Particle Competition and Cooperation in Networks for Semi-Supervised Learning

Semi-supervised learning is one of the important topics in machine learning, concerning with pattern classification where only a small subset of data is labeled. In this paper, a new network-based (or graph-based) semi-supervised classification model is proposed. It employs a combined random-greedy walk of particles, with competition and cooperation mechanisms, to propagate class labels to the whole network. Due to the competition mechanism, the proposed model has a local label spreading fashion, i.e., each particle only visits a portion of nodes potentially belonging to it, while it is not allowed to visit those nodes definitely occupied by particles of other classes. In this way, a "divide-and-conquer" effect is naturally embedded in the model. As a result, the proposed model can achieve a good classification rate while exhibiting low computational complexity order in comparison to other network-based semi-supervised algorithms. Computer simulations carried out for synthetic and real-world data sets provide a numeric quantification of the performance of the method.

Probing the anomalous extinction of four young star clusters: the use of colour-excess, main-sequence fitting and fractal analysis

Aims. We studied four young star clusters to characterise their anomalous extinction or variable reddening and asses whether they could be due to contamination by either dense clouds or circumstellar effects. Methods. We evaluated the extinction law (R-V) by adopting two methods: (i) the use of theoretical expressions based on the colour-excess of stars with known spectral type; and (ii) the analysis of two-colour diagrams, where the slope of the observed colour distribution was compared to the normal distribution. An algorithm to reproduce the zero-age main-sequence (ZAMS) reddened colours was developed to derive the average visual extinction (A(V)) that provides the closest fit to the observational data. The structure of the clouds was evaluated by means of a statistical fractal analysis, designed to compare their geometric structure with the spatial distribution of the cluster members. Results. The cluster NGC 6530 is the only object of our sample affected by anomalous extinction. On average, the other clusters suffer normal extinction, but several of their members, mainly in NGC 2264, seem to have high R-V, probably because of circumstellar effects. The ZAMS fitting provides A(V) values that are in good agreement with those found in the literature. The fractal analysis shows that NGC 6530 has a centrally concentrated distribution of stars that differs from the substructures found in the density distribution of the cloud projected in the A(V) map, suggesting that the original cloud was changed by the cluster formation. However, the fractal dimension and statistical parameters of Berkeley 86, NGC 2244, and NGC 2264 indicate that there is a good cloud-cluster correlation, when compared to other works based on an artificial distribution of points.

Aerial organ anatomy of Smilax syphilitica (Smilacaceae)

Smilax L. in Brazil is represented by 32 taxa and it is a taxonomically difficult genus because the plants are dioecious and show wide phenotypic variation. The analysis and use of leaf anatomy characters is recognized as a frequently successful taxonomic method to distinguish between individual taxon, when floral material is absent or minute differences in flowers and foliage exist such as in Smilax. The aim of this study was to characterize the anatomical features of the aerial organs in Smilax syphilitica collected from the Atlantic Rainforest, in Santa Teresa-ES and the Smilax aff syphilitica from the Amazon Rainforest, in Manaus, Brazil. For this, a total of three samples of Smilax were collected per site. Sample leaves and stems were fixed with FAA 50, embedded in historesin, sectioned on a rotary microtome, stained and mounted in synthetic resin. Additionally, histochemical tests were performed and cuticle ornamentation was analyzed with standard scanning electron microscopy. S. syphilitica and S. aff syphilitica differed in cuticle ornamentation, epidermal cell arrangement and wall thickness, stomata type and orientation, calcium oxalate crystal type, and position of stem thorns. Leaf blades of S. syphilitica from the Amazon Rainforest have a network of rounded ridges on both sides, while in S. aff syphilitica, these ridges are parallel and the spaces between them are filled with numerous membranous platelets. Viewed from the front, the epidermal cells of S. syphilitica have sinuous walls (even more pronounced in samples from the Amazon); while in S. aff syphilitica, these cells are also sinuous but elongated in the cross-section of the blade and arranged in parallel. Stomata of S. syphilitica are paracytic, whereas in S. aff syphilitica, are both paracytic and anisocytic, and their polar axes are directed towards the mid-vein. Calcium oxalate crystals in S. syphilitica are prisms, whereas in S. aff syphilitica, crystal sand. Thorns occur in nodes and internodes in S. syphilitica but only in internodes in S. aff syphilitica. These features have proven to be of diagnostic value and may support a separation into two species, but future studies are needed to confirm that S. aff syphilitica is indeed a new taxon. Rev. Biol. Trop. 60(3): 1137-1148. Epub 2012 September 01.

