371 research outputs found
Optical air data systems and methods
Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip
Optical air data systems and methods
Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip
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Selective incorporation of proteinaceous over nonproteinaceous cationic amino acids in model prebiotic oligomerization reactions.
Numerous long-standing questions in origins-of-life research center on the history of biopolymers. For example, how and why did nature select the polypeptide backbone and proteinaceous side chains? Depsipeptides, containing both ester and amide linkages, have been proposed as ancestors of polypeptides. In this paper, we investigate cationic depsipeptides that form under mild dry-down reactions. We compare the oligomerization of various cationic amino acids, including the cationic proteinaceous amino acids (lysine, Lys; arginine, Arg; and histidine, His), along with nonproteinaceous analogs of Lys harboring fewer methylene groups in their side chains. These analogs, which have been discussed as potential prebiotic alternatives to Lys, are ornithine, 2,4-diaminobutyric acid, and 2,3-diaminopropionic acid (Orn, Dab, and Dpr). We observe that the proteinaceous amino acids condense more extensively than these nonproteinaceous amino acids. Orn and Dab readily cyclize into lactams, while Dab and Dpr condense less efficiently. Furthermore, the proteinaceous amino acids exhibit more selective oligomerization through their α-amines relative to their side-chain groups. This selectivity results in predominantly linear depsipeptides in which the amino acids are α-amine-linked, analogous to today's proteins. These results suggest a chemical basis for the selection of Lys, Arg, and His over other cationic amino acids for incorporation into proto-proteins on the early Earth. Given that electrostatics are key elements of protein-RNA and protein-DNA interactions in extant life, we hypothesize that cationic side chains incorporated into proto-peptides, as reported in this study, served in a variety of functions with ancestral nucleic acid polymers in the early stages of life
A time of flight method to measure the speed of sound using a stereo sound card
We present an inexpensive apparatus for measuring the speed of sound, with a
time of flight method, using a computer with a stereo sound board. Students
measure the speed of sound by timing the delay between the arrivals of a pulse
to two microphones placed at different distances from the source. It can serve
as a very effective demonstration, providing a quick measurement of the speed
of sound in air; we have used it with great success in Open Days in our
Department. It can also be used for a full fledged laboratory determination of
the speed of sound in air.Comment: Accepted for publication in The Physics Teache
Local Charge of the nu=5/2 Fractional Quantum Hall State
Electrons in two dimensions and strong magnetic fields effectively lose their
kinetic energy and display exotic behavior dominated by Coulomb forces. When
the ratio of electrons to magnetic flux quanta in the system is near 5/2, the
unique correlated phase that emerges is predicted to be gapped with
fractionally charged quasiparticles and a ground state degeneracy that grows
exponentially as these quasiparticles are introduced. Interestingly, the only
way to transform between the many ground states would be to braid the
fractional excitations around each other, a property with applications in
quantum information processing. Here we present the first observation of
localized quasiparticles at nu=5/2, confined to puddles by disorder. Using a
local electrometer to compare how quasiparticles at nu=5/2 and nu=7/3 charge
these puddles, we are able to extract the ratio of local charges for these
states. Averaged over several disorder configurations and samples, we find the
ratio to be 4/3, suggesting that the local charges are e/3 at seven thirds and
e/4 at five halves, in agreement with theoretical predictions. This
confirmation of localized e/4 quasiparticles is necessary for proposed
interferometry experiments to test statistics and computational ability of the
state at nu=5/2.Comment: 6 pages, 4 figures corrected titl
High throughput mutagenesis for identification of residues regulating human prostacyclin (hIP) receptor
The human prostacyclin receptor (hIP receptor) is a seven-transmembrane G protein-coupled receptor (GPCR) that plays a critical role in vascular smooth muscle relaxation and platelet aggregation. hIP receptor dysfunction has been implicated in numerous cardiovascular abnormalities, including myocardial infarction, hypertension, thrombosis and atherosclerosis. Genomic sequencing has discovered several genetic variations in the PTGIR gene coding for hIP receptor, however, its structure-function relationship has not been sufficiently explored. Here we set out to investigate the applicability of high throughput random mutagenesis to study the structure-function relationship of hIP receptor. While chemical mutagenesis was not suitable to generate a mutagenesis library with sufficient coverage, our data demonstrate error-prone PCR (epPCR) mediated mutagenesis as a valuable method for the unbiased screening of residues regulating hIP receptor function and expression. Here we describe the generation