Exponential Recovery Research Articles

Can a first‐order exponential decay model fit heart rate recovery after resistance exercise?

The time-constant of postexercise heart rate recovery (HRRτ ) obtained by fitting heart rate decay curve by a first-order exponential fitting has being used to assess cardiac autonomic recovery after endurance exercise. The feasibility of this model was not tested after resistance exercise (RE). The aim of this study was to test the goodness of fit of the first-order exponential decay model to fit heart rate recovery (HRR) after RE. Ten healthy subjects participated in the study. The experimental sessions occurred in two separated days and consisted of performance of 1 set of 10 repetitions at 50% or 80% of the load achieved on the one-repetition maximum test [low-intensity (LI) and high-intensity (HI) sessions, respectively]. Heart rate (HR) was continuously registered before and during exercise and also for 10 min of recovery. A monoexponential equation was used to fit the HRR curve during the postexercise period using different time windows (i.e. 30, 60, 90, … 600 s). For each time window, (i) HRRτ was calculated and (ii) variation of HR explained by the model (R(2) goodness of fit index) was assessed. The HRRτ showed stabilization from 360 and 420 s on LI and HI, respectively. Acceptable R(2) values were observed from the 360 s on LI (R(2) > 0.65) and at all tested time windows on HI (R(2) > 0.75). In conclusion, this study showed that using a minimum length of monitoring (~420 s) HRR after RE can be adequately modelled by a first-order exponential fitting.

Recovery characteristics of solution-processed ZTO thin-film transistors

We investigated the negative-bias illumination stress (NBIS) and the recovery characteristics of solution-processed amorphous zinc-tin-oxide (ZTO)-based thin-film transistors (TFTs). We developed TFTs with a bottom gate structure that used SiO2 films for the gate insulator. The developed TFTs were under NBIS in air at room temperature (RT) with a gate-to-source voltage of −10 V and a white-light power density of 6.2 mW/cm2. For the devices under NBIS, the NBIS-induced instability is attributed to the combined effects of 1) the creation of a low density of subgap states such as ionized oxygen vacancies (V 2+ ) near the Fermi level in ZTO, 2) a fast and large increase in the photo-conductivity at the off-state due to photo-induced band-to-band electron-hole pair generation, and 3) the hole trapping near the ZTO/SiO2 interface. The devices under NBIS also exhibit fast exponential recovery characteristics at RT, which are attributed dominantly to detrapping of holes near the ZTO/SiO2 interface and partially to the weak stabilization of V 2+ near the interface.

Measurement of cone dark adaptation: a comparison of four psychophysical methods

Dark adaptometry is an important clinical tool for the diagnosis of a range of conditions, including age-related macular degeneration. In order to identify the most robust, clinically applicable technique for the measurement of cone dark adaptation, the repeatability and agreement of four psychophysical methods were assessed. Data were obtained from 31 healthy adults on two occasions, using four psychophysical methods. Participants' pupils were dilated, and 96% of cone photopigment was bleached before threshold was monitored in the dark using one of the techniques, selected at random. This procedure was repeated for each of the remaining methods. An exponential recovery function was fitted to all threshold recovery data. The coefficient of repeatability (CoR) was calculated to assess the repeatability of the methods, and a repeated-measures analysis of variance was used to compare mean recovery parameters. All four methods demonstrated a similar level of intersession repeatability for measurement of cone recovery, yielding CoRs between 1.18 and 1.56min. There were no statistically significant differences in estimates of mean time constant of cone recovery (cone τ) between the four methods (p=0.488); however, significant differences between initial and final cone thresholds were reported (p<0.005). All of the techniques were capable of monitoring the rapid changes in visual threshold that occur during cone dark adaptation, and the repeatability of the techniques was similar. This indicates that despite the respective advantages and disadvantages of these psychophysical techniques, all four methods would be suitable for measuring cone dark adaptation in clinical practice.

Voltage collapse detection based on local measurements

This paper is concerned with voltage collapse detection in power systems. The concepts of voltage support surface and local balancing equation are used. Likewise, the use of the impedance matching concept, requiring only measurements taken at the corresponding bus without needing a reference signal, is proposed. The impedance matching equation is solved by direct and a recursive least squares algorithm. The estimated equivalent impedance becomes a multiple of the load impedance. Thus, proximity indices to the point of collapse (PoC) that requires just voltage magnitudes are presented. Voltage instability is evaluated through direct detection of PoC in loads and transit (no-load) buses. Voltage stability margin calculation without requiring the load flow solution at the bifurcation point is proposed. Taking constant P–Q load characteristics into account, the method is tested on the IEEE 14-bus test system by the continuation power flow (CPF) to estimate the path that the impedance and the proposed indices follow through stable and unstable operation regions. A dynamic evaluation of the method is performed when exponential recovery and motor loads are embedded.

