Burst Rate Research Articles

Psilocybin reduces low frequency oscillatory power and neuronal phase-locking in the anterior cingulate cortex of awake rodents

Psilocybin is a hallucinogenic compound that is showing promise in the ability to treat neurological conditions such as depression and post-traumatic stress disorder. There have been several investigations into the neural correlates of psilocybin administration using non-invasive methods, however, there has yet to be an invasive study of the mechanism of action in awake rodents. Using multi-unit extracellular recordings, we recorded local field potential and spiking activity from populations of neurons in the anterior cingulate cortex of awake mice during the administration of psilocybin (2 mg/kg). The power of low frequency bands in the local field potential was found to significantly decrease in response to psilocybin administration, whilst gamma band activity trended towards an increase. The population firing rate was found to increase overall, with just under half of individual neurons showing a significant increase. Psilocybin significantly decreased the level of phase modulation of cells with each neural frequency band except high-gamma oscillations, consistent with a desynchronization of cortical populations. Furthermore, bursting behavior was altered in a subset of cells, with both positive and negative changes in the rate of bursting. Neurons that increased their burst firing following psilocybin administration were highly likely to transition from a phase-modulated to a phase unmodulated state. Taken together, psilocybin reduces low frequency oscillatory power, increases overall firing rates and desynchronizes local neural activity. These findings are consistent with dissolution of the default mode network under psilocybin, and may be indicative of disruption of top-down processing in the acute psychedelic state.

Arecibo observations of a burst storm from FRB 20121102A in 2016

ABSTRACT FRB 20121102A is the first known fast radio burst (FRB) from which repeat bursts were detected, and one of the best-studied FRB sources in the literature. Here we report on the analysis of 478 bursts (333 previously unreported) from FRB 20121102A using the 305-m Arecibo telescope – detected during approximately 59 hours of observations between December 2015 and October 2016. The majority of bursts are from a burst storm around September 2016. This is the earliest available sample of a large number of FRB 20121102A bursts, and it thus provides an anchor point for long-term studies of the source’s evolving properties. We observe that the bursts separate into two groups in the width-bandwidth-energy parameter space, which we refer to as the low-energy bursts (LEBs) and high-energy bursts (HEBs). The LEBs are typically longer duration and narrower bandwidth than the HEBs, reminiscent of the spectro-temporal differences observed between the bursts of repeating and non-repeating FRBs. We fit the cumulative burst rate-energy distribution with a broken power law and find that it flattens out toward higher energies. The sample shows a diverse zoo of burst morphologies. Notably, burst emission seems to be more common at the top than the bottom of our 1150–1730 MHz observing band. We also observe that bursts from the same day appear to be more similar to each other than to those of other days, but this observation requires confirmation. The wait times and burst rates that we measure are consistent with previous studies. We discuss these results, primarily in the context of magnetar models.

Simultaneous Multiple Timescale Imaging For High-Speed Accelerometry Using The FRAME-Method

Fast transient events, such as the disintegration of liquid bodies or chemical reactions between radical species, involve various processes that may occur at different timescales. Currently, there are two alternatives for monitoring such events: burst- or high-speed imaging. Burst imaging at ultra-high speeds (~ 100 MHz - THz) allows the fastest processes to be captured but only for a narrowly confined period of time and under the condition that the onset can be predicted. To monitor long lasting events with existing high-speed imaging technology, the frame rate must be reduced (~ kHz - 1 MHz) and thus processes occurring on sub-microsecond timescales cannot be observed. To date, no imaging technology is capable of visualizing detailed sub-microsecond dynamics over a long period of time. In this manuscript we present a solution to this technological gap by combining multiplexed imaging with high-speed sensor technology resulting in temporally resolved image series at two simultaneous timescales. We demonstrate its unique capability of tracking structures at MHz burst rates over a long time by, for the first time, extracting 2D accelerometry data acting upon liquid bodies at kHz frame-rates.

