JOURNAL OF FOOD SAFETY, Issue 1 2003
C.L. ERIKSSON DE REZENDE
ABSTRACT Biofilms enable foodborne pathogens to resist removal from surfaces, survive disinfection and elude detection. This study evaluated the use of Calcofluor, which binds to polysaccharides containing ,-D-glucans, to detect biofilms produced by Salmonella enterica serovar Berta and Salmonella enterica serovar Typhimurium DT104 (St DT104), Escherichia coli, Aeromonas hydrophila, Vibrio cholerae O139 and Hyphomonas adhaerens. Biofilms produced by St DT104, S. berta and V. cholerae on five types of surfaces (glass, polypropylene, TeflonÔ, stainless steel and aluminum) were detected by Calcofluor. Results suggest the potential use of Calcofluor as probes of foodborne pathogens in biofilms. [source]

INTER- AND INTRASPECIFIC VARIATION OF THE PSEUDO-NITZSCHIA DELICATISSIMA COMPLEX (BACILLARIOPHYCEAE) ILLUSTRATED BY RRNA PROBES, MORPHOLOGICAL DATA AND PHYLOGENETIC ANALYSES,

JOURNAL OF PHYCOLOGY, Issue 2 2006
Nina Lundholm
A study of 25 cultures tentatively identified as Pseudo-nitzschia delicatissima (Cleve) Heiden, and originating from geographically widely distributed locations, showed both morphological and genetic variation among strains. Use of rRNA-targeted DNA probes on 17 different strains showed large variation in the hybridization patterns. Detailed morphological studies placed the isolates into three groups. The sample on which the neotype of P. delicatissima is based was also examined, and used to establish the morphological identity of P. delicatissima. Phylogenetic analyses of 16 strains, based on sequences of internal transcriber spacer 1 (ITS1), 5.8S and ITS2 of the nuclear-encoded rDNA, supported the morphological observations and the hybridization studies, and revealed large genetic variation among strains. A combination of the morphological and molecular findings resulted in the description of two new species, P. decipiens sp. nov. and P. dolorosa sp. nov. P. dolorosa has a mixture of one or two rows of poroids in the striae whereas P. delicatissima always has two rows. In addition, P. dolorosa has wider valves and a lower density of poroids. P. decipiens differs from P. delicatissima by a higher density of striae on the valve face as well as a higher density of poroids on the girdle bands. Among the strains referred to P. delicatissima, an epitype was selected. Large genetic variation was found among the P. delicatissima strains and a subdivision into two major clades represent cryptic species. [source]

rRNA PROBES FOR IDENTIFICATION AND CHARACTERIZATION OF MARINE PHYTOPLANKTON: THEIR POTENTIAL APPLICATION FOR DNA MICROCHIPS

JOURNAL OF PHYCOLOGY, Issue 2001
Article first published online: 24 SEP 200
Groben R., Lange, M. & Medlin, L. K. Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven, Germany A fast and reliable identification of nano- and picoplankton by light microscopy is often difficult because of the lack of usable morphological characteristics, whereas electron microscopy and biochemical methods are very time consuming. Identification of toxic algae also requires a great deal of taxonomic experrtise so that false positives are not recorded. One solution is to use taxon specific rRNA probes. For this purpose we designed probes for phytoplankton taxa, including toxic algae. These probes were either labelled with Digoxigenin (DIG) and used in DNA dot blot experiments, or labelled with fluorochromes and used in whole-cell hybridisations with fluorescence microscopy or flow cytometric detection. Specific probes could be used over a broad taxonomic range from higher groups (i.e. the class of dinoflagellates) to species level (i.e. Prorocentrum lima). These probes were be used in the EU MAST project AIMS for the development of an automated identification system for marine phytoplankton in combination with flow cytometry and artificial neural networks (ANNs), in the EU MAST DETAL and in the German national project (TEPS) for the development of an early warning system for harmful algal blooms. Results using Digoxigenin (DIG)-labelled probes on picoplankton samples taken from several water bodies indicate that hierarchial re-probing of spotted samples can be achieved and this suggests that probes can be adapted to DNA microchips. Preliminary field results for a hand-held DNA microchip reader are presented. This work was supported by the German BMBF TEPS 03F0161 and the EU AIMS MAS3-CT97-0080 and EU DETAL Q5RS-2000-30778 projects. [source]

