Some considerations on aggregate sample supports for soil inventory and monitoring

Soil monitoring and inventory require a sampling strategy. One component of this strategy is the support of the basic soil observation: the size and shape of the volume of material that is collected and then analysed to return a single soil datum. Many, but not all, soil sampling schemes use aggregate supports in which material from a set of more than one soil cores, arranged in a given configuration, is aggregated and thoroughly mixed prior to analysis. In this paper, it is shown how the spatial statistics of soil information, collected on an aggregate support, can be computed from the covariance function of the soil variable on a core support (treated as point support). This is done via what is called here the discrete regularization of the core-support function. It is shown how discrete regularization can be used to compute the variance of soil sample means and to quantify the consistency of estimates made by sampling then re-sampling a monitoring network, given uncertainty in the precision with which sample sites are relocated. These methods are illustrated using data on soil organic carbon content from a transect in central England. Two aggregate supports, both based on a 20 m 20 m square, are compared with core support. It is shown that both the precision and the consistency of data collected on an aggregate support are better than data on a core support. This has implications for the design of sampling schemes for soil inventory and monitoring

High-Energy theory for close Randall Sundrum branes

We obtain an effective theory for the radion dynamics of the two-brane Randall Sundrum model, correct to all orders in brane velocity in the limit of close separation, which is of interest for studying brane collisions and early Universe cosmology. Obtained via a recursive solution of the Bulk equation of motions, the resulting theory represents a simple extension of the corresponding low-energy effective theory to the high energy regime. The four-dimensional low-energy theory is indeed not valid when corrections at second order in velocity are considered. This extension has the remarkable property of including only second derivatives and powers of first order derivatives. This important feature makes the theory particularly easy to solve. We then extend the theory by introducing a potential and detuning the branes.Comment: Version published in the Physical Review

Small linearly equivalent GG-sets and a construction of Beaulieu

Two $G$-sets ($G$ a finite group) are called linearly equivalent over a commutative ring $k$ if the permutation representations $k[X]$ and $k[Y]$ are isomorphic as modules over the group algebra $kG$. Pairs of linearly equivalent non-isomorphic $G$-sets have applications in number theory and geometry. We characterize the groups $G$ for which such pairs exist for any field, and give a simple construction of these pairs. If $k$ is \Q, these are precisely the non-cyclic groups. For any non-cyclic group, we prove that there exist $G$-sets which are non-isomorphic and \lineq over \Q, of cardinality \leq 3(#G)/2. Also, we investigate a construction of P. Beaulieu which allows us to construct pairs of transitive linearly equivalent $S_n$-sets from arbitrary $G$-sets for an arbitrary group $G$. We show that this construction works over all fields and use it construct, for each finite set \mc P of primes, $S_n$-sets linearly equivalent over a field $k$ if and only if the characteristic of $k$ lies in \mc P.Comment: v2: fixed proof of Lemma 2.

Microbial communities and bioactive compounds in marine sponges of the family Irciniidae-a review

Marine sponges harbour complex microbial communities of ecological and biotechnological importance. Here, we propose the application of the widespread sponge family Irciniidae as an appropriate model in microbiology and biochemistry research. Half a gram of one Irciniidae specimen hosts hundreds of bacterial species-the vast majority of which are difficult to cultivate-and dozens of fungal and archaeal species. The structure of these symbiont assemblages is shaped by the sponge host and is highly stable over space and time. Two types of quorum-sensing molecules have been detected in these animals, hinting at microbe-microbe and host-microbe signalling being important processes governing the dynamics of the Irciniidae holobiont. Irciniids are vulnerable to disease outbreaks, and concerns have emerged about their conservation in a changing climate. They are nevertheless amenable to mariculture and laboratory maintenance, being attractive targets for metabolite harvesting and experimental biology endeavours. Several bioactive terpenoids and polyketides have been retrieved from Irciniidae sponges, but the actual producer (host or symbiont) of these compounds has rarely been clarified. To tackle this, and further pertinent questions concerning the functioning, resilience and physiology of these organisms, truly multi-layered approaches integrating cutting-edge microbiology, biochemistry, genetics and zoology research are needed.Portuguese Foundation [PTDC/MAR/101431/2008, PTDC/BIA-MIC/3865/2012]; European Regional Development Fund (ERDF) through the Operational Competitiveness Programme (COMPETE); national funds through FCT (Foundation for Science and Technology) [PEst-C/MAR/LA0015/2011]; FCT [SFRH/BD/60873/2009]info:eu-repo/semantics/publishedVersio

Where next for research on teaching assistants:The case for an international response

