600 research outputs found
The Ecosystem Approach to Fisheries: Issues, Terminology, Principles, Institutional Foundations, Implementation and Outlook
Ecosystems are complex and dynamic natural units that produce goods and services beyond those of benefit to fisheries. Because fisheries have a direct impact on the ecosystem, which is also impacted by other human activities, they need to be managed in an ecosystem context. The meaning of the terms 'ecosystem management', 'ecosystem based management', 'ecosystem approach to fisheries'(EAF), etc., are still not universally defined and progressively evolving. The justification of EAF is evident in the characteristics of an exploited ecosystem and the impacts resulting from fisheries and other activities. The rich set of international agreements of relevance to EAF contains a large number of principles and conceptual objectives. Both provide a fundamental guidance and a significant challenge for the implementation of EAF. The available international instruments also provide the institutional foundations for EAF. The FAO Code of Conduct for Responsible Fisheries is particularly important in this respect and contains provisions for practically all aspects of the approach. One major difficulty in defining EAF lies precisely in turning the available concepts and principles into operational objectives from which an EAF management plan would more easily be developed. The paper discusses these together with the types of action needed to achieve them. Experience in EAF implementation is still limited but some issues are already apparent, e.g. in added complexity, insufficient capacity, slow implementation, need for a pragmatic approach, etc. It is argued, in conclusion, that the future of EAF and fisheries depends on the way in which the two fundamental concepts of fisheries management and ecosystem management, and their respective stakeholders, will join efforts or collide
Dust and dark Gamma-Ray Bursts: mutual implications
In a cosmological context dust has been always poorly understood. That is
true also for the statistic of GRBs so that we started a program to understand
its role both in relation to GRBs and in function of z. This paper presents a
composite model in this direction. The model considers a rather generic
distribution of dust in a spiral galaxy and considers the effect of changing
some of the parameters characterizing the dust grains, size in particular. We
first simulated 500 GRBs distributed as the host galaxy mass distribution,
using as model the Milky Way. If we consider dust with the same properties as
that we observe in the Milky Way, we find that due to absorption we miss about
10% of the afterglows assuming we observe the event within about 1 hour or even
within 100s. In our second set of simulations we placed GRBs randomly inside
giants molecular clouds, considering different kinds of dust inside and outside
the host cloud and the effect of dust sublimation caused by the GRB inside the
clouds. In this case absorption is mainly due to the host cloud and the
physical properties of dust play a strong role. Computations from this model
agree with the hypothesis of host galaxies with extinction curve similar to
that of the Small Magellanic Cloud, whereas the host cloud could be also
characterized by dust with larger grains. To confirm our findings we need a set
of homogeneous infrared observations. The use of coming dedicated infrared
telescopes, like REM, will provide a wealth of cases of new afterglow
observations.Comment: 16 pages, 8 figures, accepted by A&
Search for low instability strip variables in the young open cluster NGC 2516
In this paper we revise and complete the photometric survey of the
instability strip of the southern open cluster NGC 2516 published by Antonello
and Mantegazza (1986). No variable stars with amplitudes larger than
were found. However by means of an accurate analysis based on a new statistical
method two groups of small amplitude variables have been disentangled: one with
periods (probably Scuti stars) and one with periods
. The position in the HR diagram and the apparent time-scale may
suggest that the stars of the second group belong to a recently discovered new
class of variables, named Dor variables. They certainly deserve
further study. We also present a comparison between the results of the
photometric survey and the available pointed ROSAT observations of this
cluster.Comment: 7 pages, 2 ps figures. Accepted for P.A.S.
A successful experimental model for intimal hyperplasia prevention using a resveratrol eluting balloon
Objective: Restenosis due to intimal hyperplasia is a major clinical problem that compromises the success of angioplasty
and endovascular surgery. Resveratrol (RSV) has demonstrated a beneficial effect on restenosis from angioplasty. Unfortunately,
the physicochemical characteristics of RSV reduce the practicality of its immediate clinical application. This
work proposes an experimental model aiming to setup an intravessel, elutable, RSV-containing compound.
Methods: A 140 mg/mL RSV sterile injectable solution with a suitable viscosity for intravascular administration by drugdelivery
catheter (RSV-c) was prepared. This solution was locally administered in the common iliac artery of adult male
New Zealand White rabbits using a dedicated device (Genie; Acrostak, Geneva, Switzerland) after the induction of intimal
hyperplasia by traumatic angioplasty. The RSV concentrations in the wall artery were determined, and the thickness of the
harvested iliac arteries was measured over a 1-month period.
Results: The Genie catheter was applied in rabbit vessels, and the local delivery resulted in an effective reduction in restenosis
after plain angioplasty. Notably, RSV-c forced into the artery wall by balloon expansion might accumulate in the interstitial
areas or within cells, avoiding the washout of solutions. Magnification micrographs showed intimal proliferation was
significantly inhibited when RSV-c was applied. Moreover, no adverse events were documented in in vitro or in vivo studies.