Simultaneous Measurements of Ion Temperature by Segmented Tunnel and Katsumata Probe

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-7 2008
J. Adámek
Abstract Simultaneous measurements of the ion temperature by the segmented tunnel and Katsumata probe in the CASTOR tokamak are reported. The segmented tunnel probe measures two ion saturation currents Iseg 1, Iseg 2 towards two segments of the tunnel. The axis of the tunnel is aligned with the total magnetic field. The value of the ratio of these two currents combined with the results of the PIC modeling provides the ion temperature. Design and experimental arrangement of the Katsumata probe enable us to measure the pure ion current by sweeping the applied voltage. The ion temperature is then estimated from the exponential part of the measured I , V characteristic. Simultaneous measurements of the ion temperature by the segmented tunnel and Katsumata probe agree within a few eV. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

A Phenomenological Probe Model of Fast Ion Measurement Using a Hybrid Directional Probe

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-7 2008
K. Nagaoka
Abstract A phenomenological probe model was developed for quantitative fast-ion-measurement using a hybrid directional probe (HDP), which is a directional probe to measure ion current and heat flux at the same position. The secondary electrons due to fast-ion-injection onto the probe surface enhances the ion-saturation-current, thus a thermal probe method was required for quantitative measurement of fast ions. The model gives a simple expression of the secondary electron yield as a function of ion currents and heat fluxes measured by the HDP, and can determine the net fast-ion-current without the calibrations of the thermal probe method. The model was applied to the experimental results of fast-ion-measurements using a HDP in CHS, and the secondary electron yield obtained by the model agrees with the calibration results of the HDP. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Comparison of Langmuir Probe and Laser Thomson Scattering Methods in the Electron Temperature Measurement in Divertor Simulator MAP-II

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2006
A. Okamoto
Abstract In order to investigate details of anomaly in the Langmuir probe current (I)-voltage (V) characteristics, electron temperatures and densities are measured by both Langmuir probe and laser Thomson scattering methods. The electron densities measured with both methods show good agreement in hydrogen-molecular assisted recombination (H2 -MAR) plasmas. On the other hand, the electron temperatures measured with Langmuir probe are overestimated compared with that obtained from the Thomson scattering spectrum in the H2 -MAR plasmas. Histogram of electron current deviated from its average shows that fluctuation appeared in the electron current becomes large and the histogram distorted in temperature-overestimated condition, especially when the probe voltage is negatively biased. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Measurements of Directional Flow Using a Directional Langmuir Probe in Weakly Magnetized Plasmas

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2006
T. Shikama
Abstract Measurement of flow directed with respect to the magnetic field is performed using a directional Langmuir probe (DLP). A previously proposed practical formula for measurement of the Mach number under a weakly magnetized condition is modified for application to the directional flow field which consists of parallel and azimuthal flow components. The effect of density gradient caused by the rotational DLP measurement in the measurement of the radial profile of ion current angular distribution is modified. For the verification of the DLP measurement, parallel flow velocity is measured from the Doppler shift of HeII emission, while azimuthal flow velocity is calculated from E × B and diamagnetic drifts. It is revealed that this method provides plausible Mach numbers in the parallel and azimuthal directions with inclusion of the effect of density gradient. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Physical properties of Dy and La doped SnO2 thin films prepared by a cost effective vapour deposition technique

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006
J. Joseph
Abstract Stannous oxide (SnO2) thin film is one of the most widely used n-type transparent semi-conductor films in electronics, electro-optics and solar energy conversion. By achieving controlled non-stoichiometry, we can get good transparency and high electrical conductivity simultaneously in SnO2 thin films. Dy and La doped SnO2 thin films have been prepared by a cost effective vapour deposition technique. The structural, photo-electronic, optical and electrical properties of the doped and undoped films were studied. The results of X-ray Diffraction studies reveals the polycrystalline nature of the films with preferential orientation along the (101), (211) and (301) planes and their average grain size variation for different deposition temperature. Photoconductivity and Photovoltaic studies of the films were also performed. The optical properties of these films were studied by measuring their optical transmission as a function of wavelength. The optical transmission is found to be increased on Dy doping and decreased on La doping. The band gap, refractive index and thickness of the films were calculated from U-V transmittance and Absorption graphs. The optical band gap of undoped film is found to be 4.08 eV, but on doping it shifts to lower energies and then increases on increasing the concentration of both dopants. Its electrical parameters such as sheet resistance, resistivity, mobility, Hall coefficient, and carrier concentration were determined by Four Probe, Van der Pauw and Hall Probe method. On doping with Dy, carrier conversion takes place from n-type to p-type and p-conductivity dominates. On La doping no carrier conversion takes place but resistivity decreases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Newly Developed Ultrasonic Probe With Ropeway System for Transpapillary Intraductal Ultrasonography of the Bilio,Pancreatic Ductal System

