Entire Samples Research Articles

Extending Photocatalytic Activity of TiO2 Nanoparticles to Visible Region of Illumination by Doping of Cerium

Cerium-doped Titanium dioxide (TiO(2)) nanoparticles are prepared by sol-gel method. Doping shifts the UV absorption edge of TiO(2) to the visible region, making it efficient for visible light photocatalysis. Incorporation of cerium decreases the effective band gap of TiO(2) and increases the Urbach energy levels. At the dopant concentrations of 0.015 and 0.025 mol the luminescence intensity increases compared to undoped TiO(2); however, the luminescence is quenched at 0.035 mol. Quenching of luminescence indicates efficient separation of charge carriers. Undoped TiO(2) is showing poor performance in the photocatalytic degradation of methyl orange under visible light. However, on cerium doping its photoactivity is increased, and is drastically enhanced at 0.035 mol of cerium. Further increase in Ce(3+) doping level to 0.045 mol results in the reduction of the photodegradation of the dye. On UV irradiation, entire samples show good photocatalytic activity up to 30 min, but their efficiency decreases when irradiation time is increased to 45 min. Irradiation for longer time results in negative charging of the TiO(2) surface with migrating electrons. The negatively charged surface repels the OH(-) ion and O(2) molecule from adsorbing on its surface thus decreasing the availability of hydroxyl and superoxide radical for dye degradation.

The role of inflammation and matrix metalloproteinases in equine endometriosis

Equine endometriosis is a multifactorial disease considered to be a major cause of equine infertility. The purpose of this study was to evaluate the reliability of histomorphological grading for biopsy-like samples compared to entire uterine wall samples, to examine the association between the degree of endometriosis with animal age, and to investigate the role of inflammation in endometriosis and the expression of different matrix metalloproteinases in equine endometrium. Histomorphological lesions in 35 uterine samples were examined while comparing biopsy-like samples and entire-wall samples. Seventeen uterine samples were stained with antibodies against MMP-2, MMP-9, MMP-14, and TIMP-2. The morphologic evaluation results of the biopsy-like tissue and entire-wall samples were significantly correlated. Endometriosis in older mares (>12 years of age) was more severe than in young mares (2~4 years of age), confirming the positive correlation between animal age and disease severity, while inflammation was poorly related to the degree of endometriosis. MMP-2 and MMP-14 were detected in stromal cells, while MMP-9 and TIMP-2 were both found in stromal and glandular epithelial cells. There were no significant differences in MMPs expression between the two groups (young vs. old mares). Additional studies on the activity of MMPs could further define the role of these enzymes in equine endometriosis.

Assessment of genetic variation among fivehordeumspecies from Iran

In this study, simple sequence repeat (SSR) markers were used to investigate the genetic diversity and evolutionary relationships among 74 barley accessions; 15 landraces (Hordeum vulgare) and 59 wild accessions (twenty-one Hordeum spontaneum, ten Hordeum bulbosum, thirteen Hordeum murinum and fifteen Hordeum marinum). A total of 66 alleles were detected at 12 SSR loci, with an average of 5.5 alleles per locus in the entire samples. The average number of alleles (4.2) per locus was higher in H. vulgare and H. spontaneum, reflecting more genetic diversity within these two species compared with the other species. All index values of genetic diversity revealed that there was higher genetic diversity within H. vulgare landraces than within the wild species, indicating that cultivation unlikely to have caused a loss of genetic diversity in cultivated barley compared with its wild relatives. Analysis of molecular variance (AMOVA) revealed that 31% of the total observed variation was accounted for among species....

