2,775 research outputs found

    Retinal cone photoreceptors of the deer mouse Peromyscus maniculatus : development, topography, opsin expression and spectral tuning

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    A quantitative analysis of photoreceptor properties was performed in the retina of the nocturnal deer mouse, Peromyscus maniculatus, using pigmented (wildtype) and albino animals. The aim was to establish whether the deer mouse is a more suitable model species than the house mouse for photoreceptor studies, and whether oculocutaneous albinism affects its photoreceptor properties. In retinal flatmounts, cone photoreceptors were identified by opsin immunostaining, and their numbers, spectral types, and distributions across the retina were determined. Rod photoreceptors were counted using differential interference contrast microscopy. Pigmented P. maniculatus have a rod-dominated retina with rod densities of about 450.000/mm(2) and cone densities of 3000 - 6500/mm(2). Two cone opsins, shortwave sensitive (S) and middle-to-longwave sensitive (M), are present and expressed in distinct cone types. Partial sequencing of the S opsin gene strongly supports UV sensitivity of the S cone visual pigment. The S cones constitute a 5-15% minority of the cones. Different from house mouse, S and M cone distributions do not have dorsoventral gradients, and coexpression of both opsins in single cones is exceptional (<2% of the cones). In albino P. maniculatus, rod densities are reduced by approximately 40% (270.000/mm(2)). Overall, cone density and the density of cones exclusively expressing S opsin are not significantly different from pigmented P. maniculatus. However, in albino retinas S opsin is coexpressed with M opsin in 60-90% of the cones and therefore the population of cones expressing only M opsin is significantly reduced to 5-25%. In conclusion, deer mouse cone properties largely conform to the general mammalian pattern, hence the deer mouse may be better suited than the house mouse for the study of certain basic cone properties, including the effects of albinism on cone opsin expression

    Coherent network analysis technique for discriminating gravitational-wave bursts from instrumental noise

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    Existing coherent network analysis techniques for detecting gravitational-wave bursts simultaneously test data from multiple observatories for consistency with the expected properties of the signals. These techniques assume the output of the detector network to be the sum of a stationary Gaussian noise process and a gravitational-wave signal, and they may fail in the presence of transient non-stationarities, which are common in real detectors. In order to address this problem we introduce a consistency test that is robust against noise non-stationarities and allows one to distinguish between gravitational-wave bursts and noise transients. This technique does not require any a priori knowledge of the putative burst waveform.Comment: 18 pages, 11 figures; corrected corrupted figur

    Generating synthetic load profiles of residential heat pumps: a k-means clustering approach

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    The creation of synthetic heat pump load profiles is essential for energy system modeling and simulations. This paper proposes a methodology to create synthetic heat pump load profiles based on the k-means algorithm and a data set from water-to-water heat pumps from Hamelin, Germany. The quality of the generated load profiles is shown according to load factors, load distribution curves and the Pearson correlation coefficient, and is also applied on two exemplary geographies in Germany. We publish our work open-source and provide a web-based heat pump load profile generator

    Statistical thresholds for Tensor PCA

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    We study the statistical limits of testing and estimation for a rank one deformation of a Gaussian random tensor. We compute the sharp thresholds for hypothesis testing and estimation by maximum likelihood and show that they are the same. Furthermore, we find that the maximum likelihood estimator achieves the maximal correlation with the planted vector among measurable estimators above the estimation threshold. In this setting, the maximum likelihood estimator exhibits a discontinuous BBP-type transition: below the critical threshold the estimator is orthogonal to the planted vector, but above the critical threshold, it achieves positive correlation which is uniformly bounded away from zero

    Structure and Power in Multilateral Negotiations: An Application to French Water Policy

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    Stakeholder negotiation is an increasingly important policymaking tool. However, relatively little is understood about the relationship between the structure of the negotiating process and the effectiveness with which stakeholders can pursue their individual interests. We apply the Rausser- Simon multilateral bargaining model to a specific negotiation process involving water storage capacity and use in the upper Adour Basin in southwestern France. We focus on a coalition of three stakeholder groups with aligned but distinct interests. In addition to the standard indices of bargaining powerÔŽhe distribution of political weights (ÜĄccessĘ© and playersÙ utilities if an agreement is not reached, our analysis identifies other less obvious sources of power. First, a coalition member may benefit when his access is reduced if the redistribution increases the access of another coalition member who has a more favorable Üłtrategic location.Ę Second, the interests of the coalition as a whole will usually, but not always, be advanced if its members cede access to a pokesmanĘ representing their common interests. However, some members may be adversely affected. Third, restricting the extent to which coalition members can make proposals that further their own individual interests at the expense of other coalition members will usually, but not always, harm the coalition as a whole.water, bargaining, negotiations, Environmental Economics and Policy, Institutional and Behavioral Economics,

    Structure and bargaining power in multilateral negotiations : Application to water management policies in France

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    Environmental policies are characterized by a growing emphasis on participation, devolution and negotiated decision making. Increasingly, centralized top down decision making systems are being replaced by new forms of local governance. In their strongest versions, these involve delegation of formal authority to local stakeholders who are expected to decide collectively upon the management rules of local common-pool resources. Devolution is particularly important in relation to the allocation and management of scarce water resources. Indeed the French water law of 1992 institutionalised the notion of [...].

    Identification tools as part of Feedsafety research: the case of ragwort

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    Ragwort (Senecio jacobaea) and related species of the genus Senecio are the main source of pyrrolizidine alkaloids. These plants grow in road verges, meadows and production fields and they show up in parties of roughage: grass and alfalfa. Monitoring can be carried out during the field production and harvesting stages. The final objective is to reject parties with a too high contamination level. Identification tools can support the decision to accept or refuse materials for the food production chain. A ragwort model has been developed for the mobile application Determinator. This identification model includes the relevant objects (species of the genus Senecio), and a range of so called confusing objects in order to minimise the chance of false positive identifications

    First search for a stochastic gravitational-wave background from ultralight bosons

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    Ultralight bosons with masses in the range 10^(−13)  eV ≀ m_b ≀ 10^(−12)  eV can induce a superradiant instability around spinning black holes (BHs) with masses of order 10−100  M⊙. This instability leads to the formation of a rotating “bosonic cloud” around the BH, which can emit gravitational waves (GWs) in the frequency band probed by ground-based detectors. The superposition of GWs from all such systems can generate a stochastic gravitational-wave background (SGWB). In this work, we develop a Bayesian data analysis framework to study the SGWB from bosonic clouds using data from Advanced LIGO and Advanced Virgo, building on previous work by Brito et al. [Phys. Rev. D 96, 064050 (2017)]. We further improve this model by adding a BH population of binary merger remnants. To assess the performance of our pipeline, we quantify the range of boson masses that can be constrained by Advanced LIGO and Advanced Virgo measurements at design sensitivity. Furthermore, we explore our capability to distinguish an ultralight boson SGWB from a stochastic signal due to distant compact binary coalescences (CBC). Finally, we present results of a search for the SGWB from bosonic clouds using data from Advanced LIGO’s first observing run. We find no evidence of such a signal. Due to degeneracies between the boson mass and unknown astrophysical quantities such as the distribution of isolated BH spins, our analysis cannot robustly exclude the presence of a bosonic field at any mass. Nevertheless, we show that under optimistic assumptions about the BH formation rate and spin distribution, boson masses in the range 2.0×10^(−13)  eV ≀ m_b ≀ 3.8×10^(−13)  eV are excluded at 95% credibility, although with less optimistic spin distributions, no masses can be excluded. The framework established here can be used to learn about the nature of fundamental bosonic fields with future gravitational wave observations
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