An improved algorithm for narrow-band searches of continuous gravitational waves

Continuous gravitational waves signals, emitted by asymmetric spinning neutron stars, are among the main targets of current detectors like Advanced LIGO and Virgo. In the case of sources, like pulsars, which rotational parameters are measured through electromagnetic observations, typical searches assume that the gravitational wave frequency is at a given known fixed ratio with respect to the star rotational frequency. For instance, for a neutron star rotating around one of its principal axis of inertia the gravitational signal frequency would be exactly two times the rotational frequency of the star. It is possible, however, that this assumption is wrong. This is why search algorithms able to take into account a possible small mismatch between the gravitational waves frequency and the frequency inferred from electromagnetic observations have been developed. In this paper we present an improved pipeline to perform such narrow-band searches for continuous gravitational waves from neutron stars, about three orders of magnitude faster than previous implementations. The algorithm that we have developed is based on the {\it 5-vectors} framework and is able to perform a fully coherent search over a frequency band of width $\mathcal{O}$(Hertz) and for hundreds of spin-down values running a few hours on a standard workstation. This new algorithm opens the possibility of long coherence time searches for objects which rotational parameters are highly uncertain.Comment: 19 pages, 8 figures, 6 tables, submitted to CQ

A new data analysis framework for the search of continuous gravitational wave signals

Continuous gravitational wave signals, like those expected by asymmetric spinning neutron stars, are among the most promising targets for LIGO and Virgo detectors. The development of fast and robust data analysis methods is crucial to increase the chances of a detection. We have developed a new and flexible general data analysis framework for the search of this kind of signals, which allows to reduce the computational cost of the analysis by about two orders of magnitude with respect to current procedures. This can correspond, at fixed computing cost, to a sensitivity gain of up to 10%-20%, depending on the search parameter space. Some possible applications are discussed, with a particular focus on a directed search for sources in the Galactic center. Validation through the injection of artificial signals in the data of Advanced LIGO first observational science run is also shown.Comment: 21 pages, 8 figure

A semi-coherent analysis method to search for continuous gravitational waves emitted by ultra-light boson clouds around spinning black holes

As a consequence of superradiant instability induced in Kerr black holes, ultra-light boson clouds can be a source of persistent gravitational waves, potentially detectable by current and future gravitational-wave detectors. These signals have been predicted to be nearly monochromatic, with a small steady frequency increase (spin-up), but given the several assumptions and simplifications done at theoretical level, it is wise to consider, from the data analysis point of view, a broader class of gravitational signals in which the phase (or the frequency) slightly wander in time. Also other types of sources, e.g. neutron stars in which a torque balance equilibrium exists between matter accretion and emission of persistent gravitational waves, would fit in this category. In this paper we present a robust and computationally cheap analysis pipeline devoted to the search of such kind of signals. We provide a full characterization of the method, through both a theoretical sensitivity estimation and through the analysis of syntethic data in which simulated signals have been injected. The search setup for both all-sky searches and higher sensitivity directed searches is discussed.Comment: 13 pages, 13 figure

A method to search for long duration gravitational wave transients from isolated neutron stars using the generalized FrequencyHough

We describe a method to detect gravitational waves lasting $O(hours-days)$ emitted by young, isolated neutron stars, such as those that could form after a supernova or a binary neutron star merger, using advanced LIGO/Virgo data. The method is based on a generalization of the FrequencyHough (FH), a pipeline that performs hierarchical searches for continuous gravitational waves by mapping points in the time/frequency plane of the detector to lines in the frequency/spindown plane of the source. We show that signals whose spindowns are related to their frequencies by a power law can be transformed to coordinates where the behavior of these signals is always linear, and can therefore be searched for by the FH. We estimate the sensitivity of our search across different braking indices, and describe the portion of the parameter space we could explore in a search using varying fast Fourier Transform (FFT) lengths.Comment: 15 figure