Analytical tools to assess the voltage stability of induction-based distributed generators

The installation of induction distributed generators should be preceded by a careful study in order to determine if the point of common coupling is suitable for transmission of the generated power, keeping acceptable power quality and system stability. In this sense, this paper presents a simple analytical formulation that allows a fast and comprehensive evaluation of the maximum power delivered by the induction generator, without losing voltage stability. Moreover, this formulation can be used to identify voltage stability issues that limit the generator output power. All the formulation is developed by using the equivalent circuit of squirrel-cage induction machine. Simulation results are used to validate the method, which enables the approach to be used as a guide to reduce the simulation efforts necessary to assess the maximum output power and voltage stability of induction generators. (C) 2011 Elsevier Ltd. All rights reserved.

In-Flight Collision Avoidance Controller Based Only on OS4 Embedded Sensors

The major goal of this research was the development and implementation of a control system able to avoid collisions during the flight for a mini-quadrotor helicopter, based only on its embedded sensors without changing the environment. However, it is important to highlight that the design aspects must be seriously considered in order to overcome hardware limitations and achieve control simplification. The controllers of a UAV (Unmanned Aerial Vehicle) robot deal with highly unstable dynamics and strong axes coupling. Furthermore, any additional embedded sensor increases the robot total weight and therefore, decreases its operating time. The best balance between embedded electronics and robot operating time is desired. This paper focuses not only on the development and implementation of a collision avoidance controller for a mini-robotic helicopter using only its embedded sensors, but also on the mathematical model that was essential for the controller developing phases. Based on this model we carried out the development of a simulation tool based on MatLab/Simulink that was fundamental for setting the controllers' parameters. This tool allowed us to simulate and improve the OS4 controllers in different modeled environments and test different approaches. After that, the controllers were embedded in the real robot and the results proved to be very robust and feasible. In addition to this, the controller has the advantage of being compatible with future path planners that we are developing.

Measurement of event background fluctuations for charged particle jet reconstruction in Pb-Pb collisions at root s(NN)=2.76 TeV

The effect of event background fluctuations on charged particle jet reconstruction in Pb-Pb collisions at root s(NN) = 2.76 TeV has been measured with the ALICE experiment. The main sources of non-statistical fluctuations are characterized based purely on experimental data with an unbiased method, as well as by using single high p(t) particles and simulated jets embedded into real Pb-Pb events and reconstructed with the anti-k(t) jet finder. The influence of a low transverse momentum cut-off on particles used in the jet reconstruction is quantified by varying the minimum track p(t) between 0.15 GeV/c and 2 GeV/c. For embedded jets reconstructed from charged particles with p(t) > 0.15 GeV/c, the uncertainty in the reconstructed jet transverse momentum due to the heavy-ion background is measured to be 11.3 GeV/c (standard deviation) for the 10% most central Pb-Pb collisions, slightly larger than the value of 11.0 GeV/c measured using the unbiased method. For a higher particle transverse momentum threshold of 2 GeV/c, which will generate a stronger bias towards hard fragmentation in the jet finding process, the standard deviation of the fluctuations in the reconstructed jet transverse momentum is reduced to 4.8-5.0 GeV/c for the 10% most central events. A non-Gaussian tail of the momentum uncertainty is observed and its impact on the reconstructed jet spectrum is evaluated for varying particle momentum thresholds, by folding the measured fluctuations with steeply falling spectra.

