Related papers: A targeted spectral interpolation algorithm for th…

Searching for gravitational-wave signals emitted by eccentric compact binaries using a non-eccentric template bank: implications for ground-based detectors

Most of the inspiralling compact binaries are expected to be circularized by the time their gravitational-wave signals enter the frequency band of ground-based detectors such as LIGO or VIRGO. However, it is not excluded that some of these…

General Relativity and Quantum Cosmology · Physics 2009-11-13 T Cokelaer , D Pathak

First all-sky search for continuous gravitational waves from unknown sources in binary systems

We present the first results of an all-sky search for continuous gravitational waves from unknown spinning neutron stars in binary systems using LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect algorithm, the…

General Relativity and Quantum Cosmology · Physics 2014-09-24 The LIGO Scientific Collaboration , the Virgo Collaboration , J. Aasi , B. P. Abbott , R. Abbott , T. Abbott , M. R. Abernathy , T. Accadia , F. Acernese , K. Ackley , C. Adams , T. Adams , P. Addesso , R. X. Adhikari , C. Affeldt , M. Agathos , N. Aggarwal , O. D. Aguiar , A. Ain , P. Ajith , A. Alemic , B. Allen , A. Allocca , D. Amariutei , M. Andersen , R. Anderson , S. B. Anderson , W. G. Anderson , K. Arai , M. C. Araya , C. Arceneaux , J. Areeda , S. M. Aston , P. Astone , P. Aufmuth , C. Aulbert , L. Austin , B. E. Aylott , S. Babak , P. T. Baker , G. Ballardin , S. W. Ballmer , J. C. Barayoga , M. Barbet , B. C. Barish , D. Barker , F. Barone , B. Barr , L. Barsotti , M. Barsuglia , M. A. Barton , I. Bartos , R. Bassiri , A. Basti , J. C. Batch , J. Bauchrowitz , Th. S. Bauer , B. Behnke , M. Bejger , M. G. Beker , C. Belczynski , A. S. Bell , C. Bell , G. Bergmann , D. Bersanetti , A. Bertolini , J. Betzwieser , P. T. Beyersdorf , I. A. Bilenko , G. Billingsley , J. Birch , S. Biscans , M. Bitossi , M. A. Bizouard , E. Black , J. K. Blackburn , L. Blackburn , D. Blair , S. Bloemen , M. Blom , O. Bock , T. P. Bodiya , M. Boer , G. Bogaert , C. Bogan , C. Bond , F. Bondu , L. Bonelli , R. Bonnand , R. Bork , M. Born , V. Boschi , Sukanta Bose , L. Bosi , C. Bradaschia , P. R. Brady , V. B. Braginsky , M. Branchesi , J. E. Brau , T. Briant , D. O. Bridges , A. Brillet , M. Brinkmann , V. Brisson , A. F. Brooks , D. A. Brown , D. D. Brown , F. Brückner , S. Buchman , T. Bulik , H. J. Bulten , A. Buonanno , R. Burman , D. Buskulic , C. Buy , L. Cadonati , G. Cagnoli , J. Calderón Bustillo , E. Calloni , J. B. Camp , P. Campsie , K. C. Cannon , B. Canuel , J. Cao , C. D. Capano , F. Carbognani , L. Carbone , S. Caride , A. Castiglia , S. Caudill , M. Cavaglià , F. Cavalier , R. Cavalieri , C. Celerier , G. Cella , C. Cepeda , E. Cesarini , R. Chakraborty , T. Chalermsongsak , S. J. Chamberlin , S. Chao , P. Charlton , E. Chassande-Mottin , X. Chen , Y. Chen , A. Chincarini , A. Chiummo , H. S. Cho , J. Chow , N. Christensen , Q. Chu , S. S. Y. Chua , S. Chung , G. Ciani , F. Clara , J. A. Clark , F. Cleva , E. Coccia , P. -F. Cohadon , A. Colla , C. Collette , M. Colombini , L. Cominsky , M. Constancio , A. Conte , D. Cook , T. R. Corbitt , M. Cordier , N. Cornish , A. Corpuz , A. Corsi , C. A. Costa , M. W. Coughlin , S. Coughlin , J. -P. Coulon , S. Countryman , P. Couvares , D. M. Coward , M. Cowart , D. C. Coyne , R. Coyne , K. Craig , J. D. E. Creighton , T. D. Creighton , S. G. Crowder , A. Cumming , L. Cunningham , E. Cuoco , K. Dahl , T. Dal Canton , M. Damjanic , S. L. Danilishin , S. D'Antonio , K. Danzmann , V. Dattilo , H. Daveloza , M. Davier , G. S. Davies , E. J. Daw , R. Day , T. Dayanga , G. Debreczeni , J. Degallaix , S. Deléglise , W. Del Pozzo , T. Denker , T. Dent , H. Dereli , V. Dergachev , R. De Rosa , R. T. DeRosa , R. DeSalvo , S. Dhurandhar , M. Díaz , L. Di Fiore , A. Di Lieto , I. Di Palma , A. Di Virgilio , A. Donath , F. Donovan , K. L. Dooley , S. Doravari , S. Dossa , R. Douglas , T. P. Downes , M. Drago , R. W. P. Drever , J. C. Driggers , Z. Du , S. Dwyer , T. Eberle , T. Edo , M. Edwards , A. Effler , H. Eggenstein , P. Ehrens , J. Eichholz , S. S. Eikenberry , G. Endrőczi , R. Essick , T. Etzel , M. Evans , T. Evans , M. Factourovich , V. Fafone , S. Fairhurst , Q. Fang , S. Farinon , B. Farr , W. M. Farr , M. Favata , H. Fehrmann , M. M. Fejer , D. Feldbaum , F. Feroz , I. Ferrante , F. Ferrini , F. Fidecaro , L. S. Finn , I. Fiori , R. P. Fisher , R. Flaminio , J. -D. Fournier , S. Franco , S. Frasca , F. Frasconi , M. Frede , Z. Frei , A. Freise , R. Frey , T. T. Fricke , P. Fritschel , V. V. Frolov , P. Fulda , M. Fyffe , J. Gair , L. Gammaitoni , S. Gaonkar , F. Garufi , N. Gehrels , G. Gemme , E. Genin , A. Gennai , S. Ghosh , J. A. Giaime , K. D. Giardina , A. Giazotto , C. Gill , J. Gleason , E. Goetz , R. Goetz , L. Gondan , G. González , N. Gordon , M. L. Gorodetsky , S. Gossan , S. Goßler , R. Gouaty , C. Gräf , P. B. Graff , M. Granata , A. Grant , S. Gras , C. Gray , R. J. S. Greenhalgh , A. M. Gretarsson , P. Groot , H. Grote , K. Grover , S. Grunewald , G. M. Guidi , C. Guido , K. Gushwa , E. K. Gustafson , R. Gustafson , D. Hammer , G. Hammond , M. Hanke , J. Hanks , C. Hanna , J. Hanson , J. Harms , G. M. Harry , I. W. Harry , E. D. Harstad , M. Hart , M. T. Hartman , C. -J. Haster , K. Haughian , A. Heidmann , M. Heintze , H. Heitmann , P. Hello , G. Hemming , M. Hendry , I. S. Heng , A. W. Heptonstall , M. Heurs , M. Hewitson , S. Hild , D. Hoak , K. A. Hodge , K. Holt , S. Hooper , P. Hopkins , D. J. Hosken , J. Hough , E. J. Howell , Y. Hu , E. Huerta , B. Hughey , S. Husa , S. H. Huttner , M. Huynh , T. Huynh-Dinh , D. R. Ingram , R. Inta , T. Isogai , A. Ivanov , B. R. Iyer , K. Izumi , M. Jacobson , E. James , H. Jang , P. Jaranowski , Y. Ji , F. Jiménez-Forteza , W. W. Johnson , D. I. Jones , R. Jones , R. J. G. Jonker , L. Ju , Haris K , P. Kalmus , V. Kalogera , S. Kandhasamy , G. Kang , J. B. Kanner , J. Karlen , M. Kasprzack , E. Katsavounidis , W. Katzman , H. Kaufer , K. Kawabe , F. Kawazoe , F. Kéfélian , G. M. Keiser , D. Keitel , D. B. Kelley , W. Kells , A. Khalaidovski , F. Y. Khalili , E. A. Khazanov , C. Kim , K. Kim , N. Kim , N. G. Kim , Y. -M. Kim , E. J. King , P. J. King , D. L. Kinzel , J. S. Kissel , S. Klimenko , J. Kline , S. Koehlenbeck , K. Kokeyama , V. Kondrashov , S. Koranda , W. Z. Korth , I. Kowalska , D. B. Kozak , A. Kremin , V. Kringel , B. Krishnan , A. Królak , G. Kuehn , A. Kumar , P. Kumar , R. Kumar , L. Kuo , A. Kutynia , P. Kwee , M. Landry , B. Lantz , S. Larson , P. D. Lasky , C. Lawrie , A. Lazzarini , C. Lazzaro , P. Leaci , S. Leavey , E. O. Lebigot , C. -H. Lee , H. K. Lee , H. M. Lee , J. Lee , M. Leonardi , J. R. Leong , A. Le Roux , N. Leroy , N. Letendre , Y. Levin , B. Levine , J. Lewis , T. G. F. Li , K. Libbrecht , A. Libson , A. C. Lin , T. B. Littenberg , V. Litvine , N. A. Lockerbie , V. Lockett , D. Lodhia , K. Loew , J. Logue , A. L. Lombardi , M. Lorenzini , V. Loriette , M. Lormand , G. Losurdo , J. Lough , M. J. Lubinski , H. Lück , E. Luijten , A. P. Lundgren , R. Lynch , Y. Ma , J. Macarthur , E. P. Macdonald , T. MacDonald , B. Machenschalk , M. MacInnis , D. M. Macleod , F. Magana-Sandoval , M. Mageswaran , C. Maglione , K. Mailand , E. Majorana , I. Maksimovic , V. Malvezzi , N. Man , G. M. Manca , I. Mandel , V. Mandic , V. Mangano , N. Mangini , M. Mantovani , F. Marchesoni , F. Marion , S. Márka , Z. Márka , A. Markosyan , E. Maros , J. Marque , F. Martelli , I. W. Martin , R. M. Martin , L. Martinelli , D. Martynov , J. N. Marx , K. Mason , A. Masserot , T. J. Massinger , F. Matichard , L. Matone , R. A. Matzner , N. Mavalvala , N. Mazumder , G. Mazzolo , R. McCarthy , D. E. McClelland , S. C. McGuire , G. McIntyre , J. McIver , K. McLin , D. Meacher , G. D. Meadors , M. Mehmet , J. Meidam , M. Meinders , A. Melatos , G. Mendell , R. A. Mercer , S. Meshkov , C. Messenger , P. Meyers , H. Miao , C. Michel , E. E. Mikhailov , L. Milano , S. Milde , J. Miller , Y. Minenkov , C. M. F. Mingarelli , C. Mishra , S. Mitra , V. P. Mitrofanov , G. Mitselmakher , R. Mittleman , B. Moe , P. Moesta , M. Mohan , S. R. P. Mohapatra , D. Moraru , G. Moreno , N. Morgado , S. R. Morriss , K. Mossavi , B. Mours , C. M. Mow-Lowry , C. L. Mueller , G. Mueller , S. Mukherjee , A. Mullavey , J. Munch , D. Murphy , P. G. Murray , A. Mytidis , M. F. Nagy , D. Nanda Kumar , I. Nardecchia , L. Naticchioni , R. K. Nayak , V. Necula , G. Nelemans , I. Neri , M. Neri , G. Newton , T. Nguyen , A. Nitz , F. Nocera , D. Nolting , M. E. N. Normandin , L. K. Nuttall , E. Ochsner , J. O'Dell , E. Oelker , J. J. Oh , S. H. Oh , F. Ohme , P. Oppermann , B. O'Reilly , R. O'Shaughnessy , C. Osthelder , D. J. Ottaway , R. S. Ottens , H. Overmier , B. J. Owen , C. Padilla , A. Pai , O. Palashov , C. Palomba , H. Pan , Y. Pan , C. Pankow , F. Paoletti , R. Paoletti , M. A. Papa , H. Paris , A. Pasqualetti , R. Passaquieti , D. Passuello , M. Pedraza , S. Penn , A. Perreca , M. Phelps , M. Pichot , M. Pickenpack , F. Piergiovanni , V. Pierro , L. Pinard , I. M. Pinto , M. Pitkin , J. Poeld , R. Poggiani , A. Poteomkin , J. Powell , J. Prasad , S. Premachandra , T. Prestegard , L. R. Price , M. Prijatelj , S. Privitera , R. Prix , G. A. Prodi , L. Prokhorov , O. Puncken , M. Punturo , P. Puppo , J. Qin , V. Quetschke , E. Quintero , G. Quiroga , R. Quitzow-James , F. J. Raab , D. S. Rabeling , I. Rácz , H. Radkins , P. Raffai , S. Raja , G. Rajalakshmi , M. Rakhmanov , C. Ramet , K. Ramirez , P. Rapagnani , V. Raymond , V. Re , J. Read , C. M. Reed , T. Regimbau , S. Reid , D. H. Reitze , E. Rhoades , F. Ricci , K. Riles , N. A. Robertson , F. Robinet , A. Rocchi , M. Rodruck , L. Rolland , J. G. Rollins , R. Romano , G. Romanov , J. H. Romie , D. Rosińska , S. Rowan , A. Rüdiger , P. Ruggi , K. Ryan , F. Salemi , L. Sammut , V. Sandberg , J. R. Sanders , V. Sannibale , I. Santiago-Prieto , E. Saracco , B. Sassolas , B. S. Sathyaprakash , P. R. Saulson , R. Savage , J. Scheuer , R. Schilling , R. Schnabel , R. M. S. Schofield , E. Schreiber , D. Schuette , B. F. Schutz , J. Scott , S. M. Scott , D. Sellers , A. S. Sengupta , D. Sentenac , V. Sequino , A. Sergeev , D. Shaddock , S. Shah , M. S. Shahriar , M. Shaltev , B. Shapiro , P. Shawhan , D. H. Shoemaker , T. L. Sidery , K. Siellez , X. Siemens , D. Sigg , D. Simakov , A. Singer , L. Singer , R. Singh , A. M. Sintes , B. J. J. Slagmolen , J. Slutsky , J. R. Smith , M. Smith , R. J. E. Smith , N. D. Smith-Lefebvre , E. J. Son , B. Sorazu , T. Souradeep , L. Sperandio , A. Staley , J. Stebbins , J. Steinlechner , S. Steinlechner , B. C. Stephens , S. Steplewski , S. Stevenson , R. Stone , D. Stops , K. A. Strain , N. Straniero , S. Strigin , R. Sturani , A. L. Stuver , T. Z. Summerscales , S. Susmithan , P. J. Sutton , B. Swinkels , M. Tacca , D. Talukder , D. B. Tanner , S. P. Tarabrin , R. Taylor , A. P. M. ter Braack , M. P. Thirugnanasambandam , M. Thomas , P. Thomas , K. A. Thorne , K. S. Thorne , E. Thrane , V. Tiwari , K. V. Tokmakov , C. Tomlinson , A. Toncelli , M. Tonelli , O. Torre , C. V. Torres , C. I. Torrie , F. Travasso , G. Traylor , M. Tse , D. Ugolini , C. S. Unnikrishnan , A. L. Urban , K. Urbanek , H. Vahlbruch , G. Vajente , G. Valdes , M. Vallisneri , J. F. J. van den Brand , C. Van Den Broeck , S. van der Putten , M. V. van der Sluys , J. van Heijningen , A. A. van Veggel , S. Vass , M. Vasúth , R. Vaulin , A. Vecchio , G. Vedovato , J. Veitch , P. J. Veitch , K. Venkateswara , D. Verkindt , S. S. Verma , F. Vetrano , A. Viceré , R. Vincent-Finley , J. -Y. Vinet , S. Vitale , T. Vo , H. Vocca , C. Vorvick , W. D. Vousden , S. P. Vyachanin , A. Wade , L. Wade , M. Wade , M. Walker , L. Wallace , M. Wang , X. Wang , R. L. Ward , M. Was , B. Weaver , L. -W. Wei , M. Weinert , A. J. Weinstein , R. Weiss , T. Welborn , L. Wen , P. Wessels , M. West , T. Westphal , K. Wette , J. T. Whelan , D. J. White , B. F. Whiting , K. Wiesner , C. Wilkinson , K. Williams , L. Williams , R. Williams , T. Williams , A. R. Williamson , J. L. Willis , B. Willke , M. Wimmer , W. Winkler , C. C. Wipf , A. G. Wiseman , H. Wittel , G. Woan , J. Worden , J. Yablon , I. Yakushin , H. Yamamoto , C. C. Yancey , H. Yang , Z. Yang , S. Yoshida , M. Yvert , A. Zadrożny , M. Zanolin , J. -P. Zendri , Fan Zhang , L. Zhang , C. Zhao , X. J. Zhu , M. E. Zucker , S. Zuraw , J. Zweizig