MULTISTAGE MUTUAL INFORMATION FOR INFORMATIVE GENE SELECTION

An important issue in the design of gene selection algorithm for microarray data analysis is the formation of suitable criterion function for measuring the relevance between different gene expressions. Mutual information (MI) is a widely used criterion function but it calculates the relevance on the entire samples only once which cannot exactly identify the informative genes. This paper proposes a novel idea of computing MI in stages. The proposed multistage mutual information (MSMI) computes MI, initially using all the samples and based on the classification performance produced by artificial neural network (ANN), MI is repeatedly calculated using only the unclassified samples until there is no improvement in the classification accuracy. The performance of the proposed approach is evaluated using ten gene expression data sets. Simulation result shows that the proposed approach helps to improve the discriminate power of the genes with regard to the target disease of a microarray sample. Statistical analysis of the test result shows that the proposed method selects highly informative genes and produces comparable classification accuracy than the other approaches reported in the literature.

Risk of Community-Acquired Pneumonia in Veteran Patients to Whom Proton Pump Inhibitors Were Dispensed

Observational studies linking proton pump inhibitor (PPI) exposure with community-acquired pneumonia (CAP) have reported either modest or no associations. Accordingly, we studied PPI exposure and CAP in veteran patients, using a retrospective, nested case-control design. From linked pharmacy and administrative databases of the New England Veterans Healthcare System, we identified 71985 outpatients newly prescribed PPIs between 1998 and 2007; 1544 patients met criteria for CAP subsequent to PPI initiation; 15440 controls were matched through risk-set sampling by age and time under observation. Crude and adjusted odds ratios comparing current with past PPI exposures, as well as tests for interactions, were conducted for the entire and stratified samples. Current PPI use associated with CAP (adjusted odds ratio [OR], 1.29 [95% confidence interval {CI}, 1.15-1.45]). Risks were not substantially altered by age or year of diagnosis. Dementia (n = 85; P = .062 for interaction) and sedative/tranquilizer use (n = 224; P = .049 for interaction) were likely effect modifiers increasing a PPI-CAP association; conversely, for some chronic medical conditions, PPI-associated CAP risks were reversed. PPI exposures between 1 and 15 days increased CAP risks, compared with longer exposures, but PPI initiation also frequently occurred shortly after CAP diagnoses. Prescribed PPI doses >1 dose/day also increased PPI-associated CAP risks. Among the veterans studied, current compared with past PPI exposures associated modestly with increased risks of CAP. However, our observations that recent treatment initiation and higher PPI doses were associated with greater risks, and the inconsistent PPI-CAP associations between patient subgroups, indicate that further inquiries are needed to separate out coincidental patterns of associations.

Testing for nonlinearity of exchange rates: an information‐theoretic approach

Purpose – This study seeks to explore the nature of a data‐generating process for four dollar exchange rates.Design/methodology/approach – Using a discrete parametric modeling approach, an efficient test statistic was computed for nonlinearity in terms of variance of the residuals of the linear and nonlinear autoregressive models by Akaike Information Criterion, and a surrogate data analysis was conducted.Findings – It shows that a nonlinear autoregressive model outperforms a linear stochastic model in certain subsamples of baht, pound, ringgit, and yen dollar exchange rates. However, when the test statistics using different model orders and the data for the entire samples are estimated, it appears that the nonlinear model has a better performance than the linear model in fitting Thai and Malaysian currencies. The nonlinear model performs better than the linear model in the case of the UK pound in two thirds of the models, but the linear models completely outperform the nonlinear models for the yen data.R...

Genetic diversity, population genetic structure and demographic history of Przewalski’s gazelle (Procapra przewalskii): implications for conservation

The Przewalski’s gazelle (Procapra przewalskii) is one of the most endangered antelope species in the world. It is endemic to China and is a flagship species in the eastern part of the Qinghai–Tibet plateau. To establish effective conservation measures on this species, genetic information such as genetic structure is needed. However, there has not been a comprehensive genetic assessment on this gazelle using nuclear DNA markers yet. Here, we employed 13 microsatellite loci to investigate genetic diversity, population genetic structure and demographic history of Przewalski’s gazelle using noninvasive samples of 169 wild gazelles collected from nine populations. A total of 76 alleles were detected from the entire samples, mean allele number was 5.85, and overall HO and HE were 0.525 and 0.552, respectively. Structure and GENELAND analyses found six genetic groups in the nine populations. Between the inferred genetic groups, significant genetic differentiation and low migration rates were detected. Demographic analyses indicated that Przewalski’s gazelle experienced genetic bottleneck and severe population decline, with the ancestral effective population size reducing to less than one percent. Based on the results of this study, we provide several conservation recommendations for Przewalski’s gazelle, such as six management units, periodic monitoring and special conservation consideration on the Qiejitan population.

