Machine learning-driven dynamic risk prediction for highly pathogenic avian influenza at poultry farms in Republic of Korea: Daily risk estimation for individual premises.

Highly pathogenic avian influenza (HPAI) is a fatal zoonotic disease that damages the poultry industry and endangers human lives via exposure to the pathogen. A risk assessment model that precisely predicts high-risk groups and occurrence of HPAI infection is essential for effective biosecurity measures that minimize the socio-economic losses of massive outbreaks. However, the conventional risk prediction approaches have difficulty incorporating the broad range of factors associated with HPAI infections at poultry holdings. Therefore, it is difficult to accommodate the complexity of the dynamic transmission mechanisms and generate risk estimation on a real-time basis. We proposed a continuous risk prediction framework for HPAI occurrences that used machine learning algorithms (MLAs). This integrated environmental, on-farm biosecurity, meteorological, vehicle movement tracking, and HPAI wild bird surveillance data to improve accuracy and timeliness. This framework consisted of (i) the generation of 1788 predictors from six types of data and reconstructed them with an outcome variable into a data mart based on a temporal assumption (i.e. infected period and day-ahead forecasting); (ii) training of the predictors with the temporally rearranged outcome variable that corresponded to HPAI H5N6 infected state at each individual farm on daily basis during the 2016-2017 HPAI epidemic using three different MLAs [Random Forest, Gradient Boosting Machine (GBM), and eXtreme Gradient Boosting]; (iii) predicting the daily risk of HPAI infection during the 2017-2018 HPAI epidemic using the pre-trained MLA models for each farm across the country. The models predicted the high risk to 8-10 out of 19 infected premises during the infected period in advance. The GBM MLAs outperformed the 7-day forecasting of HPAI prediction at individual poultry holdings, with an area under the curve (AUC) of receiver operating characteristic of 0.88. Therefore, this approach enhances the flexibility and timing of interventions against HPAI outbreaks at poultry farms.

Effects of repetitive transcranial magnetic stimulation on masseter motor-neuron pool excitability.

OBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) has been widely used to modulate the excitability of the cortical control of limbs muscles, but rarely in the cortical control of human masseter muscles. This study aims to investigate the effects of rTMS on masseter motor-neuron pool excitability in humans. MATERIALS AND METHODS: A total of 20 healthy participants were selected and received a total of three rTMS sessions involving stimulation of the right masseter-motor complex: one session of 10-Hz rTMS, one session of 1-Hz rTMS and one session of sham rTMS at an intensity of 80% of the active motor threshold (AMT). The masseter AMT, motor-evoked potentials (MEPs), cortical-silent period (CSP), and short-interval intracortical inhibition (SICI) were measured before and after each rTMS session. RESULTS: The masseter SICI was significantly decreased following 10-Hz rTMS, with no significant changes in AMT, MEPs or CSP. No significant differences in masseter AMT, MEPs, CSP or SICI were observed in either the 1-Hz, or sham rTMS groups. CONCLUSIONS: The present findings demonstrate that high-frequency rTMS increases masseter motor-neuron pool excitability.

Excitability of the central masticatory pathways in patients with sleep bruxism.

Since sleep bruxism (SB) is defined as a stereotyped movement and mainly associated with rhythmic masticatory muscle activity, the aim of this study was to get a better understanding on the subcortical and cortical networks related to the excitability of the central masticatory pathways in SB patients. Of 26 SB patients (12 females and 14 males; mean age: 24.9±4.0 years) and 30 normal subjects (18 females and 12 males; mean age: 24.1±3.1 years) selected, the motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) in masseter muscles, and the masseter inhibitory reflex (MIR) elicited by magnetic stimulation with single and double-shock techniques were studied. The MEPs elicited by TMS were similar in both SB patients and normal subjects. As for the MIR elicited by single magnetic stimulation, the latency and duration of the early silent periods (SP1) between the two groups were similar; but in 5 patients the late silent periods (SP2) was absent, and this difference in the frequency of absence of the SP2 between SB patients and normal subjects was significant; with double-shock technique, the recovery of SP2 was significantly lower in SB patients compared to normal subjects. These results suggested an abnormal excitability of the central masticatory in SB patients; and it is also indicated that SB may be mainly under the influence of brainstem networks rather than that of cortical networks.

[The masseter inhibitory reflex and the recovery of the reflex after magnetic stimulation in normal subjects].

OBJECTIVE: To analyze the masseter inhibitory reflex (MIR) and the recovery cycle of the MIR reflex after magnetic stimulation in normal subjects. METHODS: In 30 healthy subjects we studied the MIR evoked by single magnetic stimulation in the mental territory. Masseter electromyographic activity, latency and duration of the early silent periods (SP1) and late silent periods (SP2), and SP2 amplitude percent were recorded. Paired stimuli technique was used, conditioning and test stimuli were delivered at different interstimulus intervals (ISI), ie.100, 200, 300, 400, 500, and 600 ms, then the recovery cycle of the MIR was analyzed. RESULTS: Latency of SP1 was 12.1 (11.1, 14.4) ms, and duration of the SP1 was (17.3 ± 2.9) ms. Latency of SP2 was (47.7 ± 6.0) ms, and duration of the SP2 was (39.7 ± 13.3) ms. SP2 amplitude percent was 100.0%. With the paired stimuli technique, SP1 of the inhibitory reflex evoked by the test stimuli was found to be stable at every ISIs, but SP2 of the inhibitory reflex evoked by the test stimuli, instead, varied according to different ISI. With the short ISI, the area of SP2 evoked by the test stimuli was reduced, and with the increase of the ISI, the recovery degree of the area of SP2 evoked by the test stimuli was ascending, at 100 ms the SP2 amplitude percent was 17.1%, at 400 ms it was 93.4%, and it was close to 100% at 600 ms. CONCLUSIONS: The study indicates that the use of the MIR elicited by the single and paired magnetic stimulation may be useful to examine or quantify some craniofacial diseases.