Metal nanoparticles for microscopy and spectroscopy

Metal nanoparticles interact strongly with light due to a resonant response of their free electrons. These ‘plasmon’ resonances appear as very strong extinction and scattering for particular wavelengths, and result in high enhancements of the local field compared to the incident electric field. In this chapter we introduce the reader to the optical properties of single plasmon particles as well as finite clusters and periodic lattices, and discuss several applications

The XMM-Newton serendipitous survey - II. First results from the AXIS high galactic latitude medium sensitivity survey

We present the first results on the identifications of a medium sensitivity survey (X-ray flux limit 2 x 10(-14) erg cm(-2) s(-1) in the 0.5-4.5 keV band) at high galactic latitude (\b\ > 20degrees) carried out with the XMM-Newton X-ray observatory within the AXIS observing programme. This study is being conducted as part of the XMM-Newton Survey Science Centre activities towards the identification of the sources in the X-ray serendipitous sky survey. The sample contains 29 X-ray sources in a solid angle of 0.26 deg(2) (source density 113 +/- 21 sources deg(-2)), out of which 27 (93%) have been identified. The majority of the sources are broad-line AGN (19), followed by narrow emission line X-ray emitting galaxies (6, all of which turn out to be AGN), 1 nearby non-emission line galaxy (NGC 4291) and 1 active coronal star. Among the identified sources we find 2 broad-absorption line QSOs (z similar to 1.8 and z similar to 1.9), which constitute similar to10% of the AGN population at this flux level, similar to optically selected samples. Identifications of a further 10 X-ray sources fainter than our survey limit are also presented

Towards the clinical implementation of pharmacogenetics in bipolar disorder.

BackgroundBipolar disorder (BD) is a psychiatric illness defined by pathological alterations between the mood states of mania and depression, causing disability, imposing healthcare costs and elevating the risk of suicide. Although effective treatments for BD exist, variability in outcomes leads to a large number of treatment failures, typically followed by a trial and error process of medication switches that can take years. Pharmacogenetic testing (PGT), by tailoring drug choice to an individual, may personalize and expedite treatment so as to identify more rapidly medications well suited to individual BD patients.DiscussionA number of associations have been made in BD between medication response phenotypes and specific genetic markers. However, to date clinical adoption of PGT has been limited, often citing questions that must be answered before it can be widely utilized. These include: What are the requirements of supporting evidence? How large is a clinically relevant effect? What degree of specificity and sensitivity are required? Does a given marker influence decision making and have clinical utility? In many cases, the answers to these questions remain unknown, and ultimately, the question of whether PGT is valid and useful must be determined empirically. Towards this aim, we have reviewed the literature and selected drug-genotype associations with the strongest evidence for utility in BD.SummaryBased upon these findings, we propose a preliminary panel for use in PGT, and a method by which the results of a PGT panel can be integrated for clinical interpretation. Finally, we argue that based on the sufficiency of accumulated evidence, PGT implementation studies are now warranted. We propose and discuss the design for a randomized clinical trial to test the use of PGT in the treatment of BD

The ROSAT International X-ray/Optical Survey (RIXOS): source catalogue

We describe the ROSAT International X-ray/Optical Survey (RIXOS), a medium-sensitivity survey and optical identification of X-ray sources discovered in ROSAT high Galactic latitude fields (|b|>28°) and observed with the Position Sensitive Proportional Counter (PSPC) detector. The survey made use of the central 17 arcmin of each ROSAT field. A flux limit of 3×10−14 erg cm−2 s−1 (0.5–2 keV) was adopted for the survey, and a minimum exposure time of 8000 s was required for qualifying ROSAT observations. X-ray sources in the survey are therefore substantially above the detection threshold of each field used, and many contain enough counts to allow the X-ray spectral slope to be estimated. Spectroscopic observations of potential counterparts were obtained of all sources down to the survey limit in 64 fields, totalling a sky area of 15.77 deg2. Positive optical identifications are made for 94 per cent of the 296 sources thus examined. A further 18 fields (4.44 deg2), containing 105 sources above the 3×10−14 erg cm−2 s−1 survey limit, are completely optically identified to a higher flux of 8×10−14 erg cm−2 s−1 (0.5–2 keV). Optical spectroscopic data are supplemented by deep CCD imaging of many sources to reveal the morphology of the optical counterparts, and objects too faint to register on Sky Survey plates. The faintest optical counterparts have R∼22. This paper describes the survey method, and presents a catalogue of the RIXOS sources and their optical identifications. Finding charts based on Sky Survey data are given for each source, supplemented by CCD imaging where necessary

Adherence to Antiretroviral Treatment and Correlation with Risk of Hospitalization among Commercially Insured HIV Patients in the United States