Effects of chronic alkalinity stress on immune response in Nile tilapia (Oreochromis niloticus) infected with Aeromonas hydrophila

Under suitable environmental conditions, fish have a functional immune system and are therefore expected to have high disease resistance, growth rate and reproductive activity. To explore the effects of chronic alkalinity stress on the immune response in Nile tilapia, tilapia (291.1 ± 47.2 g) were exposed to 10 mmol/L and 30 mmol/L of sodium bicarbonate alkaline water (AW). At 31 d of alkalinity stress, the fish were infected by Aeromonas hydrophila and the cumulative mortality was calculated within 7 d. The immune-related indexes of peripheral blood cells, enzyme activities (Lys, Alp, C3 and IgM) and gene expression (tlr5, il-1β and γ-ifn) in the liver, spleen and gill of Nile tilapia were assessed at 1 and 31 d of alkalinity stress and 1 and 7 d post-infection. The results showed that: 1) the cumulative mortality of tilapia in 10 mmol/L AW was 26.7%, which was significantly lower than 66.7% in 30 mmol/L AW and 51.11% in freshwater (FW); 2) At 1 d post-infection, the respiratory burst and lymphocyte proliferation rates at 10 mmol/L AW were higher than at 30 mmol/L AW and FW; 3) Alp activity at 10 mmol/L AW was higher than at 30 mmol/L AW in the liver and spleen after infection; 4) At 31 d of alkalinity stress and 7 d post-infection, the tlr5 mRNA expression level in the liver and spleen at 10 mmol/L AW was higher than at 30 mmol/L AW and FW. At 7 d post-infection, the γ-ifn mRNA expression level in the gill of tilapia in 10 mmol/L AW was higher than in 30 mmol/L AW and FW. The il-1β mRNA expression level at 30 mmol/L AW was significantly higher than at 10 mmol/L AW at most time points in the spleen and gill; 5) At 7 d post-infection, the activities or expression level of Lys, Alp, C3, IgM, tlr5 and γ-ifn in the spleen of tilapia in 30 mmol/L AW were lower than in 10 mmol/L AW and FW. The above results showed that long-term feeding of Nile tilapia in 10 mmol/L carbonate AW can promote immune function and reduce mortality from bacterial infection.

The Discovery of a Rotating Radio Transient J1918–0449 with Intriguing Emission Properties with the Five-hundred-meter Aperture Spherical Radio Telescope

In this study, we report on a detailed single-pulse analysis of the radio emission from a rotating radio transient (RRAT) J1918−0449, which is discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The sensitive observations were carried out on 2021 April 30 using the FAST with a central frequency of 1250 MHz and a short time resolution of 49.152 μs, which forms a reliable basis to probe single-pulse emission properties in detail. The source was successively observed for around 2 hr. A total of 83 dispersed bursts with significance above 6σ are detected over 1.8 hr. The source’s dispersion measure (DM) and rotational period are determined to be 116.1 ± 0.4 pc cm−3 and 2479.21 ± 0.03 ms, respectively. The share of registered pulses from the total number of observed periods is 3.12%. No underlying emission is detected in the averaged off-pulse profile. For bursts with fluence larger than 10 Jy ms, the pulse energy follows a power-law distribution with an index of −3.1 ± 0.4, suggesting the existence of bright pulse emission. We find that the distribution of time between subsequent pulses is consistent with a stationary Poisson process and find no evidence of clustering over the 1.8 hr observations, giving a mean burst rate of one burst every 66 s. Close inspection of the detected bright pulses reveals that 21 pulses exhibit well-defined quasiperiodicities. The subpulse drifting is present in nonsuccessive rotations with periodicity of 2.51 ± 0.06 periods. Finally, possible physical mechanisms are discussed.

