3,153 research outputs found
Temperature sensitivity of the pyloric neuromuscular system and its modulation by dopamine
We report here the effects of temperature on the p1 neuromuscular system of the stomatogastric system of the lobster (Panulirus interruptus). Muscle force generation, in response to both the spontaneously rhythmic in vitro pyloric network neural activity and direct, controlled motor nerve stimulation, dramatically decreased as temperature increased, sufficiently that stomach movements would very unlikely be maintained at warm temperatures. However, animals fed in warm tanks showed statistically identical food digestion to those in cold tanks. Applying dopamine, a circulating hormone in crustacea, increased muscle force production at all temperatures and abolished neuromuscular system temperature dependence. Modulation may thus exist not only to increase the diversity of produced behaviors, but also to maintain individual behaviors when environmental conditions (such as temperature) vary
Trustworthiness as a Limitation on Network Neutrality
The policy debate over how to govern access to broadband networks has largely ignored the objective of network trustworthiness-a set of properties (including security, survivability, and safety) that guarantee expected behavior. Instead, the terms of the network access debate have focused on whether imposing a nondiscrimination or network neutrality obligation on network providers is justified by the condition of competition among last-mile providers. Rules proposed by scholars and policymakers would allow network providers to deviate from network neutrality to protect network trustworthiness, but none of these proposals has explored the implications of such exceptions for either neutrality or trustworthiness.
This Article examines the relationship between network trustworthiness and network neutrality and finds that providing a trustworthiness exception is a viable way to accommodate trustworthiness within a network neutrality rule. Network providers need leeway to block or degrade traffic within their own subnets, and trustworthiness exceptions can provide them with sufficient flexibility to do so. But, the Article argues, defining the scope of a trustworthiness exception is critically important to the network neutrality rule as a whole: an unduly narrow exception could thwart innovative network defenses, while a broad exception could allow trustworthiness to become a pretext that protects a wide range of discrimination that network neutrality advocates seek to prevent. Furthermore, monitoring network providers\u27 use of a trustworthiness exception is necessary to ensure that it remains an exception, rather than becoming a rule. The Article therefore proposes that network providers be required to disclose data regarding their use of a trustworthiness exception . It also offers a general structure for managing these disclosure
An optical spectroscopic survey of the 3CR sample of radio galaxies with z<0.3. III. Completing the sample
We present optical nuclear spectra for nine 3CR radio sources obtained with
the Telescopio Nazionale Galileo, that complete our spectroscopic observations
of the sample up to redshifts 0.3. We measure emission line luminosities
and ratios, and derive a spectroscopic classification for these sources.Comment: Accepted for publication in A&A. We provide as additional material
two tables presenting the main data for the whole sample, combining the
results presented here with those of Paper I and Paper I
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Bottom-up Markup Fluctuations
We study markup cyclicality in a granular macroeconomic model with oligopolistic competition. We characterize the comovement of firm, sectoral, and economy-wide markups with sectoral and aggregate output following firm-level shocks. We then quantify the modelâs ability to reproduce salient features of the cyclical properties of markups in French administrative firm-level data, from the bottom (firm) level to the aggregate level. Our model helps rationalize various, seemingly conflicting, measures of markup cyclicality in the French data
Studies and perspectives of plasminogen activators
The fibrinolytic system participates in a variety of physiological and pathological processes. It consists of an inactive proenzyme, plasminogen, which can be activated to the active serine protease plasmin by the action of different types of plasminogen activators. The main function of the fibrinolytic system is to dissolve fibrin deposits in blood vessels. Thrombogenesis can be influenced by an insufficient or ineffective fibrinolytic system. The tissue-type plasminogen activator (t-PA) receives considerable attention since its deficiency has been shown to be a leading cause for thrombophilic situations. Increases of its main inhibitor (PAI) probably play a similar role. Using the advantages of recombinant DNA technology modem thrombolytic drugs based on the structure of plasminogen activators are applied for the therapy of thromboembolic diseases. Structure and function of the fibrinolytic system are outlined in the following review. Diagnostic evaluation of the fibrinolytic system and therapeutic considerations are discussed.Biomedical Reviews 1992; 1: 33-38
Cooperation, Proximity, and Social Innovation: Three Ingredients for Industrial Medium-Sized Townsâ Renewal?
Over several decades, medium-sized industrial towns have suffered from a combination of economic and political processes: Deindustrialization, metropolization, and withdrawal of public services. After two decades in which they have been somewhat neglected (in favor of metropolises), there have recently been State and European public policies aimed at them. Medium-sized cities are not homogeneous and present several trajectories. Based on quantitative approach in France, we highlight the very diverse socio-economic dynamics of French medium-sized industrial towns. Thus, far from widespread decline or shrinking dynamics, some of these cities are experiencing an economic rebound. This is the case of Romans-sur-IsĂšre, a medium-sized town located in the south-east of France. Focusing our qualitative analyze on this city, we try to understand this type of process. In this medium-sized town, former capital of the shoe industry, local stakeholders, private, and public try to support a productive renewal. The results of our case study highlight the role that cooperation, spatial and organizational proximity, and social innovation could play in the renewal of productive economy in medium-sized industrial towns. Even if the economic situation remains difficult for many medium-sized cities in France as in Europe, we argue that they could have a productive future making and ultimately take advantages of their âmedium-sizedâ attributes.
