Data Analysis of the Allegro Gravitational Wave Detector.

The Allegro gravitational wave detector has been operational from 1991-1994, and 1996-present. We present a detailed description of the detector and the data acquisition system. Two distinct types of data analysis are detailed. First, we describe the search for burst sources of gravitational radiation. These are impulse forces acting on the bar, presumably from the stellar collapse associated with supernovae. Construction of the optimal filter for burst signals is described, as well as its application to the data from the detector. The uncertainties introduced into timing and signal strength estimates due to stationary noise are measured, giving the windows for both quantities in coincidence searches. Second, we describe a very different type of analysis, the search for a continuous source of gravitational radiation from a rotating neutron star. Unlike the burst events which last on the order of a millisecond, this signal is expected to persist for the duration of the experiment. Since Allegro is sensitive at frequencies near 1 kHz, only neutron stars with spin periods near 2 ms are potential sources. Since there are no known sources of this type for Allegro, we directed the search towards the globular cluster 47 Tucanae. This was due to the large number of millisecond pulsars located there. No claim to have detected a CW signal is made, although a number of candidates are identified. The analysis puts a constraint of 3\times10\sp{-24} on the gravitational strain emitted from a pulsar in 47 Tucanae

La metanfetamina induce nel topo inclusioni neuronali e un incremento di alfa-sinucleina all'interno dei neuroni dopaminergici

La presenza di inclusioni neuronali è una caratteristica anatomopatologica di un ampio numero di malattie neurodegenerative come la Malattia di Parkinson (MdP). Questi inclusi, noti anche come corpi di Lewy, sono inclusioni di natura principalmente proteica che si trovano all’interno dei neuroni dopaminergici della substantia nigra pars-compacta (SNpc), nei neuroni della corteccia cerebrale e nel proencefalo basale. Queste inclusioni sono state descritte come aggregati citoplasmatici neuronali debolmente eosinofili. L’accumulo di questi aggregati citoplasmatici, è un fenomeno complesso che può avere molte cause. Uno dei meccanismi biochimici che possono causare l’accumulo di tali formazioni, è rappresentato dal sistema Ubiquitina-Proteasoma che, insieme all’autofagia, è il principale meccanismo cellulare di degradazione delle proteine anomale, mutate o eccessivamente espresse. Il mancato funzionamento del sistema Ubiquitina-Proteasoma, anche in maniera parziale, infatti, è in grado di determinare un accumulo di proteine nel citosol cellulare che, aggregandosi, formano le inclusioni o corpi di Lewy. Presenza costante nei corpi di Lewy è l’alfa-sinucleina, una proteina presinaptica la cui funzione è ancora in gran parte sconosciuta. L’alfa-sinucleina è presente nei corpi di Lewy, fin dai primi stadi della loro formazione tanto che ne costituisce il marker specifico. Gli studi condotti dal nostro gruppo su cellule PC12 trattate con metanfetamina (METH) hanno permesso di osservare la formazione di inclusioni citoplasmatiche contenenti alfa-sinucleina. Al fine di indagare questo fenomeno in maniera più approfondita, abbiamo condotto una serie di ricerche in vivo su topi C57/Black (N=40). Al primo gruppo di animali (N=20) è stata somministrata (i.p.) METH alla dose di 5 mg/kg per tre volte ad intervalli di due ore, mentre al secondo gruppo (N=20), e stata somministrata soluzione salina con le stesse modalità e con le stesse tempistiche. I topi trattati e di controllo sono stati sacrificati dopo sette giorni dalla somministrazione. Nove topi per gruppo sono stati usati per indagini morfologiche (microscopia ottica e microscopia elettronica) mentre i rimanenti, undici topi per gruppo, sono stati impiegati sia per l’analisi con Western Blotting che per il dosaggio delle monoamine mediante HPLC. Il modello sperimentale di MdP da noi utilizzato è stato validato per mezzo della microscopia ottica e dei saggi biochimici. Nei topi trattati con METH si è osservata una notevole denervazione dopaminergica striatale consistente con una significativa riduzione della dopamina striatale e dei suoi principali metaboliti rispetto ai controlli Inoltre, nei neuroni dopaminergici della SNpc abbiamo potuto osservare la presenza di inclusioni positive per l’?-sinucleina ed un aumento dell’espressione dell’ alfa-sinucleina stessa. La somministrazione di METH induce quindi una significativa riduzione dei terminali dopaminergici a livello striatale ed un incremento nell’espressione di alfa-sinucleina nei neuroni dopaminergici della SNpc. Inoltre, l’aumento di alfa-sinucleina è strettamente correlato alla formazione di inclusi neuronali, nei quali questa proteina è costantemente presente

On Upper Limits for Gravitational Radiation

A procedure with a Bayesan approach for calculating upper limits to gravitational wave bursts from coincidence experiments with multiple detectors is described.Comment: 10 pages, 2 figures, latex files using cernlik.cls (included). This paper and related work are also available at http://grwav3.roma1.infn.it/pia/papersweb.html Version number 2: text unchanged. Modified two references, adding the hep number

