Inoculation history affects community composition in experimental freshwater bacterioplankton communities

Priority effects occur when the arrival order of species or genotypes has a lasting effect on community or population structure. For freshwater bacteria , priority effects have been shown experimentally among individual species, but no experiments have been performed using complex natural communities. We investigated experimentally whether a foreign bacterioplankton community influences the community assembly trajectory when inoculated prior to the local community, whether inoculation time lag affects priority effects, and how the individual OTUs responded to time lag. Two bacterioplankton communities from dissimilar ponds were inoculated into one of the natural media with a time lag of 0, 12, 36 or 60 h, giving advantage in time to the foreign community . All three time lags resulted in priority effects, as the final community composition of these treatments differed significantly from that of the treatment with no time lag, but compositional shifts were not linear to inoculation time lag. The responses of individual OTUs to time lag were highly diverse and not predictable based on their immigration history or relative abundance in the inocula or control. The observed impact and complexity of priority effects in multispecies systems emphasize the importance of this process in structuring both natural and industrial bacterial communities.     

A measure of explained variation for event history data

Summary There is no shortage of proposed measures of prognostic value of survival models in the statistical literature. They come under different names, including explained variation, correlation, explained randomness, and information gain, but their goal is common: to define something analogous to the coefficient of determination R² in linear regression. None however have been uniformly accepted, none have been extended to general event history data, including recurrent events, and many cannot incorporate time‐varying effects or covariates. We present here a measure specifically tailored for use with general dynamic event history regression models. The measure is applicable and interpretable in discrete or continuous time; with tied data or otherwise; with time‐varying, time‐fixed, or dynamic covariates; with time‐varying or time‐constant effects; with single or multiple event times; with parametric or semiparametric models; and under general independent censoring/observation. For single‐event survival data with neither censoring nor time dependency it reduces to the concordance index. We give expressions for its population value and the variance of the estimator and explore its use in simulations and applications. A web link to R software is provided.     

Stronger compensatory growth in a permanent-pond Lestes damselfly relative to temporary-pond Lestes

Compensatory growth where animals compensate for time stress or transient nutritional or thermal stress by accelerating their growth rate is widespread. We know, however, relatively little about the evolution and ecological correlates of compensatory growth. For this we need studies on congeneric species with known phylogenetic relationships that also focus on the associated largely understudied costs. Here we tested for compensatory growth and associated costs in response to time stress (manipulated by photoperiod) and a transient period of starvation or cooling in larvae of the permanent-pond damselfly Lestes eurinus , and compare the results with former studies on temporary-pond Lestes . Larvae showed full compensation in body mass at emergence for all combinations of time stress and starvation or cooling. Unexpectedly, compensatory growth to starvation or cooling was not stronger under time stress. Instead, males under time stress delayed emergence after these transient stressors. In line with a stronger compensatory growth response to time stress than to the other stressors, physiological costs in terms of a reduced investment in immune response (measured as phenoloxidase activity) and energy storage (measured as fat content) were detected only under time stress. Compared to temporary-pond Lestes , L. eurinus showed stronger compensatory growth to time stress. We hypothesize that the stronger compensatory (growth) response in permanent-pond Lestes co-evolved with their derived slower lifestyle when they invaded permanent ponds.     

'You don't make genetic test decisions from one day to the next'--using time to preserve moral space

The part played by time in ethics is often taken for granted, yet time is essential to moral decision making. This paper looks at time in ethical decisions about having a genetic test. We use a patient-centred approach, combining empirical research methods with normative ethical analysis to investigate the patients' experience of time in (i) prenatal testing of a foetus for a genetic condition, (ii) predictive or diagnostic testing for breast and colon cancer, or (iii) testing for Huntington's disease (HD). We found that participants often manipulated their experience of time, either using a stepwise process of microdecisions to extend it or, under the time pressure of pregnancy, changing their temporal 'depth of field'. We discuss the implications of these strategies for normative concepts of moral agency, and for clinical ethics.     

Transient dynamics in metapopulation response to perturbation

Transient time in population dynamics refers to the time it takes for a population to return to population-dynamic equilibrium (or close to it) following a perturbation in the environment or in population size. Depending on the direction of the perturbation, transient time may either denote the time until extinction (or until the population has decreased to a lower equilibrium level), or the recovery time needed to reach a higher equilibrium level. In the metapopulation context, the length of the transient time is set by the interplay between population dynamics and landscape structure. Assuming a spatially realistic metapopulation model, we show that transient time is a product of four factors: the strength of the perturbation, the ratio between the metapopulation capacity of the landscape and a threshold value determined by the properties of the species, and the characteristic turnover rate of the species, adjusted by a factor depending on the structure of the habitat patch network. Transient time is longest following a large perturbation, for a species which is close to the threshold for persistence, for a species with slow turnover, and in a habitat patch network consisting of only a few dynamically important patches. We demonstrate that the essential behaviour of the n-dimensional spatially realistic Levins model is captured by the one-dimensional Levins model with appropriate parameter transformations.     