DIGESTIVE ENDOSCOPY, Issue 3 2000
Naotaka Fujita
Background: Intraductal ultrasonography of the bile/pancreatic duct using a thin-caliber ultrasonic probe (IDUS) provides excellent images of these ducts and the surrounding structures. Insertion of the device through the papilla of Vater is essential to carry out this examination. We developed a new probe with a ropeway system (XUM5RG-29R; Olympus, Tokyo) for transpapillary IDUS. Its usefulness such as ease of application and safety were prospectively evaluated. Patients and methods: During the period of October 1997 to April 1998, transpapillary IDUS using the probe was performed in 194 patients at seven medical institutions. The success rates of insertion of the probe into the bile/pancreatic duct, observation of the area of interest, and the incidence of complications were evaluated. Results: Passage of the probe through the papilla was successful without difficulty in all the patients. Successful introduction of the probe into the pancreatic duct, bile duct and both of the ducts was achieved in 98.4, 100 and 85% of the patients, respectively. Once the probe was introduced into the aimed duct, it was possible to obtain IDUS images of the area of interest in all but five patients. Mild acute pancreatitis developed in eight patients (4.1%), all of whom recovered with conservative therapy only. Conclusions: It is possible to introduce the new ultrasonic probe into the desired duct once a guide wire has been inserted. This type of ultrasonic probe is quite useful when performing transpapillary IDUS of the bile and/or pancreatic duct. [source]

Rapid detection and identification of counterfeit of adulterated products of synthetic phosphodiesterase type-5 inhibitors with an atmospheric solids analysis probe

DRUG TESTING AND ANALYSIS, Issue 2 2010
Marian Twohig
Abstract The market success of the three approved synthetic phosphodiesterase type-5 (PDE-5) inhibitors for the treatment of erectile dysfunction has led to an explosion in counterfeit versions of these drugs. In parallel a large market has developed for herbal products claimed to be natural alternatives to these synthetic drugs. The herbal products are heavily advertised on the internet and are freely available to purchase without prescription. Furthermore, adulteration of these supposed natural medicines is a very common and serious phenomenon. Recent reports have shown that the adulteration has extended to the analogues of the three approved synthetic PDE-5 inhibitors. An Atmospheric Solids Analysis Probe (ASAP) was used for the direct analysis of the counterfeit pharmaceuticals and herbal products. Using the ASAP combined with time-of-flight mass spectrometry (TOF MS) it was possible to detect fraudulent counterfeit tablets. The physical appearance of the pills resembled the pills from the original manufacturer but contained the wrong active pharmaceutical ingredient (API). Detecting adulteration for five herbal supplements marketed as natural alternatives to PDE-5 inhibitors was also possible using the ASAP. Three types of adulteration were found in the five samples: adulteration with tadalafil or sildenafil, mixed adulteration (tadalafil and sildenafil), and adulteration with analogues of these drugs. Copyright © 2010 John Wiley & Sons, Ltd. [source]

A Contactless Impedance Probe for Simple and Rapid Determination of the Ratio of Liquids with Different Permittivities in Binary Mixtures

ELECTROANALYSIS, Issue 1 2009
Franti, ek Opekar
Abstract Simple contactless cells with planar or tubular electrodes have been designed for measurement of the permittivity of solutions. The cells, connected to an integrated circuit of astable multivibrator, respond primarily to the capacitance component of the cell impedance, the multivibrator frequency depends in a defined manner on the solution permittivity and is readily used as the analytical signal in determinations of the ratios of components in binary liquid mixtures; water solution of methanol, ethanol and dioxane have been tested. The response of the cell with planar electrodes satisfies well the simple theoretical model and both the cells provide results with a sufficient sensitivity, a low LOD value (units of %vol) and a good precision (around 1%rel). The cell simplicity, small dimensions, long-term stability and the possibility of powering them from a battery make them suitable for hand-held meters. As an example of application in practice, the content of ethanol was determined in the car fuel petrol. [source]

