13,617 research outputs found
Searching for chemical inhomogeneities in Open Clusters: Analysis of the CN and CH Molecular Band Strengths in NGC 2158, NGC 2420, NGC 2682, NGC 7789 and Berkeley 29
Context: The total mass of a cluster, being the main parameter determining
its ability to host more than one stellar generation, may constitute a
threshold below which the cluster is able to form only a single stellar
population. AIms: Our goal is to investigate the existence of star-to-star
variations of CN and CH band strengths, related to the N and C abundances,
respectively, among the stars in five open cluster (NGC 2158, NGC 2420, NGC
2682, NGC 7789 and Berkeley 29) similar to those observed in globular clusters
and linked with the existence of multiple populations therein. Since these
systems are less massive than globulars, our results may allow us to constrain
the lower mass necessary to form more than one stellar population. Methods: We
measured the strength of the CN and CH bands, which correlate with the C and N
abundances, using four molecular indices in low-resolution SDSS/SEGUE spectra.
Results: We found that for four of the open clusters (NGC 2158, NGC 2420, NGC
2682 and Berkeley 29) all the stars studied in each of them have similar CN and
CH band strengths within the uncertainties since neither anomalous spreads nor
bimodalities have been detected in their CN and CH distributions. In contrast,
for NGC 7789 we found an anomalous spread in the strength of the CN molecular
band at 3839 \AA which is larger than the uncertainties. However, the small
number of stars studied in this cluster implies that further analysis is needed
to confirm the existence of chemical inhomogeneities in this cluster.Comment: 11 pages, 9 figures, Accepted for publication in A&A, Tables 7, 8 and
9 will be publish onlin
Characterization of femtosecond laser written waveguides for integrated biochemical sensing
Fluorescence detection is known to be one of the most sensitive among the different optical sensing techniques. This work focuses on excitation and detection of fluorescence emitted by DNA strands labeled with fluorescent dye molecules that can be excited at a specific wavelength. Excitation occurs via optical channel waveguides written with femtosecond laser pulses applied coplanar with a microfluidic channel on a glass chip. The waveguides are optically characterized in order to facilitate the design of sensing structures which can be applied for monitoring the spatial separation of biochemical\ud
species as a result of capillary electrophoresis
Dual regimes of ion migration in high repetition rate femtosecond laser inscribed waveguides
Ion migration in high repetition rate femtosecond laser inscribed waveguides
is currently being reported in different optical glasses. For the first time we
discuss and experimentally demonstrate the presence of two regimes of ion
migration found in laser written waveguides. Regime-I, corresponds to the
initial waveguide formation mainly via light element migration (in our case
atomic weight < 31u), whereas regime-II majorly corresponds to the movement of
heavy elements. This behavior brings attention to a problem which has never
been analyzed before and that affects laser written active waveguides in which
active ions migrate changing their local spectroscopic properties. The
migration of active ions may in fact detune the pre-designed optimal values of
active photonic devices. This paper experimentally evidences this problem and
provides solutions to avert it.Comment: 4 pages, 5 figure
Electoral Accountability and Fiscal Federalism:The Case of Peru
Accountability is at the heart of the democratic enterprise. One commonly touted benefit of decentralization is that it promotes this accountability by allowing sub-national governments to target fiscal policy more precisely to the varying preferences of people in different locales. But if accountability is really functioning as it should, then citizens should use the ballot box to reward and punish local officials for their concrete policy behavior. In other words, we should not only be able to link the presence of decentralization with improvements in local public goods, but we should also be able to connect voting behavior in specific locales with the competence of local politicians. Because of the empirical challenges, few scholars have attempted test this prediction directly. Using government information as well as data coded for this project, we examine the case of Peru, assessing how measures of local government success affect the probability of reelection and recall. We find that, when Mayors manage their waste collection and education portfolios more effectively, they are more likely to win office in subsequent elections. They are also less likely to be removed in recall votes. More than that, when Mayors spend more overall, and especially when they spend more on capital projects, we find that their probability of reelection improves, and their risk of recall declines. Overall, our results show clearly that Peru’s citizens use their votes rationally to reward and punish locally elected politicians. This gives substance and support to the notion that, at least under certain circumstances, accountability can function well under decentralized government
The Effects of Media Campaigns on Individual Attitudes towards Tax Compliance; Quasi-Experimental evidence from survey data in Pakistan
Pakistan has consistently performed low on taxation, with revenue collection hovering around 10 percent of GDP. Tax reforms have been attempted but without significant gains in revenue collection. Due to the recalcitrance of tax revenues, the tax authority attempted to enlist voluntary compliance as one of the avenues for its efforts to increase collections. This paper examines the effectiveness of media campaigns in the TV and national newspapers used by the Federal Board of Revenues of Pakistan to increase awareness, tax filing, and, ultimately, tax morale. We use survey data that were collected in 2014 immediately after a communication campaign by Pakistan’s Federal Board of Revenue. Using coarsened exact matching, we construct treatment and control groups that are nearly identical in terms of pretreatment balance of demographic and behavioral predictors of high tax morale. We find improved perceptions towards tax compliance in Pakistan for respondents exposed to the TV and newspaper advertisements. The choice of the advertisement’s delivery device is important since the latter is more effective. Our findings provide empirical evidence that well timed campaigns can enhance voluntary compliance in tax filing
A Comparative Analysis of Southeastern States’ Income Tax Treatment of Exporters
Exporters are vital to the health of the U.S. economy as well as to individual state economies. As such, this study analyzes the export-related provisions of the southeastern states’ income tax laws and proposes tax policy changes that could potentially improve the tax environment for exporters while enhancing the overall economic environment in those states.
