OBJECTIVE

We examined the effects of movement interference on high-frequency oscillations (HFOs) and N20m in 10 healthy subjects.

METHODS

For the movement interference condition, somatosensory evoked magnetic fields (SEFs) following electric median nerve stimulation were recorded during voluntary movement of the digits. For the control condition, the SEFs were recorded without interference. The N20m and HFOs were separated by 3-300Hz and 300-900Hz bandpass filtering. Then, the peak-to-peak amplitudes were measured.

RESULTS

Both interference/control amplitude ratios for the N20m and HFOs were smaller than 100%. In contrast, the HFO/N20m amplitude index, which was calculated by dividing the interference/control amplitude ratio for the HFOs with that for the N20m, was significantly greater in the movement interference condition than in the control condition.

CONCLUSIONS

Although the overall amplitude of the HFOs was decreased by movement, enhancement of the HFOs by the movement was revealed by the HFO/N20m amplitude index. Thus, we suggest that the HFOs represent activity of the inhibitory interneurons excited by both thalamocortical afferent impulses and excitatory synaptic inputs from pyramidal neurons in area 3b through their local axon collaterals, thereby reflecting both feed-forward and feedback inhibitory effects onto the post-synaptic pyramidal neurons.

The present study examined whether both vowel-shortening and vowel-lengthening violations would elicit a semantic field component in native speakers of Japanese, and whether such a component would also be observed in phonemic violations. Stimuli contained semantically correct and incorrect versions of two types of vowel duration (shortening and lengthening), and semantically deviant words with phonemic violations. Five hundred Japanese sentences were aurally presented to each subject, while neuromagnetic fields were recorded using a dual 37-channel gradiometer system. A prominent magnetic field component, peaking at around 400 ms after the onset of the target word, was elicited by vowel-shortening and phonemic violations in the left hemisphere only, but not vowel-lengthening violations. This semantic field component was labeled the 'SeF-M400'. The results suggest that auditory semantic mechanism is more sensitive to vowel-shortening violations than to vowel-lengthening violations.

Pulsed field gradient (PFG) diffusion measurement has a lot of applications in NMR and MRI. Its analysis relies on the ability to obtain the signal attenuation expressions, which can be obtained by averaging over the accumulating phase shift distribution (APSD). However, current theoretical models are not robust or require approximations to get the APSD. Here, a new formalism, an effective phase shift diffusion (EPSD) equation method is presented to calculate the APSD directly. This is based on the idea that the gradient pulse effect on the change of the APSD can be viewed as a diffusion process in the virtual phase space (VPS). The EPSD has a diffusion coefficient, K(β)(t)D rad(β)/s(α), where α is time derivative order and β is a space derivative order, respectively. The EPSD equations of VPS are built based on the diffusion equations of real space by replacing the diffusion coefficients and the coordinate system (from real space coordinate to virtual phase coordinate). Two different models, the fractal derivative model and the fractional derivative model from the literature were used to build the EPSD fractional diffusion equations. The APSD obtained from solving these EPSD equations were used to calculate the PFG signal attenuation. From the fractal derivative model the attenuation is exp(-γ(β)g(β)δ(β)Df1t(α)), a stretched exponential function (SEF) attenuation, while from the fractional derivative model the attenuation is Eα,1(-γ(β)g(β)δ(β)Df2t(α)), a Mittag-Leffler function (MLF) attenuation. The MLF attenuation can be reduced to SEF attenuation when α=1, and can be approximated as a SEF attenuation when the attenuation is small. Additionally, the effect of finite gradient pulse widths (FGPW) is calculated. From the fractal derivative model, the signal attenuation including FGPW effect is exp[ -Df1∫0(τ) K(β)(t)dt(α)]. The results obtained in this study are in good agreement with the results in literature. Several expressions that describe signal attenuation have not been reported and that can be of great importance for the PFG experiments. This EPSD equation method provides a new, simple path to calculate signal attenuation of PFG NMR experiments.

