Showing 21 - 30 of 722 Items
Global divergence of the human follicle mite Demodex folliculorum: Persistent associations between host ancestry and mite lineages
Date: 2015-12-29
Creator: Michael F. Palopoli
Daniel J. Fergus
Samuel Minot
Dorothy T. Pei
W. Brian, Simison
Iria Fernandez-Silva
Megan S. Thoemmes
Robert R. Dunn
Michelle Trautwein
Access: Open access
- Microscopic mites of the genus Demodex live within the hair follicles of mammals and are ubiquitous symbionts of humans, but little molecular work has been done to understand their genetic diversity or transmission. Here we sampled mite DNA from 70 human hosts of diverse geographic ancestries and analyzed 241 sequences from the mitochondrial genome of the species Demodex folliculorum. Phylogenetic analyses recovered multiple deep lineages including a globally distributed lineage common among hosts of European ancestry and three lineages that primarily include hosts of Asian, African, and Latin American ancestry. To a great extent, the ancestral geography of hosts predicted the lineages of mites found on them; 27% of the total molecular variance segregated according to the regional ancestries of hosts. We found that D. folliculorum populations are stable on an individual over the course of years and that some Asian and African American hosts maintain specific mite lineages over the course of years or generations outside their geographic region of birth or ancestry. D. folliculorum haplotypes were much more likely to be shared within families and between spouses than between unrelated individuals, indicating that transmission requires close contact. Dating analyses indicated that D. folliculorum origins may predate modern humans. Overall, D. folliculorum evolution reflects ancient human population divergences, is consistent with an out-of-Africa dispersal hypothesis, and presents an excellent model system for further understanding the history of human movement.
Religion and science in the Eastern mediterranean
Date: 2016-09-01
Creator: Robert Morrison
Access: Open access
- “Science and Orthodox Christianity: An Overview” is an ambitious survey that reminds scholars of science in Islamic societies that the conversation between Islam and science is really a conversation between Islam and science in different contexts and that conversations between Islam and science can be found with less renowned scientific developments such as prophetic medicine. This response points out parallels in how Greek Orthodox and Ottoman Muslim scholars mediated new developments in Western European science and in how both Greek Orthodox and some Ottoman Muslim scholars propounded a mathematical humanism. Finally, it argues that the account of post-1453 scientific exchange is more complex than “Science and Orthodox Christianity” intimates. At the least, if there was no scholarly exchange between Greek Orthodox Christians, on the one hand, and, on the other hand, Muslims and Jews—who, in turn, enjoyed scholarly exchange with the West well after 1453—there are clearly two different Easts.
Civil Society under the Law ‘On Foreign Agents’: NGO Strategies and Network Transformation
Date: 2018-04-21
Creator: Maria Tysiachniouk
Svetlana Tulaeva
Laura A. Henry
Access: Open access
- This essay analyses how the ‘foreign agent’ law has been interpreted and implemented by the Russian authorities and examines diverse NGO survival strategies in response to the ‘foreign agent’ label. The foreign agent law has disrupted and transformed resource mobilisation strategies and transnational NGO networks. Based on qualitative research on environmental NGOs, we offer a typology of NGO responses to the foreign agent law, providing examples to show how the organisations attempt to ensure their survival.
