Predicting Herbivore Feeding Times

An understanding of animal time budgets is crucial to behavioural biology. Although many studies have analysed time budgets of individual species, only a few have made interspecific comparisons. Here we take an interspecific look at one part of the time budget, feeding time. We hypothesize that feeding time can be predicted by the amount of time an animal needs to reach satiation. This time should be equal to the ratio of handling time to digestion time. For 19 herbivorous species from insects to mammals, we calculate this ratio and compare it to the observed feeding time. The mean difference between calculated and observed values is small (a half hour per 24 h‐day), indicating that herbivore feeding times can often be approximated by the ratio of handling time to digestion time. We make three points concerning the time allocated to feeding in herbivores based on this interspecific comparison. First, our analysis suggests that herbivores often feed to satiation, which could mean that they are often released from time constraints. It is also possible, however, that while herbivores have enough time to reach satiation, they do not necessarily have sufficient time to choose the most desirable diet. Wilson's principle of stringency theoretically supports the former interpretation. It suggests that animals experience periods in their life in which they are time‐constrained but that these periods are the exception rather than the rule. Most optimal foraging studies have assumed the opposite. The second point of this paper is therefore a recommendation: to consider the possibility that animals may often be released from time constraints. The third and final point is that feeding time is independent of body mass in our analysis. This is because handling time scales with body mass according to a parameter that is similar to the one for digestion time, and feeding time can be approximated by the ratio of handling time to digestion time.     

三种笼养灵长类活动时间分配的比较研究

采用焦点动物法和连续记录法对3种笼养灵长类活动时间分配进行比较研究。结果表明,川金丝猴Rhi-nopithecus roxellanae和熊猴Macaca assamensis用于休息的时间多于猕猴Macaca mulatta,移动时间则相反;川金丝猴和猕猴用于理毛的时间多于熊猴。不同性别年龄组之间的活动时间分配有差异,主要表现在川金丝猴母亲用于理毛的时间明显多于成年儿子,用于玩耍的时间则相反;猕猴成年雄性的移动时间和理毛时间多于成年雌性,玩耍时间则少于成年雌性;熊猴成年雌性的移动时间多于成年雄性,与成年个体相比,幼体花更多的时间用于玩耍,而相应的减少了其休息时间。     

新生儿抚触及其临床意义

目的：探讨抚触对新生儿发育的影响。方法：将180例新生儿随机分为抚触组91例和对照组89例。分别测量、观察新生儿摄入奶量与体重、胎便转黄时间、生理性黄疸开始消退时间、完全消退时间及睡眠时间。结果：抚触组新生儿的摄入奶量与体重均增加,胎便转黄时间、生理性黄疸开始消退时间、完全消退时间均减少,睡眠时间延长,两组新生儿在摄入奶量、体重、胎便初排时间及胎便转黄时间、新生儿生理性黄疸开始消退和完全消退时间、睡眠时间均有明显差异（P〈0.05）。结论：抚触对促进新生儿身心的健康发育有明显效果。     

Soil moisture determines the recovery time of ecosystems from drought

Recovery time, the time it takes for ecosystems to return to normal states after experiencing droughts, is critical for assessing the response of ecosystems to droughts; however, the spatial dominant factors determining recovery time are poorly understood. We identify the global patterns of terrestrial ecosystem recovery time based on remote sensed vegetation indices, analyse the affecting factors of recovery time using random forest regression model, and determine the spatial distribution of the dominant factors of recovery time based on partial correlation. The results show that the global average recovery time is approximately 3.3 months, and that the longest recovery time occurs in mid-latitude drylands. Analysis of affecting factors of recovery time suggests that the most important environmental factor affecting recovery time is soil moisture during the recovery period, followed by temperature and vapour pressure deficit (VPD). Recovery time shortens with increasing soil moisture and prolongs with increasing VPD; however, the response of recovery time to temperature is nonmonotonic, with colder or hotter temperatures leading to longer recovery time. Soil moisture dominates the drought recovery time over 58.4% of the assessed land area, mostly in the mid-latitudes. The concern is that soil moisture is projected to decline in more than 65% regions in the future, which will lengthen the drought recovery time and exacerbate drought impacts on terrestrial ecosystems, especially in southwestern United States, the Mediterranean region and southern Africa. Our research provides methodological insights for quantifying recovery time and spatially identifies dominant factors of recovery time, improving our understanding of ecosystem response to drought.     