Electrochemical Biosensor for the Detection of Interaction Between Arsenic Trioxide and DNA Based on Guanine Signal

ELECTROANALYSIS, Issue 7 2003
Mehmet Ozsoz
Abstract The interaction of arsenic trioxide (As2O3) with calf thymus double-stranded DNA (dsDNA), calf thymus single-stranded DNA (ssDNA) and also 17-mer short oligonucleotide (Probe,A) was studied electrochemically by using differential pulse voltammetry (DPV) with carbon paste electrode (CPE) at the surface and also in solution. Potentiometric stripping analysis (PSA) was employed to monitor the interaction of As2O3 with dsDNA in solution phase by using a renewable pencil graphite electrode (PGE). The changes in the experimental parameters such as the concentration of As2O3, and the accumulation time of As2O3 were studied by using DPV; in addition, the reproducibility data for the interaction between DNA and As2O3 was determined by using both electrochemical techniques. After the interaction of As2O3 with dsDNA, the DPV signal of guanine was found to be decreasing when the accumulation time and the concentration of As2O3 were increased. Similar DPV results were also found with ssDNA and oligonucleotide. PSA results observed at a low DNA concentration such as 1,ppm and a different working electrode such as PGE showed that there could be damage to guanine bases. The partition coefficients of As2O3 after interaction with dsDNA and ssDNA in solution by using CPE were calculated. Similarly, the partition coefficients (PC) of As2O3 after interaction with dsDNA in solution was also calculated by PSA at PGE. The features of this proposed method for the detection of DNA damage by As2O3 are discussed and compared with those methods previously reported for the other type of DNA targeted agents in the literature. [source]

The C-4 Configuration as a Probe for the Study of Glycosidation Reactions

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2004
Anne Bülow
Abstract The difference in the electron-withdrawing powers of axial and equatorial OBn was used as a probe to investigate the glycosidation reaction. The reactivity of perbenzylated glucosyl and galactosyl donors were compared under a range of glycosidation conditions that involved variations in catalyst, solvent, and glycosyl acceptor. Generally, the galactosyl donor had a reactivity four to five times higher than the glucosyl donor, which is in accord with the transition state having positive character. In certain cases, however, particularly when triflate was present, equal reactivity of glucosyl and galactosyl donors were found. The results are explained in terms of changes in the rate-determining steps. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

A Highly Sensitive Hybrid Colorimetric and Fluorometric Molecular Probe for Cyanide Sensing Based on a Subphthalocyanine Dye,

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2006
E. Palomares
Abstract A highly sensitive, selective colorimetric and fluorometric molecular probe based on a subphthalocyanine dye has been developed for cyanide-anion determination in aqueous solution. It has also been shown that a carboxysubphthalocyanine derivative can be covalently anchored to transparent mesoporous nanocrystalline high-surface-area metal oxide films to detect low concentrations of cyanide anion in pure water with no interference from other anionic or cationic species. [source]

The Use of Terahertz Spectroscopy as a Sensitive Probe in Discriminating the Electronic Properties of Structurally Similar Multi-Walled Carbon Nanotubes

ADVANCED MATERIALS, Issue 38-39 2009
Edward P. J. Parrott
Terahertz spectroscopy is used to definitively distinguish between two multiwalled carbon nanotubes (see figure), which have commercial applications in a number of advanced materials. Other techniques do not provide a sensitive discrimination of the measured properties. This observation is rationalized by considering the dielectric nature of the materials and the relationship of this to their structural differences. [source]

SensLED: An Electro-Optical Active Probe for Oxygen Determination

ADVANCED MATERIALS, Issue 34 2009
Stefan Sax
A novel concept for an electro-optical active gas probe capable of oxygen detection is presented. Based on a modified organic light-emitting device, we demonstrate that a reversible analyte,indicator interaction can be used for analyte determination. [source]

A "Nanoprism" Probe for Nano-optical Applications

ADVANCED MATERIALS, Issue 12 2009
Taekyeong Kim
"Nanoprism" probes are fabricated for nano-optical applications. The fabrication process is scalable for mass-production, and can be used to prepare nanoprobes terminated with virtually any nanostructure, such as nanoprisms, ZnO nanorods, and nanoparticles. ANSOM imaging was performed on a nanoparticle using Au-nanoprism probes, revealing field localization at the vertices of the nanoprism. [source]

