Influence of emergence timing of weeds on the establishment of woody natives and ground cover species

Les invasions biològiques són produïdes per espècies transportades per l'home fora de la regió d'origen a altres regions on s'estableixen i expandeixen. Són actualment de les majors causes de perduda de biodiversitat, amb el canvi d'usos del sòl, tret rellevant en zones insulars. Comprendre mecanismes de competència amb les espècies autòctones és clau per gestionar el problema. L’experiment evidencia diferències de creixement de 7 plantes natives australianes (3 espècies d’eucaliptus, 3 espècies d’acàcia, 1 pasturatge natiu), competint intraespecífica (entre mateixa espècie) i interespecíficament (acàcies o eucaliptus convivint amb pasturatge natiu) plantejant tres tractaments (sense males herbes, males herbes i males herbes a posteriori) per definir la naturalesa de la interacció dels diferents tipus funcionals d'espècies. S’analitzen tendències temporals de creixement de plàntules, així com la supervivència. S’ha detectat una moderada correlació entre taxes de creixement d’espècies i mida de la llavor, (p ≈ 0.6), així com una correlació entre la supervivència i la humitat del sòl (p ≈ 0.5); efectes estacionals. A curt termini i en escenari de primavera la convivència amb males herbes reporta creixement nul. Tractaments sense males herbes, presenten major supervivència en escenaris en competència interespecífica. A llarg termini les espècies amb major supervivència són les que conviuen amb pasturatge natiu i sense males herbes, indicant un efecte beneficiós en espècies millor adaptades a la sequera (E. loxophleba).

Décret du 6 mars 1934 relatif à la réforme des études médicales

[Décret. 1934-03-06]

Life events in conversion disorder: Role of timing and nature of events

Aims: To compare the frequency of life events in the year preceding illness onset in a series of Conversion Disorder (CD) patients, with those of a matched control group and to characterize the nature of those events in terms of "escape" potential. Traditional models of CD hypothesise that relevant stressful experiences are "converted" into physical symptoms to relieve psychological pressure, and that the resultant disability allows "escape" from the stressor, providing some advantage to the individual. Methods: The Life Events and Difficulties Schedule (LEDS) is a validated semi-structured interview designed to minimise recall and interviewer bias through rigorous assessment and independent rating of events. An additional "escape" rating was developed. Results: In the year preceding onset in 25 CD patients (mean age 38.9 years ± 8) and a similar matched period in 13 controls (mean age 36.2 years ± 10), no significant difference was found in the proportion of subjects having ≥ 1 severe event (CD 64%, controls 38%; p=0.2). In the last month preceding onset, a higher number of patients experienced ≥1 severe events than controls (52% vs 15%, odds ratio 5.95 (CI: 1.09-32.57)). Patients were twice as much more likely to have a severe escape events than controls, in the month preceding onset (44% vs 7%, odds ratio 9.43 (CI: 1.06-84.04). Conclusion: Preliminary data from this ongoing study suggest that the time frame (preceding month) and the nature ("escape") of the events may play an important role in identifying key events related to CD onset.

Oscillations, phase-of-firing coding, and spike timing-dependent plasticity: an efficient learning scheme

Recent experiments have established that information can be encoded in the spike times of neurons relative to the phase of a background oscillation in the local field potential—a phenomenon referred to as “phase-of-firing coding” (PoFC). These firing phase preferences could result from combining an oscillation in the input current with a stimulus-dependent static component that would produce the variations in preferred phase, but it remains unclear whether these phases are an epiphenomenon or really affect neuronal interactions—only then could they have a functional role. Here we show that PoFC has a major impact on downstream learning and decoding with the now well established spike timing-dependent plasticity (STDP). To be precise, we demonstrate with simulations how a single neuron equipped with STDP robustly detects a pattern of input currents automatically encoded in the phases of a subset of its afferents, and repeating at random intervals. Remarkably, learning is possible even when only a small fraction of the afferents (~10%) exhibits PoFC. The ability of STDP to detect repeating patterns had been noted before in continuous activity, but it turns out that oscillations greatly facilitate learning. A benchmark with more conventional rate-based codes demonstrates the superiority of oscillations and PoFC for both STDP-based learning and the speed of decoding: the oscillation partially formats the input spike times, so that they mainly depend on the current input currents, and can be efficiently learned by STDP and then recognized in just one oscillation cycle. This suggests a major functional role for oscillatory brain activity that has been widely reported experimentally.

