The JCMT Transient Survey: Four-year Summary of Monitoring the Submillimeter Variability of Protostars

We present the four-year survey results of monthly submillimeter monitoring of eight nearby (<500 pc) star-forming regions by the JCMT Transient Survey. We apply the Lomb–Scargle Periodogram technique to search for and characterize variability on 295 submillimeter peaks brighter than 0.14 Jy beam−1, including 22 disk sources (Class II), 83 protostars (Class 0/I), and 190 starless sources. We uncover 18 secular variables, all of them protostars. No single-epoch burst or drop events and no inherently stochastic sources are observed. We classify the secular variables by their timescales into three groups: Periodic, Curved, and Linear. For the Curved and Periodic cases, the detectable fractional amplitude, with respect to mean peak brightness, is ∼4% for sources brighter than ∼0.5 Jy beam−1. Limiting our sample to only these bright sources, the observed variable fraction is 37% (16 out of 43). Considering source evolution, we find a similar fraction of bright variables for both Class 0 and Class I. Using an empirically motivated conversion from submillimeter variability to variation in mass accretion rate, six sources (7% of our full sample) are predicted to have years-long accretion events during which the excess mass accreted reaches more than 40% above the total quiescently accreted mass: two previously known eruptive Class I sources, V1647 Ori and EC 53 (V371 Ser), and four Class 0 sources, HOPS 356, HOPS 373, HOPS 383, and West 40. Considering the full protostellar ensemble, the importance of episodic accretion on few years timescale is negligible—only a few percent of the assembled mass. However, given that this accretion is dominated by events on the order of the observing time window, it remains uncertain as to whether the importance of episodic events will continue to rise with decades-long monitoring

Areas of environmental concern in the Netherlands

Veel woongebieden in Nederland ondervinden milieuproblemen. Vooral de grote steden hebben last van geluidsoverlast en vervuilde lucht, door hoge concentraties fijn stof, stikstofdioxide en omgevingslawaai. Deze problemen spelen vooral in Rotterdam, Amsterdam, Den Haag, Utrecht en Noord-Brabant. Dit blijkt uit een globale kwaliteitinventarisatie door het RIVM van de milieuproblemen in 2008. Hierbij werd gekeken naar de kwaliteit van lucht, geluid en bodem en naar lokale risico's op het gebied van externe veiligheid. Per postcodegebied staat op de kaarten aangegeven welke milieuproblemen zich daar voordoen en hoe ernstig ze zijn. Deze kaarten en onderliggende gegevens zijn te raadplegen op: http://geodata.rivm.nl/gmr/gmr.html De kaarten zijn bedoeld voor beleidsmakers, planologen en de lokale bevolking. Zij bieden een overzicht van de gebieden waarin aandacht voor het milieu nodig is. Daarnaast hebben ze een signalerende functie voor nieuwe ruimtelijke ontwikkelingen, zoals grootschalige nieuwbouw op milieubelaste onbebouwde locaties. Deze milieukwaliteitinventarisatie omvat voor het eerst alle postcodegebieden in Nederland en niet alleen de stedelijke gebieden. Bovendien is een aantal geluidaspecten toegevoegd: luchtvaartgeluid, windturbinegeluid en de kans op geluidhinder door grote industrieterreinen. De inventarisatie is niet uitputtend, nog niet alle milieuaspecten zijn tot dusver in kaart gebracht. Dit geldt onder andere voor straling, mogelijke risico's door hoogspanningsleidingen of lokale geluidproblematiek door bedrijven. Ook groepsrisico's (externe veiligheid) en asbestverontreiniging konden nog niet worden meegenomen.Many residential areas in the Netherlands experience environmental problems. These are particularly evident within the major cities, which suffer from the effects of noise pollution due to increasing exposure to noise in the surroundings and air pollution, resulting from fine particles and nitrogen dioxide in the air. The cities of Amsterdam, Rotterdam, The Hague and Utrecht and the Province of North Brabant are specific examples of areas where such environmental problems play a major role. This is the conclusion drawn by the National Institute for Public Health and the Environment (RIVM) based on an inventory it carried in 2008. The inventory comprised an assessment of air quality, noise, soil and external safety risks and is presented as a set of colour-coded maps and associated data. For each postal area in the Netherlands, the maps show the type of environmental damage occurring and the number of dwellings exposed. The postal maps and results are available at: http://geodata.rivm.nl/gmr/gmr.html. The maps provide policy makers, urban planners and local populations with a comprehensive overview of the residential areas urgently needing attention from an environmental standpoint. They can also be used for global assessments of new development plans. This inventory is the first of its kind to provide quantitative environmental data on all postal areas in the Netherlands - and not only on urban regions. A number of parameters associated with noise pollution have also been included, such as noise from airports, noise risks from large industrial areas and wind turbine noise. The inventory in its present form is not conclusive as some environmental aspects remain as yet unsurveyed. These include possible risks arising from exposure to radiation, power pylons and other (local) industries. Accumulated safety risks to specific groups and asbestos pollution could also not yet be included.VROM-DGM-LM