Using a low-noise 49-channel dc-SQUID system spinal somatosensory evoked fields (SEF) were recorded which were generated by compound action currents evoked upon posterior tibial nerve stimulation. The SEF mapping showed the action current propagation along the sciatic nerve, lumbosacral plexus and cauda equina in parallel to simultaneously recorded electrical potentials (SEP). For a reliable intraindividual side-to-side comparison of spinal SEFs the right and left tibial nerves were stimulated in alternating order; this procedure minimizes artifactual inter-nerve SEF map differences due to eventual patient-to-sensor displacements which might occur in serial measurements. These large-area lumbar SEF mappings open up several clinical perspectives for magnetoneurography, in particular with respect to the 3D-localization of proximal conduction blocks.

Our previous demonstration that the M100 somatosensory evoked magnetic field (SEF) has a similar temporal profile, dipole orientation and source location whether induced by activation (ON-M100) or deactivation (OFF-M100) of electrical stimulation suggests a common cortical system to detect sensory change. While we have not recorded such change-driven components earlier than M100 using electrical stimulation, clear M50 responses were reported using both ON and OFF mechanical stimulation (Onishi et al. in Clin Neurophysiol 121:588-593, 2010). To examine the significance of M50 and M100 in reflecting the detection of somatosensory changes, we recorded these waveforms in 12 healthy subjects (9 males and 3 females) by magnetoencephalography in response to mechanical stimulation from a piezoelectric actuator. Onset and offset (ON and OFF) stimuli were randomly presented with three preceding steady state (PSS) durations (0.5, 1.5 and 3 s) in one consecutive session. Results revealed that (i) onset and offset somatosensory events elicited clear M50 and M100 components; (ii) M50 and M100 components had distinct origins, with M50 localised to the contralateral primary somatosensory cortex (cS1) and M100 to the bilateral secondary somatosensory cortex (iS2, cS2); and (iii) the amplitude of M50 in cS1 was independent of the PSS durations, whereas that of M100 in S2 was dependent on the PSS durations for both ON and OFF events. These findings suggest that the M50 amplitude in cS1 reflects the number of activated mechanoreceptors during Onset and Offset, whereas the M100 amplitude in S2 reflects change detection based on sensory memory for Onset and Offset stimuli at least in part. We demonstrated that the M50 in cS1 and M100 in S2 plays different roles in the change detection system in somatosensory modality.

It is widely accepted that the supplementary eye fields (SEF) are involved in the control of voluntary eye movements. However, recent evidence suggests that SEF may also be important for unconscious and involuntary motor processes. Indeed, Sumner et al. ([2007]: Neuron 54:697-711) showed that patients with micro-lesions of the SEF demonstrated an absence of subliminal inhibition as evoked by masked-prime stimuli. Here, we used double-pulse transcranial magnetic stimulation (TMS) in healthy volunteers to investigate the role of SEF in subliminal priming. We applied double-pulse TMS at two time windows in a masked-prime task: the first during an early phase, 20-70 ms after the onset of the mask but before target presentation, during which subliminal inhibition is present; and the second during a late phase, 20-70 ms after target onset, during which the saccade is being prepared. We found no effect of TMS with the early time window of stimulation, whereas a reduction in the benefit of an incompatible subliminal prime stimulus was found when SEF TMS was applied at the late time window. These findings suggest that there is a role for SEF related to the effects of subliminal primes on eye movements, but the results do not support a role in inhibiting the primed tendency. Hum Brain Mapp 38:339-351, 2017. © 2016 Wiley Periodicals, Inc.

Another academic year is underway, and schools in England can again choose whether or not to teach sex and relationships education (SRE). The evidence in favour of making SRE a requirement in all schools is stacked higher than ever. One girl in four starts her period before she has learned about it, and 38% of boys do not learn anything about wet dreams before they experience them ( Sex Education Forum (SEF) 2016a ), which shows that even biological aspects of SRE are falling short.

With the development of the ultra high voltage transmission technology, the voltage level of transmission line rised. Accordingly, the strength of electric field in the vicinity of transmission line increased, thus possible health effects from electric field have caused many public attentions. In this study, in order to compare effects induced by static electric field (SEF) and power frequency electric field (PFEF) on immune function, Institute of Cancer Research (ICR) mice were exposed to 35 kV/m SEF (0 Hz) and PFEF (50 Hz),respectively. Several indicators of white blood cell, red blood cell as well as hemoglobin in peripheral blood were tested after exposure of 7, 14 and 21 days, respectively. There was no significant difference in any indicators under SEF exposure of 35 kV/m for 7d, 14d and 21d between experimental group and control group. Under the PFEF exposure of 35 kV/m, white blood cell count significantly reduced after exposure of 7d, 14d and 21d. Meanwhile, red blood cell count significantly reduced after exposure of 7d, and returned to normal level through the compensatory response of organism after exposure of 14d and 21d. Hemoglobin concentration significantly decreased only after exposure of 21d. Based on tested results of hematological indicators, SEF exposure of 35 kV/m did not affect immune functions in mice but PFEF exposure of 35 kV/m could cause a decline of immune function. This difference of effects from SEF and PFEF on immune function was possibly caused by the difference of the degree of molecular polarization and ion migration in organism under exposure of two kinds of electric fields.