In order to develop and support tax policy recommendations relating to state’s tax treatment of exporters, statistics that highlight the importance of exports to the domestic economy are reviewed. In addition, a summary of Federal tax law incentives available to exporters is provided along with several Treasury Department studies that estimate the impact the federal tax law incentives have had on the volume of exports. Also, key issues under state income tax laws regarding the treatment of export transactions are highlighted while providing a comparative analysis of the southeastern states’ treatment of export transactions using foreign sales corporations (FSC).
The results of this study demonstrate not only that disparity among the southeastern states treatment of exporters exists, but also that the method used by state governments to tax FSCs could impact the extent to which corporations find it desirable to export their goods from a particular state. Based on these findings, the authors suggest the adoption of administrative pricing rules (similar to the rules in place for Federal tax purposes) for FSCs by states not currently allowing these rules, which would decrease the effective tax rate on export sales. The reduction in taxes could ultimately provide an incentive for domiciled corporations to increase exporting activities, contributing to increased domestic jobs and overall economic activity
Fluorescence monitoring of capilarry electrophoresis separation in a lab-on-a-chip with monolithically integrated waveguides
Femtosecond-laser-written optical waveguides were monolithically integrated into a commercial lab-on-a-chip to intersect a microfluidic channel. Laser excitation through these waveguides confines the excitation window to a width of 12 ÎĽm, enabling high-spatial-resolution monitoring of different fluorescent analytes, during their migration/separation in the microfluidic channel by capillary electrophoresis. Wavelength-selective monitoring of the on-chip separation of fluorescent dyes is implemented as a proof-of-principle. We envision well-controlled microfluidic plug formation, waveguide excitation, and a low limit of detection to enable monitoring of extremely small quantities with high spatial resolution
Terminal Antennas in ACE2
The ACE Network of Excellence was a European Commission funded Network of Excellence, which lasted from 2004 to 2007. One of the activities performed by this Network was in the frame of terminal antennas. In this activity, three aspects were covered in three projects: Small antenna technologies, small terminal antenna technologies and benchmarking of small terminal antennas measurement facilities. The overall aim was to identify the newest trends in antenna design and measurement for personal communications devices, and suggest novel solutions and design methodologies for various applications. The results of this work are presented in this paper
Multi-color fluorescent DNA analysis in an integrated optofluidic lab-on-a-chip
Sorting and sizing of DNA molecules within the human genome project has enabled the genetic mapping of various illnesses. By employing tiny lab-on-a-chip devices for such DNA analysis, integrated DNA sequencing and genetic diagnostics have become feasible. However, such diagnostic chips typically lack integrated sensing capability. We address this issue by combining microfluidic capillary electrophoresis with laser-induced fluorescence detection resulting in optofluidic integration towards an on-chip bio-analysis tool [1,2]. We achieve a spatial separation resolution of 12 μm, which can enable a 20-fold enhancement in electropherogram peak resolution, leading to plate numbers exceeding one million. We demonstrate a high sizing/calibration accuracy of 99% [3], and ultrasensitive fluorescence detection (limit of detection = 65 femtomolar, corresponding to merely 2-3 molecules in the excitation/detection volume) of diagnostically relevant double-stranded DNA molecules by integrated-waveguide laser excitation. Subsequently, we introduce a principle of parallel optical processing to this optofluidic lab-on-a-chip. Different sets of exclusively color-labeled DNA fragments – otherwise rendered indistinguishable by their spatio-temporal coincidence – are traced back to their origin by modulation-frequency-encoded multi-wavelength laser excitation, fluorescence detection with a color-blind photomultiplier, and Fourier-analysis decoding. As a proof of principle, fragments from independent human genomic segments, associated with genetic predispositions to breast cancer and anemia, are extracted by multiplex ligation-dependent probe amplification, and simultaneously analyzed. Such multiple yet unambiguous optical identification of biomolecules opens new horizons for “enlightened” lab-on-a-chip devices
Multi-point, multi-wavelength fluorescence monitoring of DNA separation in a lab-on-a-chip with monolithically integrated femtosecond-laser-written waveguides
Electrophoretic separation of fluorescently labeled DNA molecules in on-chip microfluidic channels was monitored by integrated waveguide arrays, with simultaneous spatial and wavelength resolution. This is an important step toward point-of-care diagnostics with multiplexed DNA assays
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