Numerical modelling of plasticity induced by transcranial magnetic stimulation

We use neural field theory and spike-timing dependent plasticity to make a simple but biophysically reasonable model of long-term plasticity changes in the cortex due to transcranial magnetic stimulation (TMS). We show how common TMS protocols can be captured and studied within existing neural field theory. Specifically, we look at repetitive TMS protocols such as theta burst stimulation and paired-pulse protocols. Continuous repetitive protocols result mostly in depression, but intermittent repetitive protocols in potentiation. A paired pulse protocol results in depression at short (∼ 100 ms) interstimulus intervals, but potentiation for mid-range intervals. The model is sensitive to the choice of neural populations that are driven by the TMS pulses, and to the parameters that describe plasticity, which may aid interpretation of the high variability in existing experimental results. Driving excitatory populations results in greater plasticity changes than driving inhibitory populations. Modelling also shows the merit in optimizing a TMS protocol based on an individual’s electroencephalogram. Moreover, the model can be used to make predictions about protocols that may lead to improvements in repetitive TMS outcomes

Characteristics of temporal fluctuations in the hyperpolarized state of the cortical slow oscillation

We present evidence for the hypothesis that transitions between the low- and high-firing states of the cortical slow oscillation correspond to neuronal phase transitions. By analyzing intracellular recordings of the membrane potential during the cortical slow oscillation in rats, we quantify the temporal fluctuations in power and the frequency centroid of the power spectrum in the period of time before “down” to “up” transitions. By taking appropriate averages over such events, we present these statistics as a function of time before transition. The results demonstrate an increase in fluctuation power and time scale broadly consistent with the slowing of systems close to phase transitions. The analysis is complicated and limited by the difficulty in identifying when transitions begin, and removing dc trends in membrane potential

Role of tumour necrosis factor gene polymorphisms (-308 and -238) in breast cancer susceptibility and severity

Introduction Genetic polymorphisms in the promoter region of the tumour necrosis factor (TNF) gene can regulate gene expression and have been associated with inflammatory and malignant conditions. We have investigated two polymorphisms in the promoter of the TNF gene (-308 G>A and -238 G>A) for their role in breast cancer susceptibility and severity by means of an allelic association study. Methods Using a case–control study design, breast cancer patients (n = 709) and appropriate age-matched and sex-matched controls obtained from the Breast Screening Unit (n = 498) were genotyped for these TNF polymorphisms, using a high-throughput allelic discrimination method. Results Allele frequencies for both polymorphisms were similar in both breast cancer cases and controls. However, the -308 polymorphism was found to be associated with vascular invasion in breast tumours (P = 0.024). Comparison with other standard prognostic indices did not show any association for either genotype. Conclusions We demonstrated no association between the -308G>A polymorphism and the -238G>A polymorphism in the promoter region of TNF and susceptibility to breast cancer, in a large North European population. However, the -308 G>A polymorphism was found to be associated with the presence of vascular invasion in breast tumours

Appropriateness of the TOBY Application, an iPad Intervention for Children with Autism Spectrum Disorder: A Thematic Approach

This study aimed to explore the appropriateness of an ICT intervention, the Therapeutic Outcomes by You application (TOBY app), from the perspectives of the parents. Parental experiences of twenty-four parents of a child with ASD who had participated in a three-month trial using the TOBY app were collected using semi-structured interviews. Thematic analysis was conducted and themes were mapped against an appropriateness framework. Collectively, parents felt the TOBY app was relevant and important to them and their children’s needs, while expressing partial support of the TOBY app as: a positive experience for them and their children, beneficial for them and their children, a socially and ecological valid intervention, and an intervention that supported change and continuation in the skills learnt

Best practice for collar deployment of tri-axial accelerometers on a terrestrial quadruped to provide accurate measurement of body acceleration

Background: Tri-axial accelerometers are frequently deployed on terrestrial quadrupedal mammals using collars, because they are easy to fit and are thought to have minimal impact on the subject. Collar-attached devices are not fixed to the body and can move independently of the body. This may result in inaccurate measures of acceleration, reducing the accuracy of measured body movement. We determined the effect of collar size and collar weight on acceleration measured by a collar-mounted accelerometer on a quadruped mammal. The aim was to suggest best practice for sizes and weights of collars on which to deploy tri-axial accelerometers. Using pygmy goats, Capra aegagrus hircus, which were trained to walk at different speeds (0.8–3.0 km/h) on a treadmill, we measured body acceleration using a collar-mounted tri-axial accelerometer, with different collar sizes (individual neck circumference + 1 cm to + 9 cm) and collar weight (0.4% to 1.2% of individual weight). Results: There was a significant effect of collar size, collar weight and walking speed on measured acceleration. Measured acceleration was less accurate and more variable when collars were looser and heavier. To measure body acceleration more accurately, we found that collar size should be within 5 cm or 16% of an individual’s neck circumference when it was heavy (up to 1.2% of animal’s body weight) or within 7 cm (33%) of neck circumference if the collar was light (up to 0.6% of animal body weight). Conclusion: We suggest that not only reporting collar size and weight for welfare purposes, but it is also important to consider these aspects for scientific rigour, to ensure data are collected as accurately as possible. We provide guidelines for researchers fitting collar-attached devices to ensure a higher degree of accuracy of recorded body acceleration

Polymers with quadruple hydrogen-bonding end groups: controlling molecular weight using a small molecule photoswitch