3-D magnetic measurements of the bilateral somatosensory evoked fields (SEFs) by electric stimulus to the right thumb for four normal subjects were carried out, using a three-dimensional (3-D) second-order gradiometer connected to 39-channel SQUIDs, which can detect magnetic field components perpendicular to the scalp (Br) and tangential to the scalp (Btheta, Bphi) simultaneously. To discuss the relationship between the phase lag and stimulus repetition frequency (SRF), the delay times of a component synchronous with the SRFs (1.99 to 27.02 Hz) were calculated by the convolution of the reference signal and the SEF wave (BPF: 15-40 Hz). The phase lag characteristic to the SRF in the contralateral hemisphere to the stimulus was linear in the ranges below 8 Hz and above 8 Hz in all magnetic components. The phase lag characteristic of the ipsilateral hemisphere to the stimulus was linear in only below-8 Hz in all components. It was tested for significance of the linear regression slope (beta not = 0, P<0.05).

BACKGROUND

Hypoxia has been shown to change electroencephalogram parameters including frequency and amplitude, and may thus change bispectral index (BIS) and spectral entropy values. If hypoxia per se changes BIS and spectral entropy values, BIS and spectral entropy values may not correctly reflect the depth of anaesthesia during hypoxia. The aim of this study was to examine the changes in BIS and spectral entropy values during hypobaric hypoxia in volunteers.

METHODS

The study was conducted in a high-altitude chamber with 11 volunteers. After the subjects breathed 100% oxygen for 15 min at the ground level, the simulated altitude increased gradually to the 7620 m (25,000 ft) level while the subjects continued to breathe oxygen. Then, the subjects discontinued to breath oxygen and breathed room air at the 7620 m level for up to 5 min until they requested to stop hypoxic exposure. Oxygen saturation (SpO2), heart rate, 95% spectral edge frequency (SEF), BIS, response entropy (RE), and state entropy (SE) of spectral entropy were recorded throughout the study period.

RESULTS

Of the 11 subjects, seven subjects who underwent hypoxic exposure for 4 min were analysed. SpO2 decreased to 69% at the 7620 m level without oxygen. However, SEF, BIS, RE, and SE before and during hypoxic exposure were almost identical.

CONCLUSIONS

These data suggest that hypoxia of oxygen saturation around 70% does not have a strong effect on BIS and spectral entropy.

The human cerebral cortex, consisting of six layers and billions of neurons and synapses, processes sensory input from numerous sensory receptors. Noninvasive magnetoencephalographic (MEG) recordings provide a view through the skull to electrophysiological signals of the cortex on a millisecond timescale. For example, magnetic somatosensory evoked fields (SEFs) to a given peripheral somatosensory stimuli, reflect sequential activation of an extensive cortical network. Several cortical areas contributing to the SEFs can be evaluated in time and space by using source modeling. This brief review focuses on MEG studies of the human somatosensory networks with a special emphasis on tactile stimulation.

The daily use of muscle relaxants and the lack of correlation between the hemodynamic behavior and stages of general anesthesia represent the main obstacles in defining the level of cortical activity depression by the anesthetic drugs. Since classical EEG is cumbersome in the operating room, and demands special knowledge, computerized methods of EEG wave analysis have more or less replaced the 'raw' display of the electrical activity of CNS. The paper describes the place of spectral edge frequency (SEF), one of the parameters obtained by processing the EEG waves, in the list of variables which could be monitored during general anesthesia. Besides, our preliminary observations on a combination of mean blood pressure variations and SEF value are presented. In fact, we designed a hypothetical matrix of those two parameters, which seems to be a useful tool for guiding the general anesthesia. SEF kept in a pre-established range (usually 8-12 Hz) seems to be linked with a more evident hemo-dynamic stability. Some data also suggested that a stable SEF on that range contributed to a higher degree of immediate postoperative analgesia after Cesarean section. The limits of SEF oblige the scientists to go on looking for other monitored parameters, to be studied in correlation with processed EEG. Further studies are needed, in order to improve the anesthesiologist's capabilities to define correctly the stage of general anesthesia.

