568 research outputs found
To be or not to be in monetary union: A synthesis
Monetary union can benefit countries suffering from policy credibility problems if it eliminates the inflation bias and also allows for more efficient management of certain shocks. But it also carries costs as some stabilization may be feasible even in the absence of credibility, and this may be more than what an individual country can hope for in a monetary union. In this paper, we combine the stabilization and credibility branches of the currency union literature and construct a simple welfare criterion that can be used to evaluate alternative monetary arrangements. We produce examples where monetary union may be welfare improving even for low-modest levels of inflation bias (2-3%) as long as business cycles are not too a-synchronized across countries.Currency union, credibility, stabilization, inflation bias.
Financial Shocks and Optimal Policy
This paper incorporates banks as well as frictions in the market for bank capital into a standard New Keynesian model and considers the positive and normative implications of various financial shocks. It shows that the frictions matter significantly for the effects of the shocks and the properties of optimal monetary and fiscal policy. For instance, for shocks that increase banks' demand for liquidity, optimal monetary policy accepts an output contraction while it would not in the absence of the frictions (or under suitably conducted fiscal policy). We find that optimal monetary policy can be approximated by a simple interest-rate rule targeting inflation; and it also allows large adjustments in the money supply, a property reminiscent of Poole's analysis.Financial frictions, banking, optimal policy
Optimization and quality control of suspended particulate matter concentration measurement using turbidity measurements
The dry weight concentration of suspended particulate material, [SPM] (units: mg L?1), is measured by passing a known volume of seawater through a preweighed filter and reweighing the filter after drying. This is apparently a simple procedure, but accuracy and precision of [SPM] measurements vary widely depending on the measurement protocol and experience and skills of the person filtering. We show that measurements of turbidity, T (units: FNU), which are low cost, simple, and fast, can be used to optimally set the filtration volume, to detect problems with the mixing of the sample during subsampling, and to quality control [SPM]. A relationship between T and ?optimal filtration volume?, Vopt, is established where Vopt is the volume at which enough matter is retained by the filter for precise measurement, but not so much that the filter clogs. This relationship is based on an assessment of procedural uncertainties in the [SPM] measurement protocol, including salt retention, filter preparation, weighing, and handling, and on a value for minimum relative precision for replicates. The effect of filtration volume on the precision of [SPM] measurement is investigated by filtering volumes of seawater ranging between one fifth and twice Vopt. It is shown that filtrations at Vopt maximize precision and cost effectiveness of [SPM]. Finally, the 90% prediction bounds of the T versus [SPM] regression allow the quality control of [SPM] determinations. In conclusion it is recommended that existing [SPM] gravimetric measurements be refined to include measurement of turbidity to improve their precision and quality control
Data needs for hyperspectral detection of algal bloom diversity across the globe.
A group of 38 experts specializing in hyperspectral remote-sensing methods for aquatic ecosystems attended an interactive Euromarine Foresight Workshop at the Flanders Marine Institute (VLIZ) in Ostend, Belgium, June 4–6, 2019. The objective of this workshop was to develop recommendations for comprehensive, efficient, and effective laboratory and field programs to supply data for development of algorithms and validation of hyperspectral satellite imagery for micro-, macro- and endosymbiotic algal characterization across the globe. The international group of researchers from Europe, Asia, Australia, and North and South America (see online Supplementary Materials) tackled how to develop global databases that merge hyperspectral optics and phytoplankton group composition to support the next generation of hyperspectral satellites for assessing biodiversity in the ocean and in food webs and for detecting water quality issues such as harmful algal blooms. Through stimulating discussions in breakout groups, the team formulated a host of diverse programmatic recommendations on topics such as how to better integrate optics into phytoplankton monitoring programs; approaches to validating phytoplankton composition with ocean color measurements and satellite imagery; new database specifications that match optical data with phytoplankton composition data; requirements for new instrumentation that can be implemented on floats, moorings, drones, and other platforms; and the development of international task forces.