Conclusions: RSV can be advantageously administered in the arterial walls by a drug-delivery catheter to reduce the risk of
restenosis
Stabilization of linear carbon structures in a solid Ag nanoparticle assembly
Linear sp carbon nanostructures are gathering interest for the physical
properties of one-dimensional (1D) systems. At present, the main obstacle to
the synthesis and study of these systems is their instability. Here we present
a simple method to obtain a solid system where linear sp chains (i.e. polyynes)
in a silver nanoparticle assembly display a long term stability at ambient
conditions. The presence and the behavior of linear carbon is investigated by
Surface Enhanced Raman Scattering (SERS) exploiting the plasmon resonance of
the silver nanoparticles assembly. This model system opens the possibility to
investigate an intriguing form of carbon nanostructures
Impaired testicular signaling of vitamin A and vitamin K contributes to the aberrant composition of the extracellular matrix in idiopathic germ cell aplasia
Objective: To study pathogenic features of the somatic testicular microenvironment associated with idiopathic germ cell aplasia. Design: Cross-sectional study. Setting: Tertiary referral center for reproductive medicine. Patient(s): Testicular specimens from men with idiopathic nonobstructive azoospermia (iNOA) prospectively submitted to microdissection testicular sperm extraction. Of 20 specimens used for histology, 10 were also available for proteomic analysis. Primary Sertoli cells with normal karyotype and phenotype were also used. Intervention(s): Patients with iNOA were dichotomized according to a positive versus negative sperm retrieval at microdissection testicular sperm extraction, and on the isolated extracellular matrix (ECM) the proteomic analysis was performed. Main Outcome Measure(s): Proteomic analysis of the ECM from testicular specimens with positive versus negative sperm retrieval. Gene ontology enrichment was used to identify upstream regulators based on the 11 deregulated ECM proteins, which were validated by immunohistochemistry and quantitative polymerase chain reaction. Continuous variables were expressed as medians and interquartile range. Result(s): Germ cell aplasia was characterized by an increased signaling of the retinoic acid in Sertoli cells and associated with decreased expression of the basal membrane markers nidogen-2 and heparan sulfate proteoglycan-2. Decreased levels of the interstitial matrisome-associated factor IX and its regulator VKORC1 were, instead, coupled with decreased signaling of vitamin K in Leydig cells. An altered expression of a further eight ECM proteins was also found, including laminin-4 and laminin-5. Peripheral levels of the two vitamins were within the reference range in the two cohorts of iNOA men. Conclusion(s): We identified the pathogenetic signature of the somatic human testicular microenvironment, providing two vitamin-related mechanistic insights related to the molecular determinants of the idiopathic germ cell aplasia
FAVOR (FAst Variability Optical Registration) -- A Two-telescope Complex for Detection and Investigation of Short Optical Transients
An astronomical complex intended to detect optical transients (OTs) in a wide
field and follow them up with high time resolution investigation is described.Comment: 4 pages, 3 figures. To be published in "Il Nuovo Cimento",
Proceedings of the 4th Rome Workshop on Gamma-Ray Bursts in the Afterglow
Era, eds. L. Piro, L. Amati, S. Covino, B. Gendr
The REM Telescope: A robotic multiwavelength facility to promptly follow up GRB afterglows
The REM (Rapid Eye Mount) Telescope, located in la Silla Observatory Chile, is the first moderate (60 cm) aperture robotic telescope able to cover simultaneously both the visible and near-infrared (0.45–2.3 μm) wavelength range. The high-throughput Infrared Camera (REMIR) and the optical imaging spectrograph (ROSS), both equipping the REM telescope, are simultaneously fed by a dichroic and they allow to collect high-S/N data in an unprecedented large
spectral range on a telescope of this size. The wide band covered, the very fast pointing capability (60 degrees in 5 seconds) and its full robotization make REM the ideal experiment for fast transients observation. The REM observatory is an example of a versatile and agile facility necessary to complement large telescopes in fields in which rapid response and/or target pre-screening are necessary. This paper describes the main characteristics and operation modes of the REM observatory and gives an overview of preliminary results obtained during the Science Verification
Phase
GRB 070311: a direct link between the prompt emission and the afterglow
We present prompt gamma-ray, early NIR/optical, late optical and X-ray
observations of the peculiar GRB 070311 discovered by INTEGRAL, in order to
gain clues on the mechanisms responsible for the prompt gamma-ray pulse as well
as for the early and late multi-band afterglow of GRB 070311. We fitted with
empirical functions the gamma-ray and optical light curves and scaled the
result to the late time X-rays. The H-band light curve taken by REM shows two
pulses peaking 80 and 140 s after the peak of the gamma-ray burst and possibly
accompanied by a faint gamma-ray tail. Remarkably, the late optical and X-ray
afterglow underwent a major rebrightening between 3x10^4 and 2x10^5 s after the
burst with an X-ray fluence comparable with that of the prompt emission
extrapolated in the same band. Notably, the time profile of the late
rebrightening can be described as the combination of a time-rescaled version of
the prompt gamma-ray pulse and an underlying power law. This result supports a
common origin for both prompt and late X-ray/optical afterglow rebrightening of
GRB 070311 within the external shock scenario. The main fireball would be
responsible for the prompt emission, while a second shell would produce the
rebrightening when impacting the leading blastwave in a refreshed shock
(abridged).Comment: 14 pages, 11 figures, 4 tables, accepted to A&
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