5,521 research outputs found
Hydroelastic vibration analysis of partially liquid-filled shells using a series representation of the liquid
A series representation of the oscillatory behavior of incompressible nonviscous liquids contained in partially filled elastic tanks is presented. Each term is selected on the basis of hydroelastic vibrations in circular cylindrical tanks. Using a complementary energy principle, the superposition of terms is made to approximately satisfy the liquid-tank interface compatibility. This analysis is applied to the gravity sloshing and hydroelastic vibrations of liquids in hemispherical tanks and in a typical elastic aerospace propellant tank. With only a few series terms retained, the results correlate very well with existing analytical results, NASTRAN-generated analytical results, and experimental test results. Hence, although each term is based on a cylindrical tank geometry, the superposition can be successfully applied to noncylindrical tanks
Improving Taxonomic Delimitation of Fungal Species in the Age of Genomics and Phenomics
Species concepts have long provided a source of debate among biologists. These lively debates have been important for reaching consensus on how to communicate across scientific disciplines and for advancing innovative strategies to study evolution, population biology, ecology, natural history, and disease epidemiology. Species concepts are also important for evaluating variability and diversity among communities, understanding biogeographical distributions, and identifying causal agents of disease across animal and plant hosts. While there have been many attempts to address the concept of species in the fungi, there are several concepts that have made taxonomic delimitation especially challenging. In this review we discuss these major challenges and describe methodological approaches that show promise for resolving ambiguity in fungal taxonomy by improving discrimination of genetic and functional traits. We highlight the relevance of eco-evolutionary theory used in conjunction with integrative taxonomy approaches to improve the understanding of interactions between environment, ecology, and evolution that give rise to distinct species boundaries. Beyond recent advances in genomic and phenomic methods, bioinformatics tools and modeling approaches enable researchers to test hypothesis and expand our knowledge of fungal biodiversity. Looking to the future, the pairing of integrative taxonomy approaches with multi-locus genomic sequencing and phenomic techniques, such as transcriptomics and proteomics, holds great potential to resolve many unknowns in fungal taxonomic classification
On the 2d Zakharov system with L^2 Schr\"odinger data
We prove local in time well-posedness for the Zakharov system in two space
dimensions with large initial data in L^2 x H^{-1/2} x H^{-3/2}. This is the
space of optimal regularity in the sense that the data-to-solution map fails to
be smooth at the origin for any rougher pair of spaces in the L^2-based Sobolev
scale. Moreover, it is a natural space for the Cauchy problem in view of the
subsonic limit equation, namely the focusing cubic nonlinear Schroedinger
equation. The existence time we obtain depends only upon the corresponding
norms of the initial data - a result which is false for the cubic nonlinear
Schroedinger equation in dimension two - and it is optimal because
Glangetas-Merle's solutions blow up at that time.Comment: 30 pages, 2 figures. Minor revision. Title has been change
Analysis of Optical Layouts for the Phase 1 upgrade of the CERN Large Hadron Collider Insertion Regions
In the framework of the studies for the upgrade of the insertions of the CERN Large Hadron Collider, four optical layouts were proposed with the aim of reducing the beta-function at the collision point down to 25 cm. The different candidate layouts are presented. Results from the studies performed on mechanical and dynamic aperture are summarized, together with the evaluation of beam-beam effects. Particular emphasis is given to the comparison of the optics performance, which led to retain the most promising layouts for further development