USCID fifth international conference

Presented at the fifth international conference on irrigation and drainage, Irrigation and drainage for food, energy and the environment on November 3-6, 2009 in Salt Lake City, Utah.Includes bibliographical references.The urban water demand in Southwest Texas has grown rapidly in recent years due to large population increase. Regulated deficit irrigation (RDI) is one important measure for saving water while maintaining crop yield/ net benefit. An RDI field experiment was conducted at the Texas AgriLIFE Research and Extension Center at Uvalde in the summer of 2008 to examine the water saving potential. Seven irrigation schemes and four varieties were assigned to the experimental field to test their effects on lint yield. The results showed that: 1) The threshold of the replacement ratio is between 0.7 and 0.8 in fixed ratio irrigation schemes. Dynamic irrigation schemes showed a higher potential to save irrigation water. 2) The fiber quality was affected more by varieties than by irrigation schemes. A 50X (fixed 50% ratio) scheme has the potential risk to produce relatively lower quality cotton fiber by affecting fiber length and fiber yellowness. Considering its negative effect on lint yield as well, the 50X scheme is definitely not recommended. The two dynamic irrigation schemes, 50D and 70D, showed no negative effect on fiber quality. The 70D scheme has some potential to increase the fiber quality in fiber length, uniformity, fiber strength and reflectance; however, this scheme uses more irrigation water that the 50D scheme. Although further research is needed before making definitive conclusions, both dynamic schemes could be applied to maintain lint yield and fiber quality while saving more water, compared to the fixed ratio irrigation schemes

Testbed for the Pellet Launching System for JT-60SA

As part of the European contribution to the large size superconducting tokamak project JT-60SA, a new Pellet Launching System (PLS) is designed and built. The aims of the PLS are to provide efficient fuelling to the plasma and to control and mitigate Edge Localised Modes (ELMs). Two pellet sources, one for fuelling pellets, one for pacing pellets, are delivering pellets to a centrifuge launcher. The centrifuge enables precise launch of pellets according to already proven control schemes. Furthermore, this system opens a way towards a test bed for the EU-DEMO fuelling system. The new PLS has to be completed and commissioned first at the IPP Garching pellet lab and then to be shipped to QST Naka site after having demonstrated its performance. This dedicated test bed has been set up, providing suitable vacuum conditions to operate the PLS in similar conditions (except magnetic field and radiation). Maximum hydrogen throughput is about 400 mbar·L/s per pellet source. Safety issues must be considered for hydrogen inventory of pellet sources (∼100 bar·L each). In a first step, the pellet sources will be put on a test vessel providing inherent safety by a huge volume (10 m³) which makes sure that the hydrogen concentration is below 1% under all circumstances. A hydrogen safety survey prior to assembly confirmed the concept to be followed by an assessment after the installation in order to get the required license for operation. The PLS as a whole, for the time being equipped with two pellet sources, is to be certified according to explosion prevention rules (ATEX) as a product to be shipped to Naka site. To obtain this, an appropriate declaration of explosion zones inside the vacuum system and the use of suitable and certified equipment is mandatory. Such, the integration of this system can be planned and assessed on a clear technical and regulatory basis

EM-100 Precision Irrigators Network

Identifying best management practices (BMPs) promoting greater water use efficiency while maintaining crop yields is essential to the future of Texas cropping systems. Available water for irrigated crops is vital for sustaining crop production throughout the state. However, the availability of this water for irrigation is diminishing through competition by urban development and, in some regions such as the Edwards Aquifer, is falling under state regulation. The awareness and improvement of efficient irrigation and best management practices to conserve water while maintaining crop production will help preserve the aquifer levels and increase water savings to producers. One component of BMPs for conserving water use is the application of decision support systems (DSS) that are used as tools for implementing irrigation BMPs. This DSS guide was developed as a complement to TWDB Report 362, "Water Conservation Best Management Practices Guide," which is a more comprehensive report on water conservation including an "Agricultural Irrigation Water Use Management" BMPs section. The full TWDB Report 362 can be found at: http://www.twdb.state.tx.us/assistance/conservation/consindex.asp. DSS include the Texas High Plains Evapotranspiration Network (TXHPET), the Precision Irrigators Network (PIN) and the Crop Production Management (CroPMan) model. These DSS strive to promote grower awareness of water conservation strategies. Irrigation conservation strategies are proposed to result in savings of approximately 1.4 million acre-feet per year by 2060 (TWDB and TWRI). TXHPET operates 18 meteorological stations located in 15 counties across the Texas North Plains and Texas South Plains. The regional coverage of TXHPET is estimated at 4 million irrigated acres. The network offers insight to evapotranspiration (ET)-based crop water use that producers and agricultural consultants can reference when making decisions on when and how much to irrigate their crops. This information is available to data users via fax or online (http://txhighplainset.tamu.edu) and currently results in approximately 300,000 downloads or faxes annually. The PIN program was formed in 2004 with a goal of saving millions of gallons of water annually by reducing irrigation water use by as much as 20 percent over several years and currently supports several crops (corn, cotton, sorghum, wheat) in seven counties of South Central Texas. Cooperation of the PIN programs consists of area producers, Texas Agricultural Experiment Station researchers, Texas Cooperative Extension personnel, San Antonio Water System, Edwards Aquifer Authority, Texas Water Resources Institute, Texas Water Development Board, Uvalde County Underground Water Conservation District and Wintergarden Water Conservation District. The PIN database will allow producers to gain historical and real-time information for better management of irrigation scheduling. The PIN program estimates that when all irrigators in the Edwards Aquifer region implement limited irrigation scheduling, approximately 50,000 to 60,000 acre-feet of water can be saved per year and made available for purposes other than agriculture. CroPMan is a computer model designed to aid producers and agricultural consultants in optimizing crop management and maximizing production and profit through a production-risk approach. CroPMan will help growers identify limitations to crop yield, assist in making replant decisions and help recognize management practices that reduce the impact of agriculture on soil erosion and water quality. CroPMan is a Windows-based application program that can be downloaded from the CroPMan Web site (http://cropman.brc.tamus.edu)

