Recovery Latency Research Articles

Reliable multicast using adaptive caching

AbstractIn this paper, we present a detailed description of the Reliable Multicast using Adaptive Caching (RMAC) system and protocol, and describe its performance evaluation. From the idea that support based on functional processing in the network is essential to efficiently perform reliable multicast, routers that process the RMAC protocol are introduced by RMAC. RMAC can improve retransmission efficiency by packet caching and retransmission at the routers. The required cache size can be decreased by distributing the caching among the routers to adapt to the congestion. The performance evaluation by a simulation showed that RMAC has lower recovery latency compared to conventional techniques and improved scalability with respect to the number of receivers. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(10): 89–99, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1179

Active resource allocation for active reliable multicast

Local loss recovery for reliable multicast can provide significant performance improvement in terms of loss recovery latency, bandwidth consumption and network throughput. Active reliable multicast (ARM) is a novel loss recovery scheme for large-scale reliable multicast. When sufficient active resources of active routers (ARs) and associated cache are available, ARM gives good loss recovery latency performance. The authors build an analytical model for studying the optimal active resource allocation for ARM. They propose a top-down layering analysis (TDLA) approach to derive the expected loss recovery latency (ELRL). For a given multicast tree, the ELRL is derived as a function of the active resource allocation pattern. Simulation experiments reveal that high performance gains can be attained with limited active resources, which are properly allocated. It is also shown that simulation results have a good match with the analytical results. The analytical framework developed can be used for further investigation of various active resource allocation schemes and caching policies.

A prototype of a VHDL-based fault injection tool: description and application

This paper presents the prototype of an automatic and model-independent fault injection tool, to be used on an IBM-PC (or compatible) platform. The tool has been built around a commercial VHDL simulator and it is thought to implement different fault injection techniques. With this tool, a wide range of transient and permanent faults can be injected into medium-complexity models. Another remarkable aspect of the tool is the fact that it can analyse the results obtained from injection campaigns, in order to study the Error Syndrome of the system model and/or validate its fault-tolerance mechanisms. Some results of various fault injection campaigns carried out to validate the Dependability of a fault-tolerant microcomputer system are shown. We have analysed the pathology of the propagated errors, measured their latencies, and calculated both error detection and recovery latencies and coverages.

Phasic Pupil Dilation Response to Noxious Stimulation

Abstract The pupil dilation response (PDR) to a painful stimulus is a subtle, event-related increase in pupil diameter that occurs following brief noxious stimulation. It varies in amplitude with increasing stimulus intensity. Two competing hypotheses for the PDR are that (1) it reflects event-related cognitive efforts largely independent of pain, such as the task demand of discriminating intensity and readying a subjective report; and (2) like the pupillary light reflex, it is a simple reflexive response. In this study 21 subjects (11 male, 10 female) experienced painful stimuli matched in subjective intensity at two sites: finger tip and ear lobe, but they produced no subjective reports. If the PDR is a product of discriminating stimulus intensity levels and forming a report, then it should be minimal or nonexistent when subjects have no choices and make no overt judgments. On the other hand, if it is primarily a simple sympathetic reflex, then onset and peak latency should be longer for finger tip than for ear lobe stimulation because the conduction distance is longer. In addition to addressing these issues, we explored sex differences and the influence of age. Clear and similar PDRs appeared in response to stimulation of both sites despite an absence of subjective report requirements. PDR onset, peak amplitude and peak latency did not differ significantly across stimulation sites. Therefore, the PDR is neither an artifact of subjective report nor an uncomplicated sympathetic reflex. It appears to be an emotional arousal response, such as the defense response, the strength of which depends upon the magnitude of the noxious sensory input. Sex differences emerged, with women demonstrating a borderline larger PDR peak amplitude than men (P = .059) and a more rapid half recovery latency (P = .031). Age did not affect the PDR except at onset, with older subjects demonstrating a later onset latency (P = .003). The PDR may reflect preconscious processing associated with attention and perhaps other cognitive aspects of perception.

Two-year syndromal and functional recovery in 219 cases of first-episode major affective disorder with psychotic features.