Simultaneous multiple time scale imaging for kHz–MHz high-speed accelerometry

Fast transient events, such as the disintegration of liquid bodies or chemical reactions between radical species, involve various processes that may occur at different time scales. Currently, there are two alternatives for monitoring such events: burst- or high-speed imaging. Burst imaging at ultrahigh speeds ( ∼ 100 MHz to THz ) allows for the capture of nature’s fastest processes but only for a narrowly confined period of time and at a repetition rate of ∼ 10 Hz . Monitoring long lasting, rapidly evolving transient events requires a significantly higher repetition rate, which is met by existing ∼ kHz to 1 MHz high-speed imaging technology. However, the use of such systems eliminates the possibility to observe dynamics occurring on the sub-microsecond time scale. In this paper, we present a solution to this technological gap by combining multiplexed imaging with high-speed sensor technology, resulting in temporally resolved, high-spatial-resolution image series at two simultaneous time scales. We further demonstrate how the collection of such data opens up the tracking of rapidly evolving structures up to MHz burst rates over long durations, allowing, for the first time, to our knowledge, the extraction of acceleration fields acting upon the liquid bodies of an atomizing spray in two dimensions at kHz frame rates.

Repeated warm water baths decrease sympathetic activity in humans.

Acute whole body heat stress evokes sympathetic activation. However, the chronic effects of repeated moderate heat exposure (RMHE) on muscle sympathetic nerve activity (MSNA) in healthy individuals remain unclear. We performed RMHE with 4 wk (5 days/wk) of warm baths (∼40°C, for 30 min) in nine healthy older (59 ± 2 yr) volunteers. Hemodynamic variables and MSNA were examined before, 1 day after, and 1 wk following 4 wk of RMHE in a laboratory at ∼23°C. Cold pressor test (CPT) and handgrip (HG) exercise were performed during the tests. Under normothermic condition, the resting MSNA burst rate (prior, post, post 1-wk: 31.6 ± 2.0, 25.2 ± 2.0, and 27.7 ± 1.7 bursts/min; P < 0.001) and burst incidence (P < 0.001) significantly decreased after RMHE. Moreover, the resting heart rate significantly decreased after RMHE (62 ± 2, 60 ± 2, and 58 ± 2 beats/min, P = 0.031). The sensitivity of baroreflex control of MSNA and heart rate were not altered by RMHE, although the operating points were reset. The MSNA and hemodynamic responses (i.e., changes) to handgrip exercise or cold pressor test were not significantly altered. These data suggest that the RMHE evoked by warm baths decreases resting sympathetic activity and heart rate, which can be considered beneficial effects. The mechanism(s) should be examined in future studies.NEW & NOTEWORTHY To our knowledge, this is the first study to observe the effects of repeated warm baths on sympathetic nerve activity during rest and stress in healthy middle age and older individuals. The data suggest that the repeated warm baths decreased resting sympathetic activity and heart rate, which can be considered beneficial effects. This study also provides the first evidence that the repeated warm baths did not alter the baroreflex sensitivity and the sympathetic responses to stress.

Stereospecific antiseizure activity in mouse and rat epilepsy models by a pyridinium inhibitor of TNFα/NFκB signaling

Epilepsy affects over 50 million people worldwide and increases the risk of death. An intrinsic state of central inflammation, mainly driven by TNFα/NFκB signaling, may contribute to the refractory nature of some epilepsies. We have therefore hypothesized that inhibitors of this signaling pathway might be therapeutic. To test this hypothesis, we have measured the antiseizure properties of the enantiomeric compounds MRS-2481 and MRS-2485 in rodent seizure model systems. In the 6 ​Hz (44 ​mA) induced seizure test in mice, the (S) species, MRS-2485, was found to have higher protective potency and lower toxicity than the (R) species MRS-2481. However, neither of these enantiomers were protective in the MES-induced seizure test. MRS-2485 was also found to be protective in the corneal kindled mouse test. Finally, MRS-2485 reduced the post-kainate rat hippocampal slice electrical burst rate and duration. We conclude that MRS-2485, the (S)-enantiomer, is a potent inhibitor of seizure activity in mouse and rat models of epilepsy.

