In Europe, North America, and especially New Zealand, farmers and foresters
have even tried to make use of the powers of weasels for their own ends,
particularly to control various “pest” species such as voles (small mouse-like
rodents with short tails and small eyes and ears) and rabbits. But the philosophies
of weasels and of people toward such situations are quite different: What
for us is a problem, requiring elimination, is for weasels an opportunity, to be
exploited. That is why biological control by weasels seldom works (Chapters
Conserving Living Natural Resources provides students, managers, and general readers with an
introduction to the principles of managing biological resources. It presents the historical and
conceptual contexts of three seminal approaches to the management of living natural
resources: utilitarian management for harvest of featured species and control of unwanted
species, protection and restoration of populations and habitats to maintain biodiversity, and
management of complex ecosystems to sustain both productivity and biodiversity.
A ﬁnal design criteria was that the API should be cor-
rect, in that events should only be reported if they are
applicable. Consider the case where a packet arrives on
a socket, in turn generating an event. However, before
the application is notiﬁed of this pending event, it per-
forms a close() on the socket. Since the socket is no
longer open, the event should not be delivered to the ap-
plication, as it is no longer relevant.
According to the historical evidence, the first rubber trees to be tapped
extensively belonged to Castilla species. Native tappers started to harvest
latex from Hevea species when Castilla tree population almost disappeared.
After the disappearance of the primeval stands of Castilla, Hevea became the
first choice of the rubber gatherers, particularly near the streams.
Among the many difficult questions parents face
when a family member is diagnosed with cancer is
“What do I tell my children?” Fearful that they might
upset or worry their youngsters and teens, some parents
withhold the news. But even at a very young age, children
can sense when something is wrong. If not told the truth,
they might imagine that things are worse than they really are
or even that they themselves are the cause of the problem.
record of Australia is too patchy for paleontologists to say whether there were any
placental mammals in Australia at this time. Abundant Australian fossils date
back to about 25 million years ago, at which point all the mammals in Austrlia
were marsupials. They evolved into a spectacular range of forms, including kan-
garoos and koalas. It was not until 15 million years ago that Australia moved close
enough to Asia to allow placental mammals—rats and bats—to begin to colonize
The World Agroforestry Centre has classiﬁed
rubber-based systems in Indonesia according
to their intensity of management, as illustrated
by the photographs on the opposite page.
Intensively-managed monoculture rubber
plantations contain less than 1% non-rubber
trees, none of which have been planted
deliberately. Simple mixed rubber agroforests
contain up to one-third non-rubber trees,
which have been deliberately planted or
retained, between ﬁve and 20 non-rubber
species greater than 2 m in height and 5–20
non-rubber trees as tall as, or taller than, the
Fewer ﬁsh exacerbate the declines in walrus and seal
populations. Overall, there is less food available for the Yupik Eskimos of the
Arctic who rely on all of these species.
Global climate change is thus a signiﬁcant addition to the spectrum of envi-
ronmental health hazards faced by humankind. The global scale makes for unfa-
miliarity—although most of its health impacts comprise increases (or decreases)
in familiar effects of climatic variation on human biology and health.
The experience of breast cancer can also create challenges for a marriage or signif-
icant relationship. Difficulties include communication problems, difficulty coping and
sexual dysfunction (one study found that approximately 50% of women with cancer had
at least one diagnosed sexual dysfunction during the posttreatment year) (Anderson,Ander-
son, & DeProsse, 1989). However, research suggests that when marriages are strong
before the development of breast cancer, the disease does not usually disrupt the relation-
ship, and may result in an even closer relationship (Oktay & Walter, 1991).
The developed technique involves contrast
enhancement using sequentially iterative smoothing
filters, histogram equalization, and simultaneous
application of two types of edge detection processes
namely, maximum-difference edge detection  and
Canny’s edge detection . The post processed
image is combined with the original image to
accentuate the edges while eliminating noise.
Smoothing is implemented because of its effect to
reduce specific types of noise signals in the digitized