2,596 research outputs found
Estimation of the oceanic pCO<sub>2</sub> in the North Atlantic from VOS lines in-situ measurements: parameters needed to generate seasonally mean maps
Automated instruments on board Volunteer Observing Ships (VOS) have provided high-frequency pCO<sub>2</sub> measurements over basin-wide regions for a decade or so. In order to estimate regional air-sea CO<sub>2</sub> fluxes, it is necessary to interpolate between in-situ measurements to obtain maps of the marine pCO<sub>2</sub>. Such an interpolation remains, however, a difficult task because VOS lines are too distant from each other to capture the high pCO<sub>2</sub> variability. Relevant physical parameters available at large scale are thus necessary to serve as a guide to estimate the pCO<sub>2</sub> values between the VOS lines. Satellites do not measure pCO<sub>2</sub> but they give access to parameters related to the processes that control its variability, such as sea surface temperature (SST). In this paper we developed a method to compute pCO<sub>2</sub> maps using satellite data (SST and CHL, the chlorophyll concentration), combined with a climatology of the mixed-layer depth (MLD). Using 15 401 measurements of surface pCO<sub>2</sub> acquired in the North Atlantic between UK and Jamaica, between June 1994 and August 1995, we show that the parameterization of pCO<sub>2</sub> as a function of SST, CHL and MLD yields more realistic pCO<sub>2</sub> values than parameterizations that have been widely used in the past, based on SST, latitude, longitude or SST only. This parameterization was then used to generate seasonal maps of pCO<sub>2</sub> over the North Atlantic. Results show that our approach yields the best marine pCO<sub>2</sub> estimates, both in terms of absolute accuracy, when compared with an independent data set, and of geographical patterns, when compared to the climatology of Takahashi et al. (2002). This suggests that monitoring the seasonal variability of pCO<sub>2</sub> over basin-wide regions is possible, provided that sufficient VOS lines are available
Experiences of aiding autobiographical memory using the sensecam
Human memory is a dynamic system that makes accessible certain memories of events based on a hierarchy of information, arguably driven by personal significance. Not all events are remembered, but those that are tend to be more psychologically relevant. In contrast, lifelogging is the process of automatically recording aspects of one's life in digital form without loss of information. In this article we share our experiences in designing computer-based solutions to assist people review their visual lifelogs and address this contrast. The technical basis for our work is automatically segmenting visual lifelogs into events, allowing event similarity and event importance to be computed, ideas that are motivated by cognitive science considerations of how human memory works and can be assisted. Our work has been based on visual lifelogs gathered by dozens of people, some of them with collections spanning multiple years. In this review article we summarize a series of studies that have led to the development of a browser that is based on human memory systems and discuss the inherent tension in storing large amounts of data but making the most relevant material the most accessible
Articulations between commercial banks and microfinance institutions in Sub-Saharan Africa: the case of Cameroon
In this article, we evaluate, from the point of view of banks, the potential of articulations between commercial banks and microfinance institutions (MFIs) in Cameroun in terms of financing of the rural and the micro, small and medium enterprises (MSMEs). Furthermore, we seek to define the best form of partnership between the two types of institutions. The results obtained suggest that the articulations between banks and MFIs can potentially be beneficial to all stakeholders (banks, MFIs but also recipients). This study also highlights the fact that these articulations can be even more beneficial if national commercial banks, under the Cameroonian law in our case, participate rather than branches of foreign banking groups. Indeed, our research reveals that through these partnerships, from their cultural proximity and their propensity to take more risks, national commercial banks will more likely offer either directly or indirectly (through MFIs) more adapted financial products and services to both the rural and the MSMEs’ segments. The question of knowing if a better form of partnership between commercial banks and MFIs exists, results suggest that there is no better form of partnership as such; that the best form depends on the MFI’s development stage and that in any case this partnership should privilege a national commercial bank rather than a branch of a foreign bank. Even if the foreign banks’ contest might be necessary at a given stage of the process, the results make it also possible to consider a new model of interactions implying Microfinance investment vehicles and national commercial banks. This model would have the advantage to help mitigate risks that those vehicles perceive when deciding to directly invest in MFIs.Banks, Microfinance institutions, Microfinance investment vehicles, Sub-Saharan Africa, Cameroon
Variability of potato petiole nitrogen in response to nitrogen fertilizer, implications for variable management
Non-Peer ReviewedRecent increases in the cost of fertilizer nitrogen have prompted producers to assess the
potential to vary inputs in space and time to produce the highest marketable yield of
potatoes. A study was conducted from 2005 to 2007 near Brandon, Manitoba Canada, to
assess the spatial variability of potato yield in upper, middle and lower landforms on a
sandy loam soil in response to a range of nitrogen fertilizer rates and split application.
