214 research outputs found
Effetti degli oli essenziali di agrumi applicati in post-emergenza sul controllo delle infestanti e sulla comunit\ue0 microbica del suolo
Sebbene gli erbicidi sintetici ad oggi siano il mezzo pi\uf9 utilizzato per il controllo delle erbe infestanti, \ue8 ampiamente dimostrato che essi hanno un impatto negativo sul suolo, sull'ambiente e, inoltre, iniziano a manifestarsi fenomeni di resistenza. Pertanto, \ue8 importante sviluppare mezzi alternativi che siano al contempo efficaci e rispettosi dell\u2019ambiente. Gli olii essenziali estratti dalle piante sono stati da sempre utilizzati per molteplici usi come agenti battericidi, virucidi, fungicidi, insetticidi, medicinali e cosmetici. Diversi studi hanno dimostrato tali attivit\ue0 degli oli essenziali estratti dagli agrumi, ma scarsi sono gli studi che hanno investigato il loro potenziale uso come erbicidi. Inoltre, anche se diversi studi hanno dimostrato un effetto antimicrobico, tali studi sono stati condotti prevalentemente in vitro e non in vivo. Obiettivo del presente lavoro \ue8 stato quello di valutare la potenzialit\ue0 degli oli essenziali estratti dalle bucce di limone e arancia i) per limitare lo sviluppo delle erbe infestanti e ii) il loro effetto sulla comunit\ue0 microbica del suolo. Gli oli essenziali testati sono stati estratti per idrodistillazione e con pressa a freddo: LI e AI, olio essenziale di limone e arancio, rispettivamente, estratti con pressa a freddo; LU e AU, olio essenziale di limone e arancio, rispettivamente, estratti tramite idrodistillazione. Ai fini del presente lavoro, il suolo utilizzato \ue8 stato prelevato presso un campo sperimentale dell'Universit\ue0 degli Studi di Palermo. Dopo il prelievo, il suolo \ue8 stato essiccato all'aria e setacciato con setaccio con fori del diametro di un centimetro. Successivamente, 500 grammi di suolo sono stati posti in 20 vaschette di alluminio (10
7 20 cm) ed incubati in condizioni naturali. Durante l\u2019incubazione il suolo \ue8 stato mantenuto al 50% della sua capacit\ue0 idrica di campo (WHC). Dopo l\u2019emergenza delle piantine, ovvero alla comparsa della terza foglia (ventesimo giorno dall\u2019inizio dell\u2019incubazione), ciascun olio essenziale \ue8 stato applicato nebulizzandolo sulle piantine, a giorni alterni per una settimana (tre applicazioni in totale). Per ogni vaso e per ogni trattamento, sono stati applicati 5 mL di una soluzione contenente 1 L di acqua, 10 mL di olio essenziale e 1 mL di emulsionante. Nel suolo di controllo la soluzione applicata alle piantine non conteneva olio essenziale. Dopo 15 giorni dall\u2019ultima applicazione dei trattamenti, i suoli sono stati campionati in modo totale, setacciati ed analizzati per la determinazione del carbonio della biomassa microbica (metodo fumigazione-estrazione), respirazione basale (emissione di CO2) e struttura della comunit\ue0 microbica (analisi degli acidi grassi dei fosfolipidi). Inoltre, per ogni trattamento sono stati determinati alcuni parametri delle piante come peso secco e fresco totale, numero di specie e numero di piante per specie. In questo lavoro vengono riportati e discussi i principali risultati
Holistic assessment of call centre performance
In modern call centres 60â70% of the operational costs come in the form of the human agents who take the calls. Ensuring that the call centre operates at lowest cost and maximum efficiency involves a tradeâoff of the cost of agents against lost revenue and increased customer dissatisfaction due to lost calls. Modelling the performance characteristics of a call centre in terms of the agent queue alone misses key performance influencers, specifically the interaction between channel availability at the media gateway and the time a call is queued. A blocking probability at the media gateway, as low as 0.45%, has a significant impact on the degree of queuing observed and therefore the cost and performance of the call centre. Our analysis also shows how abandonment impacts queuing delay. However, the call centre manager has less control over this than the level of contention at the media gateway. Our commercial assessment provides an evaluation of the balance between abandonment and contention, and shows that the difference in cost between the best and worst strategy is ÂŁ130K per annum, however this must be balanced against a possible additional ÂŁ2.98Â m exposure in lost calls if abandonment alone is used
Multivariate risks and depth-trimmed regions
We describe a general framework for measuring risks, where the risk measure
takes values in an abstract cone. It is shown that this approach naturally
includes the classical risk measures and set-valued risk measures and yields a
natural definition of vector-valued risk measures. Several main constructions
of risk measures are described in this abstract axiomatic framework.
