160 research outputs found

    Heat conduction in 2D strongly-coupled dusty plasmas

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    We perform non-equilibrium simulations to study heat conduction in two-dimensional strongly coupled dusty plasmas. Temperature gradients are established by heating one part of the otherwise equilibrium system to a higher temperature. Heat conductivity is measured directly from the stationary temperature profile and heat flux. Particular attention is paid to the influence of damping effect on the heat conduction. It is found that the heat conductivity increases with the decrease of the damping rate, while its magnitude agrees with previous experimental measurement.Comment: 4 pages, 2 figures, presented in SCCS2008 conferenc

    Localizing wild chimpanzees with passive acoustics

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    Localizing wildlife contributes in multiple ways to species conservation. Data on animal locations can reveal elements of social behavior, habitat use, population dynamics, and be useful in calculating population density. Acoustic localization systems (ALS) are a non-invasive method widely used in the marine sciences but not well established and rarely employed for terrestrial species. We deployed an acoustic array in a mountainous environment with heterogeneous vegetation, comprised of four custom-built GPS synchronized acoustic sensors at about 500 m intervals in Issa Valley, western Tanzania, covering an area of nearly 2 km2. Our goal was to assess the precision and error of the estimated locations by conducting playback tests, but also by comparing the estimated locations of wild chimpanzee calls with their true locations obtained in parallel during follows of individual chimpanzees. We assessed the factors influencing localization error, such as wind speed and temperature, which fluctuate during the day and are known to affect sound transmission. We localized 282 playback sounds and found that the mean localization error was 27 ¬Ī 21.8 m. Localization was less prone to error and more precise during early mornings (6:30 h) compared to other periods. We further localized 22 wild chimpanzee loud calls within 52 m of the location of a researcher closely following the calling individuals. We demonstrate that acoustic localization is a powerful tool for chimpanzee monitoring, with multiple behavioral and conservation applications. Its applicability in studying social dynamics and revealing density estimation among many others, especially but not exclusively for loud calling species, provides an efficient way of monitoring populations and informing conservation plans to mediate species loss

    Self-Diffusion in 2D Dusty Plasma Liquids: Numerical Simulation Results

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    We perform Brownian dynamics simulations for studying the self-diffusion in two-dimensional (2D) dusty plasma liquids, in terms of both mean-square displacement and velocity autocorrelation function (VAF). Super-diffusion of charged dust particles has been observed to be most significant at infinitely small damping rate ő≥\gamma for intermediate coupling strength, where the long-time asymptotic behavior of VAF is found to be the product of t‚ąí1t^{-1} and exp‚Ā°(‚ąíő≥t)\exp{(-\gamma t)}. The former represents the prediction of early theories in 2D simple liquids and the latter the VAF of a free Brownian particle. This leads to a smooth transition from super-diffusion to normal diffusion, and then to sub-diffusion with an increase of the damping rate. These results well explain the seemingly contradictory scattered in recent classical molecular dynamics simulations and experiments of dusty plasmas.Comment: 10 pages 5 figures, accepted by PR

    Evaluation der neuronalen Mechanismen bekannter serotonerger Risikogene f√ľr psychische Erkrankungen am Beispiel der Depression