The molecular weight and topology of polymer chains is typically defined during their synthesis, after which these parameters remain fixed. This limitation has motivated efforts to develop reversibly reconfigurable polymers, which offer opportunities for advanced applications and/or efficient reprocessing. Herein, we report the preparation of a library of poly(methyl acrylate) (PMA) homopolymers and a poly(methyl methacrylate) (PMMA) homopolymer bearing pendant hydrogen bonding motifs (HBMs) which have the potential to generate reconfigurable materials. This approach includes the synthesis of alkyne-functional HBMs which were successfully coupled to an azide-functionalised RAFT agent via alkyne/azide “click” chemistry. The resulting ureidopyrimidinone (UPy) and amidonaphthyridine (NAP) RAFT agents could successfully be used to prepare PMA, but the attempt using the diamidonaphthyridine (DAN) RAFT agent was unsuccessful. In this example, a post-polymerisation technique was demonstrated as a viable alternative (in this case with a PMMA homopolymer). To demonstrate proof-of-concept that this can be achieved using a supramolecular approach: a small molecule photoswitch comprising ditopic azobenzene linked ureidopyrimidinone (UPy) was shown to effect reconfiguration of polymer molecular weight of DAN-functionalised PMMA under visible/UV light irradiation. In the cis (Z) photostationary state, intramolecular UPy·UPy homodimerization within the photoswitch was preferred, whereas in the trans (E) configuration, the need for UPy to satisfy its hydrogen-bonding requirements resulted in intermolecular DAN·UPy heterodimerization with the DAN motif of poly(methyl-methacrylate) resulting in a doubling of its molecular weight as observed by 1H DOSY NMR spectroscopy

Regge and Okamoto symmetries

We will relate the surprising Regge symmetry of the Racah-Wigner 6j symbols to the surprising Okamoto symmetry of the Painleve VI differential equation. This then presents the opportunity to give a conceptual derivation of the Regge symmetry, as the representation theoretic analogue of the author's previous derivation of the Okamoto symmetry. [The resulting derivation is quite simple, so it would be surprising if it has not been previously observed. Any references would be appreciated!]Comment: 14 page

Generalized Drinfeld-Sokolov Reductions and KdV Type Hierarchies

Generalized Drinfeld-Sokolov (DS) hierarchies are constructed through local reductions of Hamiltonian flows generated by monodromy invariants on the dual of a loop algebra. Following earlier work of De Groot et al, reductions based upon graded regular elements of arbitrary Heisenberg subalgebras are considered. We show that, in the case of the nontwisted loop algebra $\ell(gl_n)$, graded regular elements exist only in those Heisenberg subalgebras which correspond either to the partitions of $n$ into the sum of equal numbers $n=pr$ or to equal numbers plus one $n=pr+1$. We prove that the reduction belonging to the grade $1$ regular elements in the case $n=pr$ yields the $p\times p$ matrix version of the Gelfand-Dickey $r$-KdV hierarchy, generalizing the scalar case $p=1$ considered by DS. The methods of DS are utilized throughout the analysis, but formulating the reduction entirely within the Hamiltonian framework provided by the classical r-matrix approach leads to some simplifications even for $p=1$.Comment: 43 page

Prospects for dedicated energy crop production and attitudes towards agricultural straw use: the case of livestock farmers

Second generation biofuels utilising agricultural by-products (e.g. straw), or dedicated energy crops (DECs) produced on ‘marginal’ land, have been called for. A structured telephone survey of 263 livestock farmers, predominantly located in the west or ‘marginal’ upland areas of England captured data on attitudes towards straw use and DECs. Combined with farm physical and business data, the survey results show that 7.2% and 6.3% of farmers would respectively consider growing SRC and miscanthus, producing respective maximum potential English crop areas of 54,603 ha and 43,859 ha. If higher market prices for straw occurred, most livestock farmers would continue to buy straw. Reasons for not being willing to consider growing DECs include concerns over land quality, committing land for a long time period, lack of appropriate machinery, profitability, and time to financial return; a range of moral, land quality, production conflict and lack of crop knowledge factors were also cited. Results demonstrate limited potential for the production of DECs on livestock farms in England. Changes in policy support to address farmer concerns with respect to DECs will be required to incentivise farmers to increase energy crop production. Policy support for DEC production must be cognisant of farm-level economic, tenancy and personal objectives

Extensions of the matrix Gelfand-Dickey hierarchy from generalized Drinfeld-Sokolov reduction

The $p\times p$ matrix version of the $r$-KdV hierarchy has been recently treated as the reduced system arising in a Drinfeld-Sokolov type Hamiltonian symmetry reduction applied to a Poisson submanifold in the dual of the Lie algebra $\widehat{gl}_{pr}\otimes {\Complex}[\lambda, \lambda^{-1}]$. Here a series of extensions of this matrix Gelfand-Dickey system is derived by means of a generalized Drinfeld-Sokolov reduction defined for the Lie algebra $\widehat{gl}_{pr+s}\otimes {\Complex}[\lambda,\lambda^{-1}]$ using the natural embedding $gl_{pr}\subset gl_{pr+s}$ for $s$ any positive integer. The hierarchies obtained admit a description in terms of a $p\times p$ matrix pseudo-differential operator comprising an $r$-KdV type positive part and a non-trivial negative part. This system has been investigated previously in the $p=1$ case as a constrained KP system. In this paper the previous results are considerably extended and a systematic study is presented on the basis of the Drinfeld-Sokolov approach that has the advantage that it leads to local Poisson brackets and makes clear the conformal ($\cal W$-algebra) structures related to the KdV type hierarchies. Discrete reductions and modified versions of the extended $r$-KdV hierarchies are also discussed.Comment: 60 pages, plain TE