Psychotic affective disorders are the most prevalent idiopathic psychoses, but their outcome from onset has rarely been studied. In this study, the authors determined the rate and latency of syndromal recovery and rates of functional recovery after first lifetime hospitalization in patients with first-episode psychotic affective disorders. From first lifetime hospitalization in 1989-1996, 219 patients with a DSM-IV psychotic affective illness were assessed at intervals over 24 months. Time to syndromal recovery (no longer meeting DSM-IV episode criteria) was assessed by survival analysis, and functional recovery (regaining baseline vocational and residential status) was rated. Factors associated with recovery were identified by bivariate and multivariate methods. By 3, 6, 12, and 24 months after first hospitalization, syndromal recovery was attained by 65.1%, 83.7%, 91.1%, and 97.5%, respectively, of subjects. Time to syndromal recovery (6.1 weeks to 50% of subjects recovered) was shorter for patients who had bipolar disorder, were married, were age 30 or older at onset, lacked comorbidity, required relatively brief hospitalization, and received fewer medicines. Functional recovery by 6 (30.4%) and 24 months (37. 6% of patients) was 2.6-2.7 times less likely than syndromal recovery; 63.1% of those recovering syndromally did not recover functionally by 2 years. Functional recovery was associated with older age at onset and shorter hospitalization. Annual recovery rates remained stable as mean hospital length of stay decreased 3. 6-fold over the 8-year study period. Syndromal recovery was attained by most psychotic affective disorder patients soon after hospitalization, but only one-third recovered functionally by 24 months. The findings suggest that these very common psychotic illnesses can carry a grave functional prognosis from the initial episode and first hospitalization.

Scalable fair reliable multicast using active services

Scalability is of paramount importance in the design of reliable multicast transport protocols, and requires careful consideration of a number of problems such as feedback implosion, retransmission scoping, distributed loss recovery, and congestion control. In this article, we present a reliable multicast architecture that invokes active services at strategic locations inside the network to comprehensively address these challenges. Active services provide the ability to quickly and efficiently recover from loss at the point of loss. They also exploit the physical hierarchy for feedback aggregation and effective retransmission scoping with minimal router support. We present two protocols, one for packet loss recovery and another for congestion control, and describe an experimental testbed where these have been implemented. Analytical and experimental results are used to demonstrate that the active services architecture improves resource usage, reduces latency for loss recovery, and provides TCP-friendly congestion control.

Midlatency somatosensory evoked potentials and explicit memory functions during recovery from propofol/sufentanil anaesthesia

Adequate anaesthesia and avoiding awareness in patients is of major concern for anaesthesiologists during anaesthesia. In a prospective study midlatency somatosensory evoked potentials (SEP) were investigated in relation to explicit memory function during recovery from propofol/sufentanil anaesthesia. After approval of the local Ethics Committee and written informed consent 20 patients (43 ± 12 years, 71 ± 14 kg, ASA I-II) were included in the study. Anaesthesia was induced with 0.5 μg/kg sufentanil, 2 mg/kg propofol and 0.1 mg/kg vecuronium. After endotracheal intubation and normo-ventilation with FiO2 0.3 anaesthesia was maintained with 8 mg/kg/h propofol. SEPs were recorded at Erb, C6 and C4' (N20, P25, N35, P45, N50) following electrical stimulation of the median nerve (3 Hz, intensity of twofold motor threshold, 200/average, bandwidth 0.02–2 kHz). SEP recordings were performed the day before surgery (AWAKE) and during recovery from anaesthesia, until patients were able to identify a shown object (RECOVERY). Monitoring included HR, MAP, PetCO2, SaO2, arm and body temperature. The day after surgery patients were interviewed about their memory of the recovery period and classified into two groups: group 1, no memory; group 2, memory for recovery period. Statistics: Student t-test with P < 0.05 significant. Patients were able to identify a shown object 26 ± 7 min after the end of anaesthesia (RECOVERY). One day after anaesthesia nine patients did remember events during the recovery period (group 2), while 11 patients did not have any memory (group 1). At RECOVERY latencies P45 (45 ± 6 versus 51 ± 4 ms) and N50 (64 ± 12 versus 78 ± 9 ms) were significantly shorter in the patients of group 2 than in group 1 (P < 0.05). The earlier midlatency SEP components and amplitudes did not differ between the two groups. In conclusion reversal of anaesthesia induced SEP changes of latencies P45 and N50 may indicate recovery of explicit memory functions after anaesthesia. Figure Means and SD of SEP latencies 26 ± 6 min after anaesthesia.*P < 0.05 between patients with (group 2) or without memory (group1) for recovery period after 24 h; n = 20 patients.