Improved Hough search for gravitational wave pulsars

We describe an improved version of the Hough transform search for continuous gravitational waves from isolated neutron stars assuming the input to be short segments of Fourier transformed data. The method presented here takes into account…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Alicia M. Sintes , Badri Krishnan

Self-calibration of Networks of Gravitational Wave Detectors

As LIGO and Virgo are upgraded, improving calibration systems to keep pace with the anticipated signal-to-noise enhancements will be challenging. We explore here a calibration method that uses astronomical signals, namely inspiral signals…

General Relativity and Quantum Cosmology · Physics 2020-09-23 B. F. Schutz , B. S. Sathyaprakash

A weighted multidetector extension to the 5-vector method for the search of continuous gravitational wave signals

The 5-vector method is one of the main pipeline used by the LIGO-Virgo-KAGRA Collaboration for the analysis of continuous gravitational waves (CWs). This method is a matched filter in the frequency domain based on the splitting in five…

General Relativity and Quantum Cosmology · Physics 2023-11-27 Luca D'Onofrio , Rosario De Rosa , Cristiano Palomba

Doppler orbital correction for the targeted search of known pulsars with the 5-vector method

Pulsars are promising targets for the first detection of continuous gravitational waves (CWs) by the LIGO-Virgo-KAGRA (LVK) Collaboration. Targeted searches leverage critical information derived from continued monitoring of pulsars related…

General Relativity and Quantum Cosmology · Physics 2023-11-27 Luca D'Onofrio , Rosario De Rosa , Paola Leaci , Cristiano Palomba

Leveraging waveform complexity for confident detection of gravitational waves

The recent completion of Advanced LIGO suggests that gravitational waves (GWs) may soon be directly observed. Past searches for gravitational-wave transients have been impacted by transient noise artifacts, known as glitches, introduced…

Instrumentation and Methods for Astrophysics · Physics 2016-01-27 Jonah B. Kanner , Tyson B. Littenberg , Neil Cornish , Meg Millhouse , Enia Xhakaj , Francesco Salemi , Marco Drago , Gabriele Vedovato , Sergey Klimenko

New semicoherent targeted search for continuous gravitational waves from pulsars in binary systems

We present a novel semicoherent targeted search method for continuous gravitational waves (CWs) emitted by pulsars in binary systems. The method is based on a custom optimization of the coherence time, which is tailored according to the…

General Relativity and Quantum Cosmology · Physics 2025-01-06 Lorenzo Mirasola , Paola Leaci , Pia Astone , Luca D'Onofrio , Simone Dall'Osso , Alessandro De Falco , Michela Lai , Simone Mastrogiovanni , Cristiano Palomba , Alessandro Riggio , Andrea Sanna

Chasing 5-sigma: Prospects for searches for long-duration gravitational-waves without time slides

The detection of unmodeled gravitational-wave bursts by ground-based interferometric gravitational-wave detectors is a major goal for the advanced detector era. These searches are commonly cast as pattern recognition problems, where the…

General Relativity and Quantum Cosmology · Physics 2015-08-26 Michael Coughlin , Patrick Meyers , Shivaraj Kandhasamy , Eric Thrane , Nelson Christensen

Search for Continuous Gravitational Wave Signals in Pulsar Timing Residuals: A New Scalable Approach with Diffusive Nested Sampling

Detecting continuous nanohertz gravitational waves (GWs) generated by individual close binaries of supermassive black holes (CB-SMBHs) is one of the primary objectives of pulsar timing arrays (PTAs). The detection sensitivity is slated to…

Instrumentation and Methods for Astrophysics · Physics 2021-12-08 Yu-Yang Songsheng , Yi-Qian Qian , Yan-Rong Li , Pu Du , Jie-Wen Chen , Yan Wang , Soumya D. Mohanty , Jian-Min Wang