In many animal preparations, repeated stimulation at ca. 10 Hz in thalamic nuclei leads to rapid changes in the cortical evoked responses, known as the augmenting response. The present study was undertaken to evaluate whether anything similar to the augmenting response can be observed in awake human subjects when a peripheral nerve is stimulated, and whether a possible human correlate of augmenting would be modified when the subject is engaged in an active motor task. Somatosensory-evoked magnetic fields (SEFs) were recorded in healthy human subjects in response to stimulus trains (15 pulses at 10 Hz) applied to the left median nerve. SEFs were recorded in a resting condition and during a finger-tapping task performed with the stimulated hand. In the resting condition, the most marked change in the SEF configuration was a reduction of the P35m deflection and a concurrent enhancement of the N45m deflection during the 1st few stimuli of the trains. Another conspicuous feature was a prolongation of the latencies of the N45m and P60m deflections toward the end of the train. In the motor task, the response modulation during the pulse trains was in general similar to the resting condition. The most notable difference was that the P35m amplitude was markedly reduced already for the 1st pulse of the train when compared with rest. Also, the latencies of N45m and P60m were not prolonged during the train. We discuss the possibility that the reduction of P35m and a concurrent increase of N45m during a pulse train constitute a human analogue to the augmenting response, and suggest that these changes may reflect a decrease of inhibitory postsynaptic potentials (IPSPs, P35m) and an increase of secondary excitatory postsynaptic potentials (N45m) during stimulus train presentation. The reduction of P35m during motor activity compared with rest already at the beginning of stimulus trains suggests that postsynaptic IPSPs in response to afferent stimulation are reduced during active movement. Otherwise the short-term plastic changes were similar during rest and motor activity. Finally, the results suggest slowing down of intracortical network processing with repeated stimulation, and that this slowing is not present during an active motor task which depends on afferent feedback information.

OBJECTIVE

The goal of this retrospective study is to evaluate the radiologic anatomy of sphenoidal emissary foramen (SEF) by using cone-beam computed tomography (CBCT) scans.

METHODS

Three hundred seventeen (189 female and 128 male) full-head CBCT images were evaluated in this study. Incidence, diameter, shape, confluence to foramen ovale, and distance to anatomic structures of SEF were noted.

RESULTS

In the 317 analyzed images, the SEF was identified in 89 (28.1%) images. Of these, 67 (21.1%) were unilateral, 22 were (6.9%) bilateral. The maximum mean diameter of SEF was measured 2.66 mm on the right side and 2.82 mm on the left side (P = 0.16). The most observed SEF shape was oval with the incidence of 68.5% (P ≤ 0.05). Confluence was observed in 23.4% of SEF whereof 84.6% were in the left side (P ≤ 0.05).

CONCLUSIONS

Observations in this study tender new anatomic parameters regarding SEF incidence, characteristics, and distances to proximate anatomic structures. Knowledge related to SEF variations will be helpful for neurosurgeons and radiologist.

Introduction: Despite proven effectiveness of medications in preventing stone recurrence, compliance with pharmacotherapy is often poor due to cost, side effects and impact on lifestyle. We sought to compare the risk of stone recurrence between patients managed with conservative therapy versus pharmacotherapy controlling for aggressiveness of stone disease.

Methods: The Multi-center collaboration to Study Treatment Outcomes in Nephrolithiasis Evaluation (MSTONE) database contains patient data and outcomes from July 2001 to April 2015 across four centers. The database was queried for patients whose stone disease was managed with conservative therapy alone (CT, fluid and dietary recommendations) versus pharmacotherapy (PT). Patients were risk stratified according to number of previous passed stones. Within each risk group, we compared CT versus PT with respect to 2-year stone event rate and stone event-free survival (SEFS) via the Kaplan-Meier method.