Purpose: A lower daily pill burden may improve adherence to antiretroviral treatment (ART) and clinical outcomes in patients with human immunodeficiency virus (HIV). This study assessed differences in adherence using the number of pills taken per day, and evaluated how adherence correlated with hospitalization. Methodology: Commercially insured patients in the LifeLink database with an HIV diagnosis (International Classification of Diseases, 9th Revision, Clinical Modification code 042.xx) between 6/1/2006 and 12/31/2008 and receipt of a complete ART regimen were selected for inclusion. Patients were grouped according to their daily pill count and remained on ART for at least 60 days. Outcomes included adherence and rates of hospitalization. Adherence was measured as the proportion of days between the start and end of the regimen in which the patient maintained supply of all initiated ART components. Logistic regressions assessed the relationship between pills per day, adherence, and hospitalization, controlling for demographics, comorbidities, and ART-naïve (vs. experienced) status. Results: 7,073 patients met the study inclusion criteria, and 33.4%, 5.8%, and 60.8 % received an ART regimen comprising one, two, or three or more pills per day, respectively. Regression analysis showed patients receiving a single pill per day were significantly more likely to reach a 95 % adherence threshold versus patients receiving three or more pills per day (odds ratio [OR] = 1.59; P,0.001). Regardless of the number of pills received per day, patients were over 40 % less likely to have

Prediction of susceptibility to major depression by a model of interactions of multiple functional genetic variants and environmental factors

Major depressive disorder (MDD) is the most common psychiatric disorder and the second overall cause of disability. Even though a significant amount of the variance in the MDD phenotype is explained by inheritance, specific genetic variants conferring susceptibility to MDD explain only a minimal proportion of MDD causality. Moreover, genome-wide association studies have only identified two small-sized effect loci that reach genome-wide significance. In this study, a group of Mexican-American patients with MDD and controls recruited for a pharmacogenetic study were genotyped for nonsynonymous single-nucleotide polymorphisms (nsSNPs) and used to explore the interactions of multiple functional genetic variants with risk-classification tree analysis. The risk-classification tree analysis model and linkage disequilibrium blocks were used to replicate exploratory findings in the database of genotypes and phenotypes (dbGaP) for major depression, and pathway analysis was performed to explore potential biological mechanisms using the branching events. In exploratory analyses, we found that risk-classification tree analysis, using 15 nsSNPs that had a nominal association with MDD diagnosis, identified multiple increased-MDD genotype clusters and significant additive interactions in combinations of genotype variants that were significantly associated with MDD. The results in the dbGaP for major depression disclosed a multidimensional dependent phenotype constituted of MDD plus significant modifiers (smoking, marriage status, age, alcohol abuse/dependence and gender), which then was used for the association tree analysis. The reconstructed tree analysis for the dbGaP data showed robust reliability and replicated most of the genes involved in the branching process found in our exploratory analyses. Pathway analysis using all six major events of branching (PSMD9, HSD3B1, BDNF, GHRHR, PDE6C and PDLIM5) was significant for positive regulation of cellular and biological processes that are relevant to growth and organ development. Our findings not only provide important insights into the biological pathways underlying innate susceptibility to MDD but also offer a predictive framework based on interactions of multiple functional genetic variants and environmental factors. These findings identify novel targets for therapeutics and for translation into preventive, clinical and personalized health care

Comparison of tonic spinal cord stimulation, high-frequency and burst stimulation in patients with complex regional pain syndrome: a double-blind, randomised placebo controlled trial

BACKGROUND: Complex Regional Pain Syndrome (CRPS) is a disabling disease that is sometimes difficult to treat. Although spinal cord stimulation (SCS) can reduce pain in most patients with CRPS, some do not achieve the desired reduction in pain. Moreover, the pain reduction can diminish over time even after an initially successful period of SCS. Pain reduction can be regained by increasing the SCS frequency, but this has not been investigated in a prospective trial. This study compares pain reduction using five SCS frequencies (standard 40 Hz, 500 Hz, 1200 Hz, burst and placebo stimulation) in patients with CRPS to determine which of the modalities is most effective. DESIGN: All patients with a confirmed CRPS diagnosis that have unsuccessfully tried all other therapies and are eligible for SCS, can enroll in this trial (primary implantation group). CRPS patients that already receive SCS therapy, or those previously treated with SCS but with loss of therapeutic effect over time, can also participate (re-implantation group). Once all inclusion criteria are met and written informed consent obtained, patients will undergo a baseline assessment (T0). A 2-week trial with SCS is performed and, if successful, a rechargeable internal pulse generator (IPG) is implanted. For the following 3 months the patient will have standard 40 Hz stimulation therapy before a follow-up assessment (T1) is performed. Those who have completed the T1 assessment will enroll in a 10-week crossover period in which the five SCS frequencies are tested in five periods, each frequency lasting for 2 weeks. At the end of the crossover period, the patient will choose which frequency is to be used for stimulation for an additional 3 months, until the T2 assessment. DISCUSSION: Currently no trials are available that systematically investigate the importance of variation in frequency during SCS in patients with CRPS. Data from this trial will provide better insight as to whether SCS with a higher frequency, or with burst stimulation, results in more effective pain relief. TRIAL REGISTRATION: Current Controlled Trials ISRCTN3665525

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal