233 research outputs found
Informing Carbon in Arctic Reservoirs Vulnerability Experiment Flight Schedule based upon Soil and Vegetation Freeze and Thaw Event Variation along the Alaska Ecological Transect
Established in the 1990s, the Alaska Ecological Transect (ALECTRA) is composed of a series of ground stations extending from the Franklin Bluff on Alaska’s North Slope to the Kenai Peninsula, south of Anchorage. At each station, sets of thermistors are deployed to monitor vegetation tissue temperature, air temperature, and soil profile temperatures. Also sensors are deployed for monitoring sap flow in individual trees. The stations are automated, with data loggers recording this data approximately every two hours. Dates marking the spring thaw and fall freeze transitions in soil and vegetation tissues from sites in Coldfoot, Dietrich Valley, and Bonanza Creek were identified and analyzed to inform the scheduling of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) Mission’s spring and fall flights. Set to start in March 2012, the De Havilland DHC-6 Twin Otter aircraft will fly over the above mentioned sites, among others, using remote sensing technology to monitor soil moisture, freeze/thaw state, and surface temperatures as well as total atmospheric columns of carbon dioxide, methane, and carbon monoxide
Introduction: experimental, minimalist, postminimalist? Origins, definitions, communities
This volume surveys and critiques the current state of research in this area, and offers a cutting-edge and up-to-date examination of this important field, written by an international team of scholars and performers.
In recent years the music of minimalist composers such as La Monte Young, Terry Riley, Steve Reich and Philip Glass has, increasingly, become the subject of important musicological reflection, research and debate. Scholars have also been turning their attention to the work of lesser-known contemporaries such as Phill Niblock and Eliane Radigue, or to second and third generation minimalists such as John Adams, Louis Andriessen, Michael Nyman and William Duckworth, whose range of styles may undermine any sense of shared aesthetic approach but whose output is still to a large extent informed by the innovative work of their minimalist predecessors. Attempts have also been made by a number of academics to contextualise the work of composers who have moved in parallel with these developments while remaining resolutely outside its immediate environment, including such diverse figures as Karel Goeyvaerts, Robert Ashley, Arvo Pärt and Brian Eno. Theory has reflected practice in many respects, with the multimedia works of Reich and Glass encouraging interdisciplinary approaches, associations and interconnections. Minimalism’s role in culture and society has also become the subject of recent interest and debate, complementing existing scholarship, which addressed the subject from the perspective of historiography, analysis, aesthetics and philosophy. The Ashgate Research Companion to Minimalist and Postminimalist Music provides an authoritative overview of established research in this area, while also offering new and innovative approaches to the subject
Clinical Study The Effect of Withdrawal and Intake of Nicotine on Smokers' Ability to Ignore Distractors in a Number Parity Decision Task
Nicotine's attention enhancing effects are often attributed to enhancement of stimulus filtering by the attention networks. We investigated distractibility in 20 abstinent cigarette smokers (9 hours overnight; phase 1) and tested them again after smoking one cigarette (phase 2). Their performance was compared to 20 nonsmokers (no nicotine intake). In an auditory number parity decision task, participants had to make a forced choice "odd" or "even" decision about centrally presented numbers between 2 and 9, while ignoring laterally presented preceding or simultaneous novel distractors. In phase 1, distractors that preceded goal stimuli slowed reaction times (RTs) more than simultaneously presented distractors in both groups. In phase 2, nicotine intake speeded RTs in smokers in all conditions and reduced RT variability for simple number decisions and simultaneous distractors. Overall, there was a nonsignificant trend for smokers to be less accurate than nonsmokers. Accuracy in the simultaneous distractor condition decreased in both groups in phase 2. We argue that the observed nicotine-induced improvements on behavioral performance primarily reflect enhancement of top-down control of attention
A Distance-Limited Imaging Survey of Sub-Stellar Companions to Solar Neighborhood Stars
We report techniques and results of a Palomar 200-inch (5 m) adaptive optics
imaging survey of sub-stellar companions to solar-type stars. The survey
consists of Ks coronagraphic observations of 21 FGK dwarfs out to 20 pc (median
distance about 17 pc). At 1-arcsec separation (17 projected AU) from a typical
target system, the survey achieves median sensitivities 7 mag fainter than the
