/sec or 8/sec and 16/sec in a two-alternative choice task. Once the discrimination was learned, psychometric functions and bisection points were determined for tempos between the standards. Then the starlings were transferred to a new discrimination, which either maintained or changed the relationship between response keys and tempo (relational or nonrelational transfer). The results showed that the starlings generated psychometric functions for tempo with properties much like those found for discrimination of single time intervals. Also, the starlings transferred the tempo discrimination faster under the relational than the nonrelational condition. In general, starlings-like human and other nonhuman animals-perceive temporal structures as invariant over proportional changes in the duration of structural elements.     

Roosttime restlessness in captive American Robins (Turdus migratorius)

All-day observations of captive American Robins (Turdus migratorius) revealed that the birds became extremely active at dusk, the time when wild Robins typically fly some distance to a communal roost site. This roosttime restlessness occurred during every month of the year, and so was distinguishable from the migratory restlessness that the birds displayed during early morning hours of spring months. The present observations also uncovered a recapitulation effect, in that the changes in activity level that occurred within any single day (from dawn through dusk) tended to parallel the changes in activity level that occurred across the year (from spring through winter).     

Chromatic Dispersion Monitoring Method Based on Phase Shift Technique

The chromatic dispersion( CD) degrades themodulation-phase relationships of lightwave signals,reducing information-carrying capacity through pulse-broadening in digital networks and distortion in analogsystems[1,2]. The widespread use of dense wavelengthd…     

纳米ZnS的溶剂热法制备及其性能表征

采用溶剂热法制备了结晶度良好的ZnS纳米粒子,通过XRD、TEM、UV-Vis-DRS等技术对所合成的ZnS粉体的结构和理化性能进行表征,并以亚甲基蓝为目标降解物,考察了ZnS粉体在紫外光和可见光下的光催化性能。结果表明,用该方法制备的ZnS纳米粉体为六方晶系,粒径大致为30 nm,不论是在紫外光下还是在可见光下对亚甲基蓝均表现出良好的光催化性能。     

Auditory short-term memory in the budgerigar (Melopsittacus undulatus)

We trained two budgerigars (Melopsittacus undulatus) with operant techniques in a delayed matching-to-sample task using pairs of acoustic stimuli. These stimuli included simple pure tones, complex, species-specific vocalizations, and tone-vocalization combinations. The birds were then tested with different retention intervals. The budgerigars’ short-term memory was similar for complex, species-specific vocalizations and for simple pure tones. By contrast, they showed significantly better short-term memory when tested with two sounds drawn from different acoustic categories.     

三种雉科鸟类肺的比较研究

利用生物显微技术对雉鸡(Phasianus colchicus)、鹧鸪(Francolinus pintadeanus)及鹌鹑(Coturnix coturnix)的肺进行了比较,结果显示:雉鸡、鹧鸪及鹌鹑的肺与大多数鸟类相似,主要由各级支气管及其周围的呼吸毛细管组成,肺房围绕三级支气管呈辐射状排列,呼吸毛细管相互吻合成网状,周围有丰富的毛细血管网。鹌鹑肺的三级支气管、肺房、呼吸毛细管的平均直径最大,雉鸡的次之,鹧鸪的最小。     

沱江内江段冬季鸟类群落多样性研究

2007年11月至2008年3月采用路线调查法对沱江内江段地区冬季鸟类群落进行了调查,共记录到鸟类8目27科56种;其中留鸟27种（占48．2％）,冬候鸟17种（占30．4％）,夏候鸟4种（占7．1％）,旅鸟8种（占14.3％）;区系分析显示,共有东洋界鸟类11种（占19．6％）,古北界鸟类26种（占46．4％）,广布种鸟类19种（占34％）;多样性分析得出沱江内江段鸟类群落多样性指数H在4条调查样线区域分别为：1．26,1．29,1．29,1．22,冬季鸟类群落多样性指数2．53;均匀性指数分别为0．79,0．80,0．80,0．79．优势种为白鹊鸽（P=0．15）,白颊噪鹛（P=0．10813）．     

天然水体中磺胺嘧啶钠的光降解研究

磺胺嘧啶钠是环境中存在的广谱性抗生素,其对生态环境的危害日益受到关注。本文研究了天然水体中磺胺嘧啶钠在254nm紫外光辐射下的环境行为,考察了浓度、酸度对其光降解的影响,并通过化学耗氧量分析研究其光化学命运。试验结果表明,紫外光能够较快降解磺胺嘧啶钠。     

LED补光对金银花栽培影响研究

采用第四代新型光源LED辐射的红光（R,625nm）和蓝光（B,450nm）分别对金银花每日20：00-次日8：00补照12h。测定不同处理的幼苗的株高、叶片数、叶面积、茎粗、根数和叶绿素含量。研究结果表明,不同光质补光对四季金银花的生长影响显著且存在差异。总体认为,补充红光和蓝光下的金银花株高、叶片数、叶面积和叶绿素a、叶绿素b、叶绿素（a＋b）含量均显著高于对照。而且红光处理的植株最高,而且促进金银花开花。蓝光对提高叶绿素a、叶绿素b和叶绿素（a＋b）含量的影响最大。     

Beam steering in planar photonic crystal based on its anomalous dispersive properties

INTRODUCTION Photonic crystals (PhCs) are increasingly at- tracting attention due to their ability of controlling light propagation on a wavelength scale, by which a fascinating platform for a new generation of inte- grated optical devices and components can be pro- vided. Many studies on PhCs however, focused on new means of tailoring the emission and propagation of light using the photonic band gap (PBG) property whereby the photon density of states is zero. A PhC with a full PBG re…     

Overshadowing in matching-to-sample: Reduction in sample-stimulus control by differential sample behaviors

Separate groups of pigeons were trained to high levels of accuracy on 0-delay matching-to-sample with sample-response requirements that were either differential or nondifferential with respect to the sample stimuli. Differential subjects produced the comparisons by completing a differential-reinforcement-of-low-rates-of-responding 3-sec (DRL 3″) requirement during one sample and a fixed-ratio (FR 10) requirement during the other. Nondifferential subjects produced the comparisons by completing the same schedule requirement (either DRL 3″ or FR 10) for both samples. Following acquisition to criterion, the DRL and/or FR sample-response requirements were replaced by a nondifferential single-peck (CRF) requirement in order to assess the degree to which the samples had acquired control over choice in each group. This change disrupted performance in all subjects, but the disruption was greater for the differential birds, which generally performed at lower levels of accuracy and required more sessions of retraining to reach criterion levels of accuracy than the nondifferential birds. Follow-up experiments revealed that comparison choices by the differential birds were primarily controlled by their DRL vs. FR sample-specific behaviors. The relatively poor performance of the differential group during testing with CRF requirements suggests that the cue arising from the birds’ differential sample behaviorshad also overshadowed the sample stimuli for conditional control over choice. The unique, and rather unusual, aspect of this overshadowing effect is that it occurred in spite of the fact that the overshadowed cue (that provided by the samples) was necessary for producing the cue that resulted in overshadowing (the differential sample behaviors). This finding has potentially important implications for the differential outcomes effect in conditional discrimination learning and for attentional processes in compound-cue situations in general.