In COM we trust: Feasibility of USB-based event marking

Modern experimental research often relies on the synchronization of different events prior to data analysis. One way of achieving synchronization involves marking distinct events with electrical pulses (event markers or “TTL pulses”), which are continuously recorded with research hardware, and can later be temporally aligned. Traditionally, this event marking was often performed using the parallel port in standard personal computers. However, the parallel port is disappearing from the landscape of computer hardware, being replaced by a serial (COM) port, namely the USB port. To find an adequate replacement for the parallel port, we evaluated four microcontroller units (MCUs) and the LabJack U3, an often-used USB data acquisition device, in terms of their latency and jitter for sending event markers in a simulated experiment on both Windows and Linux. Our results show that all four MCUs were comparable to the parallel port in terms of both latency and jitter, and consistently achieved latencies under 1 ms. With some caveats, the LabJack U3 can also achieve comparable latencies. In addition to the collected data, we share extensive documentation on how to build and use MCUs for event marking, including code examples. MCUs are a cost-effective, flexible, and performant replacement for the disappearing parallel port, enabling event marking and synchronization of data streams.

It’s all about time: precision and accuracy of Emotiv event-marking for ERP research

Background The use of consumer-grade electroencephalography (EEG) systems for research purposes has become more prevalent. In event-related potential (ERP) research, it is critical that these systems have precise and accurate timing. The aim of the current study was to investigate the timing reliability of event-marking solutions used with Emotiv commercial EEG systems. Method We conducted three experiments. In Experiment 1 we established a jitter threshold (i.e. the point at which jitter made an event-marking method unreliable). To do this, we introduced statistical noise to the temporal position of event-marks of a pre-existing ERP dataset (recorded with a research-grade system, Neuroscan SynAmps2 at 1,000 Hz using parallel-port event-marking) and calculated the level at which the waveform peaks differed statistically from the original waveform. In Experiment 2 we established a method to identify ‘true’ events (i.e. when an event should appear in the EEG data). We did this by inserting 1,000 events into Neuroscan data using a custom-built event-marking system, the ‘Airmarker’, which marks events by triggering voltage spikes in two EEG channels. We used the lag between Airmarker events and events generated by Neuroscan as a reference for comparisons in Experiment 3. In Experiment 3 we measured the precision and accuracy of three types of Emotiv event-marking by generating 1,000 events, 1 s apart. We measured precision as the variability (standard deviation in ms) of Emotiv events and accuracy as the mean difference between Emotiv events and true events. The three triggering methods we tested were: (1) Parallel-port-generated TTL triggers; (2) Arduino-generated TTL triggers; and (3) Serial-port triggers. In Methods 1 and 2 we used an auxiliary device, Emotiv Extender, to incorporate triggers into the EEG data. We tested these event-marking methods across three configurations of Emotiv EEG systems: (1) Emotiv EPOC+ sampling at 128 Hz; (2) Emotiv EPOC+ sampling at 256 Hz; and (3) Emotiv EPOC Flex sampling at 128 Hz. Results In Experiment 1 we found that the smaller P1 and N1 peaks were attenuated at lower levels of jitter relative to the larger P2 peak (21 ms, 16 ms, and 45 ms for P1, N1, and P2, respectively). In Experiment 2, we found an average lag of 30.96 ms for Airmarker events relative to Neuroscan events. In Experiment 3, we found some lag in all configurations. However, all configurations exhibited precision of less than a single sample, with serial-port-marking the most precise when paired with EPOC+ sampling at 256 Hz. Conclusion All Emotiv event-marking methods and configurations that we tested were precise enough for ERP research as the precision of each method would provide ERP waveforms statistically equivalent to a research-standard system. Though all systems exhibited some level of inaccuracy, researchers could easily account for these during data processing.

In COM We Trust: Feasibility of USB-Based Event Marking

Modern experimental research often relies on the synchronization of different events prior to data analysis. One way of achieving synchronization involves marking distinct events with electrical pulses (event markers or “TTL pulses”), which are continuously recorded with research hardware, and can later be temporally aligned. Traditionally, this event marking was often performed using the parallel port in standard personal computers. However, the parallel port is disappearing from the landscape of computer hardware, being replaced by a serial (COM) port, namely the USB port. To find an adequate replacement for the parallel port, we evaluated four microcontroller units (MCUs) and the LabJack U3, an often used USB data acquisition device, in terms of their latency and jitter for sending event markers in a simulated experiment. Our results show that all four MCUs were comparable to the parallel port in terms of both latency and jitter, and consistently achieved latencies under one millisecond. With some caveats, the LabJack U3 can also achieve comparable latencies. In addition to the collected data, we share extensive documentation on how to build and use MCUs for event marking, including code examples. MCUs are a cost-effective, flexible, and performant replacement for the disappearing parallel port, enabling event marking and synchronization of data streams.

STI Co-infection Among HIV/AIDS Patients at H. Adam Malik General Hospital, Medan, Indonesia

Both HIV/AIDS and Sexually Transmitted Infection (STI) are transmitted through sexual activites making a parallel port of entry making the two condition increase the each other’s transmission which results as an impact to progression of HIV infection. This study aims to determine the characteristics of HIV/AIDS patients co-infected with sexually transmitted infections in H. Adam Malik General Hospital Medan between 2017 and 2018. This study is a descriptive observational study of 2422 HIV/AIDS patients attending H. Adam Malik General Hospital. Of those, 62 patients were diagnosed with STI coinfection. The majority of patients were male (85,5%) aged within the group of 25 – 49 years old (80,6%), had the level education of high school (88,7%), mostly were entrepreneurs (50%), and were single (59,7%). Most of the patients were already in their Stadium III (80,6%) clinical stage and had CD4+ count < 200/mm3 (51,6%). Condyloma acuminatum (35,5%) was found as the most common type of STI coinfection, and followed by Hepatitis B (33,9%).Based on anamnesis history, behavioral risk factors (66,1%) was the most frequent risk factor

PENGENDALI LISTRIK AKSES PARALLEL PORT DENGAN PEMROGRAMAN BORLAND DELPHI 7.0

Komputer atau disebut PC (personal Computer) sudah berada hampir di setiap rumah, gedung atau perkantoran. Kebanyakan komputer lebih sering digunakan untuk keperluan pengetikan, memutar film, mendengarkan musik dan untuk permainan atau game. Pada saat sebagian orang juga dapat menghabiskan waktu seharian di depan computer mereka. Hal ini dapat membuat orang malas untuk mengerjakan hal lain saat sibuk di depan komputer, miasalnya saja untuk menghidupkan lampu, pendingin ruangan (Air Conditioner), atau perangkat elektronik lainnya. Penelitian ini dirancang untuk mengendalikan peralatan listrik menggunakan akses parallel port dengan pemrograman Delphi 7.0. Peralatan listrik yang dikontrol adalah lampu pijar, untuk mengontrol lampu pada suatu rumah, gedung ataupun di industry-industri yang dihubungkan dan di control melalui komputer dengan memanfaatkan interface port parallel. dan untuk menghidupkan dan mematikan lampu pada suatu gedung atau tempat lainnya dapat dilakukan dengan menekan tombol-tombol yang telah dirancang pada modul program computer dan agar dapat mengakses port parallel dengan baik digunakan sebuah file library, yaitu “inpout32.dll”.