parent star. In terms of companion mass, that corresponds to sensitivities of
50MJ (1 Gyr), 70MJ (solar age), and 75MJ (10 Gyr), using the evolutionary
models of Baraffe and colleagues. Using common proper motion to distinguish
companions from field stars, we find that no system shows positive evidence of
a previously unknown substellar companion (searchable separation about 20-250
projected AU at the median target distance).Comment: 29 pages, 5 figures. Carson et al. 2008, AJ, in pres
Comparative analytical performance of multiple plasma Aβ42 and Aβ40 assays and their ability to predict positron emission tomography amyloid positivity
INTRODUCTION: This report details the approach taken to providing a dataset allowing for analyses on the performance of recently developed assays of amyloid beta (Aβ) peptides in plasma and the extent to which they improve the prediction of amyloid positivity. METHODS: Alzheimer's Disease Neuroimaging Initiative plasma samples with corresponding amyloid positron emission tomography (PET) data were run on six plasma Aβ assays. Statistical tests were performed to determine whether the plasma Aβ measures significantly improved the area under the receiver operating characteristic curve for predicting amyloid PET status compared to age and apolipoprotein E (APOE) genotype. RESULTS: The age and APOE genotype model predicted amyloid status with an area under the curve (AUC) of 0.75. Three assays improved AUCs to 0.81, 0.81, and 0.84 (P < .05, uncorrected for multiple comparisons). DISCUSSION: Measurement of Aβ in plasma contributes to addressing the amyloid component of the ATN (amyloid/tau/neurodegeneration) framework and could be a first step before or in place of a PET or cerebrospinal fluid screening study. HIGHLIGHTS: The Foundation of the National Institutes of Health Biomarkers Consortium evaluated six plasma amyloid beta (Aβ) assays using Alzheimer's Disease Neuroimaging Initiative samples. Three assays improved prediction of amyloid status over age and apolipoprotein E (APOE) genotype. Plasma Aβ42/40 predicted amyloid positron emission tomography status better than Aβ42 or Aβ40 alone
Mechanisms for the Intracellular Manipulation of Organelles by Conventional Electroporation
Conventional electroporation (EP) changes both the conductance and molecular permeability of the plasma membrane (PM) of cells and is a standard method for delivering both biologically active and probe molecules of a wide range of sizes into cells. However, the underlying mechanisms at the molecular and cellular levels remain controversial. Here we introduce a mathematical cell model that contains representative organelles (nucleus, endoplasmic reticulum, mitochondria) and includes a dynamic EP model, which describes formation, expansion, contraction, and destruction for the plasma and all organelle membranes. We show that conventional EP provides transient electrical pathways into the cell, sufficient to create significant intracellular fields. This emerging intracellular electrical field is a secondary effect due to EP and can cause transmembrane voltages at the organelles, which are large enough and long enough to gate organelle channels, and even sufficient, at some field strengths, for the poration of organelle membranes. This suggests an alternative to nanosecond pulsed electric fields for intracellular manipulations.National Science Foundation (U.S.) (NSF Graduate Research Fellowship)National Institutes of Health (U.S.) (grant No. R01-GM63857)Aegis Industries, Inc
The use of murine models for studying mechanistic insights of genomic instability in multiple myeloma
Multiple myeloma (MM) is a B-cell malignancy characterized by the accumulation of clonal plasma cells in the bone marrow. In normal plasma cell development, cells undergo programmed DNA breaks and translocations, a process necessary for generation of a wide repertoire of antigen-specific antibodies. This process also makes them vulnerable for the acquisition of chromosomal defects. Well-known examples of these aberrations, already seen at time of MM diagnosis, are hyperdiploidy or the translocations involving the immunoglobulin heavy chain. Over the recent years, however, novel aspects concerning genomic instability and its role in tumor development, disease progression and nascence of refractory disease were identified. As such, genomic instability is becoming a very relevant research topic with the potential identification of novel disease pathways. In this review, we aim to describe recent studies involving murine MM models focusing on the deregulation of processes implicated in genomic instability and their clinical impact. More specifically, we will discuss chromosomal instability, DNA damage and repair responses, development of drug resistance, and recent insights into the study of clonal hierarchy using different murine MM models. Lastly, we will discuss the importance and the use of murine MM models in the pre-clinical evaluation of promising novel therapeutic agents
Carnivore Translocations and Conservation: Insights from Population Models and Field Data for Fishers (Martes pennanti)
