Reconstruction of a Symbolic Periodic Sequence from a Sequence with Noise

The problem of constructing a periodic sequence consisting of at least eight periods is considered, based on a given sequence obtained from an unknown periodic sequence, also containing at least eight periods, by introducing noise of deletion, replacement, and insertion of symbols. To construct a periodic sequence that approximates a given one, distorted by noise, it is first required to estimate the length of the repeating fragment (period). Further, the distorted original sequence is divided into successive sections of equal length; the length takes on integer values from 80 to 120 % of the period estimate. Each obtained section is compared with each of the remaining sections, a section is selected to build a periodic sequence that has the minimum edit distance (Levenshtein distance) to any of the remaining sections, minimization is carried out over all sections of a fixed length, and then along all lengths from 80 to 120 % of period estimates. For correct comparison of fragments of different lengths, we consider the ration between the edit distance and the length of the fragment. The length of a fragment that minimizes the ratio of the edit distance to another fragment of the same length to the fragment length is considered the period of the approximating periodic sequence, and the fragment itself, repeating the required number of times, forms an approximating sequence. The constructed sequence may contain an incomplete repeating fragment at the end. The quality of the approximation is estimated by the ratio of the edit distance from the original distorted sequence to the constructed periodic sequence of the same length and this length.

The long shadow of childhood trauma for depression in midlife: examining daily psychological stress processes as a persistent risk pathway

Background Childhood trauma (CT) increases the risk of adult depression. Buffering effects require an understanding of the underlying persistent risk pathways. This study examined whether daily psychological stress processes – how an individual interprets and affectively responds to minor everyday events – mediate the effect of CT on adult depressive symptoms. Methods Middle-aged women (N = 183) reported CT at baseline and completed daily diaries of threat appraisals and negative evening affect for 7 days at baseline, 9, and 18 months. Depressive symptoms were measured across the 1.5-year period. Mediation was examined using multilevel structural equation modeling. Results Reported CT predicted greater depressive symptoms over the 1.5-year time period (estimate = 0.27, s.e. = 0.07, 95% CI 0.15–0.38, p < 0.001). Daily threat appraisals and negative affect mediated the effect of reported CT on depressive symptoms (estimate = 0.34, s.e. = 0.08, 95% CI 0.22–0.46, p < 0.001). Daily threat appraisals explained more than half of this effect (estimate = 0.19, s.e. = 0.07, 95% CI 0.08–0.30, p = 0.004). Post hoc analyses in individuals who reported at least moderate severity of CT showed that lower threat appraisals buffered depressive symptoms. A similar pattern was found in individuals who reported no/low severity of CT. Conclusions A reported history of CT acts as a latent vulnerability, exaggerating threat appraisals of everyday events, which trigger greater negative evening affect – processes that have important mental health consequences and may provide malleable intervention targets.

The Study of a Physico-Mathematical Model of the Acceleration of Storage Life Tests of Electrical and Electronic Equipment

The article proposes a solution to the problem of the variety of physico-mathematical models of EEE-storage life test acceleration by implementing a method based on the analysis of the results of accelerated tests in different modes. The objects of the study are reed relays. The article presents the main physico-mathematical models used for calculating the acceleration factor when simulating storage, as well as sets forth a description of a method for comparing these models. According to this method, the product is tested in various modes and, in accordance with the procedure for accelerated storage life testing based on the prediction of parameter time-dependent degradation, the storage period is estimated. Then, for each model, the storage period estimate is obtained for normal climatic conditions together with the standard deviation. The model with the least standard deviation is considered to be the most suitable for the tested type of product. The physico-mathematical models of the acceleration of reed relay failure mechanisms during storage were studied with the help of this technique; the most suitable is the reverse exponential model.

A comparison of the programme coverage of two therapeutic feeding interventions implemented in neighbouring districts of Malawi

ObjectiveTo compare therapeutic feeding programme coverage for severely malnourished children achieved by a community-based therapeutic care (CTC) programme and a therapeutic feeding centre (TFC) programme operating in neighbouring districts in Malawi.DesignTwo surveys were implemented simultaneously one in each of the two programme areas. Each survey used a stratified design with strata defined using the centric systematic area sample method. Thirty 100 km2 quadrats were sampled. The community or communities located closest to the centre of each quadrat were sampled using a case-finding approach. Cases were defined as children aged under 5 years with ≤ 70% of the weight-for-height median or bilateral pitting oedema. Receipt of treatment was ascertained by the child's presence in a therapeutic feeding programme or by documentary evidence. Coverage in each quadrat was estimated in two ways, a period estimate that provides an estimation of coverage for the recent period preceding the survey and a point estimate that provides an estimation of coverage at the exact point in time of the survey.ResultsOverall the period coverage was 24.55% (95% confidence interval (CI) = 17.8–31.4%) in the TFC programme and 73.64% (95% CI = 66.0–81.3%) in the CTC programme. The point coverage was 20.04% (95% CI = 13.8–26.3%) in the TFC programme and 59.95% (95% CI = 51.4–68.5%) in the CTC programme.ConclusionsIn this context, CTC gave substantially higher programme coverage than a TFC programme. Given effective treatment, this enabled higher impact of CTC on severe malnutrition in this population.

Phase shifting two coupled circadian pacemakers: implications for jet lag

Flights across time zones produce an abrupt displacement of the environmental time cues (zeitgebers), and the endogenous circadian timing system resynchronizes only gradually to the new schedule. A coupled two-oscillator model can simulate the human circadian system in temporal isolation and in artificial zeitgeber cycles. The model is here shown to explain the major features of resynchronization of circadian rhythms after time zone shifts, i.e., the rate of adjustment depends on the rhythm being measured, the number of time zones crossed, the flight direction (eastward or westward), and the strength of the zeitgebers in the new time zone. Investigations of the contribution of different model parameters to system performances suggest that intersubject differences in pacemaker periods may be a major factor in the observed variability in the effects of time zone shifts on circadian rhythms. With individualized period estimate the models can simulate case studies in which four subjects recorded their sleep-wake and core body temperature rhythms throughout simple and complex patterns of transmeridian flights.

Recent Work on Beat Cepheids at Mount Stromlo Observatory

Beat Cepheids continue to pose a number of unanswered questions concerning the behaviour of stars near the short-period end of the Cepheid instability strip; in particular, why is it that such a high proportion of stars with fundamental period ≤ 5 days exhibit simultaneous pulsation in both the fundamental and first-overtone radial modes, and why is it that these stars exhibit such a narrow range of period ratio (P1/P0 ≃ 0.71)? A programme of observation and Fourier analysis of beat Cepheids is presently being undertaken at Mount Stromlo and Siding Spring in an effort to understand these phenomena.There is now evidence that, for the two best observed stars of this class - U TrA and TU Cas, both the period and the relative mode amplitudes are slowly changing with time. U TrA was observed in detail during the years 1953-59 by Oosterhoff (1957) and Jansen (1962), and a new series of 481 five colour observations of this star was obtained by Faulkner and Shobbrook (1979) in 1977. Using E = Σ(Amp × Freq)2 summed over all the Fourier terms for a given mode as a measure of the pulsational energy associated with that mode, we can use this 20 year timebase to calculate the change in relative mode energy. For U TrA the energy of the overtone is increasing (see Table I). Similarly we can compare the fundamental period derived for these 20 years with an earlier period estimate of Oosterhoff (1957) to obtain the rate of frequency change shown.