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    Einleitung: Depression ist eine psychische Erkrankung mit hoher Lebenszeitpr√§valenz, deren Ursachen bis heute nicht ausreichend gekl√§rt sind. Ein diskutierter, neuronaler Ansatz f√ľr die gest√∂rte Regulation von Emotionen bei depressiven Patienten ist eine Beeintr√§chtigung der serotonergen Regulation limbischer und pr√§frontaler Strukturen. Schl√ľsselregionen f√ľr die Emotionsverarbeitung sind die Amygdala, der anteriore zingul√§re Kortex (ACC) sowie der pr√§frontale Kortex (PFC). Von den dorsalen Raphekernen wird dieses Netzwerk serotonerg innerviert. Der Einfluss serotonerger Polymorphismen auf das Netzwerk f√ľr Emotionsregulation l√§sst sich mittels intermedi√§rer Ph√§notypen untersuchen: Ein intermedi√§rer Ph√§notyp f√ľr die Depression ist die funktionelle Aktivit√§t w√§hrend impliziter Emotionserkennung, f√ľr den eine Assoziation mit dem 5-HTTLPR Polymorphismus der SLC6A4 Region und weitere serotonerge Polymorphismen nachgewiesen werden konnte. Ein weiterer k√ľrzlich vorgestellter intermedi√§rer Ph√§notyp ist die Habituation der neuronalen Aktivierung, f√ľr den eine h√∂here Reliabilit√§t im Vergleich zur funktionellen Aktivit√§t beobachtet werden konnte. Methoden: Serotonerge Polymorphismen ‚Äď insbesondere der 5-HTTLPR Polymorphismus sowie ein polygenetisches, serotonerges Profil (aus 5-HTTLPR, TPH1 (rs1800532), TPH2 (rs4570625), HTR1A (rs6295) und HTR2A (rs6311)) ‚Äď wurde auf Korrelationen mit funktioneller Aktivit√§t sowie Habituation w√§hrend impliziter Emotionserkennung innerhalb der Amygdala, des ACC und des dorsolateralen PFC (DLPFC) in 171 gesunden Probanden untersucht. Ergebnisse: W√§hrend monogenetische Korrelationen von 5-HTTLPR und polygenetische Korrelationen des polygenetischen Profils mit der funktionellen Aktivit√§t in der Amygdala die Korrektur f√ľr mehrfaches Testen nicht √ľberstanden, war eine starke Korrelation zwischen dem polygenetischen Profil und der Habituation in der Amygdala, dem ACC und dem DLPFC nachweisbar. Zusammenfassung: Der Effekt von 5-HTTLPR und einem polygenetischen Profil auf den etablierten intermedi√§ren Ph√§notyp der funktionellen Aktivierung verblieb insignifikant, w√§hrend sich Trends f√ľr eine Assoziation fanden. Zudem wurden Hinweise f√ľr eine genetische Beeinflussung durch serotonerge Polymorphismen auf den k√ľrzlich vorgestellten intermedi√§ren Ph√§notyp Habituation beobachtet. Wir haben Belege gefunden, die den Stellenwert pr√§frontaler Habituation als bedeutenden intermedi√§ren Ph√§notyp f√ľr MDD hervorheben.Introduction: The etiology of major depressive disorder (MDD), a psychiatric disease with a high lifetime-prevalence, remains unsolved. A neural explanation for the impaired emotion regulation in depressive patients is a dysfunctional serotonergic regulation of limbic and prefrontal regions. In particular, the amygdala, the anterior cingulate cortex (ACC) and the prefrontal cortex (PFC) are targets of serotonergic signaling and key regions of emotion processing. Intermediate phenotypes can be used to assess the influence of serotonergic polymorphisms in cerebral networks. For MDD, functional activation during implicit emotion recognition has been shown to be an intermediate phenotype. Functional activation was demonstrated to be influenced by serotonergic polymorphisms such as the 5-HTTLPR polymorphism of the SLC6A4 region. Furthermore, a recently published intermediate phenotype, habituation, was found to be a more reliable intermediate phenotype than functional activation. Methods: We investigated the effects of serotonergic polymorphisms ‚Äď of monogenic 5-HTTLPR and a polygenic, serotonergic multi-marker score (made of 5-HTTLPR, TPH1 (rs1800532), TPH2 (rs4570625), HTR1A (rs6295) and HTR2A (rs6311)) ‚Äď on functional activity and habituation during implicit emotion recognition in the amygdala, the ACC and the dorsolateral PFC (DLPFC) in 171 healthy subjects. Results: Monogenic effects of 5-HTTLPR and polygenic effects of the multi-marker score on functional activation in the amygdala did not survive correction for multiple testing. However, a strong correlation between multi-marker score and habituation in the amygdala, the ACC and DLPFC was prevalent. Conclusion: Whilst the association of 5-HTTLPR and a polygenic multi-marker score on the well-studied intermediate phenotype functional activation did not survive multiple correction, hints for a correlation were observable. We further provided evidence for a recently proposed intermediate phenotype to be influenced by serotonergic polymorphisms, in particular a serotonergic multi-marker score. Last, we found evidence for prefrontal habituation to be an important intermediate phenotype of MDD

    Evaluation der neuronalen Mechanismen bekannter serotonerger Risikogene f√ľr psychische Erkrankungen am Beispiel der Depression