Because in situ observations of phytoplankton biogeography and abundance are scarce, and many vast oceanic regions are too remote to be routinely monitored, satellite observations are required to fully comprehend the diversity of micro-, macro-, and endosymbiotic algae and any variability due to climate change. Ocean color remote sensing that provides regular synoptic monitoring of aquatic ecosystems is an excellent tool for assessing biodiversity and abundance of phytoplankton and algae in aquatic ecosystems. However, neither the spatial, temporal, nor spectral resolution of the current ocean color missions are sufficient to characterize phytoplankton community composition adequately. The near-daily overpasses from ocean color satellites are useful for detecting the presence of blooms, but the spatial resolution is often too coarse to assess the patchy distribution of blooms, and the multiband spectral resolution is generally insufficient to identify different types of phytoplankton from each other, even if progress has undeniably been achieved during the last two decades (e.g., IOCGG, 2014). Moreover, the methods developed for multichannel sensor use are often highly tuned to a region but are inaccurate when applied broadly.
New orbital imaging spectrometers are being developed that cover the full visible and near-infrared spectrum with a large number of narrow bands dubbed “hyperspectral” (e.g., TROPOMI, PRISMA, EnMAP, PACE, CHIME, SBG). Hyper-spectral methods have been explored for many years to assess phytoplankton groups and map seafloor habitats. However, the utility of hyperspectral imaging still needs to be demonstrated across diverse aquatic regimes. Aquatic applications of hyperspectral imagery have been limited by both the technology and the ability to validate products. Some of the past hyperspectral space-based sensors have suffered from calibration artifacts, low sensitivity in aquatic ecosystems (e.g., CHRIS, HICO), and very low spatial resolution (e.g., SCIAMACHY), but the next generation of sensors are planned to have high signal-to-noise ratio and improved performance over aquatic targets. Providing data to develop and validate hyperspectral approaches to characterize phytoplankton groups across the globe poses new challenges. Several recent studies have documented gaps that need to be filled in order to assess algal diversity across the globe (IOCCG, 2014; Mouw et al., 2015; Bracher et al., 2017), which promoted/inspired the formation of this workshop
How physicians caring for adult patients presenting a chronic mental disturbance take account of the difficulties their patients’ children under 18: Preliminary study
AbstractAimsTo study how physicians caring for adult patients presenting a chronic mental disturbance take account of the difficulties of their patients’ children under 18.MethodExploratory and qualitative study based on an in-depth study of interviews.Study populationThirteen physiatrists or neurologists following brain-damaged patients and 12 psychiatrists following patients with chronic psychiatric disorders.ResultsIn the two groups of physicians, diversified practices in catering for the issues of the patient's parenthood, child–parent relationships, and difficulties experienced by the child. The child's difficulties are not approached as such. For many of the physicians, representations of the parenting function, and of the child's needs and difficulties are not often used in work with the patient. Patient-centred care appears at odds with catering for the patient's children and their specific difficulties. The seriousness of the mental pathologies, their chronic nature, and the fact that they can affect the patient in his/her parental functioning and concerns, appear as factors in the reluctance of physicians. Other reasons are lack of familiarity with issues relating to childhood, and the feeling of encroaching on a private and intimate sphere. The representations of physicians with regard to parenthood, parent–child relations, and the needs and difficulties of children, are often not integrated into the corpus of knowledge. These issues are more often aspects of physicians’ own experience.ConclusionThe conflict of values and the uneasiness of the physicians suggest the need for ethical reflection groups or Balint groups
Insurance: Models, Digitalization, and Data Science
International audienc
A synthetic optical database generated by radiative transfer simulations in support of studies in ocean optics and optical remote sensing of the global ocean
Radiative transfer (RT) simulations have long been used
to study the relationships between the inherent optical properties (IOPs) of
seawater and light fields within and leaving the ocean, from which ocean
apparent optical properties (AOPs) can be calculated. For example, inverse
models used to estimate IOPs from ocean color radiometric measurements have been
developed and validated using the results of RT simulations. Here we describe the
development of a new synthetic optical database based on hyperspectral RT
simulations across the spectral range of near-ultraviolet to
near-infrared performed with the HydroLight radiative transfer code. The key
component of this development is the generation of a synthetic dataset of