Translocations are frequently used to restore extirpated carnivore populations. Understanding the factors that influence translocation success is important because carnivore translocations can be time consuming, expensive, and controversial. Using population viability software, we modeled reintroductions of the fisher, a candidate for endangered or threatened status in the Pacific states of the US. Our model predicts that the most important factor influencing successful re-establishment of a fisher population is the number of adult females reintroduced (provided some males are also released). Data from 38 translocations of fishers in North America, including 30 reintroductions, 5 augmentations and 3 introductions, show that the number of females released was, indeed, a good predictor of success but that the number of males released, geographic region and proximity of the source population to the release site were also important predictors. The contradiction between model and data regarding males may relate to the assumption in the model that all males are equally good breeders. We hypothesize that many males may need to be released to insure a sufficient number of good breeders are included, probably large males. Seventy-seven percent of reintroductions with known outcomes (success or failure) succeeded; all 5 augmentations succeeded; but none of the 3 introductions succeeded. Reintroductions were instrumental in reestablishing fisher populations within their historical range and expanding the range from its most-contracted state (43% of the historical range) to its current state (68% of the historical range). To increase the likelihood of translocation success, we recommend that managers: 1) release as many fishers as possible, 2) release more females than males (55–60% females) when possible, 3) release as many adults as possible, especially large males, 4) release fishers from a nearby source population, 5) conduct a formal feasibility assessment, and 6) develop a comprehensive implementation plan that includes an active monitoring program
Measurement-Induced State Transitions in a Superconducting Qubit: Within the Rotating Wave Approximation
Superconducting qubits typically use a dispersive readout scheme, where a
resonator is coupled to a qubit such that its frequency is qubit-state
dependent. Measurement is performed by driving the resonator, where the
transmitted resonator field yields information about the resonator frequency
and thus the qubit state. Ideally, we could use arbitrarily strong resonator
drives to achieve a target signal-to-noise ratio in the shortest possible time.
However, experiments have shown that when the average resonator photon number
exceeds a certain threshold, the qubit is excited out of its computational
subspace, which we refer to as a measurement-induced state transition. These
transitions degrade readout fidelity, and constitute leakage which precludes
further operation of the qubit in, for example, error correction. Here we study
these transitions using a transmon qubit by experimentally measuring their
dependence on qubit frequency, average photon number, and qubit state, in the
regime where the resonator frequency is lower than the qubit frequency. We
observe signatures of resonant transitions between levels in the coupled
qubit-resonator system that exhibit noisy behavior when measured repeatedly in
time. We provide a semi-classical model of these transitions based on the
rotating wave approximation and use it to predict the onset of state
transitions in our experiments. Our results suggest the transmon is excited to
levels near the top of its cosine potential following a state transition, where
the charge dispersion of higher transmon levels explains the observed noisy
behavior of state transitions. Moreover, occupation in these higher energy
levels poses a major challenge for fast qubit reset
Targeting the IGF-1R signaling and mechanisms for epigenetic gene silencing in human multiple myeloma
Multiple myeloma (MM) is a B cell malignancy characterized by the expansion of clonal plasmablast/plasma cells within the bone-marrow. It is well established that the bone-marrow microenvironment has a pivotal role in providing critical cytokines and cell–cell interactions to support the growth and survival of the MM tumor clone. The pathogenesis of MM is, however, only fragmentarily understood. Detailed genomic analysis reveals a heterogeneous and complex pattern of structural and numerical chromosomal aberrations. In this review we will discuss some of the recent results on the functional role and potential clinical use of the IGF-1R, one of the major mediators of growth and survival for MM. We will also describe some of our results on epigenetic gene silencing in MM, as it may indeed constitute a novel basis for the understanding of tumor initiation and maintenance in MM and thus may change the current view on treatment strategies for MM
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