Valence band tail states in disordered superlattices embedded in wide parabolic AlGaAs well

Optical properties of intentionally disordered multiple quantum well (QW) system embedded in a wide AlGaAs parabolic well were investigated by photoluminescence (PL) measurements as functions of the laser excitation power and the temperature. The characterization of the carriers localized in the individual wells was allowed due to the artificial disorder that caused spectral separation of the photoluminescence lines emitted by different wells. We observed that the photoluminescence peak intensity from each quantum well shifted to high energy as the excitation power was increased. This blue-shift is associated with the filling of localized states in the valence band tail. We also found that the dependence of the peak intensity on the temperature is very sensitive to the excitation power. The temperature dependence of the photoluminescence peak energy from each QW was well fitted using a model that takes into account the thermal redistribution of the localized carriers. Our results demonstrate that the band tails in the studied structures are caused by alloy potential fluctuations and the band tail states dominate the emission from the peripheral wells. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4730769]

Assessing apical transportation in curved canals: comparison between cross-sections and micro-computed tomography

The aim of this study was to compare two methods of assessing apical transportation in curved canals after rotary instrumentation, namely, cross-sections and micro-computed tomography (mu CT). Thirty mandibular molars were divided into two groups and prepared according to the requirements of each method. In G1 (cross-sections), teeth were embedded in resin blocks and sectioned at 2.0, 3.5, and 5.0 mm from the anatomic apex. Pre- and postoperative sections were photographed and analyzed. In G2 (mu CT), teeth were embedded in a rubber-base impression material and scanned before and after instrumentation. Mesiobuccal canals were instrumented with the Twisted File (TF) system (SybronEndo, Orange, USA), and mesiolingual canals, with the Endo Sequence (ES) system (Brasseler, Savannah, USA). Images were reconstructed, and sections corresponding to distances 2.0, 3.5, and 5.0 mm from the anatomic apex were selected for comparison. Data were analyzed using Mann-Whitney's test at a 5% significance level. The TF and ES instruments produced little deviation from the root canal center, with no statistical difference between them (P > 0.05). The canal transportation results were significantly lower (0.056 mm) in G2 than in G1 (0.089 mm) (p = 0.0012). The mu CT method was superior to the cross-section method, especially in view of its ability to preserve specimens and provide results that are more closely related to clinical situations.

Characterisation of young stellar clusters

Aims. Several embedded clusters are found in the Galaxy. Depending on the formation scenario, most of them can evolve to unbounded groups that are dissolved within 10 Myr to 20 Myr. A systematic study of young stellar clusters that show distinct characteristics provides interesting information on the evolutionary phases during the pre-main sequence. To identify and to understand these phases we performed a comparative study of 21 young stellar clusters. Methods. Near-infrared data from 2MASS were used to determine the structural and fundamental parameters based on surface stellar density maps, radial density profile, and colour-magnitude diagrams. The cluster members were selected according to their membership probability, which is based on the statistical comparison with the cluster proper motion. Additional members were selected on the basis of a decontamination procedure that was adopted to distinguish field stars found in the direction of the cluster area. Results. We obtained age and mass distributions by comparing pre-main sequence models with the position of cluster members in the colour-magnitude diagram. The mean age of our sample is similar to 5 Myr, where 57% of the objects is found in the 4-10 Myr range of age, while 43% is <4 Myr old. Their low E(B - V) indicate that the members are not suffering high extinction (AV <1 mag), which means they are more likely young stellar groups than embedded clusters. Relations between structural and fundamental parameters were used to verify differences and similarities that could be found among the clusters. The parameters of most of the objects show the same trends or correlations. Comparisons with other young clusters show similar relations among mass, radius, and density. Our sample tends to have larger radius and lower volumetric density than embedded clusters. These differences are compatible with the mean age of our sample, which we consider intermediate between the embedded and the exposed phases of the stellar clusters evolution.

Interpolation estimate for a finite-element space with embedded discontinuities

We consider a recently proposed finite-element space that consists of piecewise affine functions with discontinuities across a smooth given interface Γ (a curve in two dimensions, a surface in three dimensions). Contrary to existing extended finite element methodologies, the space is a variant of the standard conforming Formula space that can be implemented element by element. Further, it neither introduces new unknowns nor deteriorates the sparsity structure. It is proved that, for u arbitrary in Formula, the interpolant Formula defined by this new space satisfies Graphic where h is the mesh size, Formula is the domain, Formula, Formula, Formula and standard notation has been adopted for the function spaces. This result proves the good approximation properties of the finite-element space as compared to any space consisting of functions that are continuous across Γ, which would yield an error in the Formula-norm of order Graphic. These properties make this space especially attractive for approximating the pressure in problems with surface tension or other immersed interfaces that lead to discontinuities in the pressure field. Furthermore, the result still holds for interfaces that end within the domain, as happens for example in cracked domains.

