Support vector machine-based feature extractor for L/H transitions in JET

Support vector machines (SVM) are machine learning tools originally developed in the field of artificial intelligence to perform both classification and regression. In this paper, we show how SVM can be used to determine the most relevant quantities to characterize the confinement transition from low to high confinement regimes in tokamak plasmas. A set of 27 signals is used as starting point. The signals are discarded one by one until an optimal number of relevant waveforms is reached, which is the best tradeoff between keeping a limited number of quantities and not loosing essential information. The method has been applied to a database of 749 JET discharges and an additional database of 150 JET discharges has been used to test the results obtained.

Accurate and reliable image classification by using conformal predictors in the TJ-II Thomson scattering

The charge-coupled device camera of the TJ-II Thomson scattering (TS) can capture five different classes of images. Typically, different data processing is performed depending on the kind of image that is acquired. The procedure can be automated to recognize the type of image. To this end, machine learning methods (MLM) are applied. However, usually, MLM classify without confidence estimates. An image classifier based on conformal predictors has been developed for the TJ-II TS. It provides a couple of indicators (confidence and credibility) for each classification that measures the accuracy and reliability of the prediction. Results achieve success rates of about 97%. The implemented classifier is valid for any kind of images.

Mechanisms of action and medicinal applications of abscisic Acid

Since its discovery in the early 1960's, abscisic acid (ABA) has received considerable attention as an important phytohormone, and more recently, as a candidate medicinal in humans. In plants it has been shown to regulate important physiological processes such as response to drought stress, and dormancy. The discovery of ABA synthesis in animal cells has generated interest in the possible parallels between its role in plant and animal systems. The importance of this molecule has prompted the development of several methods for the chemical synthesis of ABA, which differ significantly from the biosynthesis of ABA in plants through the mevalonic acid pathway. ABA recognition in plants has been shown to occur at both the intra- and extracellularly but little is known about the perception of ABA by animal cells. A few ABA molecular targets have been identified in vitro (e.g., calcium signaling, G protein-coupled receptors) in both plant and animal systems. A unique finding in mammalian systems, however, is that the peroxisome proliferator-activated receptor, PPAR gamma, is upregulated by ABA in both in vitro and in vivo studies. Comparison of the human PPAR gamma gene network with Arabidopsis ABA-related genes reveal important orthologs between these groups. Also, ABA can ameliorate the symptoms of type II diabetes, targeting PPAR gamma in a similar manner as the thiazolidinediones class of anti-diabetic drugs. The use of ABA in the treatment of type II diabetes, offers encouragement for further studies concerning the biomedical applications of ABA.

A threonine to isoleucine missense mutation in the pericentriolar material 1 gene is strongly associated with schizophrenia

Markers at the pericentriolar material 1 gene (PCM1) have shown genetic association with schizophrenia in both a University College London (UCL) and a USA-based case-control sample. In this paper we report a statistically significant replication of the PCM1 association in a large Scottish case-control sample from Aberdeen. Resequencing of the genomic DNA from research volunteers who had inherited haplotypes associated with schizophrenia showed a threonine to isoleucine missense mutation in exon 24 which was likely to change the structure and function of PCM1 (rs370429). This mutation was found only as a heterozygote in 98 schizophrenic research subjects and controls out of 2246 case and control research subjects. Among the 98 carriers of rs370429, 67 were affected with schizophrenia. The same alleles and haplotypes were associated with schizophrenia in both the London and Aberdeen samples. Another potential aetiological base pair change in PCM1 was rs445422, which altered a splice site signal. A further mutation, rs208747, was shown by electrophoretic mobility shift assays to create or destroy a promoter transcription factor site. Five further non-synonymous changes in exons were also found. Genotyping of the new variants discovered in the UCL case-control sample strengthened the evidence for allelic and haplotypic association (P=0.02-0.0002). Given the number and identity of the haplotypes associated with schizophrenia, further aetiological base pair changes must exist within and around the PCM1 gene. PCM1 protein has been shown to interact directly with the disrupted-in-schizophrenia 1 (DISC1) protein, Bardet-Biedl syndrome 4, and Huntingtin-associated protein 1, and is important in neuronal cell growth. In a separate study we found that clozapine but not haloperidol downregulated PCM1 expression in the mouse brain. We hypothesize that mutant PCM1 may be responsible for causing a subtype of schizophrenia through abnormal cell division and abnormal regeneration in dividing cells in the central nervous system. This is supported by our previous finding of orbitofrontal volumetric deficits in PCM1-associated schizophrenia patients as opposed to temporal pole deficits in non-PCM1-associated schizophrenia patients. Caution needs to be exercised in interpreting the actual biological effects of the mutations we have found without further cell biology. However, the DNA changes we have found deserve widespread genotyping in multiple case-control populations.

