Computing Touch-Point Ambiguity on Mobile Touchscreens for Modeling Target Selection Times

Finger-Fitts law (FFitts law) is a model to predict touch-pointing times, modified from Fitts' law. It considers the absolute touch-point precision, or a finger tremor factor σa, to decrease the admissible target area and thus increase the task difficulty. Among choices such as running an independent task or performing parameter optimization, there is no consensus on the best methodology to measure σa. This inconsistency could be detrimental to HCI studies such as pointing technique evaluations and user group comparisons. By integrating the results of our 1D and 2D touch-pointing experiments and reanalyses of previous studies' data, we examined the advantages and disadvantages of each approach to compute σa. We found that the parameter optimization method is a suboptimal choice for predicting the performance.

EFFECT OF SENSORY ELECTRICAL STIMULATION ON RESTING TREMORS IN PATIENTS WITH PARKINSON’S DISEASE AND SWEDDs

Patients with scans without evidence of dopaminergic deficits (SWEDDs) show symptoms (e.g., tremors) similar to those of Parkinson’s disease (PD) patients, so they are often misdiagnosed. Sensory electrical stimulation (SES) was reported to suppress essential tremor in patients, but SES was never applied to patients with PD and SWEDDs. As the pathophysiological mechanisms of PD and SWEDDs are likely to be different, we hypothesized that the effect of SES would also be different in the two patient groups. This study aimed to test that hypothesis. Fourteen patients with PD and nine with SWEDDs participated in this study. Three wrist muscles were stimulated for 15[Formula: see text]s using SES with a stimulation intensity lower than the motor threshold. Angular motion of the index finger was measured via a triaxial gyrosensor before, during, and after stimulation. Outcome measures included the amplitude and peak frequency of the angular motion of the index finger. Tremor amplitude decreased during and after SES in patients with PD ([Formula: see text]). However, tremor amplitudes during and after SES were not different from the base level in SWEDDs patients. The peak frequency of tremors temporarily decreased during stimulation in PD patients, but not in SWEDDs patients. SES suppressed tremors in patients with PD, but not with SWEDDs. The results could help understand the pathophysiological differences of tremors between PD and SWEDDs.

Hubungan Kadar FT4 dengan Gejala Klinis yang Terkait Efek Simpatis berdasarkan Indek Wayne pada Nagari Koto Salak Kabupaten Dharmasraya

AbstrakPeningkatan aktivitas saraf simpatis dapat terjadi pada keadaan hipertiroid dan sebaliknya pada hipotiroid. Pengukuran kadar hormon tiroid dilakukan dengan mengukur kadar FT4, FT3, TSH, dll. Tujuan penelitian ini adalah untuk mengidentifikasi hubungan kadar FT4 dengan gejala klinis yang terkait efek simpatis di Nagari Koto Salak Kabupaten Dharmasraya. Penelitian ini menggunakan desain penelitian cross sectional study. Hasil penelitian didapatkan subjek dengan peningkatan kadar FT4 12,96%. Subjek dengan gejala klinis palpitasi, penurunan berat badan, nervous, berkeringat lebih dan tremor jari halus dengan persentase berturut-turut adalah 42,59%, 38,89%, 46,30%, 25,93% dan 44,44%. Analisis bivariat dengan menggunakan uji statistik chi-square diperoleh hasil tidak ada hubungan hubungan kadar FT4 dengan 5 gejala klinis yang terkait efek simpatis berdasarkan indeks Wayne (p > 0.05). Penelitian ini masih sederhana dan belum bisa menunjukkan adanya hubungan antara kadar FT4 dengan gejala klinis yang terkait efek simpatis. Sebaiknya untuk penelitian yang akan datang diharapkan dapat memiliki jumlah sampel yang banyak dan cakupan gejala klinis lain yang terlibat dalam aktivitas saraf simpatis yang lebih luas sehingga dapat lebih lengkap dan spesifik.Kata kunci: Kadar FT4, efek simpatis, gejala klinis AbstractIncreased sympathetic nerve activity may occur in the state of hyperthyroidism and conversely in hypothyroidism. Measurement of thyroid hormone levels is done by measuring the levels of FT4, FT3, TSH, etc. The objective of this study was to identify the relation between FT4 levels and the clinical symptoms of sympathetic effects in Nagari Koto Salak Kabupaten Dharmasraya. This research used cross sectional study design. According to the research found that subjects with elevated levels of FT4 12.96%. There are subjects with clinical symptoms of palpitations, weight loss, nervousness, sweating more and fine finger tremor by the following percentages is 42.59%, 38.89%, 46.30%, 25.93%, and 44.44%. From the results of the bivariate analysis using Chi-Square test is not obtained the relation between FT4 levels with 5 related clinical symptoms of sympathetic effects on wayne’s index (p> 0.05). This research was simple and could not represent the relation between FT4 levels were associated with clinical symptoms of sympathetic effects. We recommend to have more number of samples for the future research and scope of clinical symptoms that involved in the activity of the sympathetic nervous to be wider so it can be more comprehensive and specific.Keywords: FT4 levels, sympathetic effects, clinical symptom