Probe compensated single feed circularly polarized fractal-shaped microstrip antennas

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2009
P. Nageswara Rao
Abstract A single feed circularly polarized fractal boundary microstrip antenna with improved axial ratio bandwidth is presented. The low-axial ratio bandwidth of single feed circularly polarized microstrip antenna is due to its probe reactance. In this article, the inherent disadvantage of this low-AR bandwidth is overcome by compensating the probe reactance by incorporating capacitance in the form of small patch between the radiating patch and the probe. The perturbation of the patch is done using fractal curve as boundary. The proposed antenna exhibits impedance and axial ratio bandwidths of 9 and 2.2% respectively at 2.4 GHz. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source]

Integrated Microwave and Optical Scanning Probe for Magnetic Resonance Imaging

ISRAEL JOURNAL OF CHEMISTRY, Issue 1 2008
Fadi Sakran
We demonstrate a scanning microwave near-field probe based on a slit aperture that is capable of performing spatially-resolved magnetic resonance measurements in the frequency range of 3,90 GHz. We demonstrate local electron spin resonance (ESR), ferromagnetic resonance (FMR), and spin-wave resonance (SWR) studies on model materials. The probe can serve as a local contactless heater as well. We demonstrate also a further application, a dual microwave/optical near-field probe that can be useful in contactless measurements of photoconductivity and fluorescence under microwave irradiation. [source]

In-line analysis of a fluid bed pellet coating process using a combination of near infrared and Raman spectroscopy

JOURNAL OF CHEMOMETRICS, Issue 7-8 2010
Andrey Bogomolov
Abstract Near infrared (NIR) and Raman spectroscopic analyzers applied through an immersion Lighthouse Probe (LHP) were used for simultaneous in-line monitoring of a fluid bed pellet coating process. Multivariate curve resolution analysis of data, collected from four pilot-scale batches, has shown that the two techniques deliver complementary information about the process and their combination may be synergistic. This data analysis enabled a much better understanding of some of the process observations and also gave some interesting insights into the best way to use the techniques themselves. PLS regression analysis of the product moisture and the quantity of coating material sprayed was performed using NIR and Raman data blocks both separately and in combination. The performance of method combination compared to individual techniques is analyzed and discussed. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Verfahren zur vollständigen Ermittlung der R-Abhängigkeit des Rissausbreitungsverhaltens mit nur einer Probe,

MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 9 2007
A. Tesch Dr.
fatigue crack growth; Kmax -tests; threshold; Al 2524-T351 Abstract Ein neues Prüfungskonzept für Ermüdungsrisswachstumsversuche ermöglicht es mit nur einer Probe für den gesamten Bereich des Spannungsverhältnisses von R = 0,9 bis R = -1 Ermüdungsrisswachstumskurven (da/dN-,K-Kurven) für jedes beliebige R-Verhältnis zu erstellen. Zusätzlich erhält man auch die Schwellenwerte der Spannungsintensitätsschwingbreite ,Kth als Funktion von R und Kmax. In Kombination mit einer Methode zur kontinuierlichen Risslängenbestimmung, wie der Gleichstrompotenzialmethode, erfordert dieses Verfahren sehr geringen Personal- und Zeitaufwand. Das Prüfungskonzept besteht aus einer Aneinanderreihung von Kmax -konstant-Versuchen. Da die Kmax -Werte stufenweise ansteigen, sollte es bei diesem Verfahren keine Lastfolgeeffekte geben. Die ermittelten Daten stimmen sehr gut mit Ergebnissen aus da/dN-,K-Versuchen, die nach der ASTM Norm E 647 mit mehreren Proben durchgeführten wurden, überein. Die Versuche erfüllen alle Bedingungen der ASTM E 647. Procedure for the determination of the complete R-dependency of the crack growth behaviour with only one specimen A new concept for fatigue crack propagation tests has been developed. Using a single specimen, it is possible to determine fatigue crack growth curves (da/dN - ,K) for every stress ratio between R = 0.9 and R = -1. Additionally, the new concept also provides threshold values for fatigue crack growth for different values of R and Kmax. In combination with a continuous crack length measurement tool (such as the DC potential drop method) this testing procedure can be performed with minimal effort of personnel and time. The test procedure consists of a sequence of Kmax -constant tests with decreasing crack growth rates. As the applied Kmax is increasing stepwise there should be no load history effects. According to the procedures described in the ASTM Standard E 647, the results using this new testing procedure fit very well to the da/dN - ,K curves generated with different specimens. The tests also fulfil all the requirements of ASTM Standard E 647. [source]

