13,814 research outputs found
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
Reexamining The Determinants Of Fiscal Decentralization: What Is The Role Of Geography?
This paper contributes to the existing literature on the determinants of fiscal decentralization by motivating theoretically and exploring in depth the empirical relevance that geography has as determinant of fiscal decentralization. The relationship between decentralization and geography is based on the logic that more geographically diverse countries show greater heterogeneity among their citizens, including their preferences and needs for public goods and services provision. Communications and physical distance are also a very important issue and play a key role on the effect of geography over time. The theoretical model builds on the work by Arzaghi and Henderson (2002) and Panizza (1999). For the empirical estimation we use a panel data set for approximately 91 countries for the period 1960-2005. Physical geography is measured along several dimensions including elevation, land area, and climate. We construct a geographical fragmentation index and test its effect on fiscal decentralization. In addition, we interact the geographical fragmentation index with time variant infrastructure variables, in order to test the effect that infrastructure and communications have on the relationship between geography and fiscal decentralization. For robustness, we construct Gini coefficients for in-country elevation and climate. We find a positive and strong correlation between geographical factors and fiscal decentralization. We also find that while the development of infrastructure (in transportation, communications, etc.) tends to reduce the effect of geography on decentralization, this effect is rather small and mostly statistically insignificant, meaning that the impact of geography survives over time. The additional value added of this strategy is that geography and its interaction with infrastructure development may be used as an instrument for decentralization in future econometric estimations, where decentralization is used as an explanatory variable but it may be suspected to be endogenous to the economic process being studied (economic growth, political instability, macroeconomic stability, income distribution, etc.
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
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
Contamination des moules (Mytilus galloprovincialis) des côtes de la région de Dakar par les Hydrocarbures Aromatiques Polycycliques (HAPs)
Dans ce travail, nous avons etudie la contamination par les Hydrocarbures Aromatiques Polycycliques des moules recoltees au niveau des cotes de la region de Dakar. Les sites ont ete choisis en fonction des activites qui y sont developpees. Lfextraction des HAPs a ete faite au moyen dfun extracteur Soxhlet avec un melange hexane/acetone et la purification est realisee avec lfoxyde dfaluminium. Nous avons analyse lfextraitpar un chromatographe de gaz couple a un spectrographe de masse (GC/MS). Les resultats montrent que les teneurs en hydrocarbures evoluent de facon croissante en fonction du temps. Au port de Dakar, lesconcentrations passent de 5308,67 en 2007 a 17973,37 Ć’ĂŠg/kg de poids sec, en 2008. Lfevolution des hydrocarbures suit la meme tendance dans les differents sites. Ainsi, le Port concentre la plus forte teneur, ensuite suivent les sites de Mbao et de Hann. Au niveau du port, la contamination proviendrait des depots de stockages des hydrocarbures mais egalement des operations de transbordement du petrole. La zone de Mbao estpolluee par la presence de nombreuses usines dont une raffinerie qui a ces canaux directement ouvert sur la plage. Le site de Hann abrite un canal qui draine les eaux usees domestiques mais aussi les huiles de rejet des stations services. Ainsi, les moules deviennent un bon indicateur de la qualite des eaux mais egalement un danger pour la population, grande consommatrice de cette espece. Ces etudes qui constituent un etat de lieu doivent etre poursuivies afin de fournir des donnees scientifiques de base aux decideurs politiques pour la recherche de solutions durables a la pollution de notre environnement
Cholesterol and Alzheimer's Disease Risk: A Meta-Meta-Analysis