Time for a rethink: time sub‐sampling methods in disparity‐through‐time analyses

Disparity‐through‐time analyses can be used to determine how morphological diversity changes in response to mass extinctions, or to investigate the drivers of morphological change. These analyses are routinely applied to palaeobiological datasets, yet, although there is much discussion about how to best calculate disparity, there has been little consideration of how taxa should be sub‐sampled through time. Standard practice is to group taxa into discrete time bins, often based on stratigraphic periods. However, this can introduce biases when bins are of unequal size, and implicitly assumes a punctuated model of evolution. In addition, many time bins may have few or no taxa, meaning that disparity cannot be calculated for the bin and making it harder to complete downstream analyses. Here we describe a different method to complement the disparity‐through‐time tool‐kit: time‐slicing. This method uses a time‐calibrated phylogenetic tree to sample disparity‐through‐time at any fixed point in time rather than binning taxa. It uses all available data (tips, nodes and branches) to increase the power of the analyses, specifies the implied model of evolution (punctuated or gradual), and is implemented in R. We test the time‐slicing method on four example datasets and compare its performance in common disparity‐through‐time analyses. We find that the way we time sub‐sample taxa can change our interpretations of the results of disparity‐through‐time analyses. We advise using multiple methods for time sub‐sampling taxa, rather than just time binning, to gain a better understanding disparity‐through‐time.     

经鼻盲探气管插管在抢救呼吸衰竭病人中的应用

目的比较经鼻盲探气管插管和气管切开在抢救呼吸衰竭病人的治疗效果。方法回顾性对比分析同期ICU住院病人采用经鼻盲探气管插管或气管切开建立人工气道后的病情转归,使用呼吸机后血气纠正时间,使用呼吸机时间,留置气管导管时间,平均住院时间及操作并发症。结果经鼻盲探气管插管组拔管率42.9%(9/21例),拔管成功率100%(9/9例);气管切开组拔管率60.7%(17/28例),拔管成功率76.5%(13/17例),两组间比较无显著性差异(P<0.05)。使用呼吸机后血气纠正时间无明显差别,但经鼻盲探气管插管组使用呼吸机时间,留置气管导管时间,平均住院时间均短于气管切开组(P<0.05)。气管切开组操作导致的并发症发生率46.4%(13/28例),而经鼻盲探气管插管组操作导致的并发症发生率23.8%(5/21例),明显少于前者(P<0.01)。结论经鼻盲探气管插管操作简便、实用,能减少并发症,缩短使用呼吸机时间,留置气管导管时间及住院时间,在抢救呼吸衰竭病人中较气管切开术有更好的临床应用价值。     

Viscoelasticity of multicellular surfaces

Various modeling approaches have been applied to describe viscoelasticity of multicellular surfaces. The viscoelasticity is considered within three time regimes: (1) short time regime for milliseconds to seconds time scale which corresponds to sub-cellular level; (2) middle time regime for several tens of seconds to several minutes time scale which corresponds to cellular level; and (3) long time regime for several tens of minutes to several hours time scale which corresponds to supra-cellular level. Short and middle time regimes have been successfully elaborated in the literature, whereas long time viscoelasticity remains unclear. Long time regime accounts for collective cell migration. Collective cell migration could induce uncorrelated motility which has an impact to energy storage and dissipation during cell surface rearrangement. Uncorrelated motility influences: (1) volume fraction of migrating cells, (2) distribution of migrating cells, (3) shapes of migrating cell groups. These parameters influence mechanical coupling between migrating and resting subpopulations and consequently the constitutive model for long time regime.This modeling consideration indicates that additional experimental work is needed to confirm the feasibility of constitutive models which have been applied in literature for long time regime as: (1) relaxation of stress and strain, (2) storage and loss moduli as the function of time, (3) distribution of migrating cells.     