It is shown that the concept of depth-trimmed (or central) regions from the
multivariate statistics is closely related to the definition of risk measures.
In particular, the halfspace trimming corresponds to the Value-at-Risk, while
the zonoid trimming yields the expected shortfall. In the abstract framework,
it is shown how to establish a both-ways correspondence between risk measures
and depth-trimmed regions. It is also demonstrated how the lattice structure of
the space of risk values influences this relationship.Comment: 26 pages. Substantially revised version with a number of new results
adde
Lâacupuncture : comme alternative dans la prise en charge de la paralysie faciale peripherique idiopathique : experience tunisienne
La paralysie faciale pĂ©riphĂ©rique idiopathique ou Ă frigorĂ© (PfPi) est la plus frĂ©quente des paralysies faciales. Elle pose un problĂšme thĂ©rapeutique malgrĂ© la diversitĂ© des traitements proposĂ©s. Lâacupuncture est une des alternatives proposĂ©es parmi cet arsenal thĂ©rapeutique. Le but de ce travail est dâĂ©valuer lâapport de lâacupuncture dans le traitement de la PfPi et de dĂ©gager les diffĂ©rents facteurs pronostiques pouvant influencer la rĂ©cupĂ©ration de la fonction faciale. Notre Ă©tude a regroupĂ© 40 patients porteurs de PfPi recrutĂ©s aux services dâORL de lâhĂŽpital rĂ©gional de Jendouba et de lâhĂŽpital de Charles Nicolle sur une pĂ©riode de 14 mois et pris en charge aux centres dâacupuncture Ă lâhĂŽpital Mongi Slim et Ă lâhĂŽpital rĂ©gional de Jendouba. Tous les patients ont Ă©tĂ© traitĂ©s, auparavant, selon le concept de la mĂ©decine occidentale, et nâont Ă©tĂ© adressĂ©s quâaprĂšs Ă©chec du traitement mĂ©dical conventionnel. LâĂ©valuation de notre travail est basĂ©e sur deux tests : le testing musculaire de freyss et le grading de House et Brackman. LâĂ©tude statistique sâest basĂ©e sur le logiciel « SPSS ». Les rĂ©sultats de cette Ă©tude montrent que le traitement par acupuncture trouve son indication lorsque le traitement mĂ©dical conventionnel a Ă©chouĂ©, mĂȘme aprĂšs un long dĂ©lai de consultation.Mots-clĂ©s : paralysie faciale pĂ©riphĂ©rique, acupuncture, traitement.The Bellâs palsy is the most common peripheral facial paralysis. it poses a therapeutic problem despite the diversity of treatments. Acupuncture is an alternative among the proposed therapeutic arsenal. The purpose of this study was to evaluate the contribution of acupuncture in the treatment of facial paralysis and to identify different prognostic factors that may influence the recovery of facial function. Our study included 40 patients with Bellâs palsy recruited in the services of ENT in Jendouba hospital and Charles Nicolle hospital over a period of 14 months and supported in centers of acupuncture in Mongi Slim hospital and Jendouba hospital. All patients were previously under the concept of medical treatment, and were sent after failure of this treatment. The evaluation of our work is based on two tests: muscle testing of freyss and grading of House and Brackman. The study is based on statistical software "SPSS". The results of this study show that treatment with acupuncture is indicated in Bellâs palsy when conventional medical treatment has failed and even after a long period of consultation.Keywords: facial palsy, acupuncture, treatment
Synthesis of Learning from a Decade of CGIAR Research Programs
The objective of this forward-looking synthesis was to bring together learning from a decade of experience with CGIAR research programs (CRPs), based on existing evaluative evidence. The purpose of this meta-review is to review lessons from the CRP experience to inform the development of future research programs of One CGIAR. The 2021 Synthesis and Lessons Learned from a Decade of CRPs is delivered in response to the request of the CGIAR System Council and aligned with the synthesis terms of reference endorsed by SIMEC in February 2021. The synthesis examined evidence from the two phases of CRP implementation: 2011â2016 and 2017â2019. Four key issues were addressed: (1) patterns and trends between the two phases of CRPs related to the quality of science (QoS) and research for development, achievement of sustainable development outcomes, and management and governance; (2) systemwide issues affecting CRP achievements; (3) recommendations for the future orientation of CGIAR research and innovation; and (4) key evidence gaps and needs for future evaluations. A narrative synthesis approach was used, employing secondary source data from 47 existing evaluations and reviews. External evaluations were systematically coded and analyzed by senior subject matter experts (SMEs) using a standardized analytical framework. A bibliometric trend analysis was carried out, and findings were triangulated against earlier syntheses and validated by members of the Independent Science for Development Council (ISDC), CRP leaders, and expert peer reviewers
