Moment inversion problem for piecewise D-finite functions

We consider the problem of exact reconstruction of univariate functions with jump discontinuities at unknown positions from their moments. These functions are assumed to satisfy an a priori unknown linear homogeneous differential equation with polynomial coefficients on each continuity interval. Therefore, they may be specified by a finite amount of information. This reconstruction problem has practical importance in Signal Processing and other applications. It is somewhat of a ``folklore'' that the sequence of the moments of such ``piecewise D-finite''functions satisfies a linear recurrence relation of bounded order and degree. We derive this recurrence relation explicitly. It turns out that the coefficients of the differential operator which annihilates every piece of the function, as well as the locations of the discontinuities, appear in this recurrence in a precisely controlled manner. This leads to the formulation of a generic algorithm for reconstructing a piecewise D-finite function from its moments. We investigate the conditions for solvability of the resulting linear systems in the general case, as well as analyze a few particular examples. We provide results of numerical simulations for several types of signals, which test the sensitivity of the proposed algorithm to noise

Cluster Control in Oligouranyl Complexes of p-t-Butylcalix[8]arene

Formation of uranyl ion complexes of p-t-butylcalix[8]arene by reaction of the calixarene with [UO2(dmso)5]2+ in the presence of various bases leads to the crystallisation of solids with interestingly different stoichiometry, involving both di- and tri-uranate oligomers bound to the calixarene in anionic species. In all, the calixarene hexa-anion is present in a virtually identical conformation, suggesting that conformational preferences of the ligand must be a major factor controlling the form of the bound oxo-metal complex. Hydrogen bonding to the anions does not appear to be prominent even in the presence of protonated amines and this may explain the formation of some remarkable cation/solvent/simple anion clusters found within the lattices

Iron, silicate, and light co-limitation of three Southern Ocean diatom species

The effect of combined iron, silicate, and light co-limitation was investigated in the three diatom species Actinocyclus sp. Ehrenberg, Chaetoceros dichaeta Ehrenberg, and Chaetoceros debilis Cleve, isolated from the Southern Ocean (SO). Growth of all species was co-limited by iron and silicate, reflected in a significant increase in the number of cell divisions compared to the control. Lowest relative Si uptake and drastic frustule malformation was found under iron and silicate co-limitation in C. dichaeta, while Si limitation in general caused cell elongation in both Chaetoceros species. Higher light intensities similar to SO surface conditions showed a negative impact on growth of C. dichaeta and Actinocyclus sp. and no effect on C. debilis. This is in contrast to the assumed light limitation of SO diatoms due to deep wind driven mixing. Our results suggest that growth and species composition of Southern Ocean diatoms is influenced by a sensitive interaction of the abiotic factors, iron, silicate, and light

Benthic fluxes of oxygen and nutrients in sublittoral fine sands in a north-western Mediterranean coastal area