An Effective Search Method for Gravitational Ringing of Black Holes

We develop a search method for gravitational ringing of black holes. The gravitational ringing is due to complex frequency modes called the quasi-normal modes that are excited when a black hole geometry is perturbed. The detection of it will be a direct confirmation of the existence of a black hole. Assuming that the ringdown waves are dominated by the fundamental mode with least imaginary part, we consider matched filtering and develop an optimal method to search for the ringdown waves that have damped sinusoidal wave forms. When we use the matched filtering method, the data analysis with a lot of templates required. Here we have to ensure a proper match between the filter as a template and the real wave. It is necessary to keep the detection efficiency as high as possible under limited computational costs. First, we consider the white noise case for which the matched filtering can be studied analytically. We construct an efficient method for tiling the template space. Then, using a fitting curve of the TAMA300 DT6 noise spectrum, we numerically consider the case of colored noise. We find our tiling method developed for the white noise case is still valid even if the noise is colored.Comment: 17 pages, 9 figures. Accepted to Phys. Rev. D, Note correction to Eq. (3-25), A few comments added and minor typos correcte

Stochastic Background Search Correlating ALLEGRO with LIGO Engineering Data

We describe the role of correlation measurements between the LIGO interferometer in Livingston, LA, and the ALLEGRO resonant bar detector in Baton Rouge, LA, in searches for a stochastic background of gravitational waves. Such measurements provide a valuable complement to correlations between interferometers at the two LIGO sites, since they are sensitive in a different, higher, frequency band. Additionally, the variable orientation of the ALLEGRO detector provides a means to distinguish gravitational wave correlations from correlated environmental noise. We describe the analysis underway to set a limit on the strength of a stochastic background at frequencies near 900 Hz using ALLEGRO data and data from LIGO's E7 Engineering Run.Comment: 8 pages, 2 encapsulated PostScript figures, uses IOP class files, submitted to the proceedings of the 7th Gravitational Wave Data Analysis Workshop (which will be published in Classical and Quantum Gravity

The Allegro gravitational wave detector: Data acquisition and analysis

We discuss the data acquisition and analysis procedures used on the Allegro gravity wave detector, including a full description of the filtering used for bursts of gravity waves. The uncertainties introduced into timing and signal strength estimates due to stationary noise are measured, giving the windows for both quantities in coincidence searches.Comment: 26 pages, 18 figure

An all-sky search algorithm for continuous gravitational waves from spinning neutron stars in binary systems

Rapidly spinning neutron stars with non-axisymmetric mass distributions are expected to generate quasi-monochromatic continuous gravitational waves. While many searches for unknown, isolated spinning neutron stars have been carried out, there have been no previous searches for unknown sources in binary systems. Since current search methods for unknown, isolated neutron stars are already computationally limited, expanding the parameter space searched to include binary systems is a formidable challenge. We present a new hierarchical binary search method called TwoSpect, which exploits the periodic orbital modulations of the continuous waves by searching for patterns in doubly Fourier-transformed data. We will describe the TwoSpect search pipeline, including its mitigation of detector noise variations and corrections for Doppler frequency modulation caused by changing detector velocity. Tests on Gaussian noise and on a set of simulated signals will be presented.Comment: 22 pages, 10 figures, 1 table, Submitted to Classical and Quantum Gravit

A method for detecting gravitational waves coincident with gamma ray bursts

The mechanism for gamma ray bursters and the detection of gravitational waves (GWs) are two outstanding problems facing modern physics. Many models of gamma ray bursters predict copious GW emission, so the assumption of an association between GWs and GRBs may be testable with existing bar GW detector data. We consider Weber bar data streams in the vicinity of known GRB times and present calculations of the expected signal after co-addition of 1000 GW/GRBs that have been shifted to a common zero time. Our calculations are based on assumptions concerning the GW spectrum and the redshift distribution of GW/GRB sources which are consistent with current GW/GRB models. We discuss further possibilities of GW detection associated with GRBs in light of future bar detector improvements and suggest that co-addition of data from several improved bar detectors may result in detection of GWs (if the GW/GRB assumption is correct) on a time scale comparable with the LIGO projects.Comment: Accepted by MNRAS. 9 pages, 6 ps figures, MNRAS style. Proof corrections made, accepted versio

Study of the coincidences between the gravitational wave detectors EXPLORER and NAUTILUS in 2001

We report the result from a search for bursts of gravitational waves using data collected by the cryogenic resonant detectors EXPLORER and NAUTILUS during the year 2001, for a total measuring time of 90 days. With these data we repeated the coincidence search performed on the 1998 data (which showed a small coincidence excess) applying data analysis algorithms based on known physical characteristics of the detectors. With the 2001 data a new interesting coincidence excess is found when the detectors are favorably oriented with respect to the Galactic Disk