Optimal Execution: Linear Market Impact with Exponential Decay

Optimal execution of portfolio transactions is the essential part of algorithmic trading. The main result of this paper is the analytical equationfor the optimal trading trajectories with the assumption of exponential market recovery and short-time investment horizon. The formula has the same form and as simple as well known solution by GKAC ( R. Grinold and R. Kahn, R.Almgren and N.Chriss) but much more flexible. Also it is free of such undesirable features as infinite impact for finite discrete trades and instantaneous market recovery. In this revision we corrected typos and added appendix with illustrations of main equation.

Identification and application of nonlinear dynamic load models

An alternating least squares approach is developed in this paper to identify the exponential recovery dynamic load model of wide-area power systems. The nonlinear optimization problem is decomposed to two linear least squares problems, and solved in an alternating way. Then, a new algorithm for numerical derivative calculation using discrete Fourier transform is proposed to attenuate the effect of noises in the process of parameter estimation. Based on the estimated dynamic load characteristics, the application on voltage stability is analyzed. Finally, numerical and laboratory examples are conducted to demonstrate the effectiveness of the proposed methods.

Effects of Nitrosation on Cardiac Myocyte Shortening

In the heart, there are two pathways for nitric oxide (NO) signaling, the classic cGMP-PKG and S-nitrosation of proteins. The nitrosation pathway involves an oxidation of cysteine thiols by nitrosonium NO+, and can therefore be a significant, reversible post-translational modification of proteins. Previous studies using NO donors such as S-nitroso-N-acetylpenicillamine (SNAP) were unable to resolve between to two pathways. We hypothesized that nitrosation is an important post-translational modifier of myocardial contractility. To test this hypothesis, we examined the effects of S-nitroso-L-cysteine (CysNO), a selective nitrosonium donor that is actively transported into the cell, on sarcomere shortening in unloaded mouse cardiac myocytes. Perfusion of cardiac myocytes with CysNO (30 μM) resulted in the reduction of sarcomere length changes by ∼80%. This period of blunted sarcomere length changes was followed by a ∼15 second exponential recovery in sarcomere length. During the recovery phase, the maximal velocities of shortening and re-lengthening were diminished. Our data suggest a possible in vivo role of NO+ in regulating myocardial contractility.

Detection of 107 glitches in 36 southern pulsars

Timing observations from the Parkes 64-m radio telescope for 165 pulsars between 1990 and 2011 have been searched for period glitches. Data spans for each pulsar ranged between 5.3 and 20.8 yr. From the total of 1911 yr of pulsar rotational history, 107 glitches were identified in 36 pulsars. Out of these glitches, 61 have previously been reported whereas 46 are new discoveries. Glitch parameters, both for the previously known and the new glitch detections, were measured by fitting the timing residual data. Observed relative glitch sizes Δνg/ν range between 10−10 and 10−5, where ν = 1/P is the pulse frequency. We confirm that the distribution of Δνg/ν is bimodal with peaks at approximately 10−9 and 10−6. Glitches are mostly observed in pulsars with characteristic ages between 103 and 105 yr, with large glitches mostly occurring in the younger pulsars. Exponential post-glitch recoveries were observed for 27 large glitches in 18 pulsars. The fraction Q of the glitch that recovers exponentially also has a bimodal distribution. Large glitches generally have low Q, typically just a few per cent, but large Q values are observed in both large and small glitches. Observed time constants for exponential recoveries ranged between 10 and 300 d with some tendency for longer time-scales in older pulsars. Shorter time-scale recoveries may exist but were not revealed by our data which typically have observation intervals of 2–4 weeks. For most of the 36 pulsars with observed glitches, there is a persistent linear increase in |$\dot{\nu }$| (i.e. decrease in the slow-down rate |$|\dot{\nu }|$|⁠) in the interglitch interval. Where an exponential recovery is also observed, the effects of this are superimposed on the linear increase in |$\dot{\nu }$|⁠. In some but not all cases, the slope of the linear recovery changes at the time of a glitch. The |$\ddot{\nu }$| values characterizing the linear changes in |$\dot{\nu }$| are almost always positive and, after subtracting the magnetospheric component of the braking, are approximately proportional to the ratio of |$|\dot{\nu }|$| and the interglitch interval, as predicted by vortex-creep models.