Transiting exoplanets from the CoRoT space mission XX. CoRoT-20b: A very high density, high eccentricity transiting giant planet

We report the discovery by the CoRoT space mission of a new giant planet, CoRoT-20b. The planet has a mass of 4.24 +/- 0.23 M-Jup and a radius of 0.84 +/- 0.04 R-Jup. With a mean density of 8.87 +/- 1.10 g cm(-3), it is among the most compact planets known so far. Evolutionary models for the planet suggest a mass of heavy elements of the order of 800 M-circle plus if embedded in a central core, requiring a revision either of the planet formation models or both planet evolution and structure models. We note however that smaller amounts of heavy elements are expected by more realistic models in which they are mixed throughout the envelope. The planet orbits a G-type star with an orbital period of 9.24 days and an eccentricity of 0.56. The star's projected rotational velocity is v sin i = 4.5 +/- 1.0 km s(-1), corresponding to a spin period of 11.5 +/- 3.1 days if its axis of rotation is perpendicular to the orbital plane. In the framework of Darwinian theories and neglecting stellar magnetic breaking, we calculate the tidal evolution of the system and show that CoRoT-20b is presently one of the very few Darwin-stable planets that is evolving toward a triple synchronous state with equality of the orbital, planetary and stellar spin periods.

RNA extraction from ten year old formalin-fixed paraffin-embedded breast cancer samples: a comparison of column purification and magnetic bead-based technologies

Abstract Background The development of protocols for RNA extraction from paraffin-embedded samples facilitates gene expression studies on archival samples with known clinical outcome. Older samples are particularly valuable because they are associated with longer clinical follow up. RNA extracted from formalin-fixed paraffin-embedded (FFPE) tissue is problematic due to chemical modifications and continued degradation over time. We compared quantity and quality of RNA extracted by four different protocols from 14 ten year old and 14 recently archived (three to ten months old) FFPE breast cancer tissues. Using three spin column purification-based protocols and one magnetic bead-based protocol, total RNA was extracted in triplicate, generating 336 RNA extraction experiments. RNA fragment size was assayed by reverse transcription-polymerase chain reaction (RT-PCR) for the housekeeping gene glucose-6-phosphate dehydrogenase (G6PD), testing primer sets designed to target RNA fragment sizes of 67 bp, 151 bp, and 242 bp. Results Biologically useful RNA (minimum RNA integrity number, RIN, 1.4) was extracted in at least one of three attempts of each protocol in 86–100% of older and 100% of recently archived ("months old") samples. Short RNA fragments up to 151 bp were assayable by RT-PCR for G6PD in all ten year old and months old tissues tested, but none of the ten year old and only 43% of months old samples showed amplification if the targeted fragment was 242 bp. Conclusion All protocols extracted RNA from ten year old FFPE samples with a minimum RIN of 1.4. Gene expression of G6PD could be measured in all samples, old and recent, using RT-PCR primers designed for RNA fragments up to 151 bp. RNA quality from ten year old FFPE samples was similar to that extracted from months old samples, but quantity and success rate were generally higher for the months old group. We preferred the magnetic bead-based protocol because of its speed and higher quantity of extracted RNA, although it produced similar quality RNA to other protocols. If a chosen protocol fails to extract biologically useful RNA from a given sample in a first attempt, another attempt and then another protocol should be tried before excluding the case from molecular analysis.