First Passage Time Analysis of Animal Movement and Insights into the Functional Response

Movement plays a role in structuring the interactions between individuals, their environment, and other species. Although movement models coupled with empirical data are widely used to study animal distribution, they have seldom been used to study search time. This paper proposes first passage time as a novel approach for understanding the effect of the landscape on animal movement and search time. In the context of animal movement, first passage time is the time taken for an animal to reach a specified site for the first time. We synthesize current first passage time theory and derive a general first passage time equation for animal movement. This equation is related to the Fokker–Planck equation, which is used to describe the distribution of animals in the landscape. We illustrate the first passage time method by analyzing the effect of territorial behavior on the time required for a red fox to locate prey throughout its home range. Using first passage time to compute search times, we consider the effect of two different searching modes on a functional response. We show that random searching leads to a Holling type III functional response. First passage time analysis provides a new tool for studying how animal movement may influence ecological processes.     

农田中三种鹭科鸟类日取食动态研究

2007年春、夏季,采用瞬时扫描取样法和焦点动物取样法,在广西北伦河口国家级自然保护区的农田进行池鹭Ardeola bacchuss、白鹭Egretta garzetta和牛背鹭Bubulcus ibis日取食动态研究。结果表明3种鹭在各个时间段内的取食个体数、取食时间存在较大差异,其取食个体的日变动均呈现较规则的"U"型。池鹭和牛背鹭各时间段内的取食个体数、休息个体数、休息时间差异极显著(F>F0.01),取食时间差异显著(F>F0.05)。池鹭和白鹭的取食时间和休息时间差异显著(F>F0.05),各时间段内的取食个体数、休息个体数呈不显著差异(FF0.05),而取食时间和休息时间差异不显著(F相似文献   

Symmetric time warping, Boltzmann pair probabilities and functional genomics

Given two time series, possibly of different lengths, time warping is a method to construct an optimal alignment obtained by stretching or contracting time intervals. Unlike pairwise alignment of amino acid sequences, classical time warping, originally introduced for speech recognition, is not symmetric in the sense that the time warping distance between two time series is not necessarily equal to the time warping distance of the reversal of the time series. Here we design a new symmetric version of time warping, and present a formal proof of symmetry for our algorithm as well as for one of the variants of Aach and Church [1]. We additionally design quadratic time dynamic programming algorithms to compute both the forward and backward Boltzmann partition functions for symmetric time warping, and hence compute the Boltzmann probability that any two time series points are aligned. In the future, with the availability of increasingly long and accurate time series gene expression data, our algorithm can provide a sense of biological significance for aligned time points – e.g. our algorithm could be used to provide evidence that expression values of two genes have higher Boltzmann probability (say) in the G1 and S phase than in G2 and M phases. Algorithms, source code and web interface, developed by the first author, are made publicly available via the Boltzmann Time Warping web server at bioinformatics.bc.edu/clotelab/. Research partially supported by National Science Foundation grant DBI-0543506.     

Duality between time series and networks

Studying the interaction between a system's components and the temporal evolution of the system are two common ways to uncover and characterize its internal workings. Recently, several maps from a time series to a network have been proposed with the intent of using network metrics to characterize time series. Although these maps demonstrate that different time series result in networks with distinct topological properties, it remains unclear how these topological properties relate to the original time series. Here, we propose a map from a time series to a network with an approximate inverse operation, making it possible to use network statistics to characterize time series and time series statistics to characterize networks. As a proof of concept, we generate an ensemble of time series ranging from periodic to random and confirm that application of the proposed map retains much of the information encoded in the original time series (or networks) after application of the map (or its inverse). Our results suggest that network analysis can be used to distinguish different dynamic regimes in time series and, perhaps more importantly, time series analysis can provide a powerful set of tools that augment the traditional network analysis toolkit to quantify networks in new and useful ways.     