Effects of Hydrogen Treatment and Air Annealing on Ultrafast Charge Carrier Dynamics in ZnO Nanowires Under in Situ Photoelectrochemical Conditions

ZnO nanowires (NWs) grown by the hydrothermal method on fluorine-doped tin oxide glass substrate were characterized by scanning electron microscopy, optical absorption, photoelectrochemical photocurrent density, and ultrafast transient absorption pump probe spectroscopy. The as-grown NWs were annealed in air, pure hydrogen atmosphere, or annealed first with air annealing followed by hydrogen treatment. By TA spectroscopy, the samples exhibited a triple exponential transient bleach recovery with lifetimes on the fast (10–15 ps), medium (100–200 ps), and slow (>1 ns) time scale, attributed to shallow donor mixed with electron hole plasma recombination, donor bound recombination, and donor–acceptor pair recombination (DAP), respectively. The as-grown samples were dominated by donor and DAP recombination. Air annealing improved the crystal structure but had little effect on hole trapping. Significantly, the hydrogen-treated NWs showed a reduction in hole trapping and DAP recombination. Hole trapping was attributed to zinc vacancies (VZn) and hydrogen was proposed to passivate these defects. The photocurrent density of the air annealed and cotreated NWs were measured, the latter of which showed improved performance which was attributed to, in part, decreased hole trap states and improved electrical conductivity. In situ ultrafast TA spectroscopy was used to study the photoanodes under working conditions as a function of applied bias. For both samples, the medium time constant became faster with increasing applied bias. A model was proposed to extract the electron–hole separation time constant.

Lesions to Primary Sensory and Posterior Parietal Cortices Impair Recovery from Hand Paresis after Stroke

BackgroundNeuroanatomical determinants of motor skill recovery after stroke are still poorly understood. Although lesion load onto the corticospinal tract is known to affect recovery, less is known about the effect of lesions to cortical sensorimotor areas. Here, we test the hypothesis that lesions of somatosensory cortices interfere with the capacity to recover motor skills after stroke.MethodsStandardized tests of motor skill and somatosensory functions were acquired longitudinally over nine months in 29 patients with stroke to the pre- and postcentral gyrus, including adjacent areas of the frontal, parietal and insular cortices. We derived the recovery trajectories of each patient for five motor subtest using least-squares curve fitting and objective model selection procedures for linear and exponential models. Patients were classified into subgroups based on their motor recovery models. Lesions were mapped onto diffusion weighted imaging scans and normalized into stereotaxic space using cost-function masking. To identify critical neuranatomical regions, voxel-wise subtractions were calculated between subgroup lesion maps. A probabilistic cytoarchitectonic atlas was used to quantify of lesion extent and location.ResultsTwenty-three patients with moderate to severe initial deficits showed exponential recovery trajectories for motor subtests that relied on precise distal movements. Those that retained a chronic motor deficit had lesions that extended to the center of the somatosensory cortex (area 2) and the intraparietal sulcus (areas hIP1, hIP2). Impaired recovery outcome correlated with lesion extent on this areas and somatosensory performance. The rate of recovery, however, depended on the lesion load onto the primary motor cortex (areas 4a, 4p).ConclusionsOur findings support a critical role of uni-and multimodal somatosensory cortices in motor skill recovery. Whereas lesions to these areas influence recovery outcome, lesions to the primary motor cortex affect recovery dynamics. This points to a possible dissociation of neural substrates for different aspects of post-stroke recovery.

Calorimetric assessment of adsorbents bonded to metal surfaces: Application to type A silica gel bonded to aluminium

Abstract A recent publication concerned the use of a thermoelectric module to control temperature in an inert sample and to meter heat flow to the sample. This technique has been adapted for an active sample containing a layer of Type A beaded silica gel particles, bonded to aluminium at which point the sample temperature was measured. The adsorption of water vapour was considered, as might occur in adsorption chillers. During experiments, nominal sample temperatures were maintained to within 0.2 K and accuracy of heat flow measurement generally to within 11% not withstanding a correction for heat losses. The rejected heat of adsorption was fitted to an exponential recovery with r 2 > 99% yielding the adsorption capacity and kinetic rate constant for each experiment. For the silica gel selected (Type A) and in the loading range 3%–30%, previous data published by a different research team were reproduced to within 10% (3 mm diameter particles) and 20% (1 mm diameter particles). Kinetic rate constants were far bigger than would be inferred from Knudsen diffusion alone. The constants fell onto straight lines on Arrhenius plots; the inferred activation energies were far less than two independent measurements for RD type silica gels, but in line with one theoretical expectation. Kinetic rate constants did not vary in inverse proportion to the square of particle diameter; the same discrepancy is partly evident in other publications.

