A voting approach to identify a small number of highly predictive genes using multiple classifiers

<p>Abstract</p> <p>Background</p> <p>Microarray gene expression profiling has provided extensive datasets that can describe characteristics of cancer patients. An important challenge for this type of data is the discovery of gene sets which can be used as the basis of developing a clinical predictor for cancer. It is desirable that such gene sets be compact, give accurate predictions across many classifiers, be biologically relevant and have good biological process coverage.</p> <p>Results</p> <p>By using a new type of multiple classifier voting approach, we have identified gene sets that can predict breast cancer prognosis accurately, for a range of classification algorithms. Unlike a wrapper approach, our method is not specialised towards a single classification technique. Experimental analysis demonstrates higher prediction accuracies for our sets of genes compared to previous work in the area. Moreover, our sets of genes are generally more compact than those previously proposed. Taking a biological viewpoint, from the literature, most of the genes in our sets are known to be strongly related to cancer.</p> <p>Conclusion</p> <p>We show that it is possible to obtain superior classification accuracy with our approach and obtain a compact gene set that is also biologically relevant and has good coverage of different biological processes.</p

Control of micro-inverters as an overvoltage prevention method under high PV- penetration

Low voltage (LV) residential grids are generally not designed for high penetration of photovoltaic (PV) distributed generation. Maximization of PV output is not only opposed by solar energy intermittency, but also by grid impacts in form of reverse power flow and overvoltage. More intelligent control of PV inverters is required to balance the voltage requirements of the grid and maximum energy yield wanted by the end user. This paper discusses how micro-inverter topology could be utilized to handle overvoltage problem and avoid power output losses by applying an innovative control method. Control is realized as partial generation shedding at PV module level which is an optimized alternative comparing to conventional, entire PV array tripping in the event of overvoltage.Niskonapięciowe systemy paneli słonecznych do użytku domowego mają istotne ograniczenia dotyczące intensywności zachodzących w nich zjawisk fotowoltaicznych. Ujemny wpływ na maksymalną efektywność tego typu układów mają nie tylko okresowe przerwy w nasłonecznieniu, lecz również przepięcia występujące w tych układach. Skuteczne sterowanie pracą przełączników napięcia jest bardzo istotne dla zapewnienia wymaganego napięcia oraz maksymalizacji mocy dostarczanej do końcowego użytkownika. W pracy zaprezentowano koncepcję wykorzystania topologii mikroprzełączników oraz nowatorską metodę ich sterowania, umożliwiającą rozwiązywanie problemów związanych z przepięciami oraz zmniejszenia strat mocy wyjściowej. Sterowanie jest realizowane na poziomie poszczególnych modułów fotowoltaicznych

Applicability of true voltage unbalance approximation formula for unbalance monitoring in LV networks with single-phase distributed generation

\u3cp\u3eIn the hierarchy of power transmission and distribution systems, the three-phase LV distribution networks are most susceptible to voltage unbalance (VU). The main causes are large presence of randomly distributed single-phase loads and, following the latest trends, the increasing presence of single-phase distributed generators. Most widely accepted VU calculation is based on percentile ratio of negative and positive sequence voltage (voltage unbalance factor, VUF). Obtaining sequence voltages is a complex domain calculation and requires simultaneous sampling of three-phase voltages and angles. This is why the existing VU monitoring and mitigation solutions are dominantly three-phase. Without an additional three-phase aggregation device, there is an inherent gap in VU monitoring for single-phase loads and generators. In this paper, the data concentrators for a growing PV micro-inverter niche are identified as an infrastructure that could be exploited to somewhat close this gap. Due to potential technical limitations of PV data concentrators, a non-complex VUF approximation formula is tested as a light calculation alternative, by comparing it against conventional VUF. The comparison results are obtained from Monte Carlo load flow simulation for an unbalanced LV network.\u3c/p\u3

Sustainable transition to high PV penetration:curtailment retrofit for the already deployed micro-inverters

\u3cp\u3eIncreasing photovoltaic (PV) capacity in low voltage networks is limited by occasional congestion, resulting in unacceptable voltage levels. Network managers and policy makers are getting aware of this problem and various technical recommendations are given. Of special interest are ancillary services (reactive power control and active power curtailment) that could be provided by the smart inverters. Most PV inverters deployed to date are solely designed to maximize power output. To make the transition towards smart inverters, they either have to be replaced or retrofitted. Retrofit can be a more sustainable option, especially if it can be done only by software intervention ( soft retrofit ). This paper presents a curtailment method suitable for the already deployed micro-inverters without needing to replace them. Sequential module-level tripping is an optimized overvoltage trip scheme that achieves curtailment on a system level, without modifying the functionality of individual micro-inverter unit. The proposed method was simulated for an increased PV penetration scenario for a Dutch LV network. The annual feed-in losses of curtailment were compared against conventional overvoltage protection. Depending on the location of PV in the distribution network, 62-100% less feed-in loss was achieved with the proposed curtailment method.\u3c/p\u3

Microinverter curtailment strategy for increasing photovoltaic penetration in low-voltage networks

Transition toward smart distribution networks with high penetration of photovoltaics (PVs) will involve incidental generation curtailment as an alternative to grid reinforcements. Microinverters are taking over popularity of string inverters in residential and some commercial areas mainly due to increased energy harvest. This paper demonstrates how microinverters with a modified overvoltage protection scheme could provide a reliable curtailment solution and accommodate additional PV capacity. Two wide-area curtailment schemes were proposed for a typical Dutch residential feeder with densely clustered PV. First, a single worst-case scenario was used to demonstrate the capabilities of the proposed curtailment schemes: the distribution network operators can optimize between various priorities such as total feeder output, economic equality between connected parties, voltage levels, voltage unbalance, and curtailment execution time. Second, a yearly comparison was made against conventional overvoltage protection and the results show 62%–100% reduction in overvoltage losses

Live-cell imaging screen to determine responses of 160 kinase inhibitors against normal and glioblastoma-derived neural stem cells.

<p>(A) Glioblastoma subtype gene expression signatures established Verhaak et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077053#pone.0077053-Verhaak1" target="_blank">[7]</a> (left panel) were assessed in a set of GNS cell lines (right panel). (B) Correlations between subtype centroid values determined by Verhaak et al. and gene expression in GNS cells. G144 exhibits clear correspondence to the ‘proneural’ subtype, whereas G166 and G179 have greater similarities to the mesenchymal and neural/mesenchymal subtypes, respectively. (C) Summary of screening strategy based on these three GNS cell lines and a genetically normal NS cell (CB660). (D) Proliferation curves generated for each compound over a 3–6 day period identify J101 (red line) as an agent that can selectively block expansion of GNS cells. (E) Significant events were identified affecting GNS cells but not NS cells, and cytotostatic/cytotoxic compounds reducing confluence in all GNS cells >2.2 standard deviations from the average of DMSO controls are shown (<i>P</i> = 0.01). The full data for the screen are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077053#pone.0077053.s007" target="_blank">Table S1</a>. (F) Example phase contrast images acquired for G179 and CB660 prior to treatment with J101 (0 h) and 60 h.</p