The mass-loss return from evolved stars to the Large Magellanic Cloud

The total dust return rate from AGB and RSG star outflows is an important constraint to galactic chemical evolution models. However, this requires detailed radiative transfer (RT) modeling of individual stars, which becomes impractical for large data sets. Another approach is to select the best-fit spectral energy distribution (SED) from a grid of dust shell models, allowing for a faster determination of the luminosities and mass-loss rates for entire samples. We have developed the Grid of RSG and AGB ModelS (GRAMS) to measure the mass-loss return from evolved stars. The models span the range of stellar, dust shell and grain properties relevant to evolved stars. In this paper we present the carbon-star grid and compare our results with data of Large Magellanic Cloud (LMC) carbon stars from the SAGE and SAGE-Spec programs. We generate spherically symmetric dust shell models using the 2Dust code, with hydrostatic models for the central stars. We explore five values of the inner radius R_in of the dust shell (1.5, 3, 4.5, 7 and 12 R_star). We use amorphous carbon dust mixed with 10% silicon carbide by mass. The grain sizes follows a KMH distribution. The models span 26 values of 11.3 um optical depth, ranging from 0.001 to 4. For each model, 2Dust calculates the output SED from 0.2 to 200 um. Over 12,000 models have dust temperatures below 1800 K. The GRAMS synthetic photometry is in good agreement with SAGE photometry for LMC carbon-rich and extreme AGB star candidates, as well as spectroscopically confirmed carbon stars from the SAGE-Spec study. Our models reproduce the IRAC colors of most of the extreme AGB star candidates, consistent with the expectation that a majority of these enshrouded stars have carbon-rich dust. Finally, we fit the SEDs of some well-studied carbon stars and compare the resulting luminosities and mass-loss rates with those from previous studies.

Fluorescent and nonlinear optical features of CdTe quantum dots

The study of photoluminescence and nonlinear optical properties of red (emitted at 650 nm), yellow (emitted at 570 nm) and green (emitted at 530 nm) CdTe quantum dots (QD) spin coated on quartz substrate that had been prepared by changing the ratio between octadecylphosphonic acid and octadecence within 0.1:1–1:1 was carried out. Spectral width of the emission spectra indicates an enhancement with the increasing of QDs sizes, namely ca. 25, 28 and 50 nm for the QD size of 2.5, 3.5 and 5 nm, correspondingly. The entire QDs samples feature a spherical morphology with a relatively narrow size distribution. The optical second harmonic generation (SHG) stimulated by coherent bicolor treatment at 1,540 nm and its second harmonic generation was studied versus the laser light power density and incident angle.

High diversity of tropical peatland ecosystem types in the Pastaza-Marañón basin, Peruvian Amazonia

