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Search Results: 1 - 10 of 4684 matches for " Erik Lindquist "
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Annular bone growth in phalanges of five Neotropical Harlequin Frogs (Anura: Bufonidae: Atelopus)
Erik Lindquist,Michael Redmer,Emily Brantner
Phyllomedusa : Journal of Herpetology , 2012,
Abstract: Skeletochronological studies were conducted on museum specimensrepresenting five species of the highly threatened Neotropical genus Atelopus (Bufonidae). We detected annular bone growth (expressed as lines of arrested growth [LAGs]) patterns in each species, and this might provide insight to understand demographic constituency infuture studies. In four of the five species under consideration, LAG counts in fore and hind limb bone occurred in a 1:1 ratio, indicating that bone growth was consistent within each individual. The use of skeletochronology in understanding historic and existing populations of Atelopus might assist in situ and ex situ population managers in making informed strategic conservation plans.
Ecological Niche of the 2003 West Nile Virus Epidemic in the Northern Great Plains of the United States
Michael C. Wimberly, Michael B. Hildreth, Stephen P. Boyte, Erik Lindquist, Lon Kightlinger
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003744
Abstract: Background The incidence of West Nile virus (WNv) has remained high in the northern Great Plains compared to the rest of the United States. However, the reasons for the sustained high risk of WNv transmission in this region have not been determined. To assess the environmental drivers of WNv in the northern Great Plains, we analyzed the county-level spatial pattern of human cases during the 2003 epidemic across a seven-state region. Methodology/Principal Findings County-level data on WNv cases were examined using spatial cluster analysis, and were used to fit statistical models with weather, climate, and land use variables as predictors. In 2003 there was a single large cluster of elevated WNv risk encompassing North Dakota, South Dakota, and Nebraska along with portions of eastern Montana and Wyoming. The relative risk of WNv remained high within the boundaries of this cluster from 2004–2007. WNv incidence during the 2003 epidemic was found to have a stronger relationship with long-term climate patterns than with annual weather in either 2002 or 2003. WNv incidence increased with mean May–July temperature and had a unimodal relationship with total May–July precipitation. WNv incidence also increased with the percentage of irrigated cropland and with the percentage of the human population living in rural areas. Conclusions/Significance The spatial pattern of WNv cases during the 2003 epidemic in the northern Great Plains was associated with both climatic gradients and land use patterns. These results were interpreted as evidence that environmental conditions across much of the northern Great Plains create a favorable ecological niche for Culex tarsalis, a particularly efficient vector of WNv. Further research is needed to determine the proximal causes of sustained WNv transmission and to enhance strategies for disease prevention.
Audit, Anthropology, and the Way Forward.
Johan Lindquist
EspacesTemps.net , 2011,
Abstract: As the theme of this traverse clearly states, during the last decade, in the wake of books such as Bill Reading’s The University in Ruins (1997), there has been an increasing academic concern with Audit Cultures (Marilyn Strathern, 2000) or Audit Society (Michael Power, 1997). Particularly within the European University system, a form of critique has taken shape in response to, among other issues, norms for publication in peer-review journals, intensifying cycles of research ...
Weak capacity and modulus comparability in Ahlfors regular metric spaces
Jeff Lindquist
Mathematics , 2015,
Abstract: Let $(Z,d,\mu)$ be a compact, connected, Ahlfors $Q$-regular metric space with $Q>1$. Using a hyperbolic filling of $Z$, we define the notions of the $p$-capacity between two open subsets $A, B \subseteq Z$ and of the weak covering $p$-capacity of a path family $\Gamma$. We show comparability results and quasisymmetric invariance. As an application of our methods we deduce a result due to Tyson on the geometric quasiconformality of quasisymmetric maps between compact, Ahlfors $Q$-regular metric spaces.
“Under the influence of an exotic nature...national remembrances are insensibly effaced”: Threats to the European Subject in Humboldt’s Personal Narrative of Travels to the Equinoctial Regions of the New Continent
Jason H. Lindquist
HiN. Alexander von Humboldt im Netz , 2004,
Abstract: Article in English, Abstract in English. My essay attends to a number of passages in Alexander von Humboldt’s Personal Narrative in which the Prussian explorer expresses anxiety about the apparent dangers posed by the overwhelmingly productive tropical landscapes he observes. In these passages, the excesses of an “exotic nature” threaten European identity and modes of civilization—and they trouble the accuracy of Humboldt’s own observational project. I also explore Humboldt’s related worry that South American vegetable (and visual) overload will exert a destabilizing effect on his aesthetic sensibility, disrupting his ability to represent the “New Continent” accurately in writing. Finally, I sketch the influence of Humboldt’s representations of tropical excess on nineteenth-century British cultural thought and literary practice. Studying the instabilities experienced by Personal Narrative’s expatriates and colonists promises to draw out important tensions latent in Humboldt’s treatment of tropical landscape and to illuminate broader epistemological and aesthetic shifts being worked out during the period.
