Artificial Rhythms Research Articles

The Right Stuff? The Original Double Jay as Site for Youth Counterculture

The Right Stuff? The Original Double Jay as Site for Youth Counterculture

Stabilisation of beta and gamma oscillation frequency in the mammalian olfactory bulb

The dynamics of the mammalian olfactory bulb (OB) is characterized by local field potential (LFP) oscillations either slow, in the theta range (2-10Hz, tightly linked to the respiratory rhythm), or fast, in the beta (15-30Hz) or gamma (40-90Hz) range. These fast oscillations are known to be modulated by odorant features [1] and animal experience or state [2][3], but both their mechanisms and implication in coding are still not well understood. In this study, we used a double canulation protocol to impose artificial breathing rhythms to anesthetized rats while recording the LFP in the OB. We observed that despite the changes in the input air flow parameters (frequency or flow rate), the main characteristics of fast oscillations (duration, frequency or amplitude) were merely constant. We thus made the hypothesis that fast beta and gamma oscillations dynamics are entirely determined by the OB network properties and that external stimulation was only able put the network in a state which permits the generation of one or the other oscillations (they are never present simultaneously). To test this hypothesis, we studied a simplified OB model based on previous modeling studies. In particular it includes resonant mitral cells [4] and graded synaptic inhibition [5]. Detailed analysis and numerical simulations of the model showed that two oscillatory dynamical regime can be sustained. First, a low noise regime where at each cycle, a subset of mitral cells are tightly synchronized and yield a saturation of the graded inhibition, during which mitral cell discharge is prevented. Because of this saturation, the network frequency is governed by the dynamics of the graded inhibition decay. Interestingly, this dynamics is not very sensitive to the number of mitral cells that lead to the saturation. Consequently, there is a wide range of mitral cell firing rate during which the network frequency is stable. Using standard parameters in our model, we found an oscillation frequency stable between 25 and 30Hz while the average mitral cell firing rate increased from 5Hz to 25Hz. Second, a high noise regime can be observed where the mitral cell discharge is much less regular. In this case, the network oscillations are of lower amplitude compared to the low noise regime and thus the graded inhibition is never saturated by fluctuations around its mean. The network can then be well described by a mean field approach (as described in [ 6]) and is close to a previous model of in vitro gamma oscillations [4]. With our model parameters, oscillations in this regime have higher frequency, typically in the gamma range (50Hz-90Hz) but their frequency is highly sensitive to the level of input excitation to the mitral cells. This discrepancy with our experimental result could be relieved by the in vitro experimental observation that mitral cell stimulus excitatory input is all or none [7]. Indeed this could provide a stable external input to the network and thus also stabilize the gamma frequency. Finally, we have shown that our model can account for the two stable oscillatory regimes observed in the OB in vivo. However our model does not take into account the spatial activation of the OB and the study of how spatially segregated oscillatory generators interact and potentially synchronize is an ongoing work.

Improving authentication accuracy using artificial rhythms and cues for keystroke dynamics-based authentication

Keystroke dynamics-based authentication (KDA) is to verify a user’s identity using not only the password but also keystroke dynamics. With a small number of patterns available, data quality is of great importance in KDA applications. Recently, the authors have proposed to employ artificial rhythms and tempo cues to improve data quality: consistency and uniqueness of typing patterns. This paper examines whether improvement in uniqueness and consistency translates into improvement in authentication performance in real-world applications. In particular, we build various novelty detectors using typing patterns based on various strategies in which artificial rhythms and/or tempo cues are implemented. We show that artificial rhythms and tempo cues improve authentication accuracies and that they can be applicable in practical authentication systems.

In the Arms of Morpheus: Actelion Keeps Sleepers from Waking

Your sleep cycles ebb and flow, governed by hormones and light, just as tides are pulled by the moon. But the artificial rhythms of our society, including shift work and air travel across time zones, are not conducive to rest. A third of Americans suffer from sleeplessness, according to the NIH. Because screening and diagnosis is not uniform, prevalence is uncertain. At least 30 million Americans are estimated to experience insomnia, but the number could be much higher. It is unclear how many are chronic insomniacs.

