2,751 research outputs found
Synthesis of the silky sifaka’s distribution (Propithecus candidus)
In this paper we 1) review the population abundance and distribution of Propithecus candidus, 2) comment on Rabearivony et al. (2015) and Rasolofoson et al. (2007) regarding P. candidus elevational range, distribution, and lack of occurrence in the pet trade
On the origin of trisomy 21 Down syndrome
Background: Down syndrome, characterized by an extra chromosome 21 is the most common genetic cause for congenital malformations and learning disability. It is well known that the extra chromosome 21 most often originates from the mother, the incidence increases with maternal age, there may be aberrant maternal chromosome 21 recombination and there is a higher recurrence in young women. In spite of intensive efforts to understand the underlying reason(s) for these characteristics, the origin still remains unknown. We hypothesize that maternal trisomy 21 ovarian mosaicism might provide the major causative factor.
Results: We used fluorescence in situ hybridization (FISH) with two chromosome 21-specific probes to determine the copy number of chromosome 21 in ovarian cells from eight female foetuses at gestational age 14–22 weeks. All eight phenotypically normal female foetuses were found to be mosaics, containing ovarian cells with an extra chromosome 21. Trisomy 21 occurred with about the same frequency in cells that had entered meiosis as in pre-meiotic and ovarian
mesenchymal stroma cells.
Conclusion: We suggest that most normal female foetuses are trisomy 21 ovarian mosaics and the maternal age effect is caused by differential selection of these cells during foetal and postnatal development until ovulation. The exceptional occurrence of high-grade ovarian mosaicism may
explain why some women have a child with Down syndrome already at young age as well as the associated increased incidence at subsequent conceptions. We also propose that our findings may explain the aberrant maternal recombination patterns previously found by family linkage analysis
Acoustic And Olfactory Communication In Eastern Sifakas (Propithecus Sp.) And Rhesus Macaques (Macaca Mullata)
This dissertation contains three studies of acoustic and olfactory communication in several species of nonhuman primates. The first is a longitudinal study of "gecker" distress vocalizations in infant rhesus monkeys (Macaca mullata) during the first 24 months of life. Acoustic and behavioral analyses revealed age, sex, and maternal response differences across several temporal, spectral, and amplitude measures, but little context-specific acoustic differentiation. Female geckers showed higher spectral peaks and bout durations, while male geckers were higher in amplitude and less noisy. Developmentally, gecker usage peaked at four months of age for both sexes, with male geckers nonetheless tending to occur at younger ages than those of females. In sum, gecker acoustics appear to be well designed to draw the attention of mothers and other listeners, while also potentially becoming aversive. The second study examines the acoustic structure and function of "zzuss" vocalizations in wild silky sifakas (Propithecus candidus) in northeastern Madagascar. Acoustically, the calls combined separate turbulent noise and tonal components, often including frequency jumps and rapid, highly frequency-modulated components. Although silky sifakas are sexually monomorphic, male and female zzuss calls were acoustically different, most importantly in fundamental frequency and amplituderelated features. All acoustic measures differed between individuals, with fundamental frequency related variables again playing the largest role. Overall, zzuss calls are multi-function vocalizations used both for terrestrial disturbance and group coordination. They are shaped for salience, localizability, and caller identification, rather than to have word-like meaning. The final study examines non-nutritive tree gouging by wild silky sifakas (P. candidus) and Milne-Edwards' sifakas (P. edwardsi). Species differences were found in gouge mark morphology. Dominant males had longer gouge marks and gouged most frequently, with seasonal peaks just before and during the mating season. The resource gouging hypothesis was tested and supported in silky sifakas. A multiple regression analysis revealed that the number of gouges per tree species was predicted by the percentile rank of those species as food tree species and sleep tree species. Gouging appears to be an honest species specific signal of male status which may promote scent longevity and attract the visual attention of conspecifics
Does Social Media Sentiment Predict Bitcoin Trading Volume?
Social media sentiment is proven to be an important feature in financial forecasting. While the effect of sentiment is complex and time-varying for traditional financial assets, its role in cryptocurrency markets is unclear. This research explores the predictive power of public sentiment on Bitcoin trading volume. We develop a novel sentiment analysis pipeline for processing Bitcoin-related tweets and achieve state-of-the-art accuracy on a benchmark dataset. Our pipeline also leverages information gain theory to incorporate the impact of textual and non-textual features. We use such features to discern a non-linear relationship between public sentiment and Bitcoin trading volume and discover the optimal predictive horizon for Bitcoin. This research provides a useful module and a foundation for future studies and understanding of Bitcoin market dynamics, and its interaction with social media buzzing
Logging of Rare Rosewood and Palisandre (Dalbergia spp.) within Marojejy National Park, Madagascar
Illegal logging of precious wood has emerged as one of the most severe threats to Madagascar’s northeastern rainforests. Thousands of logs, worth millions of dollars, have recently been confiscated at ports of Vohémar, Antalaha, and Toamasina. This report details the logging of rare, endemic rosewood and palisandre (Dalbergia baronii, D. louveli, and D. madagascariensis) within the eastern and northeastern portions of Marojejy National Park, Madagascar. Harvesting these heavy hardwoods is a labor intensive activity requiring coordination between localresidents who manually cut the trees, but receive little profit, and a criminal network of exporters, domestic transporters, and corrupt officials who initiate the process and reap most of the profits. Structured interviews of residents identified three major perceived causes: decline in value of the local vanilla cash crop, extremely high value of rosewood, and local poverty. The impacts of such selective logging include violating local taboos as well as ecological consequences such as increased likehood of fire, invasive species, impaired habitat, and loss in genetic diversity. Recommendations include listing D. louveli under CITES Appendix III, increasing the involvement of thejudicial system, no future authorizations for the gathering of precious wood, reforestation, and extensive monitoring along strategic roadways
Solvable Theory of a Strange Metal at the Breakdown of a Heavy Fermi Liquid
We introduce an effective theory for quantum critical points in heavy fermion
systems involving a change in carrier density without symmetry breaking. The
new theory captures a strong coupling metallic fixed point, leading to robust
marginal Fermi liquid transport phenomenology, within a controlled large
limit. This is contrasted with the conventional so-called "slave boson" theory
of the Kondo breakdown, where the large limit describes a weak coupling
fixed point and non-trivial transport behavior may only be obtained through
uncontrolled corrections. We compute the weak field Hall coefficient
within the effective model as the system is tuned across the transition. We
find that between the two plateaus, reflecting the different carrier densities
in the two Fermi liquid phases, the Hall coefficient can develop a peak in the
critical crossover regime, consistent with recent experimental findings. In the
regime of strong damping of emergent bosonic excitations, the critical point
also displays a near-universal "Planckian" transport lifetime,
.Comment: 20 pages, 10 figures, Supplement include
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