Do fire and seed additions alter strong seed timing and priority effects on prairie establishment?, 2011

Many prairie restoration projects are hampered by a lack of knowledge on how to restore the high diversity found in prairies, while at the same time preventing the establishment of a large weedy component. Methods are needed to increase diversity and abundance of native species while minimizing exotic species invasions in both 1) newly planted restorations and 2) established restorations. We established an experiment in Story and Monona counties in 2005 to determine the effects of different native cover crop species and timing of seeding on the establishment of new prairie restorations. We found that adding a 30-species prairie mix in early spring led to diverse native communities, but adding the mix in the late summer or the following year after cover crops established led to low diversity communities dominated by exotics. The identity of cover crops affected communities less than timing of seed additions. A second seed addition added to ash after a spring fire in the seventh year (Monona County site) increased recruitment from the prairie mix slightly, but the increase was not enough to cause convergence in the treatments. Surprisingly, the second seed addition increased diversity only in communities that were already the most diverse (i.e., in plots seeded with the prairie mix in early spring before cover crops established). These results imply that 1) cover crops are not effective for establishing prairie and 2) over seeding into established plots may not be an easy and efficient way to increase native recruitment and lower weedy species abundances. Therefore, focusing on establishing high levels of recruitment and diversity and excluding weedy species during the critical time early in establishment should be a priority for new projects.

Procès relatif à la publication du catalogue intitulé "Livres du boudoir de Marie-Antoinette", prétendue contre-façon imputée aux éditeurs sur la plainte de M. J. Taschereau, directeur de la Bibliothèque impériale. Réquisitoire de M. Hémar. Plaidoyer de Me Gallien. Jugement en faveur de M. Gay, éditeur et de M. Louis Lacour, auteur de la publication... [Suivi d'un appendice signé : Louis Lacour.]

[Factum. Gay, Jules (éditeur). 1864]

Gender-related psychological and behavioural correlates of pubertal timing in a national sample of Swiss adolescents.

The potential consequences of early and late puberty on the psychological and behavioural development of the adolescent are not well known. This paper presents focused analyses from the Swiss SMASH study, a self-administered questionnaire survey conducted among a representative sample of 7488 adolescents from 16 to 20 years old. Data from participants reporting early or late timing of puberty were compared with those reporting average timing of maturation. Early maturing girls reported a higher rate of dissatisfaction with body image (OR=1.32) and functional symptoms (OR=1.52) and reported engaging in sexual activity more often (OR=1.93). Early maturing boys reported engaging in exploratory behaviours (sexual intercourse, legal and illegal substance use) at a significantly higher rate (OR varying between 1.4 and 1.99). Both early and late maturing boys reported higher rates of dysfunctional eating patterns (OR=1.59 and 1.38, respectively), victimisation (OR=1.61 and 1.37, respectively) and depressive symptoms (OR=2.11 and 1.53, respectively). Clinicians should take into account the pubertal stage of their patients and provide them, as well as their parents, with appropriate counselling in the field of mental health and health behaviour.

The timing of exploratory decision-making revealed by single-trial topographic EEGanalyses.

Decision-making in an uncertain environment is driven by two major needs: exploring the environment to gather information or exploiting acquired knowledge to maximize reward. The neural processes underlying exploratory decision-making have been mainly studied by means of functional magnetic resonance imaging, overlooking any information about the time when decisions are made. Here, we carried out an electroencephalography (EEG) experiment, in order to detect the time when the brain generators responsible for these decisions have been sufficiently activated to lead to the next decision. Our analyses, based on a classification scheme, extract time-unlocked voltage topographies during reward presentation and use them to predict the type of decisions made on the subsequent trial. Classification accuracy, measured as the area under the Receiver Operator's Characteristic curve was on average 0.65 across 7 subjects. Classification accuracy was above chance levels already after 516 ms on average, across subjects. We speculate that decisions were already made before this critical period, as confirmed by a positive correlation with reaction times across subjects. On an individual subject basis, distributed source estimations were performed on the extracted topographies to statistically evaluate the neural correlates of decision-making. For trials leading to exploration, there was significantly higher activity in dorsolateral prefrontal cortex and the right supramarginal gyrus; areas responsible for modulating behavior under risk and deduction. No area was more active during exploitation. We show for the first time the temporal evolution of differential patterns of brain activation in an exploratory decision-making task on a single-trial basis.

Cover crops and herbicide timing management on soybean yield under no-tillage system

The objective of this work was to evaluate the effect of cover crops and timing of pre-emergence herbicide applications on soybean yield under no-tillage system. The experiment consisted of four cover crops (Panicum maximum, Urochloa ruziziensis, U. brizantha, and pearl millet) and fallow, in addition to four herbicide timings (30, 20, 10, and 0 days before soybean sowing), under no-tillage system (NTS), and of two control treatments under conventional tillage system (CTS). The experimental design was a completely randomized block, in a split-plot arrangement, with three replicates. Soybean under fallow, P. maximum, U. ruziziensis, U. brizantha, and pearl millet in the NTS and soybean under U. brizantha in the CTS did not differ significantly regarding yield. Soybean under fallow in the CTS significantly reduced yield when compared to the other treatments. The amount of straw on soil surface did not significantly affect soybean yield. Chemical management of P. maximum and U. brizantha near the soybean sowing date causes significant damage in soybean yield. However, herbicide timing in fallow, U. ruziziensis, and pearl millet does not affect soybean yield.

Faillites et règlements judiciaires . [Décret n° 55-583 du 20 mai 1955, du Ministre des Finances et des affaires économiques, relatif aux faillites et règlements judiciaires et à la réhabilitation.]

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Timing and intensity of precommercial thinning and their effects on the first commercial thinning in Scots pine stands

Abstract