The complete frequency spectrum of physiological tremor can be recreated by broadband mechanical or electrical drive

Two frequency peaks of variable preponderance have been reported for human physiological finger tremor. The high-frequency peak (20–25 Hz, seen only in postural tremor) is generally attributed to mechanical resonance, whereas the lower frequency peak (8–12 Hz, seen in both postural and kinetic tremor) is usually attributed to synchronous central or reflexive neural drive. In this study, we determine whether mechanical resonance could generate both peaks. In relaxed subjects, an artificial finger tremor was evoked by random mechanical perturbations of the middle finger or random electrical muscular stimulation of the finger extensor muscle. The high and the low frequencies observed in physiological tremor could both be created by either type of artificial input at appropriate input intensity. Resonance, inferred from cross-spectral gain and phase, occurred at both frequencies. To determine any neural contribution, we compared truly passive subjects with those who exhibited some electromyographic (EMG) activity in the finger extensor; artificially created tremor spectra were almost identical between groups. We also applied electrical stimuli to two clinically deafferented subjects lacking stretch reflexes. They exhibited the same artificial tremor spectrum as control subjects. These results suggest that both typical physiological finger tremor frequencies can be reproduced by random artificial input; neither requires synchronized neural input. We therefore suggest that mechanical resonance could generate both dominant frequency peaks characteristic of physiological finger tremor. The inverse relationship between the input intensity and the resulting tremor frequency can be explained by a movement-dependent reduction in muscle stiffness, a conjecture we support using a simple computational model.

A dominant role for mechanical resonance in physiological finger tremor revealed by selective minimization of voluntary drive and movement

There is a debate in the literature about whether the low- and high-frequency peaks of physiological finger tremor are caused by resonance or central drive. One way to address this issue is to examine the consequences of eliminating, as far as possible, the resonant properties or the voluntary drive. To study the effect of minimizing resonance, finger tremor was recorded under isometric conditions and compared with normal isotonic tremor. To minimize central drive, finger tremor was generated artificially by broad-band electrical stimulation. When resonance was minimized, tremor size declined almost monotonically with increasing frequency. There was no consistent large peak at a frequency characteristic of tremor. Although there was sometimes a peak around the tremor frequency during some isometric conditions, it was extremely small and variable; therefore, any contribution of central drive was minimal. In contrast, there was always a prominent peak in the isotonic frequency spectra. Resonance was, therefore, necessary to produce the characteristic tremor peaks. When central drive was minimized by replacing voluntary muscle activation with artificial stimulation, a realistic tremor spectrum was observed. Central drive is, therefore, not required to generate a characteristic physiological tremor spectrum. In addition, regardless of the nature of the driving input (voluntary or artificial), increasing the size of the input considerably reduced isotonic tremor frequency. We attribute the frequency reduction to a movement-related thixotropic change in muscle stiffness. From these results we conclude that physiological finger tremor across a large range of frequencies is produced by natural broad-band forcing of a nonlinear resonant system, and that synchronous central input is not required.