Nanofabrication with pulsed lasers

An overview of pulsed laser-assisted methods for nanofabrication, which are currently developed in our Institute (LP3), is presented. The methods compass a variety of possibilities for material nanostructuring offered by laser-matter interactions and imply either the nanostructuring of the laser-illuminated surface itself, as in cases of direct laser ablation or laser plasma-assisted treatment of semiconductors to form light-absorbing and light-emitting nano-architectures, as well as periodic nanoarrays, or laser-assisted production of nanoclusters and their controlled growth in gaseous or liquid medium to form nanostructured films or colloidal nanoparticles. Nanomaterials synthesized by laser-assisted methods have a variety of unique properties, not reproducible by any other route, and are of importance for photovoltaics, optoelectronics, biological sensing, imaging and therapeutics.

Kisspeptin neurons in the ovine arcuate nucleus and preoptic area are involved in the preovulatory luteinizing hormone surge

Kisspeptin is the product of the Kiss1 gene that regulates GnRH secretion. In sheep, Kiss1 mRNA-expressing cells are found in the preoptic area (POA) and arcuate nucleus (ARC), and expression is up-regulated in the caudal ARC during the periovulatory period. We hypothesized that kisspeptin neurons in the ARC are activated by estradiol-17beta prior to the preovulatory LH surge. Ovariectomized ewes were treated as follows: 1) estradiol-17beta implants (sc 2 wk) to cause tonic negative feedback; 2) vehicle (no estrogen negative or positive feedback); or 3) positive feedback/GnRH surge-inducing injection of estradiol-17beta (50 microg iv). For groups 2 and 3, brains were collected 1 h after treatment and kisspeptin/Fos immunoreactivity was examined. In the caudal and mid-ARC, the percentage of kisspeptin cells that were Fos immunoreactive increased after acute estradiol treatment (group 3) over that seen in the other two groups. Kisspeptin/Fos colocalization was also quantified in ewes during the luteal and late-follicular phase of the estrous cycle, showing a trend toward an increase in colocalization in the late-follicular phase. Kisspeptin/Fos colocalization was similar in the POA across groups in both experiments. Analysis of Kiss1 mRNA by in situ hybridization revealed an increase in expression during the late-follicular phase in the caudal ARC and POA. These data suggest kisspeptin neurons located in the caudal extent of the ARC are involved in generating the positive feedback preovulatory GnRH/LH surge in the ewe, but there may also be a role for Kiss1-expressing cells in the POA.

Estradiol-17beta-responsive A1 and A2 noradrenergic cells of the brain stem project to the bed nucleus of the stria terminalis in the ewe brain: a possible route for regulation of gonadotropin releasing hormone cells

We have studied brain stem cells in the ewe brain that project to the bed nucleus of the stria terminalis (BNST) and determined if these cells are activated by estradiol-17beta. This would predicate an indirect role in the estradiol-17beta regulation of gonadotropin releasing hormone (GnRH) cells, since these receive input from the BNST. Ovariectomized ewes received 50 mug estradiol-17beta benzoate (i.m.) 1 h prior to brain collection, so that activated cells could be identified by Fos immunohistochemistry. Retrograde tracer (FluoroGold; FG), was injected into the three divisions of the BNST and labeled cells were mapped to the A1 and A2 regions and the parabrachial nucleus (PBN) of the brain stem. With FG injection into the dorsal and lateral BNST, all FG-containing cells in the caudal A1 and 45% of those in A2 stained for dopamine-beta-hydroxylase (DBH), indicating noradrenergic type. No FG-labelled cells in the PBN were DBH-positive. In A1 and A2 respectively, 42% and 46% of FG-labelled cells were Fos-positive, with no double-labeling in cells of the PBN. In ewes receiving FG injections into the ventral BNST, estrogen receptor (ER)alpha-immunoreactive nuclei were found in 82% of A1-FG labeled and 38% of A2-FG labeled cells. No FG-labelled cells of the PBN were ERalpha-positive. Anterograde tracing from A1 with microruby injection identified projections to the PBN, BNST and preoptic area (POA). Thus, A1 and A2 noradrenergic neurons project to the BNST in the ewe brain, express ERalpha and are activated by estradiol-17beta. These noradrenergic, estrogen-responsive cells may provide indirect input to GnRH cells, via the BNST.