Comparison of LISA and Atom Interferometry for Gravitational Wave Astronomy in Space

One of the atom interferometer gravitational wave missions proposed by Dimopoulos et al.1 in 2008 was called AGIS-Sat. 2. It had a suggested gravitational wave sensitivity set by the atom state detection shot noise level that started at 1 mHz, was comparable to LISA sensitivity from 1 to about 20 mHz, and had better sensitivity from 20 to 500 mHz. The separation between the spacecraft was 1,000 km, with atom interferometers 200 m long and shades from sunlight used at each end. A careful analysis of many error sources was included, but requirements on the time-stability of both the laser wavefront aberrations and the atom temperatures in the atom clouds were not investigated. After including these considerations, the laser wavefront aberration stability requirement to meet the quoted sensitivity level is about 1\times10-8 wavelengths, and is far tighter than for LISA. Also, the temperature fluctuations between atom clouds have to be less than 1 pK. An alternate atom interferometer GW mission in Earth orbit called AGIS-LEO with 30 km satellite separation has been suggested recently. The reduction of wavefront aberration noise by sending the laser beam through a high-finesse mode-scrubbing optical cavity is discussed briefly, but the requirements on such a cavity are not given. Unfortunately, such an Earth-orbiting mission seems to be considerably more difficult to design than a non-geocentric mission and does not appear to have comparably attractive scientific goals.Comment: Submitted to Proc. 46th Rencontres de Moriond: Gravitational Waves and Experimental Gravity, March 20 - 27, 2011, La Thuile, Ital

Detecting extreme mass ratio inspirals with LISA using time-frequency methods II: search characterization

The inspirals of stellar-mass compact objects into supermassive black holes constitute some of the most important sources for LISA. Detection of these sources using fully coherent matched filtering is computationally intractable, so alternative approaches are required. In a previous paper (Wen and Gair 2005, gr-qc/0502100), we outlined a detection method based on looking for excess power in a time-frequency spectrogram of the LISA data. The performance of the algorithm was assessed using a single `typical' trial waveform and approximations to the noise statistics. In this paper we present results of Monte Carlo simulations of the search noise statistics and examine its performance in detecting a wider range of trial waveforms. We show that typical extreme mass ratio inspirals (EMRIs) can be detected at distances of up to 1--3 Gpc, depending on the source parameters. We also discuss some remaining issues with the technique and possible ways in which the algorithm can be improved.Comment: 15 pages, 9 figures, to appear in proceedings of GWDAW 9, Annecy, France, December 200

Progettazione e sintesi di inibitori del recettore dendritico DC-SIGN

Il recettore delle cellule dendritiche DC-SIGN (Dendritic Cell Specific ICAM-3 Grabbing Nonintegrin) riconosce proteine altamente mannosilate o fucosilate alla superficie di molti agenti patogeni, come virus, funghi, batteri e parassiti. Almeno per alcuni di questi agenti, tra cui HIV, l'interazione con DC-SIGN sembra costituire un passaggio importante nella fase di infezione. Di conseguenza questa lectina \ue8 considerata un target interessante per la scoperta di nuovi farmaci antivirali [1]. L\u2019inibizione di DC-SIGN e\u2019 stata realizzata con sistemi multivalenti. In particolare e\u2019 stato dimostrato che polimeri dendrimerici polimannosilati sono inibitori nanomolari dell'infezione mediata da DC-SIGN da parte di modelli del virus Ebola [2,3]. Un problema importante da risolvere \ue8 pero\u2019 la stabilit\ue0 metabolica di queste strutture: esse infatti in vivo possono essere riconosciute e degradate dalle mannosidasi. Un approccio utile per migliorare la resistenza agli enzimi idrolitici prevede di utilizzare, in luogo di carboidrati, dei loro mimici capaci di interagire col recettore, ma stabili alle glicosidasi. In questo poster, descriveremo i nostri progressi nella sintesi di mimici di oligosaccaridi sia mannosilati che fucosilati progettati come potenziali inibitori monovalenti di DC-SIGN e gli studi preliminari che dimostrano la loro interazione con il recettore. Verranno inoltre illustrati i risultati preliminari relativi alla sintesi e caratterizzazione biologica di derivati polivalenti ottenuti in collaborazione con il gruppo del Dr. Javier Rojo presso il CSIC di Siviglia. Riferimenti 1. van Kooyk, Y. et al., Nat. Rev. Immunol., 2003, 3, 697-709. 2. Lasala, F.; Arce, E.; Otero, J. R.; Rojo, J.; Delgado, R. Antimicrob. Agents Chemother. 2003, 47(12), 3970. 3. Rojo, J.; Delgado, R. J. Antimicrob. Chemother. 2004, 54(3), 579

Negative Interpretation Bias Connects to Real-World Daily Affect: A Multistudy Approach