[1] Very little information exists on Amazonian peatlands with most studies on tropical peatlands concentrating on Southeast Asia. Here we describe diversity of Amazonian peatland ecosystems and consider its implications for the global diversity of tropical peatland ecosystems. Nine study sites were selected from within the most extensive wetland area of Peruvian Amazonia: the 120,000 km2 Pastaza-Maranon basin. Peat thickness was determined every 500 m from the edge toward the center of each site, and peat samples were collected from two cores per site. Samples from the entire central core and surface samples from the other core were analyzed for nutrient content. Topography of four peat deposits was measured. In order to study differences in vegetation, pixel values were extracted from a satellite image. The surface peat nutrient content of the peatlands varied from very nutrient-rich to nutrient-poor. Two of the peatlands measured for their topography were domed (5.4 and 5.8 m above the stream), one was gently sloping (1.4 m above the stream), and one was flat and occurred behind a 7 m high levee. Five different peatland vegetation types were detected on the basis of pixel values derived from the satellite image. The peat cores had considerable variation in nutrient content and showed different developmental pathways. In summary, the Pastaza-Maranon basin harbors a considerable diversity of previously undescribed peatland ecosystems, representing a gradient from atmosphere-influenced, nutrient-poor ombrotrophic bogs through to river-influenced, nutrient-rich swamps. Their existence affects the habitat diversity, carbon dynamics, and hydrology of the Amazonian lowlands, and they also provide an undisturbed analog for the heavily disturbed peatlands of Southeast Asia. Considering the factors threatening the Amazonian lowlands, there is an urgent need to investigate and conserve these peatland ecosystems, which may in the near future be among the very few undisturbed tropical ombrotrophic bogs remaining in the world.

Antioxidant profile of strawberry tree honey and its marker homogentisic acid in several models of oxidative stress

The antioxidant activity of several honeys was evaluated considering the different contribution of entire samples. The strawberry tree honey emerged as the richest in total phenols and the most active honey in the DPPH and FRAP tests, and could protect cholesterol against oxidative degradation (140°C). Homogentisic acid (2,5-dihydroxyphenylacetic acid, HGA), the main phenolic compound from strawberry tree honey, showed interesting antioxidant and antiradical activities, and protective effect against thermal-cholesterol degradation, comparable to those of well known antioxidants. Moreover, the pre-treatment with HGA significantly preserved liposomes and LDL from Cu2+-induced oxidative damage at 37°C for 2h, inhibiting the reduction of polyunsaturated fatty acids and cholesterol and the increase of their oxidative products. This phenol had no toxic effect in human intestinal epithelial Caco-2 cells within the concentration range tested (5–1000μM). HGA was able to pass through the Caco-2 monolayers, the apparent permeability coefficients (Papp) in the apical-to-basolateral and basolateral-to-apical direction were 3.48±1.22×10−6 and 2.18±0.34×10−6cm/s, respectively, suggesting a passive diffusion pathway as the dominating process. The results of the work qualify HGA as natural antioxidant, able to exert a significant in vitro protective effect and to contribute to the strawberry tree honey antioxidant activity.

Intra-channel modification of environmentally sensitive poly(N-isopropylacrylamide) hydrogel with polyaniline using interphase synthesis

A new way of preparation of conducting gels by two-phase polymerization is presented. Polyaniline was introduced to the poly(N-isopropylacrylamide) hydrogel channels by filling the hydrogel first with a solution of the oxidazing agent and next placing it in a solution of aniline in nitrobenzene. It has been found, basing on optical, Raman and SEM investigations, that polyaniline was uniformly distributed in the entire gel samples and consisted mainly of emeraldine. The swelling behavior of obtained composite gels, in respect to a change in temperature and ionic strength, was very similar to unmodified poly(N-isopropylacrylamide) hydrogel. The new material appeared to be electroactive and conductive. This new property was a strong function of the swelling ratio. The shrinking process of the composite material considerably enhanced the voltammetric response.

Assessment of Polycyclic Aromatic Hydrocarbons (PAH) and Heavy Metals in the Vicinity of an Oil Refinery in India