Age-dependent differences in sensitivity to aconitine of rat hippocampal slices

The effect of aconitine, a plant alkaloid known to bind at site 2 of the sodium channel, was investigated on neuronal excitability in hippocampal slices of adult and juvenile rats. Aconitine (0.01–1 μM) diminished the extracellularly recorded population spike in a concentration-dependent manner. At each concentration, the inhibitory action of aconitine was significantly stronger and was obtained after a shorter latency in slices of juvenile rats (20–25 days) as compared with slices of adult rats (45–50 days). When maximal inhibition was achieved, a prolonged application of aconitine evoked an increase in spike amplitude of up to 15% in slices of juvenile but not of adult rats. The latency of recovery from the aconitine-induced inhibition was also significantly shorter in slices of juvenile rats. This effect was concentration-dependent and significantly stronger in slices of juvenile rats. These observations indicate that juvenile hippocampi have a higher susceptibility to the effect of aconitine, but also provide a partial protective mechanism.

Age-dependent differences in sensitivity to aconitine of rat hippocampal slices

The effect of aconitine, a plant alkaloid known to bind at site 2 of the sodium channel, was investigated on neuronal excitability in hippocampal slices of adult and juvenile rats. Aconitine (0.01–1 μM) diminished the extracellularly recorded population spike in a concentration-dependent manner. At each concentration, the inhibitory action of aconitine was significantly stronger and was obtained after a shorter latency in slices of juvenile rats (20–25 days) as compared with slices of adult rats (45–50 days). When maximal inhibition was achieved, a prolonged application of aconitine evoked an increase in spike amplitude of up to 15% in slices of juvenile but not of adult rats. The latency of recovery from the aconitine-induced inhibition was also significantly shorter in slices of juvenile rats. This effect was concentration-dependent and significantly stronger in slices of juvenile rats. These observations indicate that juvenile hippocampi have a higher susceptibility to the effect of aconitine, but also provide a partial protective mechanism.

Desynchronization and recovery of β rhythms during brisk and slow self-paced finger movements in man

Event-related desynchronization (ERD) and recovery of EEG β rhythms (15–26 Hz) were studied during slow and brisk self-paced index finger extension and flexion. β rhythms started to recover earlier in brisk movements. Brisk movements showed no correlation between duration of EMG burst in the extensor muscle and the latency of recovery whereas slow movements did. In contrast to β-ERD which was widespread, the recovery and rebound of β rhythms occurred in a circumscribed focus close to the hand MI area.

Recovery latency analysis in younger and older adults: Role of advance information

Recovery latency is typically defined as the time taken to recover from a previous trial in a reaction‐time paradigm. Across two experiments, it was found that (a) older adults, compared to younger adults, were more likely to have increases in recovery latency and (b) these increases were dependent upon the type of advance information (i.e., prime) presented.

ラットの脳幹部と内耳における血流調節能の検討 自動調節

We studied autoregulation in the brainstem and the inner ear. Using laser-Doppler flowmetry, we measured brainstem blood flow (BBF) and cochlear blood flow (CoBF) with BP alteration in rats. With induced hypotension by exsanguination above the critical BP level, BBF tended to be preserved supposing the existence of autoregulation. Although CoBF was slightly decreased, a nonlinear relationship to BP also suggested the effect of autoregulation. When BP was raised by reinfusion, after a large temporary increase and recovery, BBF and CoBF showed small increases, and the fact also suggested the existence of autoregulation. The latency of recovery from a temporary increase in BBF was shorter than that in CoBF. These results supposed that both the brainstem and the inner ear showed autoregulation of blood flow, and the efficiency of regulation in the brainstem was superior to that in the inner ear.

Rehabilitation after severe head injury.

123 survivors of severely head injured patients presenting with coma grade III show a decreasing mean duration of coma with increasing age. The numbers and frequency of good recovery decrease, whereas poor recovery increases with age. Increase of the duration of coma grade III produces an increase of the mean latency and time of recovery and of the frequency of poor recovery, regardless of the age of the patients. Increasing age does not increase the mean latency and time of recovery systematically. The important conclusion of this analysis is, that the clinical feature of coma grade III, corresponding to GCS score of 4 and RLS of 6 and 7, indicates a different kind of brain damage at various age groups. It represents a lesser degree of brain damage for younger patients under 20, than for those over 20. In our opinion our observations do not demonstrate a better capacity of recovery of the young patients: but the young patients show a more severe clinical picture than the older patients do, if only the clinical syndrome of coma grade III with extensor rigidity, is considered as a yardstick for comparison.

Repetitive ischaemia of cat brain: pathophysiological observations

The cumulative effect of repetitive ischaemia on brain injury was studied in halothane-anaesthetized cats submitted to three episodes of global cerebro-circulatory arrest. Ischaemia of 5.0, 7.5 and 10.0 min duration was produced at hourly intervals by intrathoracic clamping of the innominate and subclavian arteries, and the resulting pathophysiological changes were evaluated by recordings on the electroencephalogram (EEG), blood flow and specific gravity. During each episode of ischaemia EEG flattened within 15 s. After ischaemia the latency of EEG recovery increased with the duration and with the number of repetitions of each ischaemic episode, indicating cumulation of electrophysiological impairment. The flow studies revealed a minor degree of hyperaemia after each ischaemic episode, followed by severe hypoperfusion in the caudate nucleus but not in the cerebral cortex. Brain oedema - as assessed by specific gravity measurements - developed in the hippocampus after three episodes of 5 min ischaemia, and in all grey matter structures investigated after three episodes of 10 min ischaemia. To evaluate the resistance of the ischaemically injured brain to respiratory hypoxia, total oxygen was repeatedly reduced to 5% for 5 min. During these episodes EEG activity progressively declined as a function of the length and the repetition of ischaemia. Parallel n.m.r. spectroscopic measurements in the same model have demonstrated that disturbances of brain energy state during the hypoxic episodes are minor even after three episodes of 10 min ischaemia. EEG suppression, in consequence, is an electrical shut-down phenomenon for the maintenance of cerebral energy state under critical conditions of oxygen delivery.

Cadmium exposure results in decreased responsiveness to ethanol

Adult male Sprague-Dawley rats were maintained on an ad lib diet containing 100 ppm cadmium (Group Cadmium-Diet) or a control diet with no added cadmium. On Day 61, all animals (N = 10/group) were challenged with a single hypnotic dose of ethanol (3.5 g/kg IP), prepared from a 20% v/v solution of tap water and a stock solution of 95% ethanol. The latency from the time of the injection until the loss of the righting reflex was recorded, as well as the latency for recovery of the reflex. The results showed a nonsignificant trend for animals exposed to cadmium to lose the righting reflex less rapidly than controls, and Cadmium-Diet animals regained the righting reflex significantly more rapidly than controls. These findings suggest that the pharmacologic effectiveness of ethanol is altered by chronic exposure to dietary cadmium. The implications of these data for other studies of cadmium/ethanol interactions are discussed.

Enhanced P3 evoked potentials and longer P3 recovery times in psychopaths.

ABSTRACTA recent study by Raine and Venables (1987) reported increased P3 amplitudes in antisocial adolescents, a replicable result indicating enhanced processing of task‐relevant events. The present study assesses whether adult psychopaths similarly show enhanced P3 amplitudes; latency of P3 recovery to baseline was also measured to assess Jutai et al.'s (1987) finding of sustained late positivity in psychopaths. EPs were measured at T3, T4, P3, and P4 to targets and nontargets during a continuous performance task in 14 psychopathic and 14 nonpsychopathic top‐security prisoners. Psychopaths showed larger P3 amplitudes to targets relative to nontargets at parietal but not temporal sites, and larger P3 recovery times. Psychopaths also scored higher on WAIS subtests sensitive to parietal lobe functioning but not on non‐parietal subtests. No laterality effects were uncovered to support a left hemisphere dysfunction theory of psychopathy. It is argued that this evidence for proficient information‐processing on parietal‐related tasks may underlie clinical reports of enhanced short‐term attentional ability in psychopaths.