The interactional consequences of epistemic indexicality – some thoughts on the epistemic marker -kamoshirenai

This chapter of the edited collection attempts to flesh out the implications of a conceptualization of modality as a fundamentally deictic system, i.e. one that indexes the speaker’s position towards the information and the participants’ knowledge thereof. The first implication is that the functional meanings achieved in interaction cannot be thought of as ‘encoded’ in a specific modal marker but they are rather contingent and ‘emergent’: they are derived from the combination of a marker’s indexical meaning with contextual (i.e. discursive and interactional) factors. They are therefore volatile, and never entirely predictable. The second implication is that, since issues of knowledge are never socially neutral, the speaker’s orientation toward the information is of significant interactional importance and the use of a modal is likely to be sensitive to social positioning in discourse. Pizziconi suggests that the study of modality in actual interaction benefits from, and at the same time provides a test for other types of analyses, and that research from an interactional perspective can shed light on the communicative role of modal markers in the construction of cognitive, affective and ultimately socio-cultural stances

The JCMT Transient Survey: Four-year Summary of Monitoring the Submillimeter Variability of Protostars

This is the author accepted manuscript. The final version is available from IOP Publishing via the DOI in this recordWe present the four-year survey results of monthly submillimeter monitoring of eight nearby (<500 pc) star-forming regions by the JCMT Transient Survey. We apply the Lomb–Scargle Periodogram technique to search for and characterize variability on 295 submillimeter peaks brighter than 0.14 Jy beam−1, including 22 disk sources (Class II), 83 protostars (Class 0/I), and 190 starless sources. We uncover 18 secular variables, all of them protostars. No single-epoch burst or drop events and no inherently stochastic sources are observed. We classify the secular variables by their timescales into three groups: Periodic, Curved, and Linear. For the Curved and Periodic cases, the detectable fractional amplitude, with respect to mean peak brightness, is ∼4% for sources brighter than ∼0.5 Jy beam−1. Limiting our sample to only these bright sources, the observed variable fraction is 37% (16 out of 43). Considering source evolution, we find a similar fraction of bright variables for both Class 0 and Class I. Using an empirically motivated conversion from submillimeter variability to variation in mass accretion rate, six sources (7% of our full sample) are predicted to have years-long accretion events during which the excess mass accreted reaches more than 40% above the total quiescently accreted mass: two previously known eruptive Class I sources, V1647 Ori and EC 53 (V371 Ser), and four Class 0 sources, HOPS 356, HOPS 373, HOPS 383, and West 40. Considering the full protostellar ensemble, the importance of episodic accretion on few years timescale is negligible—only a few percent of the assembled mass. However, given that this accretion is dominated by events on the order of the observing time window, it remains uncertain as to whether the importance of episodic events will continue to rise with decades-long monitoring