Background: Alzheimer''s disease (AD) is the most common subtype of dementia. In the last ten years, the relationship between cholesterol and AD has been investigated. Evidence suggests that cholesterol is associated with AD and represents promising targets for intervention. However, the causality of these associations is unclear. Therefore, we sought to conduct a meta-meta-analysis to determine the effect of cholesterol on the development AD. Then, we assessed the effect of serum levels of low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC) and triglycerides (TG), on AD risk. Methods: A systematic search of meta-analyses was conducted. Scopus, Web of Science, Science direct, PubMed and Google academic system databases were reviewed. Results: We found 100 primary studies and five meta-analyses to analyze the relationships between cholesterol and AD. The total effect of cholesterol on risk of AD was significant and heterogeneous. Subgroup analysis shows that LDL-C levels influence the development of AD. However, non-significant effects of HDL-C, TC and TG levels on AD were found. Conclusions: These results strengthen the evidence that LDL-C cholesterol levels increase risk for AD. More initiatives to investigate the relationship between cholesterol and AD are needed
ÂżPuede el borrador mejorar el cumplimiento tributario? Los efectos del programa Renta Web desde una perspectiva de sociologĂa tributaria
A partir de los datos contenidos en la oleada de 2016 del BarĂłmetro Fiscal del Instituto de Estudios Fiscales, este trabajo explora si los datos fiscales que la Agencia Tributaria proporciona a los contribuyentes del IRPF influyen en la moral fiscal y en el modo en el que los contribuyentes cumplimentan su declaraciĂłn. Mediante modelos probit contrastamos si los datos fiscales aumentan la moral fiscal. En segundo lugar, contrastamos si los datos fiscales sirven para disuadir la percepciĂłn de conductas fraudulentas. De acuerdo con nuestros resultados, es la relaciĂłn entre modificar los datos fiscales y la probabilidad percibida de ser inspeccionado lo que influencia tanto la moral fiscal como las percepciones sobre la cumplimentaciĂłn de la declaraciĂłn. Varias recomendaciones de polĂtica econĂłmica se derivan de los resultados obtenidos.
This paper explores the effects of pre-populated personal income tax returns on taxpayers' tax morale and tax filing behavior. The special questionnaire on Renta Web included in the 2016 wave of the Spanish Institute for Fiscal Studies Fiscal Barometer surveyed individual perceptions on pre-populating income tax returns. Using probit regression analysis, we examine whether pre-population affects tax morale. Secondly, we test whether pre-population influences perceptions of tax filing behavior. Our main results show that the relationship between making changes on the pre-filled tax form and the likelihood of being audited influences the tax morale of Spaniards, as well as their perceptions of tax filing behavior. And on their own, pre-population features do not have a clear impact on tax morale or tax filing behavior. The results may have several clear policy implications
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
The battle of the sexes starts in the oviduct: modulation of oviductal transcriptome by X and Y-bearing spermatozoa
BACKGROUND:Sex allocation of offspring in mammals is usually considered as a matter of chance, being dependent on whether an X- or a Y-chromosome-bearing spermatozoon reaches the oocyte first. Here we investigated the alternative possibility, namely that the oviducts can recognise X- and Y- spermatozoa, and may thus be able to bias the offspring sex ratio.
RESULTS:By introducing X- or Y-sperm populations into the two separate oviducts of single female pigs using bilateral laparoscopic insemination we found that the spermatozoa did indeed elicit sex-specific transcriptomic responses. Microarray analysis revealed that 501 were consistently altered (P-value <0.05) in the oviduct in the presence of Y-chromosome-bearing spermatozoa compared to the presence of X-chromosome-bearing spermatozoa. From these 501 transcripts, 271 transcripts (54.1%) were down-regulated and 230 transcripts (45.9%) were up-regulated when the Y- chromosome-bearing spermatozoa was present in the oviduct. Our data showed that local immune responses specific to each sperm type were elicited within the oviduct. In addition, either type of spermatozoa elicits sex-specific signal transduction signalling by oviductal cells.
CONCLUSIONS:Our data suggest that the oviduct functions as a biological sensor that screens the spermatozoon, and then responds by modifying the oviductal environment. We hypothesize that there might exist a gender biasing mechanism controlled by the female
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