Recovery of the electrocorticogram after incomplete and complete ischaemia of the brain

Incomplete cerebral ischaemia of 10 to 60 minutes duration was performed by reducing the perfusion pressure of completely isolated canine heads at brain temperatures of 37 and 32 degrees C. Complete cerebral ischaemia of the same duration was performed by complete stopping of the perfusion. The latency of recovery of the electrocorticogram, i.e. the time interval from the end of the cerebral ischaemia until reappearance of the first spontaneous cortical potentials, was shorter after incomplete ischaemia than after complete ischaemia. At 37 degrees C brain temperature the latency of recovery of the electrocorticogram was zero after a perfusion of the brain with a perfusion pressure of 22 mm Hg for 1 hour. After an incomplete ischaemia of 1 hour produced by a perfusion pressure of 20 mm Hg the latency of recovery was 0 to 4 minutes. Lower perfusion pressures increased the latency of recovery considerably. Reduction of brain temperature to 32 degrees C decreased the latency of recovery. At perfusion pressures of 22 mm or more there was no difference in the latency of recovery between 37 and 32 degrees C brain temperature.

Suppression of auditory nerve discharges by a contralateral stimulus

Single‐unit activity was recorded from the cochlear nerve of cats immobilized by Flaxédil. The ipsilateral ear was just above threshold; the contralateral stimulus was the same except the intensity was varied. Most neurons responded to strong contralateral tones as well as to the ipsilateral stimulus. When the stimuli to the two ears were presented simultaneously the response clearly showed direct mechanical interaction between the two sounds in the ipsilateral cochlea. In addition, for a few neurons an intense contralateral stimulus suppressed more or less completely the response to ipsilateral sound as well as the spontaneous activity. The latency and time course of suppression and recovery from it were too slow to be due to monaural two‐tone suppression, but seemed to resemble those of the inhibition induced by electrical stimulation of the crossed olivo‐cochlear bundle beneath the floor of the 4th ventricle.

Pentobarbital inhibition of progesterone-induced behavioral estrus in ovariectomized guinea pigs

Administration of pentobarbital inhibits the facilitatory effects of progesterone on the release of gonadotropins. In this experiment facilitatory effects of progesterone on lordosis behavior in guinea pigs were examined with pentobarbital anesthesia. Two major animal groups were subjects: one was short-term ovariectomized (2 weeks) and the other was long-term ovariectomized (several months). All animals received estradiol benzoate (6.6 mug s.c.) followed by progesterone (0.4 mg s.c.) 40 h later. Lordosis behavior was induced by the manual stimulation method of Young et al.29 Sodium pentobarbital (30 mg/kg) was injected 8,4 or 2 h before, simultaneously or 1, 2, 6, or 7 h after progesterone. Animals which received pentobarbital slept for 4.5-5 h with subsequent drowsiness for an additional 0.5-1 h. Pentobarbital injections given 8 h before progesterone had no effect on latency to the first lordosis or on other parameters of estrous behavior. However, pentobarbital delayed the onset of heat in estrogen treated ovariectomized guinea pigs when given 4 h before, 2 h before, or simultaneously with progesterone. The delay was directly related to the length of time the animals remained asleep after the progesterone injection, since estrous behavior was invariably displayed with the latency of controls after the animal awoke. Moreover, in animals which were awake for 1-2 h immediately after the progesterone injection before receiving pentobarbital, the latency of recovery from anesthesia to the first display of lordosis was about 1-1.5 h shorter than in the other pentobarbital groups. In contrast to the latency effects of pentobarbital, the duration of heat was unaffected by the anesthetic for all groups mentioned. In animals which received pentobarbital after they were already in heat, pentobarbital injection terminated heat and abolished it completely, since lordosis behavior was not displayed in the hours after recovery from anesthesia. Gross hypothalamic uptake of progesterone was not influenced by pentobarbital administration. Thus, it is tentatively concluded that an incubation period is necessary for progesterone to mediate the display of estrous behavior in the guinea pig in addition to the time necessary for neural uptake. The way in which pentobarbital interferes with the period of progesterone incubation is not currently known.

The recovery of the electrocorticogram of normothermic canine brains after complete cerebral ischemia.

Complete cerebral ischaemias of 1 to 30 min duration were performed under normothermic conditions in completely isolated canine heads perfused from a donor dog. The electrocorticogram was found to return in the reperfusion period following these complete ischaemias. The latency of recovery, i.e. the interval between the end of the complete cerebral ischaemia and the reappearance of the first cortical potentials, increased with increasing duration of the complete cerebral ischaemia; thus, the latency of recovery after a complete ischaemia of 30 min amounted to 11 to 12 hours.