Guidelines for the Development of Comprehensive Care Centers for Congenital Adrenal Hyperplasia: Guidance from the CARES Foundation Initiative

Patients with rare and complex diseases such as congenital adrenal hyperplasia (CAH) often receive fragmented and inadequate care unless efforts are coordinated among providers. Translating the concepts of the medical home and comprehensive health care for individuals with CAH offers many benefits for the affected individuals and their families. This manuscript represents the recommendations of a 1.5 day meeting held in September 2009 to discuss the ideal goals for comprehensive care centers for newborns, infants, children, adolescents, and adults with CAH. Participants included pediatric endocrinologists, internal medicine and reproductive endocrinologists, pediatric urologists, pediatric surgeons, psychologists, and pediatric endocrine nurse educators. One unique aspect of this meeting was the active participation of individuals personally affected by CAH as patients or parents of patients. Representatives of Health Research and Services Administration (HRSA), New York-Mid-Atlantic Consortium for Genetics and Newborn Screening Services (NYMAC), and National Newborn Screening and Genetics Resource Center (NNSGRC) also participated. Thus, this document should serve as a "roadmap" for the development phases of comprehensive care centers (CCC) for individuals and families affected by CAH.

Cigarette smoke inhalation influences bone healing of post-extraction tooth socket: a histometric study in rats

The aim of this study was to evaluate, histometrically, the bone healing of the molar extraction socket just after cigarette smoke inhalation (CSI). Forty male Wistar rats were randomly assigned to a test group (animals exposed to CSI, starting 3 days before teeth extraction and maintained until sacrifice; n=20) and a control group (animals never exposed to CSI; n=20). Second mandibular molars were bilaterally extracted and the animals (n=5/group/period) were sacrificed at 3, 7, 10 and 14 days after surgery. Digital images were analyzed according to the following histometric parameters: osteoid tissue (OT), remaining area (RA), mineralized tissue (MT) and non-mineralized tissue (NMT) in the molar socket. Intergroup analysis showed no significant differences at day 3 (p>0.05) for all parameters. On the 7th day, CSI affected negatively (p<0.05) bone formation with respect to NMT and RA (MT: 36%, NMT: 53%, RA: 12%; and MT: 39%, NMT: 29%, RA: 32%, for the control and test groups, respectively). In contrast, no statistically significant differences (p>0.05) were found at days 10 and 14. It may be concluded that CSI may affect socket healing from the early events involved in the healing process, which may be critical for the amount and quality of new-bone formation in smokers.

MicroRNA expression profile in head and neck cancer: HOX-cluster embedded microRNA-196a and microRNA-10b dysregulation implicated in cell proliferation

Abstract Background Current evidence implicates aberrant microRNA expression patterns in human malignancies; measurement of microRNA expression may have diagnostic and prognostic applications. Roles for microRNAs in head and neck squamous cell carcinomas (HNSCC) are largely unknown. HNSCC, a smoking-related cancer, is one of the most common malignancies worldwide but reliable diagnostic and prognostic markers have not been discovered so far. Some studies have evaluated the potential use of microRNA as biomarkers with clinical application in HNSCC. Methods MicroRNA expression profile of oral squamous cell carcinoma samples was determined by means of DNA microarrays. We also performed gain-of-function assays for two differentially expressed microRNA using two squamous cell carcinoma cell lines and normal oral keratinocytes. The effect of the over-expression of these molecules was evaluated by means of global gene expression profiling and cell proliferation assessment. Results Altered microRNA expression was detected for a total of 72 microRNAs. Among these we found well studied molecules, such as the miR-17-92 cluster, comprising potent oncogenic microRNA, and miR-34, recently found to interact with p53. HOX-cluster embedded miR-196a/b and miR-10b were up- and down-regulated, respectively, in tumor samples. Since validated HOX gene targets for these microRNAs are not consistently deregulated in HNSCC, we performed gain-of-function experiments, in an attempt to outline their possible role. Our results suggest that both molecules interfere in cell proliferation through distinct processes, possibly targeting a small set of genes involved in cell cycle progression. Conclusions Functional data on miRNAs in HNSCC is still scarce. Our data corroborate current literature and brings new insights into the role of microRNAs in HNSCC. We also show that miR-196a and miR-10b, not previously associated with HNSCC, may play an oncogenic role in this disease through the deregulation of cell proliferation. The study of microRNA alterations in HNSCC is an essential step to the mechanistic understanding of tumor formation and could lead to the discovery of clinically relevant biomarkers.