Petroleum products are one of the major sources of energy for industry and daily life. Growth of the petroleum industry and shipping of petroleum products has resulted in the pollution. Populations living in the vicinity of oil refinery waste sites may be at greater risk of potential exposure to polycyclic aromatic hydrocarbons (PAH) through inhalation, ingestion, and direct contact with contaminated media. PAH have often been found to coexist with environmental pollutants including heavy metals due to similar pollution sources. The levels and distribution patterns of Σ16 PAH (sum of the 16 PAH) and heavy metals (lead, copper, nickel, cobalt, and chromium) were determined in soil and sediment in the vicinity (5 km radius) of an oil refinery in India. Concentrations of Σ16 PAH in the soils and sediments were found to be 60.36 and 241.23 ppm, respectively. Higher amount of PAH in sediments as compared to soil is due to low water solubility of PAH, settled in the bottom of aquatic bodies. The levels of lead, copper, nickel, cobalt, and chromium (total) in soil were 12.52, 13.52, 18.78, 4.84, and 8.29 ppm, while the concentrations of these metals in sediments were 16.38, 47.88, 50.15, 7.07, and 13.25 ppm, respectively. Molecular diagnostics indices of PAH (Ratio of Phenanthrene/Anthracene, Fluranthene/Pyrene) calculated for soil and sediment samples indicate that the oil refinery environment is contaminated with PAH from petrogenic as well as pyrolytic origin and heavy vehicular traffic on the Agra- Delhi National highway. Sixteen PAH priority pollutants were detected in the United States in entire samples collected near oil refinery areas and concentrations of Σ16 PAH in soil was found to be 1.20 times higher than the threshold value for PAH in soil by ICRCL (Inter-Departmental Committee on the Redevelopment of Contaminated Land). This concentration could lead to disastrous consequences for the biotic and abiotic components of the ecosystem and may affect the soil quality, thus impairing plant growth and its bioaccumulation in food chain.

Shock-induced phase transformation in nanocrystalline iron

The shock-induced phase transformation of nanocrystalline iron with different grain sizes is investigated by using molecular dynamic simulations. The critical shock stress for shock-induced phase transformation (from body-cubic centered α phase into hexagonal-close packed ε phase) of nanocrystalline irons is about 15 GPa. Under shock compression, the nanocrystalline irons first experience elastic deformation, then plastic deformation purely caused by grain boundaries, after that phase transformation nucleated mostly at the grain boundaries, and finally nucleation areas expanding into the entire samples. These processes can be reflected by the stress profile and the particle velocity profile, and also be distinguished by local atomic structures analyses in the corresponding areas. The microstructures of the shocked samples consist of grain boundary and hexagonal-closed packed new phase with the face-cubic centered atoms as the twin boundary. The grain size obviously influences the deformation of grain boundary and the microstructure after shock compression, and turns to change the profiles of stress or velocity. The mechanism is primarily analyzed.