An Insight-HXMT Dedicated 33 day Observation of SGR J1935+2154. I. Burst Catalog

Magnetars are neutron stars with an extreme magnetic field and sometimes manifest as soft gamma-ray repeaters (SGRs). SGR J1935+2154 is one of the most prolific bursters and the first confirmed source of a fast radio burst (FRB; i.e., FRB 200428). Encouraged by the discovery of the first X-ray counterpart of FRBs, the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) implemented a dedicated 33-day-long Target of Opportunity observation of SGR J1935+2154 since 2020 April 28. With the HE, ME, and LE telescopes, Insight-HXMT provides a thorough monitoring of burst activity evolution of SGR J1935+2154, in a very broad energy range (1–250 keV) with high temporal resolution and high sensitivity, resulting in a unique valuable data set for detailed studies of SGR J1935+2154. In this work, we conduct a comprehensive analysis of this observation, including detailed burst search, identification, and temporal analyses. After carefully removing false triggers, we find a total of 75 bursts from SGR J1935+2154, out of which 70 are single pulsed. The maximum burst rate is about 56 bursts day−1. Both the burst duration and the waiting time between two successive bursts follow lognormal distributions, consistent with previous studies. We also find that bursts with longer duration (some are multipulsed) tend to occur during the period with relatively high burst rate. There is no correlation between the waiting time and the fluence or duration of either the former or latter burst. It also seems that there is no correlation between burst duration and hardness ratio, in contrast to some previous reports. In addition, we do not find any X-ray burst associated with any reported radio bursts except for FRB 200428.

The Cosmic History of Long Gamma-Ray Bursts

The cosmic formation rate of long gamma-ray bursts (LGRBs) encodes the evolution, across cosmic times, of the properties of their progenitors and of their environment. The LGRB formation rate and the luminosity function, with its redshift evolution, are derived by reproducing the largest sets of observations collected over the last four decades, namely the observer-frame prompt emission properties of the GRB samples detected by the Fermi and Compton Gamma Ray Observatory satellites and the redshift, luminosity, and energy distributions of the flux-limited, redshift-complete samples of GRBs detected by Swift. The model that best reproduces all these constraints consists of a GRB formation rate increasing with redshift ∝(1 + z)3.2, i.e., steeper than the star formation rate, up to z ∼ 3, followed by a decrease ∝(1 + z)−3. On top of this, our model also predicts a moderate evolution of the characteristic luminosity function break ∝(1 + z)0.6. Models with only luminosity or rate evolution are excluded at >5σ significance. The cosmic rate evolution of LGRBs is interpreted as their preference for occurring in environments with metallicity , consistent with theoretical models and host galaxy observations. The LGRB rate at z = 0, accounting for their collimation, is Gpc−3 yr−1 (68% confidence interval). This corresponds to ∼1% of broad-line Type Ibc supernovae producing a successful jet in the local universe. This fraction increases up to ∼7% at z ≥ 3. Finally, we estimate that at least ≈0.2−0.7 yr−1 of the Swift- and Fermi-detected bursts at z < 0.5 are jets observed slightly off-axis.

Arecoline Induces an Excitatory Response in Ventral Tegmental Area Dopaminergic Neurons in Anesthetized Rats.

Arecoline is the principle psychoactive alkaloid in areca nuts. Areca nuts are chewable seeds of Areca catechu L., which are epidemic plants that grow in tropical and subtropical countries and cause dependency after long-term use. However, the mechanisms underlying such dependency remain largely unclear, and therefore, no effective interventions for its cessation have been developed. The present study aimed to examine the effects of arecoline on neurons of the ventral tegmental area (VTA). After rats were anesthetized and craniotomized, electrophysiological electrodes were lowered into the VTA to obtain extracellular recordings. The mean firing rate of dopaminergic and GABAergic neurons were then calculated and analyzed before and after arecoline treatment. The burst characteristics of the dopaminergic neurons were also analyzed. The results showed that arecoline evoked a significant enhancement of the firing rate of dopaminergic neurons, but not GABAergic neurons. Moreover, arecoline evoked remarkable burst firings in the dopaminergic neurons, including an increase in the burst rate, elongation in the burst duration, and an enhancement in the number of spikes per burst. Collectively, the findings revealed that arecoline significantly excited VTA dopaminergic neurons, which may be a mechanism underlying areca nut dependency and a potential target for areca nut cessation therapy.