Measurement of Muscle Microvascular Oxygen Pressures: Compartmentalization of Phosphorescent Probe

MICROCIRCULATION, Issue 4 2004
DAVID C. POOLE
Objective: To determine whether the phosphorescent probe Oxyphor R2 (a palladium porphyrin dendrimer) becomes extravasated within normotensive skeletal muscle, R2 perfusion and washout studies were performed using a perfused rat hindlimb preparation. Methods: Phosphorescence signals were monitored in tibialis anterior muscles after 35 min of R2 blood perfusion and across a subsequent washout period that included vasodilation (sodium nitroprusside, SNP, ,3 × 10,2 M). Results: Two responses were evident: Group 1 (n = 4),Inflowing blood pressure and vascular conductance remained stable close to initial values and subsequently a marked vasodilation was evident with SNP (vascular conductance; R2 blood perfusion, 0.096 ± 0.005; washout, pre-SNP, 0.085 ± 0.005, post-SNP, 0.110 ± 0.005 mL/min/mmHg, p < .05, for pre- vs. post-SNP). Baseline phosphorescence signals could be monitored up to 99 ± 36 s post-SNP when the phosphorescence signal disappeared. For these muscles, palladium content was undetectable. Group 2 (n = 3),Inflowing blood pressure increased 112% and vascular conductance fell , 50%. These hindlimbs were unresponsive to SNP, phosphorescence signal was undiminished by washout and SNP, and muscles became edematous. Conclusions: These results suggest that in normotensive muscle (i.e., Group 1 above), extravasation of phosphorescent probe R2 over 35 min of perfusion is insufficient to yield a detectable phosphorescence signal in skeletal muscle. [source]

Cosmic flows on 100 h,1 Mpc scales: standardized minimum variance bulk flow, shear and octupole moments

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2010
Hume A. Feldman
ABSTRACT The low-order moments, such as the bulk flow and shear, of the large-scale peculiar velocity field are sensitive probes of the matter density fluctuations on very large scales. In practice, however, peculiar velocity surveys are usually sparse and noisy, which can lead to the aliasing of small-scale power into what is meant to be a probe of the largest scales. Previously, we developed an optimal ,minimum variance' (MV) weighting scheme, designed to overcome this problem by minimizing the difference between the measured bulk flow (BF) and that which would be measured by an ideal survey. Here we extend this MV analysis to include the shear and octupole moments, which are designed to have almost no correlations between them so that they are virtually orthogonal. We apply this MV analysis to a compilation of all major peculiar velocity surveys, consisting of 4536 measurements. Our estimate of the BF on scales of ,100 h,1 Mpc has a magnitude of |v| = 416 ± 78 km s ,1 towards Galactic l= 282°± 11° and b= 6°± 6°. This result is in disagreement with , cold dark matter with Wilkinson Microwave Anisotropy Probe 5 (WMAP5) cosmological parameters at a high confidence level, but is in good agreement with our previous MV result without an orthogonality constraint, showing that the shear and octupole moments did not contaminate the previous BF measurement. The shear and octupole moments are consistent with WMAP5 power spectrum, although the measurement noise is larger for these moments than for the BF. The relatively low shear moments suggest that the sources responsible for the BF are at large distances. [source]

