5,673 research outputs found
Supply-side peacekeeping: theories and new evidence from a panel data analysis
Why do nations with heterogeneous economies, geographic positions and institutions agree to dispatch their troops to remote conflict areas? This paper explores the domestic and international determinants of countries' contribution to peacekeeping operations from 1999 to 2009. Individual nations make their decision about where, when and how to send their military personnel as well as the justifications on which they base their involvement in sovereign states. Moral imperative for peacekeeping may be universally accepted but a country decision to participate is also based on self-interest combined to the geo-strategic dimension and finally constrained by political and technical considerations. Empirical results suggest that at the domestic level technical forces, such as the sustainability of multiple missions and military capabilities, all play a role. At the international level peacekeeping contributions are driven by the security threat that a conflict poses and the number of displaced people
Identification and Characterization of Phytoplankton in Barnegat Bay, New Jersey
Barnegat Bay is a marine estuary that encompasses 670-square miles of the eastern coast of New Jersey. The bay serves as a home to thousands of species of plants, animals, and microorganisms. During the summer months, the population of the bay increases from 576,000 to over 1.5 million residents. In 2011, the Barnegat Bay Partnership reported that environmental conditions of the bay are declining due to increased pollutants from nutrient fertilizers and runoff. Increased nitrogen levels have led to eutrophication and proliferation of phytoplankton algal blooms. Harmful algal blooms (HABs) cause a decrease in dissolved oxygen levels in the water as well as the release of harmful toxins that affect organisms inhabiting the bay, including humans.
To research and develop methods to prevent HABs from occurring, 16 Barnegat Bay sites ranging from the northern to southern regions of the bay were studied in order identify species of cyanobacteria, such as Synechococcus and Prochlorococcus, and other phytoplankton such as diatoms and dinoflagellates. Polymerase chain reaction (PCR), microscopy, and flow cytometry were utilized to generate profiles of each site. Collectively, the utilization of the three methods detected phytoplankton species such as Synechococcus, Prochlorococcus, and Cylindrotheca fusiformis. Viral plaque assays using viral lysate from each site detected the presence of cyanophage as a natural control for phytoplankton populations
Task oriented nonlinear control laws for telerobotic assembly operations
The goal of this research is to achieve very intelligent telerobotic controllers which are capable of receiving high-level commands from the human operator and implementing them in an adaptive manner in the object/task/manipulator workspace. Initiatives by the authors at Integrated Systems, Inc. to identify and develop the key technologies necessary to create such a flexible, highly programmable, telerobotic controller are presented. The focus of the discussion is on the modeling of insertion tasks in three dimensions and nonlinear implicit force feedback control laws which incorporate tool/workspace constraints. Preliminary experiments with dual arm beam assembly in 2-D are presented
Not a galaxy: IRAS 04186+5143, a new young stellar cluster in the outer Galaxy
We report the discovery of a new young stellar cluster in the outer Galaxy
located at the position of an IRAS PSC source that has been previously
mis-identified as an external galaxy. The cluster is seen in our near-infrared
imaging towards IRAS 04186+5143 and in archive Spitzer images confirming the
young stellar nature of the sources detected. There is also evidence of
sub-clustering seen in the spatial distributions of young stars and of gas and
dust.
Near- and mid-infrared photometry indicates that the stars exhibit colours
compatible with reddening by interstellar and circumstellar dust and are likely
to be low- and intermediate-mass YSOs with a large proportion of Class I YSOs.
Ammonia and CO lines were detected, with the CO emission well centred near
the position of the richest part of the cluster. The velocity of the CO and
NH lines indicates that the gas is Galactic and located at a distance of
about 5.5 kpc, in the outer Galaxy.
Herschel data of this region characterise the dust environment of this
molecular cloud core where the young cluster is embedded. We derive masses,
luminosities and temperatures of the molecular clumps where the young stars
reside and discuss their evolutionary stages.Comment: 14 pages, 15 figure
Kualitas Spermatozoa Tikus Wistar (Rattus Norvegicus) Setelah Pemaparan Obat Nyamuk Elektrik Berbahan Aktif Transflutrin
: Transflutrin (C15H12CL2F4O2) is an active substance, a derivative of pyrethroid compounds found in electric mosquito repellent. Previous studies showed that group of pyrethroid insecticides can play a role in causing histological changes in testes, decreased testicular weight and reducing diameter of seminiferous tubules. The purpose of this study was to determine the quality of wistar male sperm that are exposed to electric mosquito repellent with transflutrin as active ingredients. This study is experimental with completely randomized design, conducted for 52 days by using eight wistar which consists of two wistar as controls P0, 3 wistar with exposure to electric insect repellent for 8 hours/day (P1), and 3 other wistar for 12 hours/day (P2). The results of this study, the concentration of spermatozoa in the treatment group P1 and P2 respectively at 54.17 x 106 spermatozoa/ml and 45.5 x 106 spermatozoa / ml, in the control group P0 of 59.25 x 106 spermatozoa/ml. Abnormal sperm motility in P1 and P2 is 40% and 35%, at P0 is 45%. Morphologically normal spermatozoa in P1 and P2 is 49% and 78%. It can be concluded that exposure to electric mosquito repellent with transflutrin as active ingredients causes a decrease in sperm quality
Case history : a magnetic and GPR prospection on a Roman rural villa in western Piedmont (Italy )
To explore an archaeological site in western Piedmont we proceed to a multimethod survey using fast methods and taking
also into account the information achievable after a 2D or 3D data processing and/or rendering.