The initiation and development of small peat-forming ecosystems adjacent to lakes in the north central Canadian low arctic during the Holocene
Date: 2017-07-01
Creator: Philip Camill
Charles E. Umbanhowar
Christoph Geiss
Mark B. Edlund
Will O., Hobbs
Allison Dupont
Catherine Doyle-Capitman
Matthew Ramos
Access: Open access
- Small peat-forming ecosystems in arctic landscapes may play a significant role in the regional biogeochemistry of high-latitude systems, yet they are understudied compared to arctic uplands and other major peat-forming regions of the North. We present a new data set of 25 radiocarbon-dated permafrost peat cores sampled around eight low arctic lake sites in northern Manitoba (Canada) to examine the timing of peat initiation and controls on peat accumulation throughout the Holocene. We used macrofossils and charcoal to characterize changes in the plant community and fire, and we explored potential impacts of these local factors, as well as regional climatic change, on rates of C accumulation and C stocks. Peat initiation was variable across and within sites, suggesting the influence of local topography, but 56% of the cores initiated after 3000 B.P. Most cores initiated and remained as drier bog hummock communities, with few vegetation transitions in this landscape. C accumulation was relatively slow and did not appear to be correlated with Holocene-scale climatic variability, but C stocks in this landscape were substantial (mean = 45.4 kg C m ), potentially accounting for 13.2 Pg C in the Taiga Shield ecozone. To the extent that small peat-forming systems are underrepresented in peatland mapping, soil organic carbon (SOC) stocks may be underestimated in arctic regions. Mean fire severity appeared to be negatively correlated with C accumulation rates. Initiation and accumulation of soil C may respond to both regional and local factors, and substantial lowland soil C stocks have the potential for biogeochemical impacts on adjacent aquatic ecosystems. −2
Conical wave propagation and diffraction in two-dimensional hexagonally packed granular lattices
Date: 2016-01-25
Creator: C. Chong
P. G. Kevrekidis
M. J. Ablowitz
Yi Ping Ma
Access: Open access
- Linear and nonlinear mechanisms for conical wave propagation in two-dimensional lattices are explored in the realm of phononic crystals. As a prototypical example, a statically compressed granular lattice of spherical particles arranged in a hexagonal packing configuration is analyzed. Upon identifying the dispersion relation of the underlying linear problem, the resulting diffraction properties are considered. Analysis both via a heuristic argument for the linear propagation of a wave packet and via asymptotic analysis leading to the derivation of a Dirac system suggests the occurrence of conical diffraction. This analysis is valid for strong precompression, i.e., near the linear regime. For weak precompression, conical wave propagation is still possible, but the resulting expanding circular wave front is of a nonoscillatory nature, resulting from the complex interplay among the discreteness, nonlinearity, and geometry of the packing. The transition between these two types of propagation is explored.
Stolen Future, Broken Present: The Human Significance of Climate Change
Date: 2014-01-01
Creator: David A Collings
Access: Open access
- This book argues that climate change has a devastating effect on how we think about the future. Once several positive feedback loops in Earth’s dynamic systems, such as the melting of the Arctic icecap or the drying of the Amazon, cross the point of no return, the biosphere is likely to undergo severe and irreversible warming. Nearly everything we do is premised on the assumption that the world we know will endure into the future and provide a sustaining context for our activities. But today the future of a viable biosphere, and thus the purpose of our present activities, is put into question. A disappearing future leads to a broken present, a strange incoherence in the feel of everyday life. We thus face the unprecedented challenge of salvaging a basis for our lives today. That basis, this book argues, may be found in our capacity to assume an infinite responsibility for ecological disaster and, like the biblical Job, to respond with awe to the alien voice that speaks from the whirlwind. By owning disaster and accepting our small place within the inhuman forces of the biosphere, we may discover how to live with responsibility and serenity whatever may come. (Publisher's Description) Freely available online at https://quod.lib.umich.edu/o/ohp/12832550.0001.001
Electronic branching ratio of the lepton
Date: 1992-01-01
Creator: R. Ammar
P. Baringer
D. Coppage
R. Davis
M., Kelly
N. Kwak
H. Lam
S. Ro
Y. Kubota
M. Lattery
J. K. Nelson
D. Perticone
R. Poling
S. Schrenk
R. Wang
M. S. Alam
I. J. Kim
B. Nemati
V. Romero
C. R. Sun
P. N. Wang
M. M. Zoeller
G. Crawford
R. Fulton
K. K. Gan
H. Kagan
R. Kass
J. Lee
R. Malchow
F. Morrow
M. K. Sung
Access: Open access
- Using data accumulated by the CLEO I detector operating at the Cornell Electron Storage Ring, we have measured the ratio R=( e» e ) 1 where " 1 is the decay rate to final states with one charged particle. We find R=0.2231 0.0044 0.0073 where the first error is statistical and the second is systematic. Together with the measured topological one-charged-particle branching fraction, this yields the branching fraction of the lepton to electrons, Be=0.192 0.004 0.006. © 1992 The American Physical Society.
Inclusive (2P) production in (3S) decay
Date: 1991-01-01
Creator: R. Morrison
D. Schmidt
M. Procario
D. R. Johnson
K., Lingel
P. Rankin
J. G. Smith
J. Alexander
M. Artuso
C. Bebek
K. Berkelman
D. Besson
T. E. Browder
D. G. Cassel
E. Cheu
D. M. Coffman
P. S. Drell
R. Ehrlich
R. S. Galik
M. Garcia-Sciveres
B. Geiser
B. Gittelman
S. W. Gray
D. L. Hartill
B. K. Heltsley
K. Honscheid
J. Kandaswamy
N. Katayama
D. L. Kreinick
J. D. Lewis
G. S. Ludwig
Access: Open access
- Using the CsI calorimeter of the CLEO II detector, the spin triplet b(2P) states are observed in (3S) radiative decays with much higher statistics than seen in previous experiments. The observed mass splittings are not described well by theoretical models, while the relative branching ratios agree with predictions that include relativistic corrections to the radiative transition rates. © 1991 The American Physical Society.
