No abstract

Our study shows that: (i) altered activity variants of CYP2C9, CYP2C19, and CYP2D6 occur globally in all geographic regions, reaching extremely high frequencies in some populations; (ii) each of the CYP genes studied shows a distinct geographic pattern of variation; (iii) population substructure can strongly affect the variation seen in pharmacogenetic loci; and (iv) several geographic regions of pharmacogenetic interest are still poorly characterized.

The aim of this paper is to quantitatively testify the ‘small‐scale sequential star formation’ hypothesis in and around bright‐rimmed clouds (BRCs). As a continuation of the recent attempt by Ogura et al., we have carried out BVIc photometry of four more BRC aggregates along with deeper re‐observations of two previously observed BRCs. Again, quantitative age gradients are found in almost all the BRCs studied in the present work. Archival Spitzer/Infrared Array Camera data also support this result. The global distribution of near‐infrared excess stars in each H ii region studied here clearly shows evidence that a series of radiation‐driven implosion processes proceeded in the past from near the central O star(s) towards the peripheries of the H ii region. We found that in general weak‐line T‐Tauri stars (WTTSs) are somewhat older than classical T‐Tauri stars (CTTSs). Also the fraction of CTTSs among the T‐Tauri stars (TTSs) associated with the BRCs is found to decrease with age. These facts are in accordance with the recent conclusion by Bertout, Siess & Cabrit that CTTSs evolve into WTTSs. It seems that in general the equivalent width of Hα emission in TTSs associated with the BRCs decreases with age. The mass function (MF) of the aggregates associated with the BRCs of the morphological type ‘A’ seems to follow that found in young open clusters, whereas ‘B/C’‐type BRCs show significantly steeper MF.

We present optical photometric and polarimetric observations of stars towards NGC 1931 with the aim to derive the cluster parameters such as distance, reddening, age and luminosity/mass function as well as to understand the dust properties and star formation in the region. The distance to the cluster is found to be 2.3±0.3 kpc and the reddening E(B − V ) in the region is found to be variable. The stellar density contours reveal two clustering in the region. The observations suggest differing reddening law within the cluster region. Polarization efficiency of the dust grains towards the direction of the cluster is found to be less than that for the general diffuse interstellar medium (ISM). The slope of the mass function (-0.98±0.22) in the southern region in the mass range 0.8 < M/M ⊙ < 9.8 is found to be shallower in comparison to that in the northern region (-1.26±0.23), which is comparable to the Salpeter value (-1.35). The K-band luminosity function (KLF) of the region is found to be comparable to the average value of slope (∼0.4) for young clusters obtained by Lada & Lada (2003), however, the slope of the KLF is steeper in the northern region as compared to the southern region. The region is probably ionized by two B2 main-sequence type stars. The mean age of the young stellar objects (YSOs) is found to be 2±1 Myr which suggests that the identified YSOs could be younger than the ionizing sources of the region. The morphology of the region, the distribution of the YSOs as well as ages of the YSOs and ionizing sources indicate a triggered star formation in the region.

The aim of this paper is to present the results of photometric investigations of the central cluster of the W5 E H II region as well as a follow-up study of the triggered star formation in and around bright-rimmed clouds (BRCs). We have carried out wide-field UBVI C and deep VI C photometry of the W5 E H II region. A distance of ∼2.1 kpc and a mean age of ∼1.3 Myr have been obtained for the central cluster. The young stellar objects (YSOs) associated with the region are identified on the basis of near-infrared and mid-infrared observations. We confirmed our earlier results that the average age of the YSOs lying on/inside the rim is younger than those lying outside the rim. The global distribution of the YSOs shows an aligned distribution from the ionizing source to the BRCs. These facts indicate that a series of radiation-driven implosion processes proceeded from near the central ionizing source towards the periphery of the W5 E H II region. We found that, in general, the age distributions of the Class II and Class III sources are the same. This result is apparently in contradiction to the conclusion by Bertout, Siess & Cabrit and Chauhan et al. that classical T Tauri stars evolve to weak-line T Tauri stars. The initial mass function of the central cluster region in the mass range 0.4 ≤ M/M ≤ 30 can be represented by = −1.29 ± 0.04. The cumulative mass functions indicate that in the mass range 0.2 ≤ M/M ≤ 0.8, the cluster region and BRC NW have more low-mass YSOs compared to BRCs 13 and 14.