Phase-separation perspective on dynamic heterogeneities in glass-forming liquids.

We study dynamic heterogeneities in a model glass former whose overlap with a reference configuration is constrained to a fixed value. We find that the system phase separates into regions of small and large overlap, indicating that a nonzero surface tension plays an important role in the formation of dynamical heterogeneities. We calculate an appropriate thermodynamic potential and find evidence of a Maxwell construction consistent with a spinodal decomposition of two phases. Our results suggest that even in standard, unconstrained systems dynamic heterogeneities are the expression of an ephemeral phase-separating regime ruled by a finite surface tension.

Analysis of the chaotic component of the sinusal R-R intervals as a tool for detecting a silent cardiac dysautonomia in type 2 diabetes mellitus.

This study explores the heart rate (HR) variability (V) in order to detect whether the chaotic component of the sinusal R-R intervals (SRRI) can be interpreted as an early indicator of a silent cardiac neurovegetative dysautonomia in apparently uncomplicated Type 2 diabetic patients (DP). The SRRI were provided by the 24-h Holter ECG of 10 Type 2 DP (5 M and 5 F, mean age = 41 +/- 5 years). Control data were obtained by the 24-h Holter ECG of 10 clinically healthy subjects (CHS, 5 M and 5 F, mean age = 38 +/- 6 years). The chaotic component of HRV was investigated via the correlation dimension (CD) analysis (A) of the SRRI, performed per each hour of the ECG recording. The hourly-qualified series of SRRI, HR and CD index (I) were, in turn, analyzed via methods of conventional statistics and chronobiology, the latter ones for assessing the circadian rhythm (CR). The CDI CR was found to peak during the night in CHS, and to be unphysiologically rotated to the diurnal hours of the day in Type 2 DP. The diurnal inversion of the CDI CR in Type 2 DP suggests that the chaotic component of HRV shows an abnormal rhythnic pattern over the day-night period. Considering that the investigated Type 2 DP were lacking of documentable signs of cardiac neuropathy, it is hypothesized that the diurnal phase of shift CDI CR might be a potential indicator of a silent autonomic cardiac dysfunction in Type 2 DP. Such a hypothesis waits for further confirmations.

A lower level of entropy in circadian rhythm of the sinus R-R intervals suggests a prevalence of the cardiac sympathetic regulation in early physiological pregnancy.

The study estimates the unpredictable disorder (chaos) within the 24 h pattern of sinus R-R intervals (SRRI) in clinically healthy pregnant women (CHPW) and clinically healthy non-pregnant women (CHNPW), in order to evaluate the early gestational changes in neurovegetative cardiac pacing. SRRI were provided by the 24-h Holter ECG of 10 CHPW and 10 CHNPW. SRRI were investigated by descriptive conventional statistics by means of the Time and Frequency Domain Analysis, and subsequently, in their chaotic component by means of entropy analysis. Both the SRRI and entropy were tested via the Cosinor method to better decipher whether or not the periodic disorder in heart rate variability is modified in pregnancy as a result of a gestational tonic resetting of the cardiac sympatho-vagal regulation. Cosinor analysis documented that the circadian rhythm of both the SRRI and entropy were preserved in CHNPW and CHPW. However, the circadian rhythm of SRRI and entropy in CHPW exhibited a significantly decreased 24 h mean. Via the analysis of the rhythmicity of entropy, this study has documented that the chaos in the 24 h pattern of SRRI is less prominent in CHPW than in CHNPW. Such a reduction of level in the deterministic periodic chaos of heart rate variability provides evidence that, in early pregnancy, a tonic elevation of the sympathetic activity regulates cardiac pacing.

[Circadian periodicity in human heart rate daily variability disorders: subsequent demonstrations through a chronobiological approach to the values of estimated alpha exponent on sinusal R-R intervals]. / Periodicità circadiana del disordine nella variabilità giornaliera della frequenza cardiaca umana: ulteriore dimostrazione tramite approccio cronobiologico ai valori dell'esponente alfa stimato sugli intervalli sinusali R-R.

OBJECTIVE: The present study is aimed at giving a further demonstration that the disorder in human heart rate variability is characterized by a circadian periodicity. Such an evidence has been provided by estimating the alpha exponent of the Lévy's stable distribution approximated to the histogram of the differences between the durations of two adjacent sinusal R-R intervals. MATERIALS AND METHODS: The purpose has been pursued by estimating the alpha exponent on fragments of one hour of the Holter electrocardiogram executed in 10 clinically healthy subjects (5 males and 5 females, ranging in age from 23 to 30 years). RESULTS: The chronobiological analysis of the hourly-qualified values of the alpha exponent has demonstrated a significant circadian rhythm for this coefficient. CONCLUSIONS: The significant circadian periodicity of the alpha exponent is a further evidence that the disorder in human heart rate variability, herein represented by the extreme variability of the differences between the durations of two consecutive sinusal R-R intervals, is characterized by a periodic recursivity.