The northern cross fast radio burst project – II. Monitoring of repeating FRB 20180916B, 20181030A, 20200120E, and 20201124A

ABSTRACT In this work, we report the results of a 19-month fast radio burst observational campaign carried out with the north–south arm of the Medicina Northern Cross radio telescope at 408 MHz in which we monitored four repeating sources: FRB20180916B, FRB20181030A, FRB20200120E, and FRB20201124A. We present the current state of the instrument and the detection and characterization of three bursts from FRB20180916B. Given our observing time, our detections are consistent with the event number we expect from the known burst rate (2.7 ± 1.9 above our 10σ, 38 Jy ms detection threshold) in the 5.2 d active window of the source, further confirming the source periodicity. We detect no bursts from the other sources. We turn this result into a 95 per cent confidence level lower limit on the slope of the differential fluence distribution α to be α &amp;gt; 2.1 and α &amp;gt; 2.2 for FRB20181030A and FRB20200120E, respectively. Given the known rate for FRB20201124A, we expect 1.0 ± 1.1 bursts from our campaign, consistent with our non-detection.

Linking the rates of neutron star binaries and short gamma-ray bursts

Short gamma-ray bursts are believed to be produced by both binary neutron star (BNS) and neutron star-black hole (NSBH) mergers. We use current estimates for the BNS and NSBH merger rates to calculate the fraction of observable short gamma-ray bursts produced through each channel. This allows us to constrain merger rates of BNS to $\mathcal{R}_{\rm{BNS}}=384^{+431}_{-213}{\rm{Gpc}^{-3} \rm{yr}^{-1}}$ ($90\%$ credible interval), a $16\%$ decrease in the rate uncertainties from the second LIGO--Virgo Gravitational-Wave Transient Catalog, GWTC-2. Assuming a top-hat emission profile with a large Lorentz factor, we constrain the average opening angle of gamma-ray burst jets produced in BNS mergers to $\approx 15^\circ$. We also measure the fraction of BNS and NSBH mergers that produce an observable short gamma-ray burst to be $0.02^{+0.02}_{-0.01}$ and $0.01 \pm 0.01$, respectively and find that $\gtrsim 40\%$ of BNS mergers launch jets (90\% confidence). We forecast constraints for future gravitational-wave detections given different modelling assumptions, including the possibility that BNS and NSBH jets are different. With $24$ BNS and $55$ NSBH observations, expected within six months of the LIGO-Virgo-KAGRA network operating at design sensitivity, it will be possible to constrain the fraction of BNS and NSBH mergers that launch jets with $10\%$ precision. Within a year of observations, we can determine whether the jets launched in NSBH mergers have a different structure than those launched in BNS mergers and rule out whether $\gtrsim 80\%$ of binary neutron star mergers launch jets. We discuss the implications of future constraints on understanding the physics of short gamma-ray bursts and binary evolution.

P 47 The Impact of directional deep brain stimulation on subthalamic beta power in Parkinson's disease