[EN] Traditionally, benthic metabolism in sublittoral permeable sands have not been widely studied, although these sands can have a direct and transcendental impact in coastal ecosystems. This study aims to determine oxygen and nutrient fluxes at the sediment-water interface and the study of possible interactions among environmental variables and the benthic metabolism in well-sorted fine sands. Eight sampling campaigns were carried out over the annual cycle in the eastern coast of Spain (NW Mediterranean) at 9 m depth station with permeable bottoms. Water column and sediment samples were collected in order to determine physico-chemical and biological variables. Moreover, in situ incubations were performed to estimate the exchange of dissolved solutes in the sediment-water interface using dark and light benthic chambers. Biochemical compounds at the sediment surface ranged between 160 and 744 mu g g(-1) for proteins, 296 and 702 mu g g(-1) for carbohydrates, and between 327 and 1224 [mu g C g(-1) for biopolymeric carbon. Chloroplastic pigment equivalents in sediments were mainly composed by chlorophyll a (1.81-2.89 mu g g(-1)). These sedimentary organic descriptors indicated oligotrophic conditions according to the biochemical approach used. In this sense, the most abundant species in the macrobenthic community were sensitive to organic enrichment. In dark conditions, benthic fluxes behaved as a sink of oxygen and a source of nutrients. Oxygen fluxes (between -26,610 and -10,635 mu mol m(-2) d(-1)) were related with labile organic fraction (r= -0.86, p < 0.01 with biopolymeric carbon; r= -0.91, p < 0.01 with chloroplastic pigment equivalents). Daily fluxes of dissolved oxygen, that were obtained by adding light and dark fluxes, were only positive in spring campaigns (6966 mu mol m(-2) d(-1)) owing to the highest incident irradiance levels (r=0.98, p < 0.01) that stimulate microphytobenthic primary production. Microphytobenthos played an important role on benthic metabolism and was the main primary producer in this coastal ecosystem. However, an average annual uptake of 31 mmol m-2 d(-1) of oxygen and a release of DIN and Si(OH)(4) (329 and 68 mmol m(-2) d(-1) respectively) were estimated in these bottoms, which means heterotrophic conditions. (C) 2015 Elsevier Ltd. All rights reserved.We are grateful for the valuable comments of anonymous reviewers on previous version of the manuscript. This research was supported by the Conselleria d'Educacio (Generalitat Valenciana).Sospedra, J.; Falco, S.; Morata, T.; Gadea, I.; Rodilla, M. (2015). Benthic fluxes of oxygen and nutrients in sublittoral fine sands in a north-western Mediterranean coastal area. Continental Shelf Research. 97:32-42. doi:10.1016/j.csr.2015.02.002S32429

Comparing glacial and Holocene opal fluxes in the Pacific sector of the Southern Ocean

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 24 (2009): PA2214, doi:10.1029/2008PA001693.The silicic acid leakage hypothesis (SALH) predicts that during glacial periods excess silicic acid was transported from the Southern Ocean to lower latitudes, which favored diatom production over coccolithophorid production and caused a drawdown of atmospheric CO2. Downcore records of 230Th-normalized opal (biogenic silica) fluxes from 31 cores in the Pacific sector of the Southern Ocean were used to compare diatom productivity during the last glacial period to that of the Holocene and to examine the evidence for increased glacial Si export to the tropics. Average glacial opal fluxes south of the modern Antarctic Polar Front (APF) were less than during the Holocene, while average glacial opal fluxes north of the APF were greater than during the Holocene. However, the magnitude of the increase north of the APF was not enough to offset decreased fluxes to the south, resulting in a decrease in opal burial in the Pacific sector of the Southern Ocean during the last glacial period, equivalent to approximately 15 Gt opal ka−1. This is consistent with the work of Chase et al. (2003a), and satisfies the primary requirement of the SALH, assuming that the upwelled supply of Si was approximately equivalent during the Holocene and the glacial period. However, previous results from the equatorial oceans are inconsistent with the other predictions of the SALH, namely that either the Corg:CaCO3 ratio or the rate of opal burial should have increased during glacial periods. We compare the magnitudes of changes in the Southern Ocean and the tropics and suggest that Si escaping the glacial Southern Ocean must have had an alternate destination, possibly the continental margins. There is currently insufficient data to test this hypothesis, but the existence of this sink and its potential impact on glacial pCO2 remain interesting topics for future study.Funding for this research was provided in part by the U.S. NSF (grant OPP02-30268). We thank the core repository at LDEO and the Antarctic Research Facility at FSU for providing samples

Giant regular polyhedra from calixarene carboxylates and uranyl

Self-assembly of large multi-component systems is a common strategy for the bottom-up construction of discrete, well-defined, nanoscopic-sized cages. Icosahedral or pseudospherical viral capsids, built up from hundreds of identical proteins, constitute typical examples of the complexity attained by biological self-assembly. Chemical versions of the so-called 5 Platonic regular or 13 Archimedean semi-regular polyhedra are usually assembled combining molecular platforms with metals with commensurate coordination spheres. Here we report novel, self-assembled cages, using the conical-shaped carboxylic acid derivatives of calix[4]arene and calix[5]arene as ligands, and the uranyl cation UO22+ as a metallic counterpart, which coordinates with three carboxylates at the equatorial plane, giving rise to hexagonal bipyramidal architectures. As a result, octahedral and icosahedral anionic metallocages of nanoscopic dimensions are formed with an unusually small number of components

