Long-term polarimetric observations of OH127.8+0.0

OH 1612 and 1667 MHz masers from the well known object OH127.8+0.0 were mon- itored in full-polarization mode over a period of 6.5 years and mapped with MERLIN at one epoch. The OH variability pattern of the star is typical of extremely long- period AGB stars. The distance determined from the 1612 MHz light curve and a new measurement of the angular radius is 3.87 (0.28) kpc. At both frequencies, the flux of polarized emission tightly follows the total flux variations while, the degrees of circu- lar and linear polarization are constant within measurement accuracy.. There is net polarization at both lines. The magnetic field strength estimated from a likely Zeeman pair is -0.6 mG at the distance of 5400 au from the star.At the near and far sides of the envelope, the polarization vectors are well aligned implying a regular structure of the magnetic field. The polarization characteristics of the OH maser emission suggest a radial magnetic field which is frozen in the stellar wind.Comment: 12 pages, 9 figure

Milliarcsecond structure of water maser emission in two young high-mass stellar objects associated with methanol masers

The 22.2 GHz water masers are often associated with the 6.7 GHz methanol masers but owing to the different excitation conditions they likely probe independent spatial and kinematic regions around the powering young massive star. We compared the emission of these two maser species on milliarcsecond scales to determine in which structures the masers arise and to test a disc-outflow scenario where the methanol emission arises in a circumstellar disc while the water emission comes from an outflow. We obtained high-angular and spectral resolution 22.2 GHz water maser observations of the two sources G31.581+00.077 and G33.641-00.228 using the EVN. In both objects the water maser spots form complex and filamentary structures of sizes 18-160 AU. The emission towards the source G31.581+00.077 comes from two distinct regions of which one is related to the methanol maser source of ring-like shape. In both targets the main axis of methanol distribution is orthogonal to the water maser distribution. Most of water masers appear to trace shocks on a working surface between an outflow/jet and a dense envelope. Some spots are possibly related to the disc-wind interface which is as close as 100-150 AU to the regions of methanol emission.Comment: 10 pages, accepted to Astronomy and Astrophysic

Magnetic field in Cepheus A as deduced from OH maser polarimetric observations

We present the results of MERLIN polarization mapping of OH masers at 1665 and 1667 MHz towards the Cepheus A star-forming region. The maser emission is spread over a region of 6 arcsec by 10 arcsec, twice the extent previously detected. In contrast to the 22 GHz water masers, the OH masers associated with H II regions show neither clear velocity gradients nor regular structures. We identified ten Zeeman pairs which imply a magnetic field strength along the line-of-sight from -17.3 to +12.7 mG. The magnetic field is organised on the arcsecond scale, pointing towards us in the west and away from us in the east side. The linearly polarized components, detected for the first time, show regularities in the polarization position angles depending on their position. The electric vectors of OH masers observed towards the outer parts of H II regions are consistent with the interstellar magnetic field orientation, while those seen towards the centres of H II regions are parallel to the radio-jets. A Zeeman quartet inside a southern H II region has now been monitored for 25 years; we confirm that the magnetic field decays monotonically over that period.Comment: 10 pages, 6 figures,accepted for publication in MNRA

Lexical development in language acquistion and learning

Rozdział poświęcony jest zagadnieniom związanym z przyswajaniem słownictwa obcojęzycznego. Omawia różne znaczenia takich pojęć, jak słownik (ang. lexicon), słownik wewnętrzny (ang. mental lexicon) i słowo (ang. word). Analizuje odpowiedź na pytanie „Co to znaczy znać dane słowo?” w odniesieniu do takich aspektów wiedzy leksykalnej, jak wymowa, pisownia, świadomość budowy wyrazu, łączenie formy słowa z jego znaczeniem, skojarzenia i związki między wyrazami, funkcje gramatyczne, kolokacje, ograniczenia co do użycia słowa. Zagadnienie słownika wewnętrznego przedstawione jest w kontekście wybranych modeli przetwarzania słownictwa. Podniesiono również kwestię integracji i rozdziału wewnętrznych słowników dwujęzycznych. Omówiono etapy przyswajania słownictwa języka pierwszego oraz zagadnienia dotyczące przyswajania słownictwa języka drugiego w nawiązaniu do wspomnianych wcześniej aspektów wiedzy leksykalnej