197 research outputs found
Parameter-space metric of semicoherent searches for continuous gravitational waves
No full textContinuous gravitational-wave (CW) signals such as emitted by spinning neutron stars are an important target class for current detectors. However, the enormous computational demand prohibits fully coherent broadband all-sky searches for prior unknown CW sources over wide ranges of parameter space and for yearlong observation times. More efficient hierarchical “semicoherent” search strategies divide the data into segments much shorter than one year, which are analyzed coherently; then detection statistics from different segments are combined incoherently. To optimally perform the incoherent combination, understanding of the underlying parameter-space structure is requisite. This problem is addressed here by using new coordinates on the parameter space, which yield the first analytical parameter-space metric for the incoherent combination step. This semicoherent metric applies to broadband all-sky surveys (also embedding directed searches at fixed sky position) for isolated CW sources. Furthermore, the additional metric resolution attained through the combination of segments is studied. From the search parameters (sky position, frequency, and frequency derivatives), solely the metric resolution in the frequency derivatives is found to significantly increase with the number of segments
A sliding coherence window technique for hierarchical detection of continuous gravitational waves
No full textA novel hierarchical semicoherent technique is presented for all-sky surveys for continuous gravitational-wave sources, such as rapidly spinning non-axisymmetric neutron stars. Analyzing year-long detector data sets over realistic ranges of parameter space using fully-coherent matched-filtering is computationally prohibitive. Thus more efficient, so-called hierarchical techniques are essential. Traditionally, the standard hierarchical approach consists of dividing the data into non-overlapping segments of which each is coherently analyzed and subsequently the matched-filter outputs from all segments are combined incoherently. The present work proposes to break the data into subsegments being shorter than the desired maximum coherence time span (size of the coherence window). Then matched-filter outputs from the different subsegments are efficiently combined by "sliding" the coherence window in time: Subsegments whose time-stamps are closer than coherence window size are combined coherently, otherwise incoherently. Compared to the standard scheme at the same coherence time baseline, data sets longer by about 50% - 100% would have to be analyzed to achieve the same search sensitivity as with the sliding coherence window approach. Numerical simulations attest the analytically estimated improvement
Resist?ncia e consci?ncia na ponta da chuteira: futebol e ditadura nas p?ginas da Placar no per?odo de 1982 a 1984
No full textEl objeto de este trabajo es la relaci?n entre el f?tbol y la apertura pol?tica en los a?os
entre 1982 y 1984. Donde se busca evaluar si los jugadores de f?tbol tienen alguna
influencia sobre el proceso de democratizaci?n de la pol?tica brasile?a. El estudio se
basar? en el an?lisis de revistas, m?s espec?ficamente en los ejemplares de Placar.
El per?odo dictatorial en el pa?s ven?a pasando por un per?odo de crisis desde hace
algunos a?os y eso se ven?a imponiendo sobre la naci?n. El f?tbol, tambi?n ven?a
manteni?ndose de forma conservadora, sin dar mucha libertad a sus atletas. Los
profesionales ligados al f?tbol, principalmente un grupo de atletas, no ten?an tanta
conciencia de clase. El f?tbol tambi?n fue utilizado como una herramienta publicitaria
por el gobierno, vali?ndose de una din?mica de distracci?n. En el momento en que
algunos atletas como S?crates, Wladimir, Casagrande y Ad?lson, se ponen a expresar
la lucha pol?tica, con la llamada "Democracia Corintiana", visando la (re)
democratizaci?n no s?lo en los clubes, pero tambi?n se insertan en la lucha por las
"Directas "Ya, participando en la sociedad brasile?a.O objeto deste trabalho ? a rela??o entre o futebol e a abertura pol?tica nos anos entre
1982 e 1984. Onde se procura aferir se os jogadores de futebol t?m alguma influ?ncia
sobre o processo de democratiza??o da pol?tica brasileira. O estudo estar? embasado
sobre a an?lise de revistas, mais especificamente nos exemplares da Placar. O
per?odo ditatorial no pa?s vinha passando por um per?odo de crise j? h? alguns anos e
isso vinha se impondo sobre a na??o. O futebol, tamb?m vinha se mantendo de forma
conservadora, sem dar muita liberdade a seus atletas. Os profissionais ligados ao
futebol, principalmente um grupo de atletas, n?o tinham tanta consci?ncia de classe.
