Multiplex recurrence networks

We have introduced a multiplex recurrence network approach by combining recurrence networks with the multiplex network approach in order to investigate multivariate time series. The potential use of this approach is demonstrated on coupled map lattices and a typical example from palaeobotany research. In both examples, topological changes in the multiplex recurrence networks allow for the detection of regime changes in their dynamics. The method goes beyond classical interpretation of pollen records by considering the vegetation as a whole and using the intrinsic similarity in the dynamics of the different regional vegetation elements. We find that the different vegetation types behave more similarly when one environmental factor acts as the dominant driving force.

Position and orientation of the westerly jet determined Holocene rainfall patterns in China

Proxy-based reconstructions and modeling of Holocene spatiotemporal precipitation patterns for China and Mongolia have hitherto yielded contradictory results indicating that the basic mechanisms behind the East Asian Summer Monsoon and its interaction with the westerly jet stream remain poorly understood. We present quantitative reconstructions of Holocene precipitation derived from 101 fossil pollen records and analyse them with the help of a minimal empirical model. We show that the westerly jet-stream axis shifted gradually southward and became less tilted since the middle Holocene. This was tracked by the summer monsoon rain band resulting in an early-Holocene precipitation maximum over most of western China, a mid-Holocene maximum in north-central and northeastern China, and a late-Holocene maximum in southeastern China. Our results suggest that a correct simulation of the orientation and position of the westerly jet stream is crucial to the reliable prediction of precipitation patterns in China and Mongolia.

The basic mechanisms behind the East Asian Summer Monsoon remain poorly understood. Using proxy-based reconstructions and simulations, here the authors show that changes in the orientation and position of the westerly jet stream resulted in regionally asynchronous Holocene precipitation maxima.

Monsoon forced evolution of savanna and the spread of agro-pastoralism in peninsular India

An unresolved issue in the vegetation ecology of the Indian subcontinent is whether its savannas, characterized by relatively open formations of deciduous trees in C₄-grass dominated understories, are natural or anthropogenic. Historically, these ecosystems have widely been regarded as anthropogenic-derived, degraded descendants of deciduous forests. Despite recent work showing that modern savannas in the subcontinent fall within established bioclimatic envelopes of extant savannas elsewhere, the debate persists, at least in part because the regions where savannas occur also have a long history of human presence and habitat modification. Here we show for the first time, using multiple proxies for vegetation, climate and disturbances from high-resolution, well-dated lake sediments from Lonar Crater in peninsular India, that neither anthropogenic impact nor fire regime shifts, but monsoon weakening during the past ~ 6.0 kyr cal. BP, drove the expansion of savanna at the expense of forests in peninsular India. Our results provide unambiguous evidence for a climate-induced origin and spread of the modern savannas of peninsular India at around the mid-Holocene. We further propose that this savannization preceded and drove the introduction of agriculture and development of sedentism in this region, rather than vice-versa as has often been assumed.

[Preclinical resuscitation--which factors influence the long-term course? A 5-year follow-up]

OBJECTIVE

The factors that influence long-term survival after out-of-hospital resuscitations were investigated.

PATIENTS AND METHODS

Between 1985 and 1989, out of a total of 8403 responded emergency calls, 505 resuscitations were undertaken out of hospital by the emergency medical service in Göppingen. All emergency calls were recorded uniformly. Of the 505 resuscitations, 154 were primarily successful (30.5%), and 58 were secondarily successful, i.e. the patients were ultimately discharged from hospital. In 56 of them the further course could be followed at least 5 years after the resuscitation (45 males, 11 females; mean age 57 [10-83] years). The patients' charts were analysed; in 51 cases data could be obtained from the family doctor, from ambulant care or from home visits.

RESULTS

34 patients (60.4%) were still alive 5 years after the resuscitation. The highest death rate (16%) was in the first post-resuscitation year. Prognostically unfavourable factors were: advanced age (P < 0.01), underlying cardiac disease (n = 49; P < 0.025), especially coronary heart disease (n = 34; P < 0.01). Patients with primary ventricular fibrillation and previous myocardial infarction (n = 10) had a poorer prognosis than those with acute infarction (n = 24; P < 0.05). Reduced survival chances occurred in those with impaired left ventricular function, as measured echocardiographically (P < 0.05), or with cardiac arrhythmias, Lown classes III and IV (P < 0.05), as well as in those with severe neurological sequelae (n = 8; P < 0.08).

CONCLUSION

Long-term prognosis depends, in the first instance, on the resuscitated patient's basic condition and not so much on the circumstances of the resuscitation.