Clinical evaluation of sizofiran combined with irradiation in patients with cervical cancer. A randomized controlled study; a five-year survival rate

Following a previous report we ascertained the effectiveness of sizofiran (Schizophyllan:SPG) to prolong the survival and time to recurrence of the patients with Stage II or III cervical cancer, as evaluated in a 5-year randomized controlled study conducted in 19 institutions in Japan. Of the overall patients with Stage II or III cancer, time to recurrence and survival rate in the group on SPG were significantly longer than in the control group. In the Stage II patients, there was significant difference in time to recurrence, and survival of SPG group tended to be longer than that of the control group. However, in the Stage III patients, there was no significant difference in either time to recurrence or survival rate.     

Hydrophilic excipients modulate the time lag of time-controlled disintegrating press-coated tablets

An oral press-coated tablet was developed by means of direct compression to achieve the time-controlled disintegrating or rupturing function with a distinct predetermined lag time. This press-coated tablet containing sodium diclofenac in the inner core was formulated with an outer shell by different weight ratios of hydrophobic polymer of micronized ethylcellulose (EC) powder and hydrophilic excipients such as spray-dried lactose (SDL) or hydroxypropyl methylcellulose (HPMC). The effect of the formulation of an outer shell comprising both hydrophobic polymer and hydrophilic excipients on the time lag of drug release was investigated. The release profile of the press-coated tablet exhibited a time period without drug release (time lag) followed by a rapid and complete release phase, in which the outer shell ruptured or broke into 2 halves. The lag phase was markedly dependent on the weight ratios of EC/SDL or EC/HPMC in the outer shell. Different time lags of the press-coated tablets from 1.0 to 16.3 hours could be modulated by changing the type and amount of the excipients. A semilogarithmic plot of the time lag of the tablet against the weight ratios of EC/SDL or EC/HPMC in the outer shell demonstrated a good linear relationship, withr=0.976 andr=0.982, respectively. The predetermined time lag prior to the drug release from a press-coated tablet prepared by using a micronized EC as a retarding coating shell can be adequately scheduled with the addition of hydrophilic excipients according to the time or site requirements.     

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.     

The Effect of Climatic Factors on the Activity Budgets of Barbary Macaques (Macaca sylvanus)

Climatic conditions can significantly affect the behavior of animals and constrain their activity or geographic distribution. Barbary macaques (Macaca sylvanus) are one of the few primates that live outside the tropics. Here we analyze if and how the activity budgets of Barbary macaques are affected by climatic variables, i.e., air temperature, relative humidity, rainfall, and snow coverage. We collected scan sampling data on the activity budgets of four groups of macaques living in the Middle Atlas Mountains of Morocco from June 2008 to January 2011. This habitat is characterized by extreme seasonal changes, from cold and snowy winters to hot and dry summers. The activity budgets of the macaques differed across months but not across the time of day (with the exception of time spent feeding). The monkeys spent significantly more time feeding or foraging when there was no snow than when snow coverage was moderate or major. Daily rainfall was positively related to resting time and negatively to time spent moving or in social behavior. Air temperature was negatively related to time spent feeding or foraging. Finally, time spent on social behavior was significantly lower when relative humidity was high. These data indicate that environmental factors significantly affect the time budgets of endangered Barbary macaques, a species that has been little studied in the wild. Our findings support previous studies on temperate primates in showing that snow coverage can have negative consequences on the feeding ecology and survival of these species.     

Estimation of the mean waiting time of a customer subject to balking: a simulation study

To a customer, the waiting time for order processing for a product or service is important information for order placement. If the time foreseen for order fulfillment is long, the order might be lost to a competitor. In particular, modern principles of supply chain management highly suggest information sharing between entities in the chain and information technology has enabled customers to conveniently consider the waiting time for a potential balking decision. To help determine the design and operation of a manufacturing or service system in which a customer may balk based on the foreseen waiting time, this paper develops procedures to estimate the average waiting time of an order. Either the procedures allow the maximum waiting time for a balking decision to be random or do not require knowledge of the arrival process of customers before balking if the balking limit is known. For generality of the model, this paper considers general inter-arrival and service time distributions, and uses the simulation and regression approach.     