Update on treatment options for Lambert–Eaton myasthenic syndrome: focus on use of amifampridine
Lindquist S,Stangel M
Neuropsychiatric Disease and Treatment , 2011,
Abstract: Sabine Lindquist, Martin StangelSection Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Hannover, GermanyAbstract: In Lambert–Eaton myasthenic syndrome (LEMS), antibodies against presynaptic voltage-gated calcium channels reduce the quantal release of acetylcholine, causing muscle weakness and autonomic dysfunction. More than half of the affected patients have associated small cell lung cancer, and thorough screening for an underlying malignancy is crucial. The mainstay of treatment for LEMS is symptomatic but immunotherapy is needed in more severely affected patients. Symptomatic therapies aim at increasing the concentration of acetylcholine at the muscle endplate. While acetylcholinesterase inhibitors were the first drugs to be used for the amelioration of symptoms, 3,4-diaminopyridine (3,4-DAP, amifampridine) has been shown to be more effective. 3,4-DAP blocks presynaptic potassium channels, thereby prolonging the action potential and increasing presynaptic calcium concentrations. This then results in increased quantal release of acetylcholine. The efficacy of 3,4-DAP for increasing muscle strength and resting compound muscle action potentials has been demonstrated by four placebo-controlled trials. Side effects are usually mild, and the most frequently reported are paresthesias. The most common serious adverse events are epileptic seizures. 3,4-DAP is currently the treatment of choice in patients with Lambert–Eaton myasthenic syndrome.Keywords: Lambert–Eaton myasthenic syndrome, symptomatic treatment, management, 3,4-diaminopyridine, amifampridine
Issues in Complementary Therapies: How We Got to Where We Are
Snyder, M., Lindquist, R
Online Journal of Issues in Nursing , 2001,
Abstract: Consumer interest in and use of complementary/alternative therapies has increased exponentially in the past decades. Although many of the over 1800 therapies have not been used in the delivery of nursing care, a number of these therapies have a long tradition of use in nursing. Additionally, nurses have conducted research on selected complementary therapies. Nursing is in an excellent position to be a leader in integrating these therapies into the Western biomedical health model and in continuing the research that will provide a better scientific base for the use of complementary therapies.
The Circulant Rational Covariance Extension Problem: The Complete Solution
Anders Lindquist,Giorgio Picci
Mathematics , 2012,
Abstract: The rational covariance extension problem to determine a rational spectral density given a finite number of covariance lags can be seen as a matrix completion problem to construct an infinite-dimensional positive-definite Toeplitz matrix the north-west corner of which is given. The circulant rational covariance extension problem considered in this paper is a modification of this problem to partial stochastic realization of reciprocal and periodic stationary process, which are better represented on the discrete unit circle $\mathbb{Z}_{2N}$ rather than on the discrete real line $\mathbb{Z}$. The corresponding matrix completion problem then amounts to completing a finite-dimensional Toeplitz matrix that is circulant. Another important motivation for this problem is that it provides a natural approximation, involving only computations based on the fast Fourier transform, for the ordinary rational covariance extension problem, potentially leading to an efficient numerical procedure for the latter. The circulant rational covariance extension problem is an inverse problem with infinitely many solutions in general, each corresponding to a bilateral ARMA representation of the underlying periodic (reciprocal) process. In this paper we present a complete smooth parameterization of all solutions and convex optimization procedures for determining them. A procedure to determine which solution that best matches additional data in the form of logarithmic moments is also presented.
The Statistical Analysis of fMRI Data
Martin A. Lindquist
Quantitative Biology , 2009, DOI: 10.1214/09-STS282
Abstract: In recent years there has been explosive growth in the number of neuroimaging studies performed using functional Magnetic Resonance Imaging (fMRI). The field that has grown around the acquisition and analysis of fMRI data is intrinsically interdisciplinary in nature and involves contributions from researchers in neuroscience, psychology, physics and statistics, among others. A standard fMRI study gives rise to massive amounts of noisy data with a complicated spatio-temporal correlation structure. Statistics plays a crucial role in understanding the nature of the data and obtaining relevant results that can be used and interpreted by neuroscientists. In this paper we discuss the analysis of fMRI data, from the initial acquisition of the raw data to its use in locating brain activity, making inference about brain connectivity and predictions about psychological or disease states. Along the way, we illustrate interesting and important issues where statistics already plays a crucial role. We also seek to illustrate areas where statistics has perhaps been underutilized and will have an increased role in the future.
Modeling of Stationary Periodic Time Series by ARMA Representations
Anders Lindquist,Giorgio Picci
Statistics , 2015,
Abstract: This is a survey of some recent results on the rational circulant covariance extension problem: Given a partial sequence $(c_0,c_1,\dots,c_n)$ of covariance lags $c_k=\mathbb{E}\{y(t+k)\overline{y(t)}\}$ emanating from a stationary periodic process $\{y(t)\}$ with period $2N>2n$, find all possible rational spectral functions of $\{y(t)\}$ of degree at most $2n$ or, equivalently, all bilateral and unilateral ARMA models of order at most $n$, having this partial covariance sequence. Each representation is obtained as the solution of a pair of dual convex optimization problems. This theory is then reformulated in terms of circulant matrices and the connections to reciprocal processes and the covariance selection problem is explained. Next it is shown how the theory can be extended to the multivariate case. Finally, an application to image processing is presented.
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