C++ Pointers and Strings

Ana Ravelo

Description

• mémoire

1C++ Spring 2000 Arrays 1 C++ Pointers and Strings C++ Spring 2000 Arrays 2 Pointers A pointer is a variable that holds the address of something else. . . . . . . MEMORY 0 1 2 3 4 5 81345 81346 81347 Address int foo; int *x; foo = 123; x = &foo; foo x 123 3 C++ Spring 2000 Arrays 3 int *x; • x is a pointer to an integer.

• string manipulation functions
• handling functions
• caller
• foo
• pointer
• string
• array
• points
• address
• int

Sujets

• Mémoire
• Pointer
• Function
• String
• Manipulation
• Caller
• Address

Informations

• Publié par: ossu
• Nombre de lectures: 53
• Langue: English

Extrait

Marine Geology http://ic.ucsc.edu/~acr/ocea280/ Ravelo
Ocean Sciences 280/Earth Sciences 102 Fall 2011
Problem Set #2. Due Monday, 24 October 2011 by IN SECTION. Late problem sets will not be
graded or given credit.
Most parts of the problem set are required for all students. Specific parts of the problem set
marked “Graduate students” are additional questions required for those enrolled in Ocean
Sciences 280. Undergraduates can do these additional questions for “extra credit.”
1. The two-box ocean model: Biogeochemical cycling and nutrient profiles. (+6 points)
Biological activity in surface waters takes up nearly all of the inorganic nutrients supplied to
surface waters in most areas of the ocean, with the supply of most nutrient elements to surface
waters primarily by upwelling. Particle production occurs in surface waters and results in a flux of
relatively rapidly sinking particles to the deep ocean, where these particles can be regenerated
back to their dissolved inorganic constituents. Dissolved phosphate is an essential nutrient for the
production of organic matter, and silicate is required and limiting for the production of biogenic
opal hard parts by organisms.
Refer to the dissolved phosphate and dissolved silicate profiles shown in class (see slides posted
on-line from 10/6 and 10/11 lecture). For parts a and b, use diagrams as appropriate in your
answers. Answer each part in no more than one paragraph each, using your own words.
a. Explain how the processes of particle formation and regeneration in the water column result
in the main features of the vertical profiles observed for these two dissolved nutrient elements.
Refer to the biological pump as shown in MBC Fig. 2.3 and the “two-box model,” MBC, Fig. 2.20,
in your explanation.
b. What are the differences between the Atlantic and Pacific phosphate and silicate profiles?
For example, compare their concentration differences at the surface and at 2500 m. Explain
these differences, using the pathway of deep ocean circulation in the modern ocean. See Fig.
2.22, MBC, for a phosphate map.
d. Graduate students. (+3 points)
Many glacial-interglacial cycles have occurred over the past 2.7 m.y., with large global ice
volume changes, primarily from Northern hemisphere glaciation. The most recent interval of
maximum ice volume, known as the “last glacial maximum,” reached its peak at ~22.4 ka
(ka=kiloyears before present), with sufficient global ice volume to result in a sea level lowering of
124 m. Areas in the North Atlantic where deep water forms in the modern ocean may have had
significant ice cover for all or part of the year, inhibiting or reducing deep water formation.
There is independent evidence from tracers in sedimentary records that North Atlantic Deep
Water (NADW) formation was significantly reduced (at least in relative terms) at the last glacial
maximum. The amount of time from the last glacial maximum to the present is too short for there
to be any substantial change in the total amount of dissolved phosphate or silicate in the
ocean, although their distributions between the ocean basins will have changed with circulation
change.
What effects would the reduction in NADW formation have on the differences between the
profiles of phosphate and silicate from the Atlantic and the Pacific? Use diagrams as
appropriate and explain your conclusions.
Problem Set 2
Page 1Marine Geology http://ic.ucsc.edu/~acr/ocea280/ Ravelo
Ocean Sciences 280/Earth Sciences 102 Fall 2011