Petiole nitrogen, determined late in the growing season, was correlated with potato yield
and was used to assess nitrogen sufficiency through the growing season. Petiole nitrogen
varied with time during the growing season, from uniform levels in June across all
fertilizer treatments, to those which varied with fertilizer treatment in July and August.
Furthermore potato petiole nitrogen was higher in lower landforms during July and
August, where higher total and marketable yields were recorded. The potential for split
application of nitrogen in potatoes based on management zones or sensor readings will
have to be carefully assessed to account for temporal and spatial variability
Do riverine barriers, history or introgression shape the genetic structuring of a common shrew (Sorex araneus) population?
The common shrew (Sorex araneus) is subdivided into numerous chromosome races. The Valais and Cordon chromosome races meet and hybridize at a mountain river in Les Houches (French Alps). Significant genetic structuring was recently reported among populations found on the Valais side of this hybrid zone. In this paper, a phylogenetic analysis and partial Mantel tests are used to investigate the patterns and causes of this structuring. A total of 185 shrews were trapped at 12 localities. All individuals were typed for nine microsatellite loci. Although several mountain rivers are found in the study area, riverine barriers do not have a significant influence on gene flow. Partial Mantel tests show that our result is caused by the influence of the hybrid zone with the Cordon race. The geographical patterns of this structuring are discussed in the context of the contact zone, which appears to extend up to a group of two rivers. The glacier they originate from is known to have cut the Arve valley as recently as 1818. The recent history of this glacier, its moraine and possibly rivers, may therefore be linked to the history of this hybrid zone
Structure of worldwide populations of Lasioderma serricorne (Coleoptera: Anobiidae) as revealed by amplified fragment length polymorphism profiles
The cigarette beetle Lasioderma serricorne through transportation affects the infestation of stored tobacco. Using amplified fragment length polymorphism (AFLP), DNA polymorphisms were assessed in 16 populations of L. serricorne collected from 15 countries. The dendrograms constructed from profile distance matrices revealed well-supported colony clusters. There was no clear clustering as a function of the geographic origin of the samples. The results suggest extensive insect dispersal among geographical regions due to movement of infested commodities worldwide. This first AFLP population study of a stored-product insect demonstrates the potential of AFLP for distinguishing L. serricorne population
In vivo testing of a novel adjustable glaucoma drainage device.
PURPOSE: We report on the in vivo testing of a novel noninvasively adjustable glaucoma drainage device (AGDD), which features an adjustable outflow resistance, and assess the safety and efficiency of this implant.
METHODS: Under general anesthesia, the AGDD was implanted on seven white New Zealand rabbits for a duration of 4 months under a scleral flap in a way analogous to the Ex-PRESS device and set in an operationally closed position. The IOP was measured on a regular basis on the operated and control eyes using a rebound tonometer. Once a month the AGDD was adjusted noninvasively from its fully closed to its fully open position and the resulting pressure drop was measured. The contralateral eye was not operated and served as control. After euthanization, the eyes were collected for histology evaluation.
