Roach Robots to the Rescue
When buildings collapse, it is extremely difficult to safely locate and rescue people
trapped inside. Victims may be wedged into small spaces, and unstable rubble could
collapse on rescue workers. An alternative to human rescue workers may be robotic
cockroaches. Real cockroaches are protected by strong yet flexible exoskeletons. They
can also flatten their bodies through tiny cracks. A robotics researcher from Harvard
University and a biomechanics expert from the University of California, Berkeley, were
inspired to create mini robots that have the same features. The roach robots can squeeze
through small spaces and skitter over unstable environments. Fitted with cameras and
microphones, they could be used in disasters to locate victims.
What is the main idea of the passage?
Inspired by the strength and quickness of cockroaches, researchers created
robots with the same characteristics.
Cockroach-like robots can fit through small cracks and move through unstable
rubble.
It is dangerous to search inside collapsed buildings, but cockroach-like robots
can go places where human searchers can't or shouldn't.

this question is confusing, could you reword it?

explanation:

answer; ///it examines the interaction between genetics and culture in shaping human biology;

can you explain it better

clearcutting reproduces a new even-aged stand by completely removing the mature stand.

clearcutting as a silvicultural treatment has several characteristics:

it causes a sudden environmental change

it removes the seed source from the regeneration area

the configuration of the clearcut may affect seed dispersal

it begins a new rotation

it will eliminate some pests that require forest cover

overall, it temporarily removes the forest cover, transforming the forest community and environment.

clearcutting followed by artificial (seeded or planted) regeneration has several advantages:

we can avoid delay in restocking the site

we can introduce a selected species, seed source, and genotype

we can control arrangement and spacing

we can achieve uniformity in the new stand

we can overcome the problems associated with securing sufficient natural regeneration.

the shelterwood method involves the removal of most of the mature stand at the end of the rotation, but a portion of the mature stand is left standing.   the shelterwood method serves three basic purposes:

to prepare the stand for production of abundant seed

to modify the environment in a way that promotes germination and survival of the selected species

to build up the amount and size of advance regeneration to ensure the prompt restocking of the new stand following overstory removal.

the shelterwood method involves a sequence of 3 cuttings:

preparatory cuttings: make the seed trees more vigorous and set the stage for regeneration. see our thinning page for more information.

establishment/seed cuttings: open up enough vacant growing space to allow establishment of the new regeneration.

removal cuttings: uncover the new crop to allow it to fill the growing space.

the residual trees in the shelterwood must:

be sturdy and windfirm

be able to survive exposure

flower and reproduce seed

be the best trees of the mature stand

keep in mind that the shelter trees must not occupy the entire site.   a void must be created in order to make room for the new regeneration. the amount of shelter to leave will depend on the following factors:

species characteristics (seeding and shelter requirements)

the number of cuttings in the cutting sequence (1, 2, or 3)

landowner objectives

the size of the area to be regenerated

the final removal harvest level required to be profitable

the shelter must be removed before it impedes the growth of the new stand or threatens its survival.