and functional characterization of an epPCR derived mutagenesis library compromising >4000 mutants of the hIP receptor. We introduce next generation sequencing as a useful tool to validate the quality of mutagenesis libraries by providing information about the coverage, mutation rate and mutational bias. We identified 18 mutants of the hIP receptor that were expressed at the cell surface, but demonstrated impaired receptor function. A total of 38 non-synonymous mutations were identified within the coding region of the hIP receptor, mapping to 36 distinct residues, including several mutations previously reported to affect the signaling of the hIP receptor. Thus, our data demonstrates epPCR mediated random mutagenesis as a valuable and practical method to study the structurefunction relationship of GPCRs. © 2014 Bill et al
The Rat Grimace Scale: A partially automated method for quantifying pain in the laboratory rat via facial expressions
We recently demonstrated the utility of quantifying spontaneous pain in mice via the blinded coding of facial expressions. As the majority of preclinical pain research is in fact performed in the laboratory rat, we attempted to modify the scale for use in this species. We present herein the Rat Grimace Scale, and show its reliability, accuracy, and ability to quantify the time course of spontaneous pain in the intraplantar complete Freund's adjuvant, intraarticular kaolin-carrageenan, and laparotomy (post-operative pain) assays. The scale's ability to demonstrate the dose-dependent analgesic efficacy of morphine is also shown. In addition, we have developed software, Rodent Face Finder®, which successfully automates the most labor-intensive step in the process. Given the known mechanistic dissociations between spontaneous and evoked pain, and the primacy of the former as a clinical problem, we believe that widespread adoption of spontaneous pain measures such as the Rat Grimace Scale might lead to more successful translation of basic science findings into clinical application
Spectroscopy of new brown dwarf members of rho Ophiuchi and an updated initial mass function
To investigate the universality hypothesis of the initial mass function in
the substellar regime, the population of the rho Ophiuchi molecular cloud is
analysed by including a new sample of low-mass spectroscopically confirmed
members. To that end, we have conducted a large spectroscopic follow-up of
young substellar candidates uncovered in our previous photometric survey. The
spectral types and extinction were derived for a newly found population of
substellar objects, and its masses estimated by comparison to evolutionary
models. A thoroughly literature search was conducted to provide an up-to-date
census of the cluster, which was then used to derive the luminosity and mass
functions, as well as the ratio of brown dwarfs to stars in the cluster. These
results were then compared to other young clusters. It is shown that the study
of the substellar population of the rho Ophiuchi molecular cloud is hampered
only by the high extinction in the cluster ruling out an apparent paucity of
brown dwarfs. The discovery of 16 new members of rho Ophiuchi, 13 of them in
the substellar regime, reveals the low-mass end of its population and shows the
success of our photometric candidate selection with the WIRCam survey. The
study of the brown dwarf population of the cluster reveals a high disk fraction
of 76 (+5-8)%. Taking the characteristic peak mass of the derived mass function
and the ratio of brown dwarfs to stars into account, we conclude that the mass
function of rho Ophiuchi is similar to other nearby young clusters.Comment: Accepted to A&A (30 December 2011); v2 includes language editin
Ecology and diversity of culturable fungal species associated with soybean seedling diseases in the Midwestern United States
Aims: To isolate and characterize fungi associated with diseased soybean seedlings in Midwestern soybean production fields and to determine the influence of environmental and edaphic factors on their incidence.
Methods and Results: Seedlings were collected from fields with seedling disease history in 2012 and 2013 for fungal isolation. Environmental and edaphic data associated with each field was collected. 3036 fungal isolates were obtained and assigned to 76 species. The most abundant genera recovered were Fusarium (73%) and Trichoderma (11.2%). Other genera included Mortierella, Clonostachys, Rhizoctonia, Alternaria, Mucor, Phoma, Macrophomina and Phomopsis. Most recovered species are known soybean pathogens. However, non-pathogenic organisms were also isolated. Crop history, soil density, water source, precipitation and temperature were the main factors influencing the abundance of fungal species.
Conclusion: Key fungal species associated with soybean seedling diseases occurring in several US production regions were characterized. This work also identified major environment and edaphic factors affecting the abundance and occurrence of these species.
Significance and Impact of the Study: The identification and characterization of the main pathogens associated with seedling diseases across major soybean-producing areas could help manage those pathogens, and devise more effective and sustainable practices to reduce the damage they cause
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