Anomalous SZ contribution to three-year WMAP data

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2007
R. M. Bielby
ABSTRACT We first show that the new Wilkinson Microwave Anisotropy Probe (WMAP) 3-yr data confirm the detection by Myers et al. of an extended SZ signal centred on 606 Abell (ACO) clusters with richness class, R, 2. Our results also show SZ decrements around APM and 2MASS groups at increased significance than previously detected. We then follow the approach of Lieu, Mittaz & Zhang and compare the stacked WMAP results for the decrement in 31 clusters with ROSAT X-ray profiles where Lieu et al. found on average less SZ decrement in the WMAP 1-yr data than predicted. We confirm that in the 3-yr data these same clusters again show less SZ decrement than the X-ray data predict. We then analysed the WMAP results for the 38 X-ray clusters with OVRO/BIMA measured SZ decrements as presented by Bonamente et al.. We again find that the average decrement is measured to be significantly less (5.5,) than predicted by the Chandra X-ray data. Thus while we confirm the original detection of an extended SZ effect by Myers et al., these X-ray comparisons may now suggest that the central SZ amplitudes detected by WMAP may actually be lower than expected. One possible explanation is that there is contamination of the WMAP SZ signal by radio sources in the clusters but we argue that this appears implausible. We then consider the possibility that the SZ decrement has been lensed away by foreground galaxy groups. Such a model predicts that the SZ decrement should depend on cluster redshift. A reduction in the SZ decrement with redshift is suggested from the ACO cluster sample and also from comparing the samples of Lieu et al. and Bonamente et al.. However, the mass power spectrum would require a far higher amplitude than currently expected if lensing was to explain the SZ deficit in high-redshift clusters. [source]

Cosmic microwave background signal in Wilkinson Microwave Anisotropy Probe three-year data with fastica

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
D. Maino
ABSTRACT We present an application of the fast Independent Component Analysis (fastica) to the Wilkinson Microwave Anisotropy Probe (WMAP) three-year data with the goal of extracting the cosmic microwave background (CMB) signal. We evaluate the confidence of our results by means of Monte Carlo simulations including the CMB, foreground contaminations and instrumental noise specific to each WMAP frequency band. We perform a complete analysis involving all or a subset of the WMAP channels in order to select the optimal combination for CMB extraction, using the frequency scaling of the reconstructed component as a figure of merit. We find that the combination KQVW provides the best CMB frequency scaling, indicating that the low-frequency foreground contamination in Q, V and W bands is better traced by the emission in the K band. The CMB angular power spectrum is recovered up to the degree scale; it is consistent within errors for all WMAP channel combinations considered, and in close agreement with the WMAP three-year results. A power spectrum analysis is made of the sky map divided into two hemispheres that have been previously reported as showing evidence of an asymmetric ratio of power on large angular scales. We then confirm the findings of several previous works with independent techniques. [source]

Foreground contamination of the WMAP CMB maps from the perspective of the matched circle test

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2006
H. Then
ABSTRACT Wilkinson Microwave Anisotropy Probe has provided cosmic microwave background (CMB) maps of the full sky. The raw data are subject to foreground contamination, in particular near to the Galactic plane. Foreground-cleaned maps have been derived, e.g. the internal linear combination map of Bennett et al., and the reduced foreground TOH map of Tegmark et al. Using S statistics, we examine whether residual foreground contamination is left over in the foreground-cleaned maps. In particular, we specify which parts of the foreground-cleaned maps are sufficiently accurate for the circle-in-the-sky signature. We generalize the S statistic, called D statistic, such that the circle test can deal with CMB maps in which the contaminated regions of the sky are excluded with masks. [source]

Constraints on the initial mass function of the first stars

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006
Raffaella Schneider
ABSTRACT Motivated by theoretical predictions that the first stars were predominantly very massive, we investigate the physics of the transition from an early epoch dominated by massive Pop III stars to a later epoch dominated by familiar low-mass Pop II/I stars by means of a numerically generated catalogue of dark matter haloes coupled with a self-consistent treatment of chemical and radiative feedback. Depending on the strength of the chemical feedback, Pop III stars can contribute a substantial fraction (several per cent) of the cosmic star formation activity even at moderate redshifts, z, 5. We find that the three z, 10 sources tentatively detected in Near Infrared Camera and Multi-Object Spectrometer (NICMOS) Ultra Deep Fields (UDFs) should be powered by Pop III stars, if these are massive; however, this scenario fails to reproduce the derived Wilkinson Microwave Anisotropy Probe (WMAP) electron scattering optical depth. Instead, both the UDFs and WMAP constraints can be fulfilled if stars at any time form with a more standard, slightly top-heavy, Larson initial mass function. [source]

Halo model at its best: constraints on conditional luminosity functions from measured galaxy statistics

