Searching For Dark Matter, With Both Eyes Closed. Essays

Searching For Dark Matter, With Both Eyes Closed. Essays Searching For Dark Matter, With Both Eyes Closed. NYTimes Article Category #2. Ciara Jamie Connolly 05.02.00 Submitted 05.04.00 Searching For Dark Matter, With Both Eyes Closed. In a deficit-reduction measure in 1993, the Congress killed plans already underway for building the superconducting super collider. This proved that the US was ill prepared to join their European colleagues in studying subatomic particles in the nucleus. This $10 billion machine designed to speed protons around a 54-mile track and collide them, so scientists could examine the quarks, elementary particles said to be at the heart of the nucleus. This machine is the utmost in technological advancement this century. European physicists are leading the way with their laboratory, unchallenged in a prestigious field the United States had pioneered. Without particle smashers, scientists are in the dark, Michael Riordan states. This article fits into Category #2 because it shows the importance of the particle accelerators in helping ascertain scientific theories. If the theories hold true then billions of tiny particles may be the explanation of the dark matter that surrounds the Milky Way galaxy in a halo. These particles are thought to have a gravitational force. The United States do not have a dismal record of international co-operation on scientific megaprojects, and without this they will be unable to finance the project. Until now American scientists have had to travel to the sites of particle accelerators, in the technological domain of the machine they had thrived to build. However, this method will not work if the United States want to remain equal partners. Without the technology it is obvious that particle physicists face a difficult future. The technology that needs to be at their fingertips is proving too expensive. If they had constant access to a superconductor collider then the scientists could further their conclusions on the dark matter of the universe.

Serotiny and the Serotinous Cone

Serotiny and the Serotinous Cone Some tree species delay seed fall because their cones are dependent on a brief blast of heat to release seed. This dependency on heat during the seed production cycle is called serotiny and becomes a heat trigger for seed drop that may take decades to occur. Natural fire has to happen to complete the seed cycle. Although serotiny is primarily caused by fire, there are other seed release triggers that may work in tandem including periodic excess moisture, conditions of increased solar heat, atmospheric drying and parent plant death. Trees that have a serotinous tenancy in North America include some species of conifers including pine, spruce, cypress and sequoia. Serotinous trees in the southern hemisphere include some angiosperms like eucalyptus in fire-prone parts of Australia and South Africa. The Process of Serotiny Most trees drop their seeds during and just after the ripening period. Serotinous trees store their seeds in the canopy via cones or pods and wait for an environmental trigger. This is the process of serotiny. Desert shrubs and succulent plants depend on periodic rainfall for seed drop but the most common trigger for serotinous trees is periodic fire. Natural periodic fires occur globally, and on average, between 50 to 150 years. With naturally occurring periodic lightning fires over millions of years, trees evolved and developed the ability to resist high heat and eventually began using that heat in their reproduction cycle. The adaptation of thick and flame-resistant bark insulated the trees internal cells to direct flame and used the rising indirect heat from fire on cones to drop seed. In serotinous conifers, mature cone scales are naturally sealed shut with resin. Most (but not all) seeds stay in the canopy until the cones are heated to 122-140 degrees Fahrenheit (50 to 60 degrees Celsius). This heat melts the resin adhesive, the cone scales open to expose the seed that then drop or drift after several days to a burned but cool planting bed. These seeds actually do best on the burnt soil available to them. The site provides reduced competition, increased light, warmth and a short term increase of nutrients in the ash. The Canopy Advantage Seed storage in the canopy uses the advantage of height and breeze to distribute seed at the appropriate time onto a good, clear seedbed in satiating quantities enough for seed-eating critters. This masting effect increases the predator seed food supply to overabundance. With this abundance of newly added seed along with adequate germination rates, more seedlings than necessary will grow when moisture and temperature conditions are seasonally average or better. It is interesting to note that there are seeds that drop annually and are not a part of the heat-induced crop. This seed leakage seems to be a natural insurance policy against rare seed failures when conditions are adverse just after a burn and result in a full crop failure. What is Pyriscence? Pyriscence is often a word misused for serotiny. Pyriscence is not as much a heat-induced method for plant seed release, as it is an organisms adaptation to a fire-prone environment. It is the ecology of an environment where natural fires are common and where post-fire conditions offer the best seed germination and seedling survival rates for the adaptive species. A great example of pyriscence can be found in a southeastern United States longleaf pine forest ecosystem. This once large habitat is shrinking in size as fire is more and more excluded as land use patterns have changed. Although Pinus palustris is not a serotinous conifer, it has evolved to survive by producing seedlings that go through a protective grass stage. The initial shoot bursts in a brief bushy growth spurt and just as suddenly stops most top growth. Over the next few years, longleaf develops a significant tap root along with dense needle tufts. A compensating resumption of fast growth returns to the pine sapling around age seven.