Advancements in Glitch Subtraction Systems for Enhancing Gravitational Wave Data Analysis: A Brief Review

Glitches are transitory noise artifacts that degrade the detection sensitivity and accuracy of interferometric observatories such as LIGO and Virgo in gravitational wave astronomy. Reliable glitch subtraction techniques are essential for…

General Relativity and Quantum Cosmology · Physics 2024-06-04 Mohammad Abu Thaher Chowdhury

Mitigation of Incoherent Spectral Lines via Adaptive Coherence Analysis for Continuous Gravitational-Wave Searches

The sensitivity of continuous gravitational-wave searches is strictly limited by non-Gaussian spectral artefacts that accumulate coherent power over long observation baselines. In this paper, we present an unsupervised mitigation framework…

General Relativity and Quantum Cosmology · Physics 2026-04-03 Ye Zhou , Karl Wette

Improving the efficiency of the detection of gravitational wave signals from inspiraling compact binaries: Chebyshev interpolation

Inspiraling compact binaries are promising sources of gravitational waves for ground and space-based laser interferometric detectors. The time-dependent signature of these sources in the detectors is a well-characterized function of a…

General Relativity and Quantum Cosmology · Physics 2015-06-25 S. Mitra , S. V. Dhurandhar , L. S. Finn

Method for detection and reconstruction of gravitational wave transients with networks of advanced detectors

We present a method for detection and reconstruction of the gravitational-wave (GW) transients with the networks of advanced detectors. Originally designed to search for transients with the initial GW detectors, it uses significantly…

General Relativity and Quantum Cosmology · Physics 2016-02-17 S. Klimenko , G. Vedovato , M. Drago , F. Salemi , V. Tiwari , G. A. Prodi , C. Lazzaro , K. Ackley , S. Tiwari , C. F. Da Silva Cost- , G. Mitselmakher

Searching for Gravitational Waves from Compact Binaries with Precessing Spins

Current searches for gravitational waves from compact-object binaries with the LIGO and Virgo observatories employ waveform models with spins aligned (or anti-aligned) with the orbital angular momentum. Here, we derive a new statistic to…

General Relativity and Quantum Cosmology · Physics 2016-07-14 Ian Harry , Stephen Privitera , Alejandro Bohé , Alessandra Buonanno

Model-Based Cross-Correlation Search for Gravitational Waves from Scorpius X-1

We consider the cross-correlation search for periodic GWs and its potential application to the LMXB Sco X-1. This method coherently combines data from different detectors at the same time, as well as different times from the same or…

General Relativity and Quantum Cosmology · Physics 2015-05-21 John T. Whelan , Santosh Sundaresan , Yuanhao Zhang , Prabath Peiris

First Low-Latency LIGO+Virgo Search for Binary Inspirals and their Electromagnetic Counterparts

Aims. The detection and measurement of gravitational-waves from coalescing neutron-star binary systems is an important science goal for ground-based gravitational-wave detectors. In addition to emitting gravitational-waves at frequencies…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 The LIGO Scientific Collaboration , The Virgo Collaboration

Time-frequency detection of Gravitational Waves

We present a time-frequency method to detect gravitational wave signals in interferometric data. This robust method can detect signals from poorly modeled and unmodeled sources. We evaluate the method on simulated data containing noise and…

General Relativity and Quantum Cosmology · Physics 2009-12-30 Warren G. Anderson , R. Balasubramanian

Toward low-latency coincident precessing and coherent aligned-spin gravitational-wave searches of compact binary coalescences with particle swarm optimization

We investigate the use of particle swarm optimization (PSO) algorithm for detection of gravitational-wave signals from compact binary coalescences. We show that the PSO is fast and effective in searching for gravitational wave signals. The…

Instrumentation and Methods for Astrophysics · Physics 2018-11-16 Varun Srivastava , K Rajesh Nayak , Sukanta Bose

Searching for periodic sources with LIGO

We investigate the computational requirements for all-sky, all-frequency searches for gravitational waves from spinning neutron stars, using archived data from interferometric gravitational wave detectors such as LIGO. These sources are…

General Relativity and Quantum Cosmology · Physics 2011-05-05 Patrick R. Brady , Teviet Creighton , Curt Cutler , Bernard F. Schutz