Cue-Evoked Dopamine Release Rapidly Modulates D2 Neurons in the Nucleus Accumbens During Motivated Behavior
Dopaminergic neurons that project from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) fire in response to unpredicted rewards or to cues that predict reward delivery. Although it is well established that reward-related events elicit dopamine release in the NAc, the role of rapid dopamine signaling in modulating NAc neurons that respond to these events remains unclear. Here, we examined dopamine's actions in the NAc in the rat brain during an intracranial self-stimulation task in which a cue predicted lever availability for electrical stimulation of the VTA. To distinguish actions of dopamine at select receptors on NAc neurons during the task, we used a multimodal sensor that probes three aspects of neuronal communication simultaneously: neurotransmitter release, cell firing, and identification of dopamine receptor type. Consistent with prior studies, we first show dopamine release events in the NAc both at cue presentation and after lever press (LP). Distinct populations of NAc neurons encode these behavioral events at these same locations selectively. Using our multimodal sensor, we found that dopamine-mediated responses after the cue involve exclusively a subset of D2-like receptors (D2Rs), whereas dopamine-mediated responses proximal to the LP are mediated by both D1-like receptors (D1R) and D2Rs. These results demonstrate for the first time that dopamine-mediated responses after cues that predict reward availability are specifically linked to its actions at a subset of neurons in the NAc containing D2Rs
Precipitation and temperature ensemble forecasts from single-value forecasts
International audienceA procedure is presented to construct ensemble forecasts from single-value forecasts of precipitation and temperature. This involves dividing the spatial forecast domain and total forecast period into a number of parts that are treated as separate forecast events. The spatial domain is divided into hydrologic sub-basins. The total forecast period is divided into time periods, one for each model time step. For each event archived values of forecasts and corresponding observations are used to model the joint distribution of forecasts and observations. The conditional distribution of observations for a given single-value forecast is used to represent the corresponding probability distribution of events that may occur for that forecast. This conditional forecast distribution subsequently is used to create ensemble members that vary in space and time using the "Schaake Shuffle" (Clark et al, 2004). The resulting ensemble members have the same space-time patterns as historical observations so that space-time joint relationships between events that have a significant effect on hydrological response tend to be preserved. Forecast uncertainty is space and time-scale dependent. For a given lead time to the beginning of the valid period of an event, forecast uncertainty depends on the length of the forecast valid time period and the spatial area to which the forecast applies. Although the "Schaake Shuffle" procedure, when applied to construct ensemble members from a time-series of single value forecasts, may preserve some of this scale dependency, it may not be sufficient without additional constraint. To account more fully for the time-dependent structure of forecast uncertainty, events for additional "aggregate" forecast periods are defined as accumulations of different "base" forecast periods. The generated ensemble members can be ingested by an Ensemble Streamflow Prediction system to produce ensemble forecasts of streamflow and other hydrological variables that reflect the meteorological uncertainty. The methodology is illustrated by an application to generate temperature and precipitation ensemble forecasts for the American River in California. Parameter estimation and dependent validation results are presented based on operational single-value forecasts archives of short-range River Forecast Center (RFC) forecasts and medium-range ensemble mean forecasts from the National Weather Service (NWS) Global Forecast System (GFS)