This choice restricted the methodologies to magnetic and GPR prospecting. The non contact
resistance imaging, in our opinion, still gives too smeared results even if indicative of resistivity
anomalies. We selected the magnetic prospecting because of the remarkable size of some of
the walls actually excavated even if, as we explain in the geological context, the probability of
collecting a significant amount of noise was high
On the shape of the mass-function of dense clumps in the Hi-GAL fields. II. Using Bayesian inference to study the clump mass function
Context. Stars form in dense, dusty clumps of molecular clouds, but little is
known about their origin, their evolution and their detailed physical
properties. In particular, the relationship between the mass distribution of
these clumps (also known as the "clump mass function", or CMF) and the stellar
initial mass function (IMF), is still poorly understood. Aims. In order to
better understand how the CMF evolve toward the IMF, and to discern the "true"
shape of the CMF, large samples of bona-fide pre- and proto-stellar clumps are
required. Two such datasets obtained from the Herschel infrared GALactic Plane
Survey (Hi-GAL) have been described in paper I. Robust statistical methods are
needed in order to infer the parameters describing the models used to fit the
CMF, and to compare the competing models themselves. Methods. In this paper we
apply Bayesian inference to the analysis of the CMF of the two regions
discussed in Paper I. First, we determine the Bayesian posterior probability
distribution for each of the fitted parameters. Then, we carry out a
quantitative comparison of the models used to fit the CMF. Results. We have
compared the results from several methods implementing Bayesian inference, and
we have also analyzed the impact of the choice of priors and the influence of
various constraints on the statistical conclusions for the preferred values of
the parameters. We find that both parameter estimation and model comparison
depend on the choice of parameter priors. Conclusions. Our results confirm our
earlier conclusion that the CMFs of the two Hi-GAL regions studied here have
very similar shapes but different mass scales. Furthermore, the lognormal model
appears to better describe the CMF measured in the two Hi-GAL regions studied
here. However, this preliminary conclusion is dependent on the choice of
parameters priors.Comment: Submitted for publication to A&A on November 12, 2013. This paper
contains 11 pages and 7 figure
Continuous-time micropower interface for neural recording applications
This paper presents a novel amplifier architecture intended for low power neural recording applications. By using continuous-time signal representation, the proposed topology predominantly leverages digital topologies taking advantage of efficient techniques used in time domain systems. This includes higher order feedback dynamics that allow direct analogue signal quantization and near ideal integrator structures for noise shaping. The system implemented in 0.18 μ m standard CMOS demonstrates the capability for low noise instrumentation with a bandwidth of 6 kHz and highly linear full dynamic range. Simulation results indicate 1.145 μW budget from 0.5 V supply voltage with an input referred thermal noise of 7.7 μVrms
Interannual variability of gps heights and environmental parameters over europe and the mediterranean area
Vertical deformations of the Earth’s surface result from a host of geophysical and geological processes. Identification and assessment of the induced signals is key to addressing outstanding scientific questions, such as those related to the role played by the changing climate on height variations. This study, focused on the European and Mediterranean area, analyzed the GPS height time series of 114 well-distributed stations with the aim of identifying spatially coherent signals likely related to variations of environmental parameters, such as atmospheric surface pressure (SP) and terrestrial water storage (TWS). Linear trends and seasonality were removed from all the time series before applying the principal component analysis (PCA) to identify the main patterns of the space/time interannual variability. Coherent height variations on timescales of about 5 and 10 years were identified by the first and second mode, respectively. They were explained by invoking loading of the crust. Single-value decomposition (SVD) was used to study the coupled interannual space/time variability between the variable pairs GPS height–SP and GPS height–TWS. A decadal timescale was identified that related height and TWS variations. Features common to the height series and to those of a few climate indices—namely, the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), the East Atlantic (EA), and the multivariate El Niño Southern Oscillation (ENSO) index (MEI)—were also investigated. We found significant correlations only with the MEI. The first height PCA mode of variability, showing a nearly 5-year fluctuation, was anticorrelated (– 0.23) with MEI. The second mode, characterized by a decadal fluctuation, was well correlated (+0.58) with MEI; the spatial distribution of the correlation revealed, for Europe and the Mediterranean area, height decrease till 2015, followed by increase, while Scandinavian and Baltic countries showed the opposite behavior
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