seawater IOPs that serves as input to RT simulations. Compared to similar
developments of optical databases in the past, the present dataset of IOPs
is characterized by the probability distributions of IOPs that are consistent
with global distributions representative of vast areas of open-ocean pelagic
environments and coastal regions, covering a broad range of optical water
types. The generation of synthetic data of IOPs associated with
particulate and dissolved constituents of seawater was driven largely by an
extensive set of field measurements of the phytoplankton absorption
coefficient collected in diverse oceanic environments. Overall, the
synthetic IOP dataset consists of 3320 combinations of IOPs. Additionally,
the pure seawater IOPs were assumed following recent recommendations. The RT
simulations were performed using 3320 combinations of input IOPs, assuming
vertical homogeneity within an infinitely deep ocean. These input IOPs were
used in three simulation scenarios associated with assumptions about
inelastic radiative processes in the water column (not considered in
previous synthetically generated optical databases) and three simulation
scenarios associated with the sun zenith angle. Specifically, the simulations
were made assuming no inelastic processes, the presence of Raman scattering
by water molecules, and the presence of both Raman scattering and
fluorescence of chlorophyll a pigment. Fluorescence of colored dissolved
organic matter was omitted from all simulations. For each of these three
simulation scenarios, the simulations were made for three sun zenith angles
of 0, 30, and 60∘ assuming clear skies, standard
atmosphere, and a wind speed of 5 m s−1. Thus, overall 29 880 RT
simulations were performed. The output results of these simulations include
radiance distributions, plane and scalar irradiances, and a whole set
of AOPs, including remote-sensing reflectance, vertical diffuse
attenuation coefficients, and mean cosines, where all optical variables are
reported in the spectral range of 350 to 750 nm at 5 nm intervals for
different depths between the sea surface and 50 m. The consistency of this
new synthetic database has been assessed through comparisons with in situ
data and previously developed empirical relationships involving IOPs and
AOPs. The database is available at the Dryad open-access repository of research
data (https://doi.org/10.6076/D1630T, Loisel et al., 2023).</p
The Force-Velocity Relation for Growing Biopolymers
The process of force generation by the growth of biopolymers is simulated via
a Langevin-dynamics approach. The interaction forces are taken to have simple
forms that favor the growth of straight fibers from solution. The
force-velocity relation is obtained from the simulations for two versions of
the monomer-monomer force field. It is found that the growth rate drops off
more rapidly with applied force than expected from the simplest theories based
on thermal motion of the obstacle. The discrepancies amount to a factor of
three or more when the applied force exceeds 2.5kT/a, where a is the step size
for the polymer growth. These results are explained on the basis of restricted
diffusion of monomers near the fiber tip. It is also found that the mobility of
the obstacle has little effect on the growth rate, over a broad range.Comment: Latex source, 9 postscript figures, uses psfig.st
Effects of deletion of the Streptococcus pneumoniae lipoprotein diacylglyceryl transferase gene lgt on ABC transporter function and on growth in vivo
Lipoproteins are an important class of surface associated proteins that have diverse roles and frequently are involved in the virulence of bacterial pathogens. As prolipoproteins are attached to the cell membrane by a single enzyme, prolipoprotein diacylglyceryl transferase (Lgt), deletion of the corresponding gene potentially allows the characterisation of the overall importance of lipoproteins for specific bacterial functions. We have used a Δlgt mutant strain of Streptococcus pneumoniae to investigate the effects of loss of lipoprotein attachment on cation acquisition, growth in media containing specific carbon sources, and virulence in different infection models. Immunoblots of triton X-114 extracts, flow cytometry and immuno-fluorescence microscopy confirmed the Δlgt mutant had markedly reduced lipoprotein expression on the cell surface. The Δlgt mutant had reduced growth in cation depleted medium, increased sensitivity to oxidative stress, reduced zinc uptake, and reduced intracellular levels of several cations. Doubling time of the Δlgt mutant was also increased slightly when grown in medium with glucose, raffinose and maltotriose as sole carbon sources. These multiple defects in cation and sugar ABC transporter function for the Δlgt mutant were associated with only slightly delayed growth in complete medium. However the Δlgt mutant had significantly reduced growth in blood or bronchoalveolar lavage fluid and a marked impairment in virulence in mouse models of nasopharyngeal colonisation, sepsis and pneumonia. These data suggest that for S. pneumoniae loss of surface localisation of lipoproteins has widespread effects on ABC transporter functions that collectively prevent the Δlgt mutant from establishing invasive infection
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