Results: A total of 245 patients, with a median follow-up of 29 months (IQR 16 - 44), were identified, including 93 on CT and 152 on PT. The overall 2-year stone-event rate was 38% for all patients. Stone events at 2 years occurred less frequently in the PT group compared to the CT group (31% vs 44%, p = 0.043), with the difference most pronounced in the high risk group (71% versus 32% for CT and PT, respectively, p = 0.058). The 30-month SEFS was significantly higher for PT (58%) than CT (46%) overall. When stratified by risk group, 30-month SEFS was statistically significantly higher for PT than CT in the intermediate risk group (65% vs 45% for PT and CT, respectively).

Conclusion: Controlling for aggressiveness of stone disease, PT was more effective than CT in reducing and delaying stone-related events. However, CT appeared to be as effective as PT in low risk patients. PT is best reserved for recurrent stone formers, regardless of metabolic background.

To evaluate the localization of responses to stimulation of the periodontal mechanoreceptors in the primary somatosensory cortex, somatosensory evoked fields (SEFs) were measured for stimulation of the left mandibular canine and first molar using magnetoencephalography in 25 healthy subjects. Tactile stimulation used a handmade stimulus device which recorded the trigger at the moment of touching the teeth.SEFs for the canine and first molar were detected in 20 and 19 subjects, respectively. Both responses were detected in the bilateral hemispheres. The latency for the canine was 62.1 ± 12.9 ms in the ipsilateral hemisphere and 65.9 ± 14.8 ms in the contralateral hemisphere. The latency for the first molar was 47.4 ± 6.6 ms in the ipsilateral hemisphere and 47.8 ± 9.1 ms in the contralateral hemisphere. The latency for the first molar was significantly shorter than that for the canine. The equivalent current dipoles were estimated in the central sulcus and localized anteroinferiorly compared to the locations for the SEFs for the median nerve. No significant differences in three-dimensional coordinates were found between the canine and first molar. These findings demonstrate the precise location of the teeth within the orofacial representation area in the primary somatosensory cortex.

Human behavior is influenced by serial decision-making: past decisions affect choices that set the context for selecting future options. A primate brain region that may be involved in linking decisions across time is the supplementary eye field (SEF), which, in addition to its well known visual responses and saccade-related activity, also signals the rules that govern flexible decisions and the outcomes of those decisions. Our hypotheses were that SEF neurons encode events during serial decision-making and link the sequential decisions with sustained activity. We recorded from neurons in the SEF of two rhesus monkeys (Macaca mulatta, one male, one female) that performed a serial decision-making task. The monkeys used saccades to select a rule that had to be applied later in the same trial to discriminate between visual stimuli. We found, first, that SEF neurons encoded the spatial parameters of saccades during rule selection but not during visual discrimination, suggesting a malleability to their movement-related tuning. Second, SEF activity linked the sequential decisions of rule selection and visual discrimination, but not continuously. Instead, rule-encoding activity appeared in a "just-in-time" manner before the visual discrimination. Third, SEF neurons encoded trial outcomes both prospectively, before decisions within a trial, and retrospectively, across multiple trials. The results thus identify neuronal correlates of rule selection and application in the SEF, including transient signals that link these sequential decisions. Its activity patterns suggest that the SEF participates in serial decision-making in a contextually dependent manner as part of a broader network.SIGNIFICANCE STATEMENT Much research has gone into studying the neurobiological basis of single, isolated decisions. An important next step is to understand how the brain links multiple decisions to generate a coherent stream of thought and behavior. We studied neural activity related to serial decision-making in an area of frontal cortex known as the supplementary eye field (SEF). Neural recordings were conducted in monkeys that performed a serial decision-making task in which they selected and applied rules. We found that SEF neurons convey signals for serial decision-making, including transient encoding of one decision at the time it is needed for the next one and longer-term representations of trial outcomes, suggesting that the region plays a role in continuity of cognition and behavior.

A serologic field (SEF) is produced by the in vitro studies of antibody-antigen interactions and usually includes serologic information processing (SIF). SIF can be regarded as the process whereby essentially "meaningless" raw data or experimental observables emanating from an input reality are structuralized and hence falsified into a "meaningful" pattern, Gestalt or output image. According to this "black box model", different "fact categories" (FC) can be identified in SEF. Traditional serology generally confounds its FC whereby fact category mistakes (FCM) are produced. Some FCM are structurally similar to the description of "mice" as four-letter animals or as a four-legged word--i.e. facts about "thing-properties" (animals, legs) are confounded with facts about "language-properties" (letters, words). In SEF, antibody and antigen molecules (thing-properties) are similarly endowed with "empty symbols" (language-properties). Due to such FCM, radically new meanings are assigned to experimental observables if the serologic language and/or theory is changed. The present meta-serologic approach consists of the design of a meta-serologic symbol language (SL-2) which includes the contemporary (simple-complex) conceptual framework (language and theory) as a limiting case. Consequently, some truly radical and revolutionary Gestalt switches will be generated when a specified SEF is mapped onto SL-2.