Foraging strategies of yakushima macaques(Macaca fuscata yakui)

I investigated the activity budget and diet of Yakushima macaques (Macaca fuscata yakui,)in warm temperate broad- leaved forest of Yakushima, Japan. Both time spent feeding and time spent moving varied considerably between half- months. However, total time spent in active behaviors— feeding time plus moving time— was stable. The composition of the diet also showed considerable variation between half- months. The macaques fed mainly on fruits, seeds,mature leaves, fallen seeds, flowers, and young leaves, each of which accounted for more than 30% of feeding time in at least 1 half- month. They also ate insects and fungi, but each of them comprised ≤ 25 and ≤ 8% of feeding time in any half- month, respectively. Time spent feeding on mature leaves, young leaves, flowers, or fallen seeds is positively correlated with total time feeding and is negatively correlated with time moving. In contrast, time feeding on fruits, seeds, insects or fungi is negatively correlated with time feeding and is positively correlated with time moving. Foraging on foods that have a low energy content, a high density, and a relatively even distribution— mature leaves— or that need much manipulation to be processed— flowers and fallen seeds— increased feeding time, while foraging on foods for which monkeys must search intensively in the forest— fruits, seeds, insects, and fungi— led to increased moving time. I examined foraging strategies of Yakushima macaques in terms of moving costs and the quality of food items. Regarding time feeding on fruits, which have more energy and may need less manipulation than other foods, as a benefit, and moving time as a cost, they seemed to employ a strategy that balanced the costs and benefits of foraging.     

Evolution of pesticide resistance: interactions between generation time and genetic, ecological, and operational factors

We used computer simulation modeling to clarify the relationship between generation time and the rate of evolution of pesticide resistance. We examined the influence of generation time under various assumptions about genetics, population dynamics and selection pressures. The simplest model demonstrated that the time required for resistance to evolve can be independent of generation time. However, interactions of generation time with genetic, biological and operational factors resulted in positive, negative, and U-shaped relationships between the number of generations per year and the time required for resistance to evolve. These results preclude any generalizations concerning the influence of generation time on resistance evolution. Some ability to predict the influence of generation time may still exist on a case-by-case basis if the context of the resistance episode can be specified.     

Bloody time revisited: New observations on time in a Papua New Guinea Village

In a 1982 paper I argued that perceptions of time scarcity in Kragur Village, Papua New Guinea, in the mid‐1970s were best understood as a reaction to new forms of authority characteristic of the growth of capitalism and calls for greater time order were grounded largely in its perceived ritual significance. More than forty years later, villagers are much more familiar with Western time, but less likely to perceive time as scarce. As in the 1970s, aspiring leaders still press for greater time order. Millenarian illusions informed advocacy of time order in the 1970s. Although today these illusions are, if not extinct, then dormant, unquestioned assumptions mirroring Western capitalist views of time inspire many of today's advocates. Yet, lacking the authority to impose new forms of time order, they have little effect on the rhythms of village life, and economic incentives to abandon comparative indifference to time remain weak.     

Flower handling efficiency of bumble bees: morphological aspects of probing time

Summary The time required for a bumble bee to visit a flower is affected by the length of the bee's glossa and its body weight, and by the depth of the flower and the volume of nectar it contains. Probing time is comprised of two components: access time and ingestion time. Access time increases linearly with flower depth, but ingestion time varies with flower depth only in flowers deeper than the length of the bee's glossa, due to a decline in the rate of ingestion of nectar. Probing time therefore increases gradually with increasing depth for flowers shallower than the bee's glossa, but beyond that depth it increases much more rapidly. The relation of probing time to flower depth influences the foraging efficiency and choice of flowers by bumble bees.     

Tracking of familial resemblance for resting blood pressure over time in the Québec Family Study

The etiology of familial resemblance for systolic (SBP) and diastolic (DBP) blood pressure, both within a single time point as well as across time points, was assessed to determine how familial etiologies underlying a trait may change across time. SBP and DBP measurements were taken roughly 12 years apart in family members participating in the longitudinal Québec Family Study. A longitudinal (bivariate) familial correlation model yields 3 types of correlations: intraindividual cross-time (e.g., father's BP at time 1 with his own BP at time 2); interindividual within-time (e.g., father time 1 with child time 1); and interindividual cross-time (e.g., father time 1 with child time 2). In addition, the change in BP across time (i.e., time 1-time 2) is examined using a univariate family correlation model. This combined method is useful in assessing the degree to which the same familial factors are operating across time (interindividual cross-time correlations), as well as the degree to which different heritable components are involved across time (change score). Maximal heritabilities for SBP were about 70% at each time point, while for DBP the heritability was larger at time 1 (87%) than time 2 (39%). Both the change scores (48% for SBP and 54% for DBP) and the cross-time comparisons (58% to 72% for SBP and 63% to 65% for DBP) evidenced significant familial resemblance. These results illustrate how simple methodologies can be used to specify how familial etiologies underlying a trait may change across time. For BP, the model includes unique familial factors that are specific to each time measurement, and an additional familial factor which is common to both time points. The factors leading to differences in longitudinal familial resemblance for BP (i.e., the unique factors) may be primarily genetic in origin, while those leading to stability across time may include both genetic and familial environmental effects. Sex and/or age interactions with the genotypes are also suggested.     