ΠΠ°ΡΡΠΎΡΡΠ²Π°Π½Π½Ρ ΡΠ½ΡΠ΅ΡΠ²Π°Π»ΡΠ½ΠΈΡ Π½ΠΎΡΠΌΠΎΠ±Π°ΡΠΈΡΠ½ΠΈΡ Π³ΡΠΏΠΎΠΊΡΠΈΡΠ½ΠΈΡ ΡΡΠ΅Π½ΡΠ²Π°Π½Ρ Π΄Π»Ρ Π°ΠΌΠ΅Π»ΡΠΎΡΠ°ΡΡΡ Π²ΠΏΠ»ΠΈΠ²Ρ Π±Π°Π»ΡΠ½Π΅ΠΎΡΠ΅ΡΠ°ΠΏΠ΅Π²ΡΠΈΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΡ ΠΊΡΡΠΎΡΡΡ Π’ΡΡΡΠΊΠ°Π²Π΅ΡΡ Π½Π° ΡΠ΅Π·ΠΈΡΡΠ΅Π½ΡΠ½ΡΡΡΡ Π΄ΠΎ Π³ΡΠΏΠΎΠΊΡΡΡ ΡΠ° Π²Π΅Π³Π΅ΡΠ°ΡΠΈΠ²Π½Ρ Π½Π΅ΡΠ²ΠΎΠ²Ρ ΡΠΈΡΡΠ΅ΠΌΡ
Π ΠΊΠ»ΠΈΠ½ΠΈΠΊΠΎ-ΡΠΈΠ·ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΌ Π½Π°Π±Π»ΡΠ΄Π΅Π½ΠΈΠΈ Π·Π° Π΄Π΅ΡΡΠΌΠΈ Ρ Π²Π΅Π³Π΅ΡΠ°ΡΠΈΠ²Π½ΠΎΠΉ Π΄ΠΈΡΡΠΎΠ½ΠΈΠ΅ΠΉ ΠΏΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Π΄ΠΎΠΏΠΎΠ»Π½Π΅Π½ΠΈΠ΅ ΡΡΠ°Π½Π΄Π°ΡΡΠ½ΠΎΠ³ΠΎ Π±Π°Π»ΡΠ½Π΅ΠΎΡΠ΅ΡΠ°ΠΏΠ΅Π²ΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ° ΠΊΡΡΠΎΡΡΠ° Π’ΡΡΡΠΊΠ°Π²Π΅Ρ ΠΈΠ½ΡΠ΅ΡΠ²Π°Π»ΡΠ½ΠΎΠΉ Π½ΠΎΡΠΌΠΎΠ±Π°ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ Π³ΠΈΠΏΠΎΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΡΠ΅Π½ΠΈΡΠΎΠ²ΠΊΠΎΠΉ ΠΏΡΠ΅Π΄ΠΎΡΠ²ΡΠ°ΡΠ°Π΅Ρ ΡΠ½ΠΈΠΆΠ΅Π½ΠΈΠ΅ ΡΠ΅ΡΡΠ° Π¨ΡΠ°Π½Π³Π΅ ΠΈ ΡΠΎΠΏΡΡΡΡΠ²ΡΡΡΠ΅Π΅ Π΅ΠΌΡ ΡΡΡΠ³ΡΠ±Π»Π΅Π½ΠΈΠ΅ ΡΠΈΠΌΠΏΠ°ΡΠΎΡΠΎΠ½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ΄Π²ΠΈΠ³Π° Π²Π΅Π³Π΅ΡΠ°ΡΠΈΠ²Π½ΠΎΠ³ΠΎ Π³ΠΎΠΌΠ΅ΠΎΡΡΠ°Π·Π°, Π° ΡΠ°ΠΊΠΆΠ΅ ΡΡΠΈΠ»ΠΈΠ²Π°Π΅Ρ ΠΏΠΎΠ»ΠΎΠΆΠΈΡΠ΅Π»ΡΠ½ΠΎΠ΅ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π±Π°Π»ΡΠ½Π΅ΠΎΡΠ΅ΡΠ°ΠΏΠΈΠΈ Π½Π° ΡΠ΅ΡΡ Π¨ΡΠ°Π½Π³Π΅, ΡΠΎΠΏΡΠΎΠ²ΠΎΠΆΠ΄Π°Π΅ΠΌΠΎΠ΅ Π²Π°Π³ΠΎΡΠΎΠ½ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΡΠ΄Π²ΠΈΠ³ΠΎΠΌ Π²Π΅Π³Π΅ΡΠ°ΡΠΈΠ²Π½ΠΎΠ³ΠΎ Π³ΠΎΠΌΠ΅ΠΎΡΡΠ°Π·Π°.In the clinical-physiological monitoring of children with vegetative dystonia is shown that the addition of standard balneotherapeutic complex spa Truskavets interval normobaric hypoxic training prevents the reduction of the hypoxic test Stange and the concomitant worsening sympathotonic shift of vegetative homeostasis, but also enhances the positive effect of balneotherapy on the test Stange, accompanied by a shift of autonomic vagotonic homeostasis
High resolution radio continuum survey of M33: I. The radio maps
We study the exponential scale length of total radio emission, the spectral
index distribution, and the linear radio polarization in the Scd galaxy M33.
Observations were carried out using the 3.6 cm dual channel and the 6.2 cm four
channel receivers of the 100--m Effelsberg telescope along with the L-band VLA
D--array at 20 cm. High spatial resolution and sensitivity in both total and
linearly polarized radio continuum emission from M33 were achieved. We found
considerable extended emission, not only from the main arms I S and I N, but
also from the weaker arms. The large--scale magnetic field exhibits
well--ordered spiral structure with almost the same orientation as that of the
optical spiral arms, however, it does not show a clear structural correlation
or anti--correlation with the optical arms. There is a north-south asymmetry in
polarization that is frequency-dependent. We found that the ring mean spectral
index versus radius increases faster beyond = 4 kpc. At each wavelength,
the exponential scale length is larger inside than outside = 4 kpc. From
the larger scales lengths at 4 kpc, we conclude that star forming
regions are mainly spread over the region 4 kpc without a dominant
nuclear concentration. Furthermore, at 4 kpc, a spatial correlation
between cosmic rays and star forming regions may exist. From the behaviour of
the mean spectral indices obtained from different pairs of the radio continuum
data at 3.6, 6.2, and 20 cm, we confirm that a decrease in the thermal fraction
causes an increase in the spectral index. The frequency-dependent asymmetry in
the polarization hints to an asymmetry in Faraday depolarization.Comment: 16 pages, 13 figures, accepted for publication in the Astronomy and
Astrophysics Journa
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