O futebol tamb?m foi utilizado como uma ferramenta publicit?ria pelo governo,
valendo-se de uma din?mica de distra??o. Ao passo que alguns atletas como
S?crates, Wladimir, Casagrande e Ad?lson, se p?em a expressar a luta pol?tica, com
a chamada ?Democracia Corintiana?, visando a (re) democratiza??o n?o s? nos
clubes, mas tamb?m se inserem na luta pelas ?Diretas J??, participando juntamente
da sociedade brasileira
Exploiting Large-Scale Correlations to Detect Continuous Gravitational Waves
No full textFully coherent searches (over realistic ranges of parameter space and year-long observation times) for unknown sources of continuous gravitational waves are computationally prohibitive. Less expensive hierarchical searches divide the data into shorter segments which are analyzed coherently, then detection statistics from different segments are combined incoherently. The novel method presented here solves the long-standing problem of how best to do the incoherent combination. The optimal solution exploits large-scale parameter-space correlations in the coherent detection statistic. Application to simulated data shows dramatic sensitivity improvements compared with previously available (ad hoc) methods, increasing the spatial volume probed by more than 2 orders of magnitude at lower computational cost
Where there's smoke there's fire? Women's experiences of smoking and cessation during pregnancy
No full textWomen who smoke during pregnancy have been identified by the New Zealand Ministry of Health as a priority group for cessation services. In addition to adverse pregnancy outcomes, the effects of cigarette exposure in utero are believed to have health implications throughout life for the developing foetus. The aim of this study was to investigate the factors that affect smoking and cessation during pregnancy. Fifteen women who had quit, tried to quit, or continued to smoke through a recent pregnancy were interviewed using face-to-face semi-structured interviews. During analysis, several key findings became apparent. Smoking played a central role in the women’s lives both in and out of pregnancy. Women were fearful and concerned about the possible effects on their growing babies. Their concerns contributed to their feelings of guilt and other negative emotions, as did frustrations over not being able to quit, adverse pregnancy outcomes and their perceived failure to meet with social expectations. However, they also doubted their concerns as most had seen, or had had their own experiences of healthy babies being born to mothers who smoked. Nonetheless, their worries led to a range of behavioural changes including spontaneously quitting, adjusting their smoking, hiding their pregnancy to continue smoking, or hiding their smoking. Changing their smoking behaviours enabled women to avoid being judged which was raised in most interviews. In addition, the importance of the context in which women lived and socialised was highlighted, as were the women’s midwives. Healthcare professionals were often spoken about in relation to the mismatch between what women wanted regarding cessation and what they were supplied. A key finding was the range of smoking statuses women presented with. This contrasts with much of the other literature that usually defines women as smokers or quitters. The use of the label ‘smoker’ in society is a generalised term that obscures differences that are important for healthcare practitioners to recognise. As a result of this study, a tool that assesses a woman’s awareness of the risks from smoking in pregnancy and openness to talking about smoking cessation has been developed. The aim is to give maternity care providers a way to broach this sensitive subject in a way that is appropriate for their client
Elucidating the crystal-chemistry of Jbel Rhassoul stevensite (Morocco) by advanced analytical techniques
No full textThe composition of Rhassoul clay is controversial regarding the nature of the puremineral clay fraction which is claimed to be stevensite rather than saponite. In this study, the raw and mineral fractions were characterized using various techniques including Fourier transform infrared spectroscopy and magic angle spinning nuclear magnetic resonance (MAS NMR). The isolated fine clay mineral fraction contained a larger amount of Al (>1 wt.%) than that reported for other stevensite occurrences. The 27Al MAS NMR technique confirmed that the mineral is stevensite in which the Al is equally split between the tetrahedral and octahedral coordination sites. The 29Si NMR spectrum showed a single unresolved resonance indicating little or no short-range ordering of silicon. The chemical composition of the stevensite from Jbel Rhassoul was determined to be ((Na0.25K0.20 (Mg5.04Al0.37Fe0.20&0.21)5.61(Si7.76Al0.24)8O20(OH)4). This formula differs from previous compositions described from this locality and shows it to be an Al-bearing lacustrine clay mineral
The Einstein@Home Survey for Gamma-ray Pulsars
No full textSince the launch of the Fermi Gamma-ray Space Telescope in 2008, the onboardLarge Area Telescope (LAT) has detected gamma-ray pulsations from more than 200 pulsars. A large fraction of these remain undetected in radio observations, and could only be found by directly searching the LAT data for pulsations. However, the sensitivity of such “blind” searches is limited by the sparse photon data and vast computational requirements. In this contribution we present the latest large-scale blind-search survey for gamma-ray pulsars, which ran on thedistributed volunteer computing system, Einstein@Home, and discovered 19 new gamma-ray pulsars. We explain how recent improvements to search techniques and LAT data reconstruction have boosted the sensitivity of blind searches, and present highlights from the survey’s discoveries. These include: two glitching pulsars; the youngest known radio-quiet gamma-ray pulsar; and two isolated millisecond pulsars (MSPs), one of which is the only known radio-quietrotationally powered MSP
A gravitational wave observatory operating beyond the quantum shot-noise limit
No full textAround the globe several observatories are seeking the first direct detection of gravitational waves (GWs). These waves are predicted by Einstein’s general theory of relativity and are generated, for example, by black-hole binary systems. Present GW detectors are Michelson-type kilometre-scale laser interferometers measuring the distance changes between mirrors suspended in vacuum. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. A quantum technology—the injection of squeezed light—offers a solution to this problem. Here we demonstrate the squeezed-light enhancement of GEO600, which will be the GWobservatory operated by the LIGO Scientific Collaboration in its search for GWs for the next 3–4 years. GEO600 now operates with its best ever sensitivity, which proves the usefulness of quantum entanglement and the qualification of squeezed light as a key technology for future GW astronomy.J. Abadie... M.R. Ganija... D.J. Hosken... J. Munch... D.J. Ottaway... P.J. Veitch... et al. J. Abadie... M. R. Ganija...D. J. Hosken... J. Munch... D. J. Ottaway... P. J. Veitch... et al., (LIGO Scientific Collaboration
Discovery Of Nine Gamma-Ray Pulsars In Fermi Large Area Telescope Data Using A New Blind Search Method
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