Extra Slides

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Extra Slides
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Scientific Models and Inquiry

• Models of atoms, periodic table, bonding, shape
• Inquiry
• Hot and cold packs
• Well Wishes case study

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Scientific Inquiry Model

• Model 1 Gateway, Week 1

Is it accurate? Is it sufficient have you done
anything that is not found in the model? What is
missing?
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Model 2 Simplest
From http//acept.la.asu.edu/courses/phs110/si/c
hapter1/main.html
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Model 3 Table
Goal the objective of doing the study
Model any and all abstractions of what is being studied or manipulated
Data observations made to represent "nature"
Evaluation comparing the model to the data, to decide if the model is okay
Revision changing the model if it is not okay
From http//www.utexas.edu/courses/bio301d/Topic
s/Scientific.method/Text.html
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Model 4 The Inquiry Cycle
Generate alternative competing hypotheses
Summarize and explain Draw conclusions relevant
to other studies
Apply model to other situations, determine its
limits
Find patterns
Experiment to determine correctness of hypothesis
http//thinkertools.soe.berkeley.edu/Pages/curricu
la.html
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Model 5 Inquiry Wheel

• Robinson, W.R. J. Chem. Educ. 2004, 81, 6,
  791-792.

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Comparing models

• What are similarities?
• Differences?
• Which model is most useful?
• Which is most comprehensive?
• Which do you like the best?
• What are the key must haves?

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Communication of Inquiry
Lab Report Research Paper Inquiry Models
Introduction/background/questions/hypothesis Experimental/method/procedure Results/data Discussion/evaluation Conclusion/communication Introduction/background/questions/hypothesis Experimental/method/procedure Results/data Discussion/evaluation Conclusion/communication Introduction/background/questions/hypothesis Experimental/method/procedure Results/data Discussion/evaluation Conclusion/communication
If you dont report your work where other
scientist can use it, have you completed the
scientific process??
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Ann Arbor Water

• 1,4-Dioxane from Pall (Gelman)

Carcinogen Between 1976 and 1985, wastewater
containing 1,4 dioxane was sprayed on their lawns
and stored in unlined lagoons.
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Dioxane
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Ann Arbor Water
Huron
Liberty
7th
Stadium

• Picture from http//www.hvcn.org/info/srsw/graph
  .JPG

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Water Treatment

• Picture from http//www.mlive.com/aanews/special
  /pall/map

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Algae Blooms
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Millers Creek

• Millers Creek
• Eroding banks
• Flooding

http//www.aamillerscreek.org/Watershed.htm
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Finishing Thermochemistry Heat and Phase Change
A

• Why do we cool down when we sweat?

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Silicon-Based Life
Is silicon-based life likely to be more stable or
less stable than carbon-based life?
J. Chem. Ed. 1988, 65, 414.
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Stability of Silicon vs Carbon

• Consider decomposition of alkanes and silanes to
  the elements (no oxygen in space for that slug to
  worry about).
• Consider combustion of silanes and alkanes (will
  those silicon-based life forms make it on
  earth?).

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Thermochemical Behavior with Respect to Reversion
to the Elements
Si2H6 (g) ? 2 Si (s) 3 H2 (g)
C2H6 (g) ? 2 C(s) 3 H2 (g)
DHof Si2H6 (g) 80.4 kJ/mol
DHof C2H6 (g) -84.7 kJ/mol
DHrxn 0 0 20.9 -80.4 kJ/mol
DHrxn 0 0 (-84.7) 84.7 kJ/mol
Exothermic !
Endothermic!
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A
Enthalpies of Vaporization
H2O(l) ? H2O(g) DH gt0
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Thermochemical Behavior with Respect to Combustion
7/2 O2 (g) Si2H6 (g) ? 2 SiO2 (s) 3 H2O (g)
DHf Si2H6 (g) -80.4 kJ/mol SiO2 (s) -911
kJ/mol H2O(g) -242 kJ/mol CO2 (g) -394
kJ/mol C2H6 (g) -85 kJ/mol
7/2 O2 (g) C2H6 (g) ? 2 CO2 (s) 3 H2O (g)
DHrxn 2(-911) 3(-242) 1(-80.4)
-2468 kJ
DHrxn 2(-394) 3(-242) 1 (-85)
-1429 kJ
Exothermic !
Exothermic!
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Silicon-Based Life
Is silicon-based life likely to be more stable or
less stable than carbon-based life? Thermochemica
l considerations indicate that silicon-based life
would tend to decompose exothermically! Our
space slug unlikely to survive.
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Water Rights

• Tri-state water war between Georgia, Alabama
  and Florida.
• The City of Atlanta permit from Corps of
  Engineers to create reservoirs on the
  Chattahoochee, Flint, and Coosa Rivers
• Retain an additional 529 million gallons of water
  per day
• Stored in Lake Sidney Lanier, Atlanta's major
  source of drinking water.
• Atlanta's long-term plan included an increase in
  withdrawals of 50 from the Chattahoochee and
  Flint by the year 2010.

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Problems

• A 200. g sample of Al is heated in a flame