Introduction : Beta power in subthalamic local field potentials (LFPs) is a well established biomarker for bradykinesia-rigidity in idiopathic Parkinson's Disease (IPS) and is a promising feedback signal for adaptive deep brain stimulation (DBS). However, the effect of directional stimulation on this biomarker has not yet been elaborated. With new DBS-systems allowing to combine directional stimulation with relatively artifact-free recordings of local field potentials (LFPs), we want to assess the impact of directionality on beta power and motor performance. Patients & Methods : So far, 6 IPS patients implanted with Medtronic SenSight directional electrodes in the subthalamic nucleus (STN) have been included in the study. LFPs were recorded post-operatively and during a 3 months follow up visit (3MFU) with the patient at rest using the Medtronic Percept PC implantable pulse-generator. Additionally, at the 3MFU, a monopolar review of all segmented contacts (separately and combined as ring) was carried out in the medication “off” state. A rotameter task was used to assess motor performance. Following each block consisting of 2 minutes of rest and 30 seconds of rotation, stimulation amplitude was increased stepwise up to a maximum amplitude of 3 mA or the occurrence of side effects. LFPs were streamed throughout the review. The primary outcome is the reduction of mean beta power with directional stimulation compared with (1) no stimulation and (2) ring stimulation. The secondary outcomes are: (1) Beta burst length distribution, (2) motor performance and (3) rate of side effects with directional compared to ring stimulation. Results : Further patient inclusion to a minimum of 10 patients is planned before the summit. Directional and ring stimulation led to dose-dependent reduction of mean beta power in the STN. Stimulation had an effect on both movement amplitude and velocity. In 4 out of 6 patients, the side effect threshold was higher with directional stimulation compared to ring stimulation. At the summit, we will also report changes in beta burst length distribution with directional compared to ring stimulation and the predictive value of beta power in postoperative intersegmental rest recordings for the clinically most effective directional contact. Conclusion : Our study contributes to characterizing LFP beta power in the context of directional stimulation and its relation to motor performance. This is a prerequisite for combining directional stimulation with beta-driven adaptive DBS, which ultimately could further improve DBS therapy.

A comparative study of luminosity functions and event rate densities of long GRBs with non-parametric method

ABSTRACT In this work, we restudy the dependence of luminosity function and event rates for different gamma-ray burst samples on the criteria of sample selection and threshold effect. To compare with many previous studies, we have chosen two samples including 88 and 118 long bursts with known redshift and peak flux over 2.6 ph cm−2 s−1, from which 79 bursts are picked out to constitute our complete sample. It is found that the evolution of luminosity with redshift can be expressed by L∝(1 + z)k with a diverse k relied more on the sample selection. Interestingly, the cumulative distributions of either non-evolving luminosities or redshifts are found to be also determined by the sample selection rather than the instrumental sensitivity. Nevertheless, the non-evolving luminosities of our samples are similarly distributed with a comparable break luminosity of L0 ∼ 1051 erg s−1. Importantly, we verify with a K-S test that three cases of event rates for the two burst samples evolve with redshift similarly except a small discrepancy due to sampling differences at low-redshift of z &amp;lt; 1, in which all event rates show an excess of Gaussian profile instead of monotonous decline no matter whether the sample is complete. Most importantly, it is found that the burst rates violate the star formation rate at low redshift, while both of them are good in agreement with each other in the higher-redshift regions as many authors discovered previously. Therefore, we predict that two types of long bursts are favored in terms of their associations with both the star formation and the cosmic metallicity.

Spectrum Allocation Scheme for IoMT Devices Using Game Theory

There are a lot of challenges like versatility, network, receptiveness, accuracy, etc… when working on an internet-connected device because of the wide usage of them across the global. Currently there is a huge demand for reliable ways to connect to wireless. Same was conveyed as part of multiple observations and many have explained how spectrum sensing helps to allocate dynamically the unlicensed frequency bands for IoT applications reducing traffic and enabling the IoT technologies. Goal of Cognitive radio is to use the unadopted spectral spaces called spectral holes. A non-cooperative game theoretic strategy is employed to study the same. Also, the formulation of a utility function in terms of spectral usage rate of the users in a CR network. For obtaining the spectral usage rate, a 2-D continuous-time Markov Chain (CTMC) scenario is proposed to obtain the strategy for the users of CR in order to choose the appropriate spectral gaps. The parameters such as percentage utilization of spectrum by varying parameters like Traffic, No. of users and Data Burst rates are studied.

