Maatregelen bij zelfstandig leren : Handreiking bij een onderzoek naar didactische en organisatorische maatregelen ten behoeve van zelfstandig werken en leren in het Studiehuis

Dit is een Ico-Isor rappor

Praktische opdrachten bij Grieks en Latijn

Dit is een Ico-Isor rappor

Скринінг діазотрофів, що здатні утворювати ефективні асоціації з рослинами пшениці

Проведено скринінг діазотрофів, виділених з ризосфери та ризоплани рослин пшениці 13 сортів. Показано, що найвищою нітрогеназною активністю характеризувався штам Azospirillum � � sp. 77, виділений з ризоплани ярої пшениці сорту Варяг. Інокуляція зазначеним штамом насіння пшениці сприяла підвищенню його схожості на 22,3 % та сухої маси паростків на 18,2 % у порівнянні з контролем, що свідчить про здатність Azospirillum sp. 77 виділяти біологічно активні речовини. Досліджуваний штам індукує деформації кореневих волосків, що підтверджує властивість Azospirillum sp. 77 викликати реакцію рослин пшениці сорту Варяг на інокуляцію. За даними попереднього скринінгу відібрано штам, здатний утворювати ефективні асоціації з рослинами пшениці.Проведен скрининг диазотрофов, выделенных из ризосферы и ризопланы растений пшеницы 13 сортов. Показано, что наибольшей нитрогеназной активностью характеризовался штамм Azospirillum sp. 77, выделенный из ризопланы яровой пшеницы сорта Варяг. Инокуляция указанным штаммом семян пшеницы способствовала увеличению всхожести на 22,3 % и сухой массы проростков на 18,2 %. в сравнении с контролем, что свидетельствует о способности Azospirillum sp. 77 выделять биологически активные вещества. Исследуемый штамм индуцирует деформации корневых волосков, что подтверждает способность Azospirillum sp. 77 вызывать реакцию растений пшеницы сорта Варяг на инокуляцию. По данным предварительного скрининга отобран штамм, способный образовывать эффективные ассоциации с растениями пшеницы.It is carried out a screening of diazotrophs, allocated from rhizosphere and rhizoplane of wheat plants of 13 sorts. It is shown, that strain Azospirillum sp. 77, allocated from rhizoplane of a spring wheat of sort Varyag, was characterized by the greatest nitrogenase activity. Inoculation of wheat seeds by specified strain promoted the increase of its germination on 22,3 % and dry weight of sprouts increase on 18,2 % in comparison with the control, that testifies the ability of Azospirillum sp. 77 to produce biologically active substances. The researched strain causes deformations of root fuzz that confirms the ability of Azospirillum sp. 77 to cause reaction on inoculation of wheat plants sorts Varyag. According to preliminary screening it is selected the strain, which capable to form effective associations with wheat plants

Perspectieven voor hoogveenherstel in Nederland : samenvatting onderzoek en handleiding hoogveenherstel 1998-2010

Het hoogveenareaal in Nederland is door ontginning, turfwinning, boekweitbrandcultuur en verdroging sterk gereduceerd. De water- en nutriëntenhuishouding van de hoogvenen zijn sterk verstoord door deze aantastingen en bovendien door de neerslag van atmosferisch stikstof (N). Verder is door deze aantastingen de variatie in terreincondities die aanwezig is in intacte hoogveenlandschappen, met name gradiënten van de zure, mineraalarme hoogveenkern naar de gebufferde, mineraalrijkere omgeving, afgenomen. Herstelmaatregelen in de hoogveenrestanten hadden wisselend succes: soms herstelden of ontwikkelden zich vegetaties met bultvormende veenmossen, meestal ontstond een drijvende laag Waterveenmos (Sphagnum cuspidatum) of een zure waterplas. Verder bleef Pijpenstrootje (Molinia caerulea) over grote oppervlakten de vegetatie domineren en vestigden zich Berken (Betula spec.). In het kader van het kennisnetwerk ‘Ontwikkeling en Beheer Natuurkwaliteit’ (OBN) is onderzoek gedaan naar de perspectieven voor hoogveenherstel in Nederland. Twee vragen stonden daarbij centraal: 1. Is hoogveenherstel mogelijk bij de huidige hoge atmosferische N-depositie? 2. Onder welke voorwaarden is succesvol herstel van de karakteristieke flora en fauna mogelijk? De belangrijkste conclusies uit dit onderzoek worden in dit rapport beschreven

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society