Nuclear spin–lattice relaxation and paramagnetic defects in carbon nanomaterials

We review recent nuclear spin–lattice relaxation studies of carbon nanomaterials, such as nanodiamonds, carbon onions, activated carbon fibers, graphene and carbon nanoscrolls. We show that a significant reduction in the relaxation time in nanoparticles compared with that in the bulk compounds and a stretched exponential magnetization recovery are caused by the interaction of nuclear spins with unpaired electron spins of paramagnetic defects, which creates an effective channel for the nuclear relaxation. We present a theoretical approach for such kind of relaxation in static and magic angle spinning regimes and explain a difference in the data received in these regimes. We also extend our approach for the case of additional contributions to the relaxation resulting from interaction of nuclear spin with conduction electrons and with adsorbed paramagnetic oxygen molecules. The developed approach allows correct interpreting of the NMR relaxation data and receiving useful information on properties of nanomaterials from the NMR measurements.

Cardiocyte Functional Data Analysis: A Novel Approach

Current laboratory methods used to assess neonatal and adult cardiocyte function include measurement of gene and protein expression levels, calcium transients, and contractility. Our goal was to develop simple tools to analyze such data readily. We created two MATLAB®-based toolboxes; the Contraction Video Processing (CVP) and the Cardiocyte Functional Response Analysis (CFRA) Toolbox. Videos of contracting cultured cardiocytes are acquired using a digital camera attached to an inverted phase microscope. Video frames are analyzed using digital imaging processing techniques along with several contraction assessment methods available through the CVP toolbox. The CVP offers direct correlation, pixel intensity tracking and Polar Fourier transform methods for the analysis of neonatal cardiocyte contraction. Analysis of adult cardiocytes includes those implemented on neonatal cardiocytes in addition to area boundary tracking, Fourier descriptor analysis, and cell length tracking methods. The resulting contraction records are processed using the CFRA toolbox to provide quantitative analyses of cardiocyte contractility and calcium transient responses. Transient data are obtained by measuring the calcium fluxes using the fluorescent dye Fluo-3, and a Photon Technology fluorometer system running Felix software. Data analysis routines have been created and tailored exclusively to the characteristics and needs of cellular cardiovascular research investigators. The analytical methods created are used to find the onset of contraction, perform signal averaging, and acquire statistical information of functional data. CFRA toolbox contractility processing yields onset time, time-to-peak, duration, and fast and slow recovery times. CFRA toolbox calcium transient signal processing yields onset time, signal intensity, and fast and slow exponential recovery rates associated with SERCA and NCX channels respectively. The toolboxes allow examination of beat-to-beat contractility and calcium transient variations within the same cardiocyte as well as from cell population to population. Supported by NIH/NIGMS SDSU MARC Program 5T34GM008303-22

Online Stimulus Reconstruction from Noisy Spike Trains

Online Stimulus Reconstruction from Noisy Spike Trains

Optimization of intermittent, simultaneous dosage of nitrite and hydrochloric acid to control sulfide and methane productions in sewers

Free nitrous acid (FNA) was previously demonstrated to be biocidal to anaerobic sewer biofilms. The intermittent dosing of FNA as a measure for controlling sulfide and methane productions in sewers is investigated. The impact of three key operational parameters namely the dosing concentration, dosing duration and dosing interval on the suppression and subsequent recovery of sulfide and methane production was examined experimentally using lab-scale sewer reactors. FNA as low as 0.26 mg-N/L was able to suppress sulfide production after an exposure of 12 h. In comparison, 0.09 mg-N/L of FNA with 6-h exposure was adequate to restrain methanogenesis effectively. The recovery of sulfide production was well described by an exponential recovery equation. Model-based analysis revealed that 12-h dosage at an FNA concentration of 0.26 mg-N/L every 5 days can reduce the average sulfide production by >80%. Economic analysis showed that intermittent FNA dosage is potentially a cost-effective strategy for sulfide and methane control in sewers.