Rapid microfluorimetry of enzyme reactions in single living cells

An optimized photon counting technique allows the microfluorimetric study of NAD⁺ (or NADP⁺) reduction-reoxidation transients in single living cells with a time resolution in the range of 1/50-1/100 sec. The transients resulting from the micro-electrophoretic addition of metabolites (e.g. Glc-6-P or Glc-1-P) can be analyzed in terms of early parameters (e.g. initial lag, rise half time or full rise time) and overall parameters (time of rise and half decay, amplitude, reoxidation time). Both the initial lag and rise half time are considerably longer with Glc-1-P than with Glc-6-P, possibly due to control at the phosphoglucomutase or compartmentation of glycolytic phosphate esters. While glycolytic NAD⁺ (or NADP⁺) reduction proceeds adequately in aerobic EL2 and EAT ascites cells (although ΔNADH/Δt is higher at anaerobiosis), it is critically dependent upon anaerobiosis in L and astrocytoma cells. Thus by rapid microfluorimetry it is possible to resolve the rising phase or other segments of the fluorescence transients into components each corresponding to a particular step in the sequence of intracellular events or control states.     

Muscle contraction and relaxation-response time in response to on or off status of visual stimulus

Background

It is unclear whether response time is affected by a stimulus cue, such as a light turned on or off, or if there are differences in response to these cues during a muscle contraction task compared with a muscle relaxation task. The objective of this study was to assess the response time of a relaxation task, including the contraction portion of the task, to a stimulus of a light turned on or off. In addition, we investigated the effect of the pre-contraction level on the relaxation task.

Results

Contraction response time was significantly shorter during the light-on status than during the light-off status (P <0.01), and relaxation response time in each maximum voluntary contraction was significantly longer during the light-on status than during the light-off status (P <0.01). The relaxation response time became longer in order of 25% to 75% maximum voluntary contraction regardless of light-on or -off status, and was significantly longer than the contraction response time (P <0.05-0.01).

Conclusions

This study found that as the contraction level increased, the relaxation response time became longer than the contraction response time regardless of light status. However, contraction response time or relaxation response time findings were opposite to this during the light-on status and light-off status: contraction response time became shorter in the light-on status than in the light-off status and relaxation response time became longer in the light-on status than in the light-off status. These results suggest that the length of each response time is affected by motor control in the higher order brain and involves specific processing in the visual system.     

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.     

Clinical evaluation of sizofiran combined with irradiation in patients with cervical cancer

Following a previous report [1] we ascertained the effectiveness of sizofiran (Schizophyllan:SPG) to prolong the survival and time to recurrence of the patients with Stage II or III cervical cancer, as evaluated in a 5-year randomized controlled study conducted in 19 institutions in Japan. Of the overall patients with Stage II or III cancer, time to recurrence and survival rate in the group on SPG were significantly longer than in the control group. In the Stage II patients, there was significant difference in time to recurrence, and survival of SPG group tended to be longer than that of the control group. However, in the Stage III patients, there was no significant difference in either time to recurrence or survival rate.     

A new method for nonhomogeneous time course expression analysis

Time course expression analysis constitutes a large portion of applications of microarray experiments. One primary goal of such experiments is to detect genes with the temporal changes over a period of time or at some interested time points. Difficulties arising from data with small number of replicates over only a few unaligned time points in multiple groups pose challenges for efficient statistical analysis. Some known methods are limited by the unverifiable assumptions or by the scope of applications for only two groups. We present a new method for detecting differentially expressed genes under nonhomogeneous time course experiments in multiple groups. The new method first models the time course curve of one gene by a Gaussian process to align the nonhomogeneous time course data and to compute the gradient of the time course curve as well, the latter of which is used as directional information to enhance the sensitivity of detection for temporal changes. Second, we adopt a nonparametric method to test a surrogate hypothesis based on the augmented data from the Gaussian process model. The proposed method is robust in terms of model fitting and testing. It does not require any distributional assumption for the observations or the test statistic and the method works for the case with as few as triplicate samples over four or five time points under multiple groups. We show the effectiveness and superiority of the new method in comparison with some existing methods using simulated models and two real data sets.     