돼지 고기의 아나볼릭 스테로이드가 Myogenic Satellite Cell의 증식과 분화에 미치는 영향

성호르몬은 근육의 발달(아나볼릭 효과)에 관여하는 것으로 잘 알려져 왔으며 인체의 치료제로 넓게 사용되고 있다. 돼지고기에는 주로 성선(정소와 난소)에서 생산되어 고기에 축적된 다양한 아나볼릭 효과를 나타내는 성호르몬이 많이 존재하는 것으로 알려져 있다. 따라서 본 연구는 돼지고기에 존재하는 아나볼릭 스테로이드를 추출하여 근육세포의 증식과 분화에 미치는 영향을 파악하고자 실시하였다. 본 연구에서 돼지의 각 조직으로부터 아나볼릭 스테로이드를 추출하는 3가지 방법(M1, M2, M3)을 개발하였다. 3가지 모든 추출방법에서 아나볼릭 스테로이드가 추출되었으며 특히 M3에서 조직 1g당 가장 많은 양을 획득할 수 있었다. M3를 이용하여 아나볼릭 스테로이드를 추출했을 때 돼지고기의 근육과 지방에서는 스테로이드 호르몬 양이 수컷에서 가장 높았고, 혈청에서는 nandrolone 과 testosterone의 양은 수컷에서 가장 높았으며, estrone와 <TEX>$17{\beta}$</TEX>-estradiol의 양은 비슷하였다. 근육세포 증식은 돼지 아나볼릭 스테로이드의 농도 의존적으로 촉진되었으며, M3에서 가장 빠르게 증식되었다. 근육세포의 분화는 추출된 아나볼릭 스테로이드 처리구가 대조구보다 더 효과적으로 분화가 잘 되는 것을 세포 모양과 유전자(AR, myoD, desmin, myogenin)를 통하여 확인할 수 있었다. 특히 M3에서 추출된 아나볼릭 스테로이드에서 myogenin과 AR 유전자가 유의적으로 높게 발현되었다(p<0.001). 전체적으로 돼지의 아나볼릭 스테로이드는 근육세포의 성장과 분화를 촉진하였다. 따라서 돼지고기에 있는 아나볼릭 스테로이드의 섭취를 통해 인체 근육의 성장과 발달에 긍정적 효과를 나타낼 수 있을 것으로 사료된다. Sex steroids are known to be involved in skeletal muscle development (anabolic effect) and are frequently used in medicines. It has been known that pork contains a variety of steroids that are mainly synthesized in the gonads (testis and ovary). Thus, the present study was conducted to evaluate the effects of anabolic steroids of pork on the proliferation and differentiation of myogenic satellite cells (MSC). Three different methods (M1, M2, and M3) were developed for the isolation and purification of steroids from porcine tissues. Among three extraction methods that we developed, M3 was the best method with respect to the quantities of steroids and the induction of MSC proliferation. Hormonal analysis showed that the steroid hormone levels were the highest in muscle and fat of intact male than those of castrated males and females. In addition, the highest serum levels of nandrolone and testosterone were detected in intact males, whereas estrone and <TEX>$17{\beta}$</TEX>-estradiol levels were similar in the entire experimental serum samples. Expression of androgen receptor (AR), myoD, desmin, and myogenin in bovine muscle cells were significantly up-regulated by the treatment of steroid extracts. The highest increas of myogenin and AR mRNA abundance were observed in the MSCs treated with M3 extract (p<0.001). Altogether, the present research showed the positive effect of steroids on MSC proliferation and differentiation in vitro. These results would certainly imply a beneficial effect of pork consumption on human muscle development.

In vitro characterization of bacteriocin producing Bacillus subtilis from milk samples

Bacillus subtilis was isolated from milk samples. Antibiotic resistance and the antimicrobial activity of B. subtilis were studied. All the four isolates of B. subtilis were sensitive to antibiotics such as streptomycin (25 μg/ml), ampicillin (10 μg/ml), penicillin (10 μg/ml), erythromycin (15 μg/ml), amoxycillin (10 μg/ml).But they were resistant to bacitracin (10 μg/ml). B. subtilis shown antibacterial activity against the selected human pathogens such as Salmonella spp, Streptococcus spp, Klebsiellaspp and E. coli. The antimicrobial substance from B. subtilis extracted with organic solvent such as ethyl actetate have also shown antibacterial activity against the human pathogens. The proteineceaous nature of the B. subtilis exerted antimicrobial activity. The amount of protein varied between 0.05 - 0.55 mg/ml and the protein was qualitatively analyzed by SDS-PAGE. The entire samples have shown peptide < 62 kDa. Key words: Bacillus subtilis, antibiotics, Salmonella spp, human pathogens, ethyl acetate, SDS PAGE.

Quarry identification of historical building materials by means of laser induced breakdown spectroscopy, X-ray fluorescence and chemometric analysis

To characterize historical building materials according to the geographic origin of the quarries from which they have been mined, the relative content of major and trace elements were determined by means of Laser Induced Breakdown Spectroscopy (LIBS) and X-ray Fluorescence (XRF) techniques. 48 different specimens were studied and the entire samples' set was divided in two different groups: the first, used as reference set, was composed by samples mined from eight different quarries located in Seville province; the second group was composed by specimens of unknown provenance collected in several historical buildings and churches in the city of Seville. Data reduction and analysis on laser induced breakdown spectroscopy and X-ray fluorescence measurements was performed using multivariate statistical approach, namely the Linear Discriminant Analysis (LDA), Principal Component Analysis (PCA) and Soft Independent Modeling of Class Analogy (SIMCA). A clear separation among reference sample materials mined from different quarries was observed in Principal Components (PC) score plots, then a supervised soft independent modeling of class analogy classification was trained and run, aiming to assess the provenance of unknown samples according to their elemental content. The obtained results were compared with the provenance assignments made on the basis of petrographical description. This work gives experimental evidence that laser induced breakdown spectroscopy measurements on a relatively small set of elements is a fast and effective method for the purpose of origin identification.