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2006
Asantha Cooray
ABSTRACT Using the conditional luminosity function (CLF; the luminosity distribution of galaxies in a dark matter halo) as the fundamental building block, we present an empirical model for the galaxy distribution. The model predictions are compared with the published luminosity function (LF) and clustering statistics from the Sloan Digital Sky Survey (SDSS) at low redshifts, galaxy correlation functions from the Classifying Objects by Medium-Band Observations 17 (COMBO-17) survey at a redshift of 0.6, the Deep Extragalactic Evolutionary Probe 2 (DEEP2) survey at a redshift of unity, the Great Observatories Deep Origins Survey (GOODS) at a redshift around 3 and the Subaru/XMM,Newton Deep Field data at a redshift of 4. The comparison with statistical measurements allows us to constrain certain parameters related to analytical descriptions on the relation between a dark matter halo and its central galaxy luminosity, its satellite galaxy luminosity, and the fraction of early- and late-type galaxies of that halo. With the SDSS r -band LF at Mr < ,17, the lognormal scatter in the central galaxy luminosity at a given halo mass in the central galaxy,halo mass, Lc(M), relation is constrained to be 0.17+0.02,0.01, with 1, errors here and below. For the same galaxy sample, we find no evidence for a low-mass cut-off in the appearance of a single central galaxy in dark matter haloes, with the 68 per cent confidence level upper limit on the minimum mass of dark matter haloes to host a central galaxy, with luminosity Mr < ,17, is 2 × 1010 h,1 M,. If the total luminosity of a dark matter halo varies with halo mass as Lc(M) (M/Msat),s when M > Msat, using SDSS data, we find that Msat= (1.2+2.9,1.1) × 1013 h,1 M, and power-law slope ,s= 0.56+0.19,0.17 for galaxies with Mr < ,17 at z < 0.1. At z, 0.6, the COMBO-17 data allows these parameters for MB < ,18 galaxies to be constrained as (3.3+4.9,3.0) × 1013 h,1 M, and (0.62+0.33,0.27), respectively. At z, 4, Subaru measurements constrain these parameters for MB < ,18.5 galaxies as (4.12+5.90,4.08) × 1012 h,1 M, and (0.55+0.32,0.35), respectively. The redshift evolution associated with these parameters can be described as a combination of the evolution associated with the halo mass function and the luminosity,halo mass relation. The single parameter well constrained by clustering measurements is the average of the total satellite galaxy luminosity corresponding to the dark matter halo distribution probed by the galaxy sample. For SDSS, ,Lsat,= (2.1+0.8,0.4) × 1010 h,2 L,, while for GOODS at z, 3, ,Lsat, < 2 × 1011 h,2 L,. For SDSS, the fraction of galaxies that appear as satellites is 0.13+0.03,0.03, 0.11+0.05,0.02, 0.11+0.12,0.03 and 0.12+0.33,0.05 for galaxies with luminosities in the r, band from ,22 to ,21, ,21 to ,20, ,20 to ,19 and ,19 to ,18, respectively. In addition to constraints on central and satellite CLFs, we also determine model parameters of the analytical relations that describe the fraction of early- and late-type galaxies in dark matter haloes. We use our CLFs to establish the probability distribution of halo mass in which galaxies of a given luminosity could be found either at halo centres or as satellites. Finally, to help establish further properties of the galaxy distribution, we propose the measurement of cross-clustering between galaxies divided into two distinctly different luminosity bins. Our analysis shows how CLFs provide a stronger foundation to built-up analytical models of the galaxy distribution when compared with models based on the halo occupation number alone. [source]

A very extended reionization epoch?

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005
A. Melchiorri
ABSTRACT The recent observations of cross temperature,polarization power spectra of the cosmic microwave background (CMB) made by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite are in better agreement with a high value of the Thomson scattering optical depth ,, 0.17. This value is close to ,= 0.3, which is taken as the upper limit in the parameter extraction analysis made by the WMAP team. However, models with ,, 0.3 provide a good fit to current CMB data and are not significantly excluded when combined with large-scale structure data. By making use of a self-consistent reionization model, we verify the astrophysical feasibility of models with ,, 0.3. It turns out that current data on various observations related to the thermal and ionization history of the intergalactic medium are not able to rule out ,, 0.3. The possibility of a very extended reionization epoch can significantly undermine the WMAP constraints on crucial cosmological parameters such as the Hubble constant, the spectral index of primordial fluctuations and the amplitude of dark matter clustering. [source]