RESULTS: The mean preoperative IOP was 11.1 ± 2.4 mm Hg. The IOP was significantly lower for the operated eye (6.8 ± 2 mm Hg) compared to the nonoperated eye (13.1 ± 1.6 mm Hg) during the first 8 days after surgery. When opening the AGDD from its fully closed to fully open position, the IOP dropped significantly from 11.2 ± 2.9 to 4.8 ± 0.9 mm Hg (P < 0.05).
CONCLUSIONS: Implanting the AGDD is a safe and uncomplicated surgical procedure. The fluidic resistance was noninvasively adjustable during the postoperative period with the AGDD between its fully closed and fully open positions
A Survey on Approximation Mechanism Design without Money for Facility Games
In a facility game one or more facilities are placed in a metric space to
serve a set of selfish agents whose addresses are their private information. In
a classical facility game, each agent wants to be as close to a facility as
possible, and the cost of an agent can be defined as the distance between her
location and the closest facility. In an obnoxious facility game, each agent
wants to be far away from all facilities, and her utility is the distance from
her location to the facility set. The objective of each agent is to minimize
her cost or maximize her utility. An agent may lie if, by doing so, more
benefit can be obtained. We are interested in social choice mechanisms that do
not utilize payments. The game designer aims at a mechanism that is
strategy-proof, in the sense that any agent cannot benefit by misreporting her
address, or, even better, group strategy-proof, in the sense that any coalition
of agents cannot all benefit by lying. Meanwhile, it is desirable to have the
mechanism to be approximately optimal with respect to a chosen objective
function. Several models for such approximation mechanism design without money
for facility games have been proposed. In this paper we briefly review these
models and related results for both deterministic and randomized mechanisms,
and meanwhile we present a general framework for approximation mechanism design
without money for facility games
5-Hydroxymethylcytosine Loss in Conjunctival Melanoma.
Conjunctival and cutaneous melanoma partially share similar clinical and molecular backgrounds. As 5-hydroxymethylcytosine (5-hmC) loss has been demonstrated in cutaneous melanoma, we decided to assess if similar changes were occurring in conjunctival melanoma.
5-methylcytosine (5-mC), 5-hmC and TET2 were respectively identified by immunohistochemistry and RNA ISH in 40 conjunctival nevi and 37 conjunctival melanomas. Clinicopathological correlations were established.
5-mC, TET2 and 5-hmC were respectively identified in 67.5%, 95% and 100% of conjunctival nevi and in 81.1%, 35.1% and 54% of conjunctival melanomas. A significant 5-hmC and TET2 loss was identified in conjunctival melanoma comparing to nevus, as well as a significant correlation between TET2 and 5-hmC expression. In the melanomas, 5-hmC expression was only significantly associated with local lymphatic invasion, but not with other clinicopathological parameters. There was a correlation between TET2 expression and the localization of the tumors. 5-mC expression was not associated with any clinicopathological parameters.
We identified a significant 5-hmC loss in conjunctival melanoma similar to cutaneous melanoma. This loss may possibly be attributed to TET2 loss or IDH1 mutations. 5-hmC loss in conjunctival melanoma may help in the differential diagnosis between atypical conjunctival nevus and conjunctival melanoma
Bribeproof mechanisms for two-values domains
Schummer (Journal of Economic Theory 2000) introduced the concept of
bribeproof mechanism which, in a context where monetary transfer between agents
is possible, requires that manipulations through bribes are ruled out.
Unfortunately, in many domains, the only bribeproof mechanisms are the trivial
ones which return a fixed outcome.
This work presents one of the few constructions of non-trivial bribeproof
mechanisms for these quasi-linear environments. Though the suggested
construction applies to rather restricted domains, the results obtained are
tight: For several natural problems, the method yields the only possible
bribeproof mechanism and no such mechanism is possible on more general domains.Comment: Extended abstract accepted to SAGT 2016. This ArXiv version corrects
typos in the proofs of Theorem 7 and Claims 28-29 of prior ArXiv versio
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