Histological and biomechanical study of dura mater applied to the technique of dura splitting decompression in Chiari type I malformation

Many techniques are described to treat Chiari type I malformation. One of them is a splitting of the dura, removing its outer layer only to reduce the risks of cerebrospinal fluid (CSF) leak. We try to show the effectiveness of this technique from histological and biomechanical observations of dura mater. Study was performed on 25 posterior fossa dura mater specimens from fresh human cadavers. Dural composition and architecture was assessed on 47 transversal and sagittal sections. Uniaxial mechanical tests were performed on 22 dural samples (15 entire, 7 split) to focus on the dural macroscopic mechanical behavior comparing entire and split samples and also to understand deformation mechanisms. We finally created a model of volume expansion after splitting. Dura mater was composed of predominant collagen fibers with a few elastin fibers, cranio-caudally orientated. The classical description of two distinct layers remained inconstant. Biomechanical tests showed a significant difference between entire dura, which presents an elastic fragile behavior, with a small domain where deformation is reversible with stress, and split dura, which presents an elasto-plastic behavior with a large domain of permanent strain and a lower stress level. From these experimental results, the model showed a volume increase of approximately 50% below the split area. We demonstrated the capability of the split dura mater to enlarge for suitable stress conditions and we quantified it by biomechanical tests and experimental model. Thus, dural splitting decompression seems to have a real biomechanical substrate to envision the efficacy of this Chiari type I malformation surgical technique.

NCBI Peptidome: a new repository for mass spectrometry proteomics data

Peptidome is a public repository that archives and freely distributes tandem mass spectrometry peptide and protein identification data generated by the scientific community. Data from all stages of a mass spectrometry experiment are captured, including original mass spectra files, experimental metadata and conclusion-level results. The submission process is facilitated through acceptance of data in commonly used open formats, and all submissions undergo syntactic validation and curation in an effort to uphold data integrity and quality. Peptidome is not restricted to specific organisms, instruments or experiment types; data from any tandem mass spectrometry experiment from any species are accepted. In addition to data storage, web-based interfaces are available to help users query, browse and explore individual peptides, proteins or entire Samples and Studies. Results are integrated and linked with other NCBI resources to ensure dissemination of the information beyond the mass spectroscopy proteomics community. Peptidome is freely accessible at http://www.ncbi.nlm.nih.gov/peptidome.

“Pyramiding: Efficient search for rare subjects”

The need to economically identify rare subjects within large, poorly mapped search spaces is a frequently encountered problem for social scientists and managers. It is notoriously difficult, for example, to identify “the best new CEO for our company,” or the “best three lead users to participate in our product development project.” Mass screening of entire populations or samples becomes steadily more expensive as the number of acceptable solutions within the search space becomes rarer. The search strategy of “pyramiding” is a potential solution to this problem under many conditions. Pyramiding is a search process based upon the idea that people with a strong interest in a topic or field tend to know people more expert than themselves. In this paper we report upon four experiments empirically exploring the efficiency of pyramiding searches relative to mass screening. We find that pyramiding on average identified the most expert individual in a group on a specific topic with only 28.4% of the group interviewed – a great efficiency gain relative to mass screening. Further, pyramiding identified one of the top 3 experts in a population after interviewing only 15.9% of the group on average. We discuss conditions under which the pyramiding search method is likely to be efficient relative to screening.