University of California, Santa Barbara

About: University of California, Santa Barbara is a education organization based out in Santa Barbara, California, United States. It is known for research contribution in the topics: Population & Laser. The organization has 30281 authors who have published 80852 publications receiving 4626827 citations. The organization is also known as: UC Santa Barbara & UCSB.

Investigating the biodiversity, ecology, and phylogeny of endosymbiotic dinoflagellates in the genus symbiodinium using the its region: in search of a “species” level marker

Abstract: The internal transcribed spacer (ITS) regions from 47 Symbiodinium (Freudenthal) isolates cultured from 34 different host species and two populations sampled from nature were sequenced and compared. Of these, 17 distinct ITS types were identified. The described species Symbiodinium goreaui, S. kawagutii, S. pilosum (Trench and Blank), S. microadriaticum (Freudenthal), and S. (=Gymnodinium) linucheae (Trench and Thinh) had ITS sequences distinct from each other. Four of these species share identical ITS sequences with uncharacterized isolates. Sequence differences among other isolates indicate that at least seven other cultured types await formal species descriptions, whereas numerous others most likely exist in nature. The Symbiodinium phylogeny is positively correlated with cell size, mycosporine-like amino acid production (UV protection), and host infectivity, whereas the production of water-soluble peridinin–chl a–protein homodimer and monomer apoproteins and isoenzyme similarity do not correlate. There is evidence, based on the lack of phylogenetic congruency with allelic variability, that sexual recombination occurs at some frequency among Symbiodinium populations. Symbiodinium isolates from the Caribbean possess identical ITS sequences to isolates originating from the Red Sea or the western Pacific. These findings indicate that some Symbiodinium species may have global biogeographic distributions.

Possible gravitational microlensing of a star in the Large Magellanic Cloud

Abstract: THERE is now abundant evidence for the presence of large quantities of unseen matter surrounding normal galaxies, including our own1,2. The nature of this ’dark matter‘ is unknown, except that it cannot be made of normal stars, dust or gas, as they would be easily detected. Exotic particles such as axions, massive neutrinos or other weakly interacting massive particles (collectively known as WIMPs) have been proposed3,4, but have yet to be detected. A less exotic alternative is normal matter in the form of bodies with masses ranging from that of a large planet to a few solar masses. Such objects, known collectively as massive compact halo objects5 (MACHOs), might be brown dwarfs or ‘jupiters’ (bodies too small to produce their own energy by fusion), neutron stars, old white dwarfs or black holes. Paczynski6 suggested that MACHOs might act as gravitational microlenses, temporarily amplifying the apparent brightness of background stars in nearby galaxies. We are conducting a microlensing experiment to determine whether the dark matter halo of our Galaxy is made up of MACHOs. Here we report a candidate for such a microlensing event, detected by monitoring the light curves of 1.8 million stars in the Large Magellanic Cloud for one year. The light curve shows no variation for most of the year of data taking, and an upward excursion lasting over 1 month, with a maximum increase of ∼2 mag. The most probable lens mass, inferred from the duration of the candidate lensing event, is ∼0.1 solar mass.

Communication Accommodation Theory

Abstract: Communication Accommodation Theory (CAT) is a general theoretical framework of both interpersonal and intergroup communication. It seeks to explain and predict why, when, and how people adjust their communicative behavior during social interaction, and what social consequences result from those adjustments. In this entry, a brief historical overview of CAT's development is first provided, and some of its basic concepts are introduced. Second, the different adjustment strategies that speakers may enact are explained, and objective and subjective measures of accommodation are distinguished. Third, the motivations underlying communicative adjustment are examined, and the ways in which they can be shaped by the sociohistorical context in which an interaction is embedded are discussed. Fourth, the social consequences of communicative adjustment (and nonadjustment) are explored, and some of the many factors that mediate and moderate people's evaluations of others’ behavior are discussed. Finally, previous CAT principles are refined and elaborated, and directions for future research are suggested. Keywords: accommodation; convergence; divergence; intergroup communication; interpersonal communication; language; overaccommodation; social identity; underaccommodation

Topography, relief, and TRMM-derived rainfall variations along the Himalaya

Abstract: [1] Along the southern Himalayan topographic front, the Indian summer monsoon modulates erosive processes and rates. To investigate the influence of topography and relief on rainfall generation and resultant erosion, we processed satellite rainfall amounts for the last 8 years (1998–2005) from the Tropical Rainfall Measurement Mission (TRMM). Based upon a spatial resolution of ∼5 × 5 km for the Himalaya, we identify (1) the spatial distribution of rainfall and (2) the large-scale relationships between topography, relief, and rainfall locations. Our results show two distinct rainfall maxima along strike in the Himalaya. The first, outer rainfall peak occurs along the southern margin of the Lesser Himalaya within a narrow band of mean elevation (0.9 ± 0.4 km) and mean relief (1.2 ± 0.2 km). The second, discontinuous, inner band typically occurs along the southern flank of the Greater Himalaya (elevation and relief: both 2.1 ± 0.3 km).