Controlled and stochastic retention concentrates dynein at microtubule ends to keep endosomes on track

Bidirectional transport of early endosomes (EEs) involves microtubules (MTs) and associated motors. In fungi, the dynein/dynactin motor complex concentrates in a comet-like accumulation at MT plus-ends to receive kinesin-3-delivered EEs for retrograde transport. Here, we analyse the loading of endosomes onto dynein by combining live imaging of photoactivated endosomes and fluorescent dynein with mathematical modelling. Using nuclear pores as an internal calibration standard, we show that the dynein comet consists of ∼55 dynein motors. About half of the motors are slowly turned over (T(1/2): ∼98 s) and they are kept at the plus-ends by an active retention mechanism involving an interaction between dynactin and EB1. The other half is more dynamic (T(1/2): ∼10 s) and mathematical modelling suggests that they concentrate at MT ends because of stochastic motor behaviour. When the active retention is impaired by inhibitory peptides, dynein numbers in the comet are reduced to half and ∼10% of the EEs fall off the MT plus-ends. Thus, a combination of stochastic accumulation and active retention forms the dynein comet to ensure capturing of arriving organelles by retrograde motors.

Diameter dependence of oxidative stability in multiwalled carbon nanotubes: Role of defects and effect of vacuum annealing

While the oxidative stability of single walled carbon nanotubes has been studied extensively, very little is known about the diameter dependence of oxidative stability in multiwalled carbon nanotubes (MWNTs) and the effect of vacuum annealing on such stability. We have investigated six sets of samples with different diameters in the range of 5–100 nm systematically by thermogravimetric analysis (TGA) before and after vacuum annealing. High resolution transmission electron microscopy studies provide evidence for structural defects in the nanotube walls. Further, it reveals that with increasing diameter, interlayer d-spacing between concentric tubes decreases. Experimental TGA profile is found to constitute multiple components of oxidation as revealed from reverse Sigmoidal fitting. Analysis of the TGA profile shows that the oxidation temperature follows an exponential recovery function with increasing diameter, while width of the differentiated TGA spectra decreases. It is shown that oxidative stability of lower diameter MWNTs are primarily controlled by lattice strain, while that of large diameter MWNTs is decided by the defects in the nanotube wall. High vacuum annealing studies in the temperature range 300–1000 °C show major improvement in the structure and oxidative stability for MWNTs annealed at 500 °C. Results are compared with those of the single walled nanotubes. The observed diameter dependence is explained on the basis of strain in the nanotube lattice and defects in the nanotube walls.

Neural Response Telemetry Reconsidered: II. The Influence of Neural Population on the ECAP Recovery Function and Refractoriness

The Neural Response Telemetry (NRT) recovery function measures the electrically evoked compound action potential (ECAP) in response to a second biphasic pulse (the probe) after masking by a first pulse (the masker). The masker-probe interval is varied and the ECAP amplitude is measured at each masker-probe interval, giving an inverse exponential recovery. The prevailing understanding of the recovery function has been that faster recovery indicates a more efficient response to the individual pulses within a pulse sequence. Psychophysical data in the past have not supported this view, and in fact, the opposite result has been observed. This study explores this phenomenon from theoretical and experimental viewpoints. Fundamentally, a distinction is made between the refractoriness of a single fiber and the refractoriness of the whole nerve. The hypothesis is that the size of the neural population heavily influences whole nerve refractoriness: large neural populations operate near threshold and are more susceptible to masking, leading to slower ECAP recovery; however, they maintain temporal responsiveness through greater numbers of nonrefractory neurons. In phase I, the hearing loss durations (indicators of neural survival) of 21 adult Nucleus Freedom implantees were compared with the corresponding median recovery function time-constants (calculated per implant array). The data were separated by implant (nine Contour, 12 Straight) and the means of these two groups were compared. The Straight array, delivering broader excitation, is expected to engage a larger neural population. In phase II, a computational model of the ECAP recovery function was constructed based on data from the cat auditory nerve. The model allows the neural population size to be manipulated; accordingly, recovery functions from different neural populations were compared. In phase III, ECAP thresholds (via AutoNRT), ECAP recovery functions, and T- and C-levels were obtained from a subset of 12 subjects. Psychophysical levels were measured using pulse train stimuli at six different stimulation rates, spanning 250 to 3500 Hz. At each electrode, the recovery function time-constant tau was compared with two measures of temporal responsiveness: (i) the gradient of the linear trend in psychophysical levels with stimulation rate; and (ii) the difference between ECAP threshold (a single pulse measure) and 900 Hz T-level (a pulse train measure). In phase I, a trend toward shorter recovery function time-constants with increasing hearing loss durations was observed. The mean recovery function time-constant of the Contour implant group (0.51 msec) was significantly shorter than that of the Straight implant group (0.90 msec). When, in phase II, the recovery functions from the computational model were compared at equal ECAP amplitude, the larger neural population was associated with slower ECAP recovery. In phase III, the recovery function time-constant was significantly correlated with both temporal responsiveness measures, with slower ECAP, recovery associated with greater temporal responsiveness, thus confirming the results of previous studies. : Slower ECAP recovery, at equal loudness, is associated with larger neural populations. The collective results suggest that this neural population view of the recovery function explains the observed association between slower ECAP recovery and greater temporal responsiveness.