Market consistent valuations with financial imperfection
In this paper, we study market consistent valuations in imperfect markets. In the first part of the paper, we observe that in an imperfect market one needs to distinguish two type of market consistencies, namely types I and II. We show that while market consistency of type I holds without very strong conditions, market consistency of type II (which in the literature is known as the usual definition of market consistency) is only well defined in perfect markets. This is important since the existing literature on market consistency considers perfect markets where the two market consistencies are equivalent. In the second part of the paper, by introducing a best estimator we find strong connections between hedging and market consistency of either type. We show under very general conditions, the type I and the type II market consistent evaluators are best estimators, and establish a two-step representation for the market consistent risk evaluators. In the third part of the paper, we present several families of market consistent evaluators in imperfect markets
On the Existence of Shadow Prices
For utility maximization problems under proportional transaction costs, it
has been observed that the original market with transaction costs can sometimes
be replaced by a frictionless "shadow market" that yields the same optimal
strategy and utility. However, the question of whether or not this indeed holds
in generality has remained elusive so far. In this paper we present a
counterexample which shows that shadow prices may fail to exist. On the other
hand, we prove that short selling constraints are a sufficient condition to
warrant their existence, even in very general multi-currency market models with
possibly discontinuous bid-ask-spreads.Comment: 14 pages, 1 figure, to appear in "Finance and Stochastics
Using equity premium survey data to estimate future wealth
We present the first systematic methods for combining different experts' responses to equity premium surveys. These techniques are based on the observation that the survey data are approximately gamma distributed. This distribution has convenient analytical properties that enable us to address three important problems that investment managers must face. First, we construct probability density functions for the future values of equity index tracker funds. Second, we calculate unbiased and minimum least square error estimators of the future value of these funds. Third, we derive optimal asset allocation weights between equities and the risk-free asset for risk-averse investors. Our analysis allows for both herding and biasedness in expert responses. We show that, unless investors are highly uncertain about expert biases or forecasts are very highly correlated, many investment decisions can be based solely on the mean of the survey data minus any expected bias. We also make recommendations for the design of future equity premium surveys
Eliciting Dirichlet and Gaussian copula prior distributions for multinomial models
In this paper, we propose novel methods of quantifying expert opinion about prior distributions for multinomial models. Two different multivariate priors are elicited using median and quartile assessments of the multinomial probabilities. First, we start by eliciting a univariate beta distribution for the probability of each category. Then we elicit the hyperparameters of the Dirichlet distribution, as a tractable conjugate prior, from those of the univariate betas through various forms of reconciliation using least-squares techniques. However, a multivariate copula function will give a more flexible correlation structure between multinomial parameters if it is used as their multivariate prior distribution. So, second, we use beta marginal distributions to construct a Gaussian copula as a multivariate normal distribution function that binds these marginals and expresses the dependence structure between them. The proposed method elicits a positive-definite correlation matrix of this Gaussian copula. The two proposed methods are designed to be used through interactive graphical software written in Java
- âŠ