Keystroke dynamics-based authentication for mobile devices

Recently, mobile devices are used in financial applications such as banking and stock trading. However, unlike desktops and notebook computers, a 4-digit personal identification number (PIN) is often adopted as the only security mechanism for mobile devices. Because of their limited length, PINs are vulnerable to shoulder surfing and systematic trial-and-error attacks. This paper reports the effectiveness of user authentication using keystroke dynamics-based authentication (KDA) on mobile devices. We found that a KDA system can be effective for mobile devices in terms of authentication accuracy. Use of artificial rhythms leads to even better authentication performance.

Improvement of keystroke data quality through artificial rhythms and cues

Keystroke dynamics based user authentication (KDA) can achieve a relatively high performance if a fairly large number of typing patterns are available. It is almost always the case that KDA is combined with password based authentication. Users are often required to change their passwords. When a user changes one's password, however, only a handful of new patterns become available. In a mobile situation, moreover, very short passwords are used. Under such a circumstance, the quality of data becomes important. Recently, artificial rhythms and cues were proposed to improve the quality of data. In this paper, we verify the effectiveness of artificial rhythms and cues through hypotheses tests using the data from 25 users under various situations. The experimental results show that artificial rhythms increase the uniqueness while cues increase the consistency.

Essentials of Heart Rhythm Analysis

This paperback illustrates the electrocardiograms of common arrhythmias and their interpretation. The first chapter deals with the formation of the automatic impulse and its conduction to the common myocardium; the second describes the standard electrocardiogram and explains how deflections and intervals are analyzed. The modalities of abnormal conduction and a descriptive listing of ectopic beats and rhythms, including flutter and fibrillation, are presented in the third and fourth chapters; the artificial pacemaker rhythms are also presented. The fifth chapter illustrates the method used by the author to analyze the arrhythmias. Chapter 6 is a collection of 100 tracings for the reader to diagnose, followed by a discussion and the interpretation by the author. An extensive glossary and an analytical index conclude the book. Manuals for the nonspecialists are becoming more popular. Books of this sort are strictly dogmatic; they must be used not to learn basic scientific information but as

The effect of imposed light rhythms on semen production of Suffolk rams

SummaryThe effects of two, symmetrically opposing, light treatments on the semen of Suffolk rams were investigated over two years. The light rhythm had an amplitude of 12 h and a cycle of 24 weeks. Data on semen volume, spermatozoa concentration, total spermatozoa per ejaculate, fructose concentration, seminal fluid fructose concentration and total fructose were collected during 38 semen collection periods. During the last 20 periods libido was assessed on the interval to mounting.The effects of treatments were assessed by fitting Fourier curves with 24-week cycles to the observed fluctuation of the differences between treatments and with 52-week cycles to the means of treatments. From periodic regression analysis of the treatment differences it is concluded that the Suffolk rams were susceptible to the artificial light rhythms and that both groups adapted to the imposed rhythms. Some effects of the pretreatment photic environment appeared to persist during the first year of the treatment period. There appeared to be a lag between the fluctuations of the semen attributes resulting in a series of sequential changes.

Photoperiodicity in Suffolk sheep

1. A gradually decreasing plane of light and increasing plane of darkness is not an essential factor for stimulating the onset of oestrus in sheep.2. Sheep being short-day breeding animals, a standard and regularly maintained rhythm of short-light and long-dark will stimulate the onset of oestrus.3. The terms short and long are used in the relative sense only, since their significance is solely a means of supplying the necessary contrast impulse to the pituitary gland.4. A ratio of 1 part of light to 2 parts or more of dark is sufficient to supply the contrast effect.5. Oestrous cycles induced by artificial light rhythms appear to be normal in all respects, con forming to the normal intervals between heat periods and associated with the ovulation of normal ova.6. The anoestrous period varies in depth, and sheep which have just entered it may be brought back into oestrus very much faster than animals which are in deep anoestrum.7. The milk yield of lactating ewes does not appear to be unduly depressed by the onset of oestrous periods induced by an artificial light-dark rhythm.