A standard procedure for measuring rodent bedding particle size and dust content

Hardwood dust can cause dermatitis, respiratory disease, allergies and nasal cancer in humans. A major concern with animal hardwood bedding is its dust content and its possible effects on animals and animal technicians. Previous reports on the quality control of rodent bedding did not specify sample size or shake time for measuring bedding particle size and dust content. These variables could alter particle size analyses. In an effort to more accurately characterize bedding particle size and dust content, 50g and 100g samples of hardwood bedding were shaken for 0.5, 1, 2, 3, 4, or 5 minutes in a portable sieve shaker containing U.S. standard sieves (Nos. 8, 20, 30 and 50) to determine optimum sample size and shake time. Significant differences (P less than 0.05 or greater) were observed in the percent of bedding retained on a No. 8 sieve when 50g and 100g samples were taken for 30 seconds or for 1 minute. Samples shaken for 2 or more minutes did not show any statistical differences in the percent of bedding which was retained on or passed through the different sieves. Major differences occurred in the percent of bedding which was retained or passed through the different sieves, when the shake time was varied from 0.5 to 5 minutes. These results indicated that 0.5 or 1 minute was definitely not enough time to accurately measure bedding particle size and dust content and that the sample size and shake time must be consistent in order to accurately compare the particle size and dust content of different shipments of bedding or to compare bedding from different vendors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Product limit estimation for infectious disease data when the diagnostic test for the outcome is measured with uncertainty

Low sensitivity and/or specificity of a diagnostic test for outcome results in biased estimates of the time to first event using product limit estimation. For example, if a test has low specificity, estimates of the cumulative distribution function (cdf) are biased towards time zero, while estimates of the cdf are biased away from time zero if a test has low sensitivity. In the context of discrete time survival analysis for infectious disease data, we develop self-consistent algorithms to obtain unbiased estimates of the time to first event when the sensitivity and/or specificity of the diagnostic test for the outcome is less than 100%. Two examples are presented. The first involves estimating time to first detection of HIV-1 infection in infants in a randomized clinical trial, and the second involves estimating time to first Neisseria gonorrhoeae infection in a cohort of Kenyan prostitutes.     

干燥密罗木复水过程中光诱导蒸腾拉力变化与复水时间的关系

该文探讨了干燥脱水后的复苏植物密罗木(Myrothamnus flabellifolia)的复水速度和复水后不同时间下的木质部压力与植物对光-暗反应的关系。研究结果表明, 密罗木整株植物和离体枝条复水时水分在茎内的上升速度都很快, 10小时左右水分即可接近枝条的顶端。在植物复水初期, 木质部压力反应随着复水时间的延长不断增加, 3周后达到正常值。这种木质部压力的调节能力可能与气孔功能的恢复程度有关。同时, 密罗木在整个复水恢复过程中受到光照时木质部压力下降的弛豫时间都明显大于植物在光源关闭时木质部压力上升的弛豫时间。表明密罗木对蒸腾速率上升过程的调节速度明显低于对蒸腾速率下降过程的调节速度。     

Time reverse automata patterns generated by Spencer-Brown's modulator: invertibility based on autopoiesis

In the present paper the self-consistency or operational closure of autopoiesis is described by introducing time explicitly. It is an extension of Spencer-Brown's idea of time, however. The definition of time is segregated into two parts, corresponding to the syntax and semantics of language, respectively. In this context, time reversibility is defined by the formalization of the relationship between time and self-consistency. This idea has also been discussed in the context of designation and/or naming. Here we will discuss it in the context of cellular automata and explain the structure of one-to-many type mappings. Our approach is the first attempt to extend autopoietic systems in terms of dynamics. It illustrates how to introduce an autopoietic time which looks irreversible, but without the concept of entropy.     

Identification of a distinct phase during melanogenesis that is sensitive to extracellular pH and ionic strength

The cell line B16/C3 will undergo melanogenesis at a specific time after plating. We have found that this time can be modulated by varying the pH of the culture medium. At high pH levels (8.2–8.6) the onset of melanogenesis occurs in 3 or 4 days, while at lower pH (6.7–7.2) it occurs in 7 or 8 days. Furthermore, the time of onset is also sensitive to the extracellular ionic strength. The addition of sodium lactate, sodium chloride, or any other salt tested delays or blocks completely the onset of melanogenesis. These effects are not simply consequence of growth inhibition, nor can they be correlated with patterns of lactate accumulation. These cells are sensitive to pH or ionic strength after entering the stationary phase just prior to the time of onset of melanogenesis. The existence of a specific pH-and ionic-strength-sensitive phase may provide an important clue to the events responsbile for differentiation in this system.