A randomised controlled trial of the clinical and cost-effectiveness of a contingency management intervention for reduction of cannabis use and of relapse in early psychosis (CIRCLE): a study protocol for a randomised controlled trial

Background: Around 35–45 % of people in contact with services for a first episode of psychosis are using cannabis. Cannabis use is associated with delays in remission, poorer clinical outcomes, significant increases in the risk of relapse, and lower engagement in work or education. While there is a clear need for effective interventions, so far only very limited benefits have been achieved from psychological interventions. Contingency management (CM) is a behavioural intervention in which specified desired behavioural change is reinforced through financial rewards. CM is now recognised to have a substantial evidence base in some contexts and its adoption in the UK is advocated by the National Institute for Health and Care Excellence (NICE) guidance as a treatment for substance or alcohol misuse. However, there is currently little published data testing its effectiveness for reducing cannabis use in early psychosis. Methods: CIRCLE is a two-arm, rater-blinded randomised controlled trial (RCT) investigating the clinical and cost-effectiveness of a CM intervention for reducing cannabis use among young people receiving treatment from UK Early Intervention in Psychosis (EIP) services. EIP service users (n = 544) with a recent history of cannabis use will be recruited. The experimental group will receive 12 once-weekly CM sessions, and a voucher reward if urinalysis shows that they have not used cannabis in the previous week. Both the experimental and the control groups will be offered an Optimised Treatment as Usual (OTAU) psychoeducational package targeting cannabis use. Assessment interviews will be performed at consent, at 3 months, and at 18 months. The primary outcome is time to relapse, defined as admission to an acute mental health service. Secondary outcomes include proportion of cannabis-free urine samples during the intervention period, severity of positive psychotic symptoms, quality-adjusted life years, and engagement in work or education. Discussion: CIRCLE is a RCT of CM for cannabis use in young people with a recent history of psychosis (EIP service users) and recent cannabis use. It is designed to investigate whether the intervention is a clinically and cost-effective treatment for cannabis use. It is intended to inform future treatment delivery, particularly in EIP settings

Global digital social learning as a strategy to promote engagement in the era of COVID-19.

Aims and objectives To assess formative and summative milestones in a digital course and the reach to low- and middle-income countries of a Massive Open Online Course focussing on supporting nurses dealing with an emerging pandemic. Background The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has ravaged the globe and increased the need for timely and accurate information from reliable sources. Access to reliable and accurate information, as well as support, is important in achieving health systems strengthening. Using a Massive Open Online Course format, an educational resource aimed at large-scale interactive participation via the Internet, and participants were engaged in a course focussing on nursing in a time of crisis and involved using social learning principles. Design Observational descriptive study. Method Routinely collected data were collated during the period of 18 May–18 July 2020 focused on both formative and summative milestones in the course. Data were separated and classified by income in accordance with the publicly accessible 2020 World Bank Open Dataset. Results During the 2-month period of observation (18 May–18 July 2020), 10,130 individuals from 156 countries enrolled in the course. More than 51% of participants were Active Learners. Thirty per cent completed over 90% of the course content by the end. There was widespread distribution of learners in low- and middle-income countries across Asia, Africa and Latin America. Conclusion The COVID-19 pandemic has underscored the importance of reliable and valid information sources. The use of Massive Open Online Course format can facilitate dissemination. Relevance to clinical practice In the context of a dynamic global pandemic, leveraging digital resources to allow access to reliable information and resources is important. Incentivising participation through recognition of learning is important. Engaging in a social learning platform also has the power for reflection, promotion of resilience and capacity for health systems strengthening