Temporal envelope programmable burst-mode Ytterbium all-fiber amplifier based, ultraviolet source at 260 nm

In this paper, we report a 100-kHz-rate femtosecond burst-mode high-power laser system with the capacity for arbitrary-envelope burst generation. After passing through a rod-type fiber amplifier, the energy of a single burst was found to reach 0.2 mJ at a 100-kHz burst rate with a pulse peak power of 5.3 mW. Using this system, we also achieved a 5.5-W second-harmonic output with a conversion efficiency of ∼ 41% and a spectral bandwidth of 4 nm. A 0.45-W ultraviolet (UV) burst was further obtained with a conversion efficiency of ∼ 12% and a spectral bandwidth of ∼ 0.4 nm, while the wavelength of the UV burst can be continuously tuned from 259.7 to 261.2 nm.

The Cl--channel TMEM16A is involved in the generation of cochlear Ca2+ waves and promotes the refinement of auditory brainstem networks in mice.

Before hearing onset (postnatal day 12 in mice), inner hair cells (IHCs) spontaneously fire action potentials, thereby driving pre-sensory activity in the ascending auditory pathway. The rate of IHC action potential bursts is modulated by inner supporting cells (ISCs) of Kölliker's organ through the activity of the Ca2+-activated Cl--channel TMEM16A (ANO1). Here, we show that conditional deletion of Ano1 (Tmem16a) in mice disrupts Ca2+ waves within Kölliker's organ, reduces the burst-firing activity and the frequency selectivity of auditory brainstem neurons in the medial nucleus of the trapezoid body (MNTB), and also impairs the functional refinement of MNTB projections to the lateral superior olive. These results reveal the importance of the activity of Kölliker's organ for the refinement of central auditory connectivity. In addition, our study suggests the involvement of TMEM16A in the propagation of Ca2+ waves, which may also apply to other tissues expressing TMEM16A.

Soil Water Content Directly Affects Bud Burst Rate in Single-Node Cuttings of Perennial Plants

The use of single-node cuttings of shoots as explants to study bud dormancy and its physiology under controlled conditions is a common practice in grapevine (Vitis vinifera L.) or other perennial plant research. In particular, this method has been extensively used to understand the effect of different chemicals on bud dormancy and bud burst. However, the soil water content in those experiments is usually not reported and its relevance is often neglected. Here, we observed that an unevenly distributed soil water content in a tray containing multiple explants results in an uneven pattern of bud burst within the same treatment. Thus, we hypothesised that soil water content can dramatically affect bud burst. To investigate this, we first established that fresh single-node cuttings were able to transport water into the buds. We then tested the rate of bud burst at different water treatments (35%, 55%, 70%, 85%, and 100% of field capacity; FC). We observed a clear dependence of bud burst on water, in which, at very low levels of water, bud burst does not occur; after 35% FC, bud burst rate increases with water content until around 85% FC; and, from 85% FC, bud burst rate becomes independent of water content. These data highlight the critical importance of monitoring soil water content in any bud burst assay in perennials. Finally, we provide a detailed protocol for determining and controlling field capacity and other soil water content indicators.

Burst-mode femtosecond fiber-feedback optical parametric oscillator

In multiphoton 3D direct laser writing and stimulated Raman scattering applications, rapid and arbitrary pulse modulation with an extremely high contrast ratio would be very beneficial. Here, we demonstrate a femtosecond fiber-feedback optical parametric oscillator (FFOPO) system in combination with pulse picking in the pump beam. This allows tunable signal output at variable burst rates from DC all the way up to 5 MHz. Furthermore, arbitrary pulse sequences can be generated. The rapid signal buildup dynamics provide individual full-power pulses with only two prepulses. This is possible without the requirement for additional injection seeding. Hereby, the intrinsically high intra-cavity losses of the FFOPO system are found to beneficial, as they enable rapid off-switching of the output as signal ring-down is efficiently suppressed. Possible applications are the reduction of the average power while maintaining a high peak power level, as well as tunable arbitrary pulse sequence generation.