Chytrid fungus infections in laboratory and introduced <i>Xenopus laevis </i>populations:assessing the risks for U.K. native amphibians

The chytrid fungus Batrachochytrium dendrobatidis (Bd) is notorious amongst current conservation biology challenges, responsible for mass mortality and extinction of amphibian species. World trade in amphibians is implicated in global dissemination. Exports of South African Xenopus laevis have led to establishment of this invasive species on four continents. Bd naturally infects this host in Africa and now occurs in several introduced populations. However, no previous studies have investigated transfer of infection into co-occurring native amphibian faunas. A survey of 27 U.K. institutions maintaining X. laevis for research showed that most laboratories have low-level infection, a risk for native species if animals are released into the wild. RT-PCR assays showed Bd in two introduced U.K. populations of X. laevis, in Wales and Lincolnshire. Laboratory and field studies demonstrated that infection levels increase with stress, especially low temperature. In the U.K., native amphibians may be exposed to intense transmission in spring when they enter ponds to spawn alongside X. laevis that have cold-elevated Bd infections. Exposure to cross-infection has probably been recurrent since the introduction of X. laevis, &gt;20years in Lincolnshire and 50years in Wales. These sites provide an important test for assessing the impact of X. laevis on Bd spread. However, RT-PCR assays on 174 native amphibians (Bufo, Rana, Lissotriton and Triturus spp.), sympatric with the Bd-infected introduced populations, showed no foci of self-sustaining Bd transmission associated with X. laevis. The abundance of these native amphibians suggested no significant negative population-level effect after the decades of co-occurrence

Characterization of the Horizontal and Vertical Sexual Transmission of Chlamydia Genital Infections in a New Mouse Model.

Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen worldwide, and there is a need to control this epidemic. So far there is no established animal model in which both the horizontal and the vertical transmission of Chlamydia can be studied. To implement a horizontal sexual transmission model, male mice were inoculated in the meatus urethra with Chlamydia muridarum and they were caged with naive female mice. Urine and vaginal swab specimens were collected for culture. To study vertical transmission, newborns were euthanized and specimens were cultured. As controls, females were mated with sham-infected male mice. All C. muridarum-inoculated male mice had positive urine cultures. As determined by serology, all females caged with C. muridarum-inoculated males became infected, and 93% of them had positive vaginal swab specimen cultures. More females mated with C. muridarum-infected male mice (35%) than females mated with sham-infected male mice (0%) were infertile (P &lt; 0.05). Also, C. muridarum-infected females delivered significantly fewer pups (3.8 ± 3.2/mouse) than control females (6.3 ± 1.6/mouse) (P &lt; 0.05). Of the newborn mice, 32% were C. muridarum positive either in the lungs or in the intestines. Female mice housed with sham-infected males had no positive vaginal swab specimen cultures or C. muridarum-positive pups. This new mouse model of horizontal and vertical sexual transmission of Chlamydia closely parallels C. trachomatis sexual transmission in humans and may be a good model system to better understand the pathogenesis of these infections