Inferring processes of cultural transmission: the critical role of rare variants in distinguishing neutrality from novelty biases

Neutral evolution assumes that there are no selective forces distinguishing different variants in a population. Despite this striking assumption, many recent studies have sought to assess whether neutrality can provide a good description of different episodes of cultural change. One approach has been to test whether neutral predictions are consistent with observed progeny distributions, recording the number of variants that have produced a given number of new instances within a specified time interval: a classic example is the distribution of baby names. Using an overlapping generations model we show that these distributions consist of two phases: a power law phase with a constant exponent of -3/2, followed by an exponential cut-off for variants with very large numbers of progeny. Maximum likelihood estimations of the model parameters provide a direct way to establish whether observed empirical patterns are consistent with neutral evolution. We apply our approach to a complete data set of baby names from Australia. Crucially we show that analyses based on only the most popular variants, as is often the case in studies of cultural evolution, can provide misleading evidence for underlying transmission hypotheses. While neutrality provides a plausible description of progeny distributions of abundant variants, rare variants deviate from neutrality. Further, we develop a simulation framework that allows for the detection of alternative cultural transmission processes. We show that anti-novelty bias is able to replicate the complete progeny distribution of the Australian data set

Dopant for sodium niobate capacitor dielectric

Sodium niobate dielectric doped with barium titanate has potential application in integrated circuits with high packing densities and voltage levels below 5 to 8 volts

NMDAR-Mediated Calcium Transients Elicited by Glutamate Co-Release at Developing Inhibitory Synapses

Before hearing onset, the topographic organization of the inhibitory sound localization pathway from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) is refined by means of synaptic silencing and strengthening. During this refinement period MNTB-LSO synapses not only release GABA and glycine but also release glutamate. This co-released glutamate can elicit postsynaptic currents that are predominantly mediated by NMDA receptors (NMDARs). To gain a better understanding of how glutamate contributes to synaptic signaling at developing MNTB-LSO inhibitory synapses, we investigated to what degree and under what conditions NMDARs contribute to postsynaptic calcium responses. Our results demonstrate that MNTB-LSO synapses can elicit compartmentalized calcium responses along aspiny LSO dendrites. These responses are significantly attenuated by the NMDAR antagonist APV. APV, however, had no effect on somatically recorded electrical postsynaptic responses, indicating little, if any, contribution of NMDARs to spike generation. NMDAR-mediated calcium responses were decreased when increasing extracellular magnesium concentrations to physiological levels indicating that MNTB-LSO synapses activate magnesium sensitive NMDAR on immature LSO dendrites. In Fura-2 AM loaded neurons, blocking GABAA and glycine receptors increased NMDAR contribution to somatic calcium responses suggesting that GABA and glycine, perhaps by shunting backpropagating action potentials, decrease the level of NMDAR activation under strong stimulus conditions

Positive electrodes of nickel-cadmium batteries

Ni hydroxide sintered electrodes which are filled electrochemically are superior to chemically treated electrodes. In the electrochemical process, the hydroxide grows on the Ni grains and possesses a well-defined porous structure. Diffusion and conducting mechanisms are therefore facilitated

Power and the Medium Munich as a Paradigm for an Analysis of Current Power Structures?

The question is, how far in the context of printing there may still happen presence-phenomena taking back the human body? Bavarian printing seems to make it possible, to give an answer. Therefore theoretical explanations on the value of re-updating and re-personalising as the basic techniques as well as re-presence as the basic intention of media-communicated political behaviour aiming at power or its retention are important. The given model itself is fruitful for processes and shifts of current politics. The 16thand the 21st century may be reasonably compared to each other, as both then and now radical changes of the media (human body or physical communication and printing on the one hand, printing and the new media on the other hand) can be observed as the communications-theoretical signature of the time. The claim of media then and now is to generate re-presence of the human body, which has consequences on the power and its production

Greek Thrace: a region populated by Christians and Muslims in the European Mediterranean