Negative interpretation bias, the tendency to appraise ambiguous stimuli as threatening, shapes our emotional lives. Various laboratory tasks, which differ in stimuli features and task procedures, can quantify negative interpretation bias. However, it is unknown whether these tasks globally predict individual differences in real-world negative (NA) and positive (PA) affect. Across two studies, we tested whether different lab-based negative interpretation bias tasks predict daily NA and PA, measured via mobile phone across months. To quantify negative interpretation bias, Study 1 (N = 69) used a verbal, self-referential task whereas Study 2 (N = 110) used a perceptual, emotional image task with faces and scenes. Across tasks, negative interpretation bias was linked to heightened daily NA. However, only negative interpretation bias in response to ambiguous faces was related to decreased daily PA. These results illustrate the ecological validity of negative interpretation bias tasks and highlight converging and unique relationships between distinct tasks and naturalistic emotion

The Challenges in Gravitational Wave Astronomy for Space-Based Detectors

The Gravitational Wave (GW) universe contains a wealth of sources which, with the proper treatment, will open up the universe as never before. By observing massive black hole binaries to high redshifts, we should begin to explore the formation process of seed black holes and track galactic evolution to the present day. Observations of extreme mass ratio inspirals will allow us to explore galactic centers in the local universe, as well as providing tests of General Relativity and constraining the value of Hubble's constant. The detection of compact binaries in our own galaxy may allow us to model stellar evolution in the Milky Way. Finally, the detection of cosmic (super)strings and a stochastic background would help us to constrain cosmological models. However, all of this depends on our ability to not only resolve sources and carry out parameter estimation, but also on our ability to define an optimal data analysis strategy. In this presentation, I will examine the challenges that lie ahead in GW astronomy for the ESA L3 Cosmic Vision mission, eLISA.Comment: 12 pages. Plenary presentation to appear in the Proceedings of the Sant Cugat Forum on Astrophysics, Sant Cugat, April 22-25, 201

Using electromagnetic observations to aid gravitational-wave parameter estimation of compact binaries observed with LISA

We present a first-stage study of the effect of using knowledge from electromagnetic (EM) observations in the gravitational wave (GW) data analysis of Galactic binaries that are predicted to be observed by the new Laser Interferometer Space Antenna in the low-frequency range, $10^{-4} \mathrm{Hz}<f<1 \mathrm{Hz}$. In particular, we examine the extent to which the accuracy of GW parameter estimation improves if we use available information from EM data. We do this by investigating whether correlations exist between the GW parameters that describe these binaries and whether some of these parameters are also available from EM observations. We used verification binaries, which are known as the guaranteed sources for eLISA and will test the functioning of the instrument. We find that of the seven parameters that characterise such a binary, only a few are correlated. The most useful result is the strong correlation between amplitude and inclination, which can be used to constrain the parameter uncertainty in amplitude by making use of the constraint of inclination from EM measurements. The improvement can be up to a factor of $\sim6.5$, but depends on the signal-to-noise ratio of the source data. Moreover, we find that this strong correlation depends on the inclination. For mildly face-on binaries ($\iota \lesssim 45^{\circ}$), EM data on inclination can improve the estimate of the GW amplitude by a significant factor. However, for edge-on binaries ($\iota \sim 90^{\circ}$), the inclination can be determined accurately from GW data alone, thus GW data can be used to select systems that will likely be eclipsing binaries for EM follow-up.Comment: 9 pages, 7 figures, accepted for publication by A&A Jul 23 v2: with reference

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

Post-Vasectomy Semen Analysis: Optimizing Laboratory Procedures and Test Interpretation through a Clinical Audit and Global Survey of Practices

Purpose: The success of vasectomy is determined by the outcome of a post-vasectomy semen analysis (PVSA). This article describes a step-by-step procedure to perform PVSA accurately, report data from patients who underwent post vasectomy semen analysis between 2015 and 2021 experience, along with results from an international online survey on clinical practice. Materials and methods: We present a detailed step-by-step protocol for performing and interpretating PVSA testing, along with recommendations for proficiency testing, competency assessment for performing PVSA, and clinical and laboratory scenarios. Moreover, we conducted an analysis of 1,114 PVSA performed at the Cleveland Clinic's Andrology Laboratory and an online survey to understand clinician responses to the PVSA results in various countries. Results: Results from our clinical experience showed that 92.1% of patients passed PVSA, with 7.9% being further tested. A total of 78 experts from 19 countries participated in the survey, and the majority reported to use time from vasectomy rather than the number of ejaculations as criterion to request PVSA. A high percentage of responders reported permitting unprotected intercourse only if PVSA samples show azoospermia while, in the presence of few non-motile sperm, the majority of responders suggested using alternative contraception, followed by another PVSA. In the presence of motile sperm, the majority of participants asked for further PVSA testing. Repeat vasectomy was mainly recommended if motile sperm were observed after multiple PVSA's. A large percentage reported to recommend a second PVSA due to the possibility of legal actions. Conclusions: Our results highlighted varying clinical practices around the globe, with controversy over the significance of non-motile sperm in the PVSA sample. Our data suggest that less stringent AUA guidelines would help improve test compliance. A large longitudinal multi-center study would clarify various doubts related to timing and interpretation of PVSA and would also help us to understand, and perhaps predict, recanalization and the potential for future failure of a vasectomy