14 research outputs found
Excitation and Disruption of a Giant Molecular Cloud by the Supernova Remnant 3C391
Using the IRAM 30-m telescope, we observed the supernova remnant 3C 391
(G31.9+0.0) and its surroundings in the CO(2-1), HCO+(1-0), CS(2-1), CS(3-2),
and CS(5-4) lines. The ambient molecular gas at the distance (9 kpc) of the
remnant comprises a giant molecular cloud whose edge is closely parallel to a
ridge of bright non-thermal radio continuum, which evidently delineates the
blast-wave into the cloud. We found that in a small (0.6 pc) portion of the
radio shell, the molecular line profiles consist of a narrow (2 km/s)
component, plus a very wide (> 20 km/s) component. Both spectral components
peak within 20" of a previously-detected OH 1720 MHz maser. We name this source
3C 391:BML (broad molecular line); it provides a new laboratory, similar to IC
443 but on a larger scale, to study shock interactions with dense molecular
gas. The wide spectral component is relatively brighter in the
higher-excitation lines. We interpret the wide spectral component as post-shock
gas, either smoothly accelerated or partially dissociated and reformed behind
the shock. The narrow component is either the pre-shock gas or cold gas
reformed behind a fully dissociative shock. Using the 3 observed CS lines, we
measured the temperature, CS column density, and H2 volume density in a dense
clump in the parent molecular cloud as well as the wide-line and narrow-line
portions of the shocked clump. The physical conditions of the narrow-line gas
are comparable to the highest-density clumps in the giant molecular cloud,
while the wide-line gas is both warmer and denser. The mass of compressed gas
in 3C 391:BML is high enough that its self-gravity is significant, and
eventually it could form one or several stars
Estudo do efeito do ozÎnio gerado durante ensaios elétricos em equipamentos de segurança confeccionados em borracha natural
Erratum: Corrigendum: Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution
International Chicken Genome Sequencing Consortium.
The Original Article was published on 09 December 2004.
Nature432, 695â716 (2004).
In Table 5 of this Article, the last four values listed in the âCopy numberâ column were incorrect. These should be: LTR elements, 30,000; DNA transposons, 20,000; simple repeats, 140,000; and satellites, 4,000. These errors do not affect any of the conclusions in our paper.
Additional information.
The online version of the original article can be found at 10.1038/nature0315
A New Fuzzy Logic Approach to Capacitated Dynamic Dial-a-Ride Problem
Almost all Dial-a-Ride problems (DARP) described in the literature pertain to the design of optimal routes and schedules
for n customers who specify pick-up and drop-off times. In this article we assume that the customer is mainly
concerned with the drop-off time because it is the most important to the customer. Based on the drop-off time specified
by the customer and the customerâs location, a pick-up time is calculated and given to the customer by the dispatching
office. We base our formulation on a dynamic fuzzy logic approach in which a new request is assigned to a vehicle.
The fuzzy logic algorithm chooses the vehicle to transport the customer by seeking to satisfy two objectives. The
first reflects the customerâs preference and minimizes the time a customer spends in the vehicle, and the second reflects
the companyâs preference and minimizes the distance a vehicle needs to travel to transport the customer. The
proposed heuristic algorithm is relatively simple and computationally efficient in comparison with most deterministic
algorithms for solving both small and large sized problems