Seit dem Vordringen der Osmanen auf europäisches Territorium im 14. Jahrhundert konnte sich im Südosten des Kontinents eine islamisch geprägte Bevölkerung etablieren, die über Jahrhunderte diesen Raum prägten. Erst seit der Gründung überwiegend christlich ausgerichteter Nationalstaaten auf dem Balkan seit dem 19. Jahrhundert wurden die islamischen Bevölkerungsgruppen mit ethnisch-türkischer Ausrichtung zu Minderheiten, deren Beziehungen zu den mehrheitlich christlich geprägten Nominalvölkern aufgrund regionaler historischer Entwicklungen oftmals schwierig sind. Die Muslime in Griechisch-Thrakien, vom Bevölkerungsaustausch zwischen Griechenland und der Türkei 1923 ausgenommen, blieben in den folgenden Jahrzehnten dabei immer politischer Spielball Griechenlands und der Türkei. Die Betonung des Türkischen in der Minderheit erweckte bei den Griechen immer wieder das Bild der Minderheit als fünfte Kolonne der Türkei, was besonders während der Militärdiktatur (1967-1974) und darüber hinaus zu Einschränkungen der Minderheitenrechte führte. Nach dieser Phase der Repressionen gelang es der Minderheit sich in der Weltöffentlichkeit Gehör zu verschaffen und mithilfe internationaler Organisation wie der EU, Griechenland zum Überdenken seiner Minderheitenpolitik zu bewegen. Der Prozess der Gleichstellung von Christen und Muslimen in Thrakien ist jedoch noch nicht abgeschlossen. Das christlich-muslimische Thrakien zeigt, welche spezifischen Beziehungsmuster sich in einer gemischtreligiösen Bevölkerung entwickeln können, die sich in charakteristischer Weise von monoreligiösen oder geschlossenen Gemeinschaften abheben. Somit lässt sich die indigene muslimische Bevölkerung in Thrakien nicht mit westeuropäischen Migrantengesellschaften vergleichen, allein, weil die thrakischen Muslime wie ihre christlichen Mitbürger die Region als ihre Heimat empfinden und somit ein anderes Selbstverständnis ausbilden konnten als z.B. muslimische Migranten in Westeuropa. (Autorenreferat)After the Ottomans advanced into European territory in the 14th century, an Islamic population was able to establish itself in the south-east of the continent and shaped the region for centuries. It was not until the largely Christian national states were established in the Balkans as of the 19th century that the Islamic population groups with Turkish ethnicity became minorities whose relationships with the Christian majority are often difficult owing to historical regional developments. The Muslims in Greek Thrace remained a political football for Greece and Turkey in the decades that followed, with the exception of the population exchange between Greece and Turkey in 1923. The emphasis on Turkish in the minority repeatedly revived the image of the minority as fifth columnists for Turkey among the Greeks, which resulted in curtailments of the minority's rights, particularly during the military dictatorship (1967-1974) and beyond. After this phase of repression, the minority succeeded in gaining an audience in the world's public and getting Greece to rethink its minority policy with the help of international organisations and the EU. However, the process of achieving equal treatment for Christians and Muslims in Thrace is not finished yet. Christian-Muslim Thrace shows the specific relationship patterns that can develop in a mixed-religion population, which have different characteristics from mono-religious or closed communities. This means that the indigenous Muslim population in Thrace cannot be compared to Western European migrant societies because both the Muslims in Thrace and their Christian compatriots see the region as their homeland and have therefore been able to develop a different identity from that of Muslim migrants in Western Europe, for example. (author's abstract

Long-term mortality after first Acute Myocardial Infarction in the light of changing therapeutic guidelines and diagnostic criteria between 1995 and 2003

Background: The introduction of new invasive therapies for acute myocardial infarction and new medication schemes for secondary prevention is thought to increase life expectancy in 28-day survivors of a first myocardial infarction. The present study examined mortality and re-infarction rate of those patients in the light of changed therapeutic guidelines. Methods: Cases of 25 to 74 year old 28-day survivors of a first definite AMI based on MONICA criteria were identified in the Coronary Event Registry in Augsburg, Southern Germany, who had their index event between the 1st of January 1995 and the 31st of December 2003. Mortality and re-infarction rates were calculated for 1 year, 3 years and total follow-up. Cox models were built to compare the rates of persons, who suffered the index event between 1995 and 1999 (Study period 1) with those who had their first AMI between 2000 and 2003 (Study period 2). Results: Crude mortality was higher in Study period 1 than in Study period 2 and higher for women than for men. Re-infarction rates remained stable for men during both study periods, but women from Study period 1 had a much higher re-infarction rate than women in Study period 2. The hazard ratios showed no significant differences for mortality and re-infarction in men. Hazard ratios of re-infarction in women were significantly reduced, but have to be treated with caution as the number of re-infarctions during Study period 2 was very small. Mortality hazard ratios in women were also not significant. Conclusions: When comparing the time periods before and after the introduction of new therapeutic guidelines, an effect on mortality or re-infarction rate cannot be established. Several reasons are probably responsible for this finding. The population of patients has changed with respect to their risk factors and new diagnostic criteria may have also contributed. Further studies are needed to illuminate these questions

Demography and Language Competition

Attempts to describe language competition and extinction in a mathematical way have enjoyed increased popularity recently. In this paper I review recent modeling approaches and, based on these findings, propose a model of reaction-diffusion type. I analyze the dynamics of interactions of a population with two monolingual groups and a group that is bilingual in these two languages. The results show that demographic factors, such as population growth or population dispersal, play an important role in the competition dynamic. Furthermore, I consider the impact of two strategies for language maintenance: adjusting the status of the endangered language and adjusting the availability of monolingual and bilingual educational resources

Evolving Environmentalism: Contentious Partnerships and Transformational Relationships Between the Environmental Justice Movement and the Mainstream Environmental Movement

Senior Project submitted to The Division of Social Studies of Bard College

A study in the elements of rapport

Thesis (M.S.)--Boston University, 1950. This item was digitized by the Internet Archive