Coordination of distinct but interacting rhythmic motor programs by a modulatory projection neuron using different co-transmitters in different ganglia
Date: 2013-05-01
Creator: Molly A. Kwiatkowski
Emily R. Gabranski
Kristen E. Huber
M. Christine Chapline
Andrew E., Christie
Patsy S. Dickinson
Access: Open access
- While many neurons are known to contain multiple neurotransmitters, the specific roles played by each co-transmitter within a neuron are often poorly understood. Here, we investigated the roles of the co-transmitters of the pyloric suppressor (PS) neurons, which are located in the stomatogastric nervous system (STNS) of the lobster Homarus americanus. The PS neurons are known to contain histamine; using RT-PCR, we identified a second co-transmitter as the FMRFamide-like peptide crustacean myosuppressin (Crust-MS). The modulatory effects of Crust-MS application on the gastric mill and pyloric patterns, generated in the stomatogastric ganglion (STG), closely resembled those recorded following extracellular PS neuron stimulation. To determine whether histamine plays a role in mediating the effects of the PS neurons in the STG, we bath-applied histamine receptor antagonists to the ganglion. In the presence of the antagonists, the histamine response was blocked, but Crust-MS application and PS stimulation continued to modulate the gastric and pyloric patterns, suggesting that PS effects in the STG are mediated largely by Crust-MS. PS neuron stimulation also excited the oesophageal rhythm, produced in the commissural ganglia (CoGs) of the STNS. Application of histamine, but not Crust-MS, to the CoGs mimicked this effect. Histamine receptor antagonists blocked the ability of both histamine and PS stimulation to excite the oesophageal rhythm, providing strong evidence that the PS neurons use histamine in the CoGs to exert their effects. Overall, our data suggest that the PS neurons differentially utilize their co-transmitters in spatially distinct locations to coordinate the activity of three independent networks. © 2013. Published by The Company of Biologists Ltd.
Molecular and mass spectral identification of the broadly conserved decapod crustacean neuropeptide pQIRYHQCYFNPISCF: The first PISCF-allatostatin (Manduca sexta- or C-type allatostatin) from a non-insect
Date: 2010-01-01
Creator: Elizabeth A. Stemmler
Emily A. Bruns
Christopher R. Cashman
Patsy S. Dickinson
Andrew E., Christie
Access: Open access
- The PISCF-allatostatins (Manduca sexta- or C-type allatostatins) are a family of pentadecapeptides characterized by a pyroglutamine blocked N-terminus, an unamidated-PISCF C-terminus, and a disulfide bridge between two internal Cys residues. Several isoforms of PISCF-AST are known, all from holometabolous insects. Using a combination of transcriptomics and mass spectrometry, we have identified the first PISCF-type peptides from a non-insect species. In silico analysis of crustacean ESTs identified several Litopenaeus vannamei (infraorder Penaeidea) transcripts encoding putative PISCF-AST precursors. Translation of these ESTs, with subsequent prediction of their putative post-translational processing, revealed the existence of as many as three PISCF-type peptides, including pQIRYHQCYFNPISCF (disulfide bridging between Cys7 and Cys14). Although none of the predicted isoforms was detected by mass spectrometry in L. vannamei, MALDI-FTMS mass profiling identified an m/z signal corresponding to pQIRYHQCYFNPISCF (disulfide bridge present) in neural tissue from 28 other decapods, which included members of six infraorders (Stenopodidea, Astacidea, Thalassinidea, Achelata, Anomura and Brachyura). Further characterization of the peptide using SORI-CID and chemical derivatization/enzymatic digestion supported the theorized structure. In both the crab Cancer borealis and the lobster Homarus americanus, MALDI-based tissue surveys suggest that pQIRYHQCYFNPISCF is broadly distributed in the nervous system; it was also detected in the posterior midgut caecum. Collectively, our data show that members of the PISCF-AST family are not restricted to the holometabolous insects, but instead may be broadly conserved within the Pancrustacea. Moreover, our data suggest that one highly conserved PISCF-type peptide, pQIRYHQCYFN-PISCF, is present in decapod crustaceans, functioning as a brain-gut paracrine/hormone. © 2009 Elsevier Inc. All rights reserved.