A general solution to the time interval omission problem applied to single channel analysis.

To obtain the open or closed time interval distributions of patch clamp signals, several workers have used a half-amplitude minimum time interval criterion. Within this framework, no transition between states of different conductance levels is considered to have taken place if it leads to a time interval smaller than a certain critical value. This procedure modifies substantially the open or closed time interval distribution of the random signal to be analyzed, since time intervals well above the time resolution of the recording system may be interrupted by short gaps that may or may not satisfy the minimum time interval criterion. We present here a general theoretical framework by means of which the effect of time interval omission on time interval distributions can be taken into account. Based on the mathematical formalism provided by the Kolmogorov forward equation, special matrix operators are first defined. The general solution to the time omission problem in its integral form is then derived. In view of the poor computational feasibility of the resulting solution, a first-order approximation is also presented. This approximation consists essentially in neglecting the contribution of the undetected gaps to the total length of the resulting time interval. The exact and approximate solutions are then applied to two special kinetic schemes commonly found in single-channel studies, namely the O-C and C-O-C models. The applicability of the proposed formalism to the time interval distribution problem of a damped random signal is finally discussed.     

Time perception,emotions and mood disorders

In this review, we describe recent internal clock models accounting for time perception and look at how they try to explain the time distortions produced by emotion. We then discuss the results of studies of patients suffering from affective disorders (depression) who experience the feeling of time slowing down. A distinction is thus made between time perception and explicit awareness of the passage of time. We conclude that the feeling that time is passing slowly is not systematically associated with a disruption in the basic mechanisms underlying time perception.     

Definition of unit internal (physiological) time

We provide a definition of the unit internal (physiological) time based on metabolism. If q(t) is specific rate of metabolism, i.e. the amount of energy (oxygen) consumed by unit of active mass per physical time unit, the unit of physiological time τ(t) is defined as physical time, during which unit of active mass consumes one unit of energy: τ(t) = 1/q(t). The dimension of unit physiological time is the same as that of unit physical time and its value depends on q(t). Therefore, the unit physiological time τ(t) is a variable value, while the internal time is unequal relative to the physical time. The more internal time units τ, i.e., elementary acts of energy consumption, fit in the unit physical time t, the longer is the unit physical time for the unit active mass relative to the internal time unit, i.e., the physical time is seemingly slowed down. And, on the contrary, the less elementary acts of energy consumption take place during unit physical time, the shorter seems unit t, i.e. physical time is seemingly accelerated. Unequal course of the internal time is determined by the curve of specific metabolism q(t) during the life under specific conditions and, hence, internal time is individual. It has been questioned that the total (during lifetime) specific metabolism, often called Rubner constant, can serve as specie specific characteristic.     

时间序列的相似性测度

时间序列（time series）是指按时间顺序排列的观测值集合,在生物信息学研究领域中,DNA序列和基因表达数据都可以视为时间序列数据。时间序列分析中很重要的环节就是刻划两个时间序列或者时间子序列的相似性,用于序列比对等。时间序列的相似性测度是时间序列研究中的基础和重点,直接影响查询、聚类等后续计算的效率和精度,在高通量基因芯片数据分析、基因网络构建等研究中,具有重要的应用,目前已引起了众多研究人员的关注,在欧氏距离的基础上进行了大量的研究,本文综述了基于欧式距离和时间弯曲的时间序列相似性测度及其相关领域的研究进展,可作为进一步研究的参考。