    Get PDF
    Einleitung: Depression ist eine psychische Erkrankung mit hoher Lebenszeitpr√§valenz, deren Ursachen bis heute nicht ausreichend gekl√§rt sind. Ein diskutierter, neuronaler Ansatz f√ľr die gest√∂rte Regulation von Emotionen bei depressiven Patienten ist eine Beeintr√§chtigung der serotonergen Regulation limbischer und pr√§frontaler Strukturen. Schl√ľsselregionen f√ľr die Emotionsverarbeitung sind die Amygdala, der anteriore zingul√§re Kortex (ACC) sowie der pr√§frontale Kortex (PFC). Von den dorsalen Raphekernen wird dieses Netzwerk serotonerg innerviert. Der Einfluss serotonerger Polymorphismen auf das Netzwerk f√ľr Emotionsregulation l√§sst sich mittels intermedi√§rer Ph√§notypen untersuchen: Ein intermedi√§rer Ph√§notyp f√ľr die Depression ist die funktionelle Aktivit√§t w√§hrend impliziter Emotionserkennung, f√ľr den eine Assoziation mit dem 5-HTTLPR Polymorphismus der SLC6A4 Region und weitere serotonerge Polymorphismen nachgewiesen werden konnte. Ein weiterer k√ľrzlich vorgestellter intermedi√§rer Ph√§notyp ist die Habituation der neuronalen Aktivierung, f√ľr den eine h√∂here Reliabilit√§t im Vergleich zur funktionellen Aktivit√§t beobachtet werden konnte. Methoden: Serotonerge Polymorphismen ‚Äď insbesondere der 5-HTTLPR Polymorphismus sowie ein polygenetisches, serotonerges Profil (aus 5-HTTLPR, TPH1 (rs1800532), TPH2 (rs4570625), HTR1A (rs6295) und HTR2A (rs6311)) ‚Äď wurde auf Korrelationen mit funktioneller Aktivit√§t sowie Habituation w√§hrend impliziter Emotionserkennung innerhalb der Amygdala, des ACC und des dorsolateralen PFC (DLPFC) in 171 gesunden Probanden untersucht. Ergebnisse: W√§hrend monogenetische Korrelationen von 5-HTTLPR und polygenetische Korrelationen des polygenetischen Profils mit der funktionellen Aktivit√§t in der Amygdala die Korrektur f√ľr mehrfaches Testen nicht √ľberstanden, war eine starke Korrelation zwischen dem polygenetischen Profil und der Habituation in der Amygdala, dem ACC und dem DLPFC nachweisbar. Zusammenfassung: Der Effekt von 5-HTTLPR und einem polygenetischen Profil auf den etablierten intermedi√§ren Ph√§notyp der funktionellen Aktivierung verblieb insignifikant, w√§hrend sich Trends f√ľr eine Assoziation fanden. Zudem wurden Hinweise f√ľr eine genetische Beeinflussung durch serotonerge Polymorphismen auf den k√ľrzlich vorgestellten intermedi√§ren Ph√§notyp Habituation beobachtet. Wir haben Belege gefunden, die den Stellenwert pr√§frontaler Habituation als bedeutenden intermedi√§ren Ph√§notyp f√ľr MDD hervorheben.Introduction: The etiology of major depressive disorder (MDD), a psychiatric disease with a high lifetime-prevalence, remains unsolved. A neural explanation for the impaired emotion regulation in depressive patients is a dysfunctional serotonergic regulation of limbic and prefrontal regions. In particular, the amygdala, the anterior cingulate cortex (ACC) and the prefrontal cortex (PFC) are targets of serotonergic signaling and key regions of emotion processing. Intermediate phenotypes can be used to assess the influence of serotonergic polymorphisms in cerebral networks. For MDD, functional activation during implicit emotion recognition has been shown to be an intermediate phenotype. Functional activation was demonstrated to be influenced by serotonergic polymorphisms such as the 5-HTTLPR polymorphism of the SLC6A4 region. Furthermore, a recently published intermediate phenotype, habituation, was found to be a more reliable intermediate phenotype than functional activation. Methods: We investigated the effects of serotonergic polymorphisms ‚Äď of monogenic 5-HTTLPR and a polygenic, serotonergic multi-marker score (made of 5-HTTLPR, TPH1 (rs1800532), TPH2 (rs4570625), HTR1A (rs6295) and HTR2A (rs6311)) ‚Äď on functional activity and habituation during implicit emotion recognition in the amygdala, the ACC and the dorsolateral PFC (DLPFC) in 171 healthy subjects. Results: Monogenic effects of 5-HTTLPR and polygenic effects of the multi-marker score on functional activation in the amygdala did not survive correction for multiple testing. However, a strong correlation between multi-marker score and habituation in the amygdala, the ACC and DLPFC was prevalent. Conclusion: Whilst the association of 5-HTTLPR and a polygenic multi-marker score on the well-studied intermediate phenotype functional activation did not survive multiple correction, hints for a correlation were observable. We further provided evidence for a recently proposed intermediate phenotype to be influenced by serotonergic polymorphisms, in particular a serotonergic multi-marker score. Last, we found evidence for prefrontal habituation to be an important intermediate phenotype of MDD