Over several decades, medium-sized industrial towns have suffered from a combination of economic and political processes: Deindustrialization, metropolization, and withdrawal of public services. After two decades in which they have been somewhat neglected (in favor of metropolises), there have recently been State and European public policies aimed at them. Medium-sized cities are not homogeneous and present several trajectories. Based on quantitative approach in France, we highlight the very diverse socio-economic dynamics of French medium-sized industrial towns. Thus, far from widespread decline or shrinking dynamics, some of these cities are experiencing an economic rebound. This is the case of Romans-sur-IsĂšre, a medium-sized town located in the south-east of France. Focusing our qualitative analyze on this city, we try to understand this type of process. In this medium-sized town, former capital of the shoe industry, local stakeholders, private, and public try to support a productive renewal. The results of our case study highlight the role that cooperation, spatial and organizational proximity, and social innovation could play in the renewal of productive economy in medium-sized industrial towns. Even if the economic situation remains difficult for many medium-sized cities in France as in Europe, we argue that they could have a productive future making and ultimately take advantages of their âmedium-sizedâ attributes.
 
Hot Populations in M87 Globular Clusters
We have obtained HST/STIS far- and near-UV photometry of globular clusters in
four fields in the gE galaxy M87. To a limit of m(FUV) = 25 we detect a total
of 66 globular clusters (GCs) in common with the deep HST optical-band study of
Kundu et al. (1999). Despite strong overlap in V- and I-band properties, the
M87 GCs have UV/optical properties that are distinct from clusters in the Milky
Way and in M31. M87 clusters, especially metal-poor ones, produce larger hot HB
populations than do Milky Way analogues. Cluster mass is probably not a factor
in these distinctions. The most metal-rich M87 GCs in our sample are near Z_sun
and overlap the local E galaxy sample in estimated Mg_2 line indices.
Nonetheless, the clusters produce much more UV light at a given Mg_2, being up
to 1 mag bluer than any gE galaxy in (FUV-V) color. The M87 GCs do not appear
to represent a transition between Milky Way-type clusters and E galaxies. The
differences are in the correct sense if the clusters are significantly older
than the E galaxies. Comparisons with Galactic open clusters indicate that the
hot stars lie on the extreme horizontal branch, rather than being blue
stragglers, and that the EHB becomes well populated for ages > 5 Gyr. We find
that 43 of our UV detections have no optical-band counterparts. Most appear to
be UV-bright background galaxies, seen through M87. Eleven NUV variable sources
detected at only one epoch in the central field are probably classical novae.
[Abridged]Comment: 70 pages, 25 figures (including 4 jpgs), 7 tables. To appear in AJ.
Full resolution version available at
http://www.astro.virginia.edu/~rwo/m87/m87-hotpops.pd
Galactic Extinction from Colors and Counts of Field Galaxies in WFPC2 Frames: An Application to GRB 970228
We develop the ``simulated extinction method'' to measure average foreground
Galactic extinction from field galaxy number-counts and colors. The method
comprises simulating extinction in suitable reference fields by changing the
isophotal detection limit. This procedure takes into account selection effects,
in particular, the change in isophotal detection limit (and hence in isophotal
magnitude completeness limit) with extinction, and the galaxy color--magnitude
relation.
We present a first application of the method to the HST WFPC2 images of the
gamma-ray burster GRB 970228. Four different WFPC2 high-latitude fields,
including the HDF, are used as reference to measure the average extinction
towards the GRB in the F606W passband. From the counts, we derive an average
extinction of A_V = 0.5 mag, but the dispersion of 0.4 mag between the
estimates from the different reference fields is significantly larger than can
be accounted by Poisson plus clustering uncertainties. Although the counts
differ, the average colors of the field galaxies agree well. The extinction
implied by the average color difference between the GRB field and the reference
galaxies is A_V = 0.6 mag, with a dispersion in the estimated extinction from
the four reference fields of only 0.1 mag. All our estimates are in good
agreement with the value of 0.81\pm0.27 mag obtained by Burstein & Heiles, and
with the extinction of 0.78\pm0.12 measured by Schlegel et al. from maps of
dust IR emission. However, the discrepancy between the widely varying counts
and the very stable colors in these high-latitude fields is worth
investigating.Comment: 14 pages, 2 figures; submitted to the Astrophysical Journa
Nitrogen Overabundance: Globular Cluster and Halo Formation
Halo globular clusters pose four succinct issues that must be solved in any
scenario of their formation: single-age, single metallicity stellar
populations; a lower limit ([Fe/H] ~ -2.3) to their average metallicity;
comprising only 1% of the stellar halo mass, and being among the oldest stars
in our Galaxy. New spectra are presented of Galactic stars and integrated
spectra of Galactic globular clusters which extend to 3250 angstroms. These
spectra show show that the most metal-poor and among the best-studied Galactic
globular clusters show strong NH3360 absorption, even though their spectral
energy distributions in the near-UV are dominated by blue horizontal branch,
AF-type stars. These strong NH features must be coming from the main sequence
stars in these clusters. These new data are combined with existing data on the
wide range of carbon and nitrogen abundance in very metal-poor ([Fe/H] < -3.5)
halo giant and dwarf stars, together with recent models of zero-metal star
formation, to make a strawman scenario for globular cluster formation that can
reproduce three of the above four issues, and well as related two of the three
issues pertaining to nitrogen overabundance. This strawman proposal makes
observational and theoretical predictions that are testable, needing specific
help from the modelers to understand all of the elemental constraints on
globular cluster and halo formation.Comment: to be published in ApJL, 2 figures, one tabl
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