OBJECTIVE

To investigate the sedative effects of guaifenesin in pigs by use of electroencephalography.

METHODS

10 Norwegian Landrace pigs (5 castrated males and 5 sexually intact females).

METHODS

Guaifenesin (150 mg/kg of body weight, IV) was administered during a 5-minute period. Using a 2-channel referential electrode configuration, electroencephalograms were recorded before, during, and after infusion of guaifenesin. Changes in spectral edge frequency 95% (SEF), median frequency (MED), and total power were evaluated.

RESULTS

After administration of guaifenesin, SEF decreased significantly, and total power increased significantly; however, MED did not change significantly. Analysis of the data did not reveal differences between pigs on the basis of sex.

CONCLUSIONS

We concluded that guaifenesin synchronized the patterns of electroencephalograms. This is a strong indication that the drug has a sedative effect in pigs.

OBJECTIVE

To determine the necessary mean infusion rate of propofol during combined nitrous oxide (N2O) and propofol spinal anesthesia by using the processed electroencephalogram (pEEG).

METHODS

Twelve elective gynecological patients were monitored by a Dräger pEEG monitor under N2O and propofol spinal anesthesia. To make it easier to detect an inadequate depth of anesthesia, muscle relaxants were not given and the patients breathed spontaneously through a laryngeal mask airway. Manual step-down infusion of propofol was employed to provide intraoperative hypnosis. Propofol infusion was titrated to maintain cardiorespiratory parameters within 20% of baseline and the 90th percentile of the spectral edge frequency (SEF 90) of the pEEG between 10 and 13.5 Hz.

RESULTS

The mean (SD) induction dose of propofol was 2.9 (0.4) mg·kg-1. The mean (SD) maintenance infusion rate was 4.2 (0.5) mg·kg-1·h-1. The mean (SD) time from the end of propofol infusion to the opening of the patient's eyes was 5.4 (2.0) min. No gross movements or intraoperative awareness was recognized. The mean (SD) SEF 90 during the maintenance of anesthesia was 12.2 (1.5) Hz, which increased significantly to 16.2 (1.9) Hz at 1 min before the patients opened their eyes in reponse to verbal commands.

CONCLUSIONS

Titration of propofol infusion using SEF during combined general and spinal anesthesia provided a rapid recovery without any clinical signs of inadequate anesthesia.

Rehabilitative therapy of the perineum (FKT, SEF and biofeedback) represents an efficient method in the treatment of urinary stress incontinence without resorting to a complete uro-genital prolapse, as in patients with urethral instability and/or incontinence. One hundred twenty-one women, 55 with urinary stress incontinence (USI), 20 with urge incontinence (UI) and 46 suffering from both types of incontinence, underwent rehabilitative therapy. On each patients the following tests were carried out: an internal test, a urodynamic test (uroflowmeter, PPU, cystomanometry and pessure/flow study), a meter UEC, situated at the bladder neck, anterior and posterior urethra, both clinostatic and orthostatic, urine test with urinoculture and a pap-test. The aim of this study is that of establishing if it is possible a) to simplify the rehabilitative sitting using only FKT with weekly treatment; b) to treat women suffering from urge incontinence or from both types, but with bladder stability (standard cystomanometria) with FKT and Ditropan (1 tablet 3 times daily for weeks therapy). One group of patients underwent rehabilitative therapy while another group underwent traditional therapy, for a minimum of 12 sitting, using also electric functional stimulation (SEF). Of 121 women who underwent rehabilitative therapy, 90 (74.4%) were healed, 30 (24.7%) improved and one (0.9%) showed no signs of improvement. Patients treated with FKT, or FKT and made as good if not better grogress than those who attended more sittings and/or underwent SEF.(ABSTRACT TRUNCATED AT 250 WORDS)