In this paper, the guest editors consider the direction of research on teaching assistants (TAs), and how academics can elevate the field within the spheres of education and the social sciences. We begin by unpicking, and endorsing, Giangreco’s idea of applying the ‘Maslow’s Hammer test’ (expressed in this special issue) to manuscripts about studies of TAs and inclusion to journal editorship and peer review processes. The purpose of the test is to address the disproportionate attention paid by researchers to a set of narrow and recurring interests, and to open up new lines of inquiry and discussions about the innovative methodological approaches required to operationalise them. Secondly, we describe a persistent and urgent research gap: the shortage of international data on TAs. Given the pre-eminence of TA deployment as a means to facilitate access to and participation in mainstream education for pupils with special educational needs, we argue that the continued lack of large-scale data on TAs’ characteristics, experiences, practices and impact poses a risk to advancing the global inclusion agenda. Finally, we make a call for expressions of interest in establishing an international research network to help expand, empower and raise the esteem the field of scholarship on TAs

Teaching assistants: their role in the inclusion, education and achievement of pupils with special educational needs

The long-term, international trend towards the inclusion of pupils with special educational needs (SEN) has been accompanied and enabled by an increase in the employment and deployment of a paraprofessional workforce, known variously as teaching assistants, teacher aides and paraeducators. Australia, Italy, Sweden, Canada, Finland, Germany, Hong Kong, Iceland, Ireland, Malta, New Zealand, South Africa, the United States and the United Kingdom have all experienced large increases in this section of their education workforces (Giangreco, Doyle, and Suter 2014). It is claimed that policies of inclusion and provision for pupils with SEN in mainstream settings in many countries rely heavily on this ‘non-teaching’ workforce (Masdeu Navarro 2015). In the last two decades, the growing prevalence and prominence of teaching assistants (TAs)1 in schools and classrooms have attracted attention from researchers, who have been keen to characterise effective models of TA deployment and to identify and measure TAs’ various forms of impact (Blatchford, Russell, and Webster 2012; Sharma & Salend, 2016). Despite this attention, the deployment and impact of TAs remains an area of contestability. While there is evidence to show that TAs can have a positive impact on learning outcomes, effects vary by the types of deployment. Large-scale research examining the impact of TAs providing general classroom support suggests that pupils, particularly those with SEN and/or low prior attainment, perform worse in classes with a TA present (Blatchford, Russell, and Webster 2012). However, results from trials where TAs are trained to deliver structured curriculum intervention programmes to individual pupils or small groups, on average, show moderate positive benefits (Slavin 2018). Opportunities for teachers and TAs to plan and work together effectively, and the nature and quality of preparation and training for both roles are strongly associated with learning outcomes (Webster et al. 2011). While positive effects have been found in terms of teacher workload and reduced stress (Blatchford, Russell, and Webster 2012), the evidence that TAs can improve pupils’ ‘soft’ skills and well-being is mixed. For example, facilitating the inclusion of pupils with SEN has unintended consequences in terms of reducing interactions with teachers and peers, and creating dependencies on adult support. This special issue on the topic of teaching assistants – which, to the best of our knowledge, would be a first for major international education journal – is both timely and important. Drawing together international research and perspectives on the role, deployment and impact of TAs from various perspectives and from a range of methodological approaches, this special issue intends to serve as an indicative summary of the research in this field to date and as a point of departure for future research and development

Magnetic exchange coupling and Curie temperature of Ni(1+x)MnSb (x=0, 0.25, 0.5, 0.75, 1) from first principles

We study the dependence of magnetic interactions and Curie temperature in Ni(1+x)MnSb system on the Ni concentration within the framework of the density-functional theory. The calculation of the exchange parameters is based on the super-cell and frozen-magnon approaches. The Curie temperatures, Tc, are calculated within the random-phase approximation. In agreement with experiment we obtain decrease of the Curie temperature with increasing Ni content.Comment: 3 pages, 2 figure

Optimal Selection of Sample Weeks for Approximating the Net Load in Generation Planning Problems

The increasing presence of variable energy resources (VER) in power systems –most notably wind and solar power– demands tools capable of evaluating the flexibility needs to compensate for the resulting variability in the system. Capacity expansion models are needed that embed unit commitment decisions and constraints to account for the interaction between hourly variability and realistic operating constraints. However, the dimensionality of this problem grows proportionally with the time horizon of the load profile used to characterize the system, requiring massive amounts of computing resources. One possible solution to overcome this computational problem is to select a small number of representative weeks, but there is no consistent criterion to select these weeks, or to assess the validity of the approximation. This paper proposes a methodology to optimally select a given number of representative weeks that jointly characterize demand and VER output for capacity planning models aimed at evaluating flexibility needs. It also presents different measures to assess the error between the approximation and the complete time series. Finally, it demonstrates that the proposed methodology yields a valid approximation for unit commitment constraints embedded in long-term planning models