Heart rate stationarity in heart transplanted patients.

The heart rate stationary was studied by tachographic of 24 Holter analysis in 15 normal subjects and in 13 recipient subjects that were heart transplanted at least 5 years and that, at the time of our research, presented a very good post-operative course. To test the stationary heart rate we performed a scanning of Holter in qualified strips of four beats in which the three consecutive intervals demonstrate a constant acceleration or deceleration sequential variations of tachographic values. The results obtained demonstrated that in normal and transplanted subjects stationary and non stationary strips are evident. Both in normal and in transplanted subjects non-stationary strips are prevalent, although in different ways: in normal subjects the stationary and non-stationary ratio is 1:1.40; in transplanted subjects the ratio is 1:1.68. Non-stationary strips, that in the cartesian plane do not demonstrate any directional variation, in normal subjects are, on average, higher than in transplanted subjects. The same phenomenon is available for the strips with only one variation. The strips with three consecutive variations are much more evident (more 50%) in transplanted subjects. These strips are also more numerous compared to the sum of all the other strips with a single variation. The statistical analysis demonstrates that the difference between the normal and the transplanted subjects is significative. Our data can suggest an absent autonomic nervous system regulation and can confirm the results we obtained in these patients using a phase space analysis of the same Holter recording.

["The memory effect" in healthy heart and transplanted heart. "Cor se ipse alit, se ipse movet, se ipse reget"]. / "L'effetto memoria" nel cuore sano e nel cuore trapiantato. "Cor se ipse alit, se ipse movet, se ipse reget".

The heart's memory, interpreted as information residue between a cardiac cycle and the subsequent one, is a very definite phenomenon (short- term memory) both in healthy subjects and in heart transplanted recipients. This "memory effect", we have observed by the autocorrelation and by the spectrum analysis of the values expressing the heartbeat acceleration variability (tachogram 24 h). The "memory effect" cannot be absolutely put down in heart transplanted recipients to interference or to the activity of the central and/or peripheral nervous system, because the heart transplanted is a denervated heart by definition. Moreover, an immediate regulating effect of hormonic factors in the short-term heartbeat regulation is not completely plausible. As already known, the heart transplanted responds to the emergency situation autonomously and autochthonously in proportion to the signals reaching it directly from the circle (vascular resistance, blood pressure, etc.). This implies the existence of functional memory that is likely to be inborn in the conduction system of the heart. Looking at the results of our research we can conclude: "cor se ipse alit, se ipse movet, se ipse reget" (it autonomously models itself to all the different modifications in the circle, it feeds itself as the organ propelling blood circulation and, if necessary, it carries on its kinetic activity autonomously).

The autocorrelation of cardiac beat as a method of research of the heart's memory (first communication).

The AA. have studied the heart's memory by autocorrelation function of heart beats in healthy. The results have demonstrated that there is positive or negative correlation in the space of the first 25-35 pulsation which follow pulsation chosen at random.

The chaotic component of human heart rate variability shows a circadian periodicity as documented by the correlation dimension of the time-qualified sinusal R-R intervals.

OBJECTIVE: This study investigates the hypothesis that the nonlinear component of human heart rate (HR) variability might show a periodic structure over the 24-h span. Such a postulate could explain how the chaotic component might coexist with the deterministic periodic variability of instantaneous HR in beat per minute. MATERIALS AND METHODS: The sinusal R-R intervals (sRRi) of the Holter EKG of 10 clinically healthy subjects (5 M, 5 F, 23-30 years) were analyzed per each hour of the day-night span according to two methods for the nonlinear chaotic variability, i.e., the correlation dimension method, and the linear periodic variability, i.e., periodic regression analysis. RESULTS: The hourly-qualified correlation integrals were found to show a significant circadian rhythm, with an acrophase located during the night in coincidence with the longest duration of the sRRi and the lowest rate of cardiac pulse. CONCLUSIONS: The rhythmic structure of the chaotic component of the human HR variability let us to think that a deterministic periodic chaos of fractal type regulates the nonlinear cardiac dynamics. Such a periodic structure allows the chaos to be compatible with the deterministic linear periodicity of circadian type which characterizes the within-day variability of human HR.

A low-cost evaluation of alcoholism treatment in a private psychiatric hospital program.

The authors designed a low-cost evaluation study to examine outcome on an alcoholism specialty unit of a private psychiatric hospital as well as to look at the effects of several post-treatment therapies. Using conservative criteria for good outcome, and accounting for the expected poorer outcome of non-respondents, they found that the program achieved a 58 percent success rate. Use of Alcoholics Anonymous and a covert sensitization exercise developed especially for the program were associated with better outcome in terms of drinking behavior post-hospitalization. It should not be difficult to conduct a similar study in other treatment settings with a low research budget.