2. Plate stratigraphy and the temporal history of the global CCD. (+8 points)
Plate stratigraphy is a useful conceptual model combining knowledge of the horizontal
movement of oceanic plates and their vertical subsidence through time with knowledge of
sediment accumulation patterns through ocean history to explain the three-dimensional
distributions of sediment types.
The mass balance for dissolved Ca in the ocean at dynamic equilibrium can be expressed as:
Ri= Rss + Rp - Rd
or Ri - Rss =
where: Ri = rate of Ca input from rivers and hydrothermal circulation
Rss = rate of Ca removal by CaCO3 sedimentation in shallow shelf areas
Rp = rate of Ca incorporation into CaCO3 shells by open ocean organisms
Rd = rate of Ca redissolution from CaCO shells in the open ocean3
Conceptually, this says that the rate at which CaCO solids accumulate in shallow shelves and in3
the open ocean above the CCD equals the rate of dissolved Ca input to the ocean.
The CCD can be pictured as a depth level which adjusts so that calcite accumulation (the rate
of removal) above the CCD (area above the CCD times the rate of shell production per unit
area) just equals the net rate of input of dissolved Ca to the ocean. Consider that a shallower
CCD means that there is less deep ocean sediment area above the CCD where calcite is
accumulating. Neglect any dissolution of calcite occurring above the CCD.
a. Two sediment types are indicated on the figure on the next page. Identify these types and
justify your identifications.
b. Draw (on the diagram) what this cross-section indicates about the depth of the present
global CCD. Explain how you reached this conclusion.
c. Draw (on the diagram) what this cross-section indicates about the depth of the global CCD
in the past. Explain how you reached this conclusion.
d. Using the mass balance statement for Ca, list three possible causes for the difference you
defined for the depths of the past and the present CCD. Explain each cause.
e. Graduate students. (+3 points)
In Problem set #1, you looked at the effects of spreading rate on ocean crust age and depth.
Imagine that spreading rates increased to twice as fast as today, causing the depth of the
ocean to decrease. Use the mass balance concepts explained above and describe HOW and
WHY the CCD would adjust to such an increase in spreading rate. Assume that the input of
calcium to the ocean does not change.
Problem Set 2
Page 2Marine Geology http://ic.ucsc.edu/~acr/ocea280/ Ravelo
Ocean Sciences 280/Earth Sciences 102 Fall 2011
Sediment
TYPE 1
(stipled
gray)
Sediment
TYPE 2
(filled in
black)
CRUST CRUST
Problem Set 2
Page 3Marine Geology http://ic.ucsc.edu/~acr/ocea280/ Ravelo
Ocean Sciences 280/Earth Sciences 102 Fall 2011
3. Plate motion and plate stratigraphy. (+6 points)
The diagram below shows a schematic of a spreading ridge at an angle to an equatorial zone
of high productivity. This might remind you of the East Pacific Rise and the equatorial Pacific.
Make the following assumptions about sedimentation in this region:
• The depth of the CCD in this region, is indicated on the diagram by the dashed line
parallel to the spreading axis, is 4500 m. For this question, you can assume it has been
constant through time.
• Biogenic Opal sediments accumulate only in the equatorial zone of high productivity
(±5º north and south of the equator, shown by the dotted lines parallel to the equator).
• Accumulation rates of calcium carbonate and opaline silica are about equal to each
other.
• Accumulation rate of detrital clay material is a factor of 10 lower than those for calcium
carbonate and opaline silica.
Draw the down-core sedimentary record you would expect to find if you sampled at the
location marked by an ⊗ on the map.
Explain the sedimentary sequence you have drawn, including relative sediment thicknesses, in
terms of plate tectonic and sedimentological processes.
We know from the studies of opaline silica deposition and the oceanic silicon cycle that the
conventional paradigm of “opal deposition = primary productivity” isn’t the whole story, but for
this problem, assume that opal deposition occurs in sediments beneath the band of equatorial
high productivity.
Problem Set 2
Page 4