    Wave spectra of 2D dusty plasma solids and liquids

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    Brownian dynamics simulations were carried out to study wave spectra of two-dimensional dusty plasma liquids and solids for a wide range of wavelengths. The existence of a longitudinal dust thermal mode was confirmed in simulations, and a cutoff wavenumber in the transverse mode was measured. Dispersion relations, resulting from simulations, were compared with those from analytical theories, such as the random-phase approximation (RPA), quasi-localized charged approximation (QLCA), and harmonic approximation (HA). An overall good agreement between the QLCA and simulations was found for wide ranges of states and wavelengths after taking into account the direct thermal effect in the QLCA, while for the RPA and HA good agreement with simulations were found in the high and low temperature limits, respectively.Comment: 26 pages, 9 figure

    DNA recovery from wild chimpanzee tools.

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    Most of our knowledge of wild chimpanzee behaviour stems from fewer than 10 long-term field sites. This bias limits studies to a potentially unrepresentative set of communities known to show great behavioural diversity on small geographic scales. Here, we introduce a new genetic approach to bridge the gap between behavioural material evidence in unhabituated chimpanzees and genetic advances in the field of primatology. The use of DNA analyses has revolutionised archaeological and primatological fields, whereby extraction of DNA from non-invasively collected samples allows researchers to reconstruct behaviour without ever directly observing individuals. We used commercially available forensic DNA kits to show that termite-fishing by wild chimpanzees (Pan troglodytes schweinfurthii) leaves behind detectable chimpanzee DNA evidence on tools. We then quantified the recovered DNA, compared the yield to that from faecal samples, and performed an initial assessment of mitochondrial and microsatellite markers to identify individuals. From 49 termite-fishing tools from the Issa Valley research site in western Tanzania, we recovered an average of 52 pg/őľl chimpanzee DNA, compared to 376.2 pg/őľl in faecal DNA extracts. Mitochondrial DNA haplotypes could be assigned to 41 of 49 tools (84%). Twenty-six tool DNA extracts yielded >25 pg/őľl DNA and were selected for microsatellite analyses; genotypes were determined with confidence for 18 tools. These tools were used by a minimum of 11 individuals across the study period and termite mounds. These results demonstrate the utility of bio-molecular techniques and a primate archaeology approach in non-invasive monitoring and behavioural reconstruction of unhabituated primate populations

    Ecological Drivers of Habitat Use by Meso Mammals in a Miombo Ecosystem in the Issa Valley, Tanzania

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    Vast stretches of East and Southern Africa are characterized by a mosaic of deciduous woodlands and evergreen riparian forests, commonly referred to as ‚Äúmiombo,‚ÄĚ hosting a high diversity of plant and animal life. However, very little is known about the communities of small-sized mammals inhabiting this heterogeneous biome. We here document the diversity and abundance of 0.5‚Äď15 kg sized mammals (‚Äúmeso-mammals‚ÄĚ) in a relatively undisturbed miombo mosaic in western Tanzania, using 42 camera traps deployed over a 3 year-period. Despite a relatively low diversity of meso-mammal species (n = 19), these comprised a mixture of savanna and forest species, with the latter by far the most abundant. Our results show that densely forested sites are more intensely utilized than deciduous woodlands, suggesting riparian forest within the miombo matrix might be of key importance to meso-mammal populations. Some species were captured significantly more often in proximity to (and sometimes feeding on) termite mounds (genus Macrotermes), as they are a crucial food resource. There was some evidence of temporal partitioning in activity patterns, suggesting hetero-specific avoidance to reduce foraging competition. We compare our findings to those of other miombo sites in south-central Africa
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