Locomotor function after long-duration space flight: effects and motor learning during recovery

Astronauts returning from space flight and performing Earth-bound activities must rapidly transition from the microgravity-adapted sensorimotor state to that of Earth's gravity. The goal of the current study was to assess locomotor dysfunction and recovery of function after long-duration space flight using a test of functional mobility. Eighteen International Space Station crewmembers experiencing an average flight duration of 185 days performed the functional mobility test (FMT) pre-flight and post-flight. To perform the FMT, subjects walked at a self selected pace through an obstacle course consisting of several pylons and obstacles set up on a base of 10-cm-thick, medium-density foam for a total of six trials per test session. The primary outcome measure was the time to complete the course (TCC, in seconds). To assess the long-term recovery trend of locomotor function after return from space flight, a multilevel exponential recovery model was fitted to the log-transformed TCC data. All crewmembers exhibited altered locomotor function after space flight, with a median 48% increase in the TCC. From the fitted model we calculated that a typical subject would recover to 95% of his/her pre-flight level at approximately 15 days post-flight. In addition, to assess the early motor learning responses after returning from space flight, we modeled performance over the six trials during the first post-flight session by a similar multilevel exponential relation. We found a significant positive correlation between measures of long-term recovery and early motor learning (P < 0.001) obtained from the respective models. We concluded that two types of recovery processes influence an astronaut's ability to re-adapt to Earth's gravity environment. Early motor learning helps astronauts make rapid modifications in their motor control strategies during the first hours after landing. Further, this early motor learning appears to reinforce the adaptive realignment, facilitating re-adaptation to Earth's 1-g environment on return from space flight.

29 glitches detected at Urumqi Observatory

Glitches detected in pulsar timing observations at the Nanshan radio telescope of Urumqi Observatory between 2002 July and 2008 December are presented. In total, 29 glitches were detected in 19 young pulsars, with this being the first detection of a glitch in 12 of these pulsars. Fractional glitch amplitudes range from a few parts in 10−11 to 3.9 × 10−6. Three ‘slow’ glitches are identified in PSRs J0631+1036, B1822−09 and B1907+10. Post-glitch recoveries differ greatly from pulsar to pulsar and for different glitches in the same pulsar. Three small glitches in PSRs B0402+61, B0525+21 and J1853+0545 show evidence for normal post-glitch recovery, but for PSRs B0144+59 and B2224+65 the spin frequency ν continually increases relative to the pre-glitch solution for hundreds of days after their small glitches. Most large glitches show some evidence for exponential post-glitch recovery on time-scales of 100–1000 d, but in some cases, e.g. PSR B1758−23, there is little or no recovery, i.e. no detectable increase in at the time of the glitch. Beside exponential recoveries, permanent increases in slowdown rate are seen for the two large glitches in PSRs B1800−21 and B1823−13. These and several other pulsars also show a linear increase in following the partial exponential recovery, which is similar to the Vela pulsar post-glitch behaviour. However, the rate of increase, ⁠, is an order of magnitude less than for the Vela pulsar. We present improved positions for 14 of the glitching pulsars. Analysis of the whole sample of known glitches shows that fractional glitch amplitudes are correlated with characteristic age with a peak at about 105 yr, but there is a spread of two or three orders of magnitude at all ages. Glitch activity is positively correlated with spin-down rate, again with a wide spread of values. For some (but not all) pulsars, there is a correlation between glitch amplitude and the duration of the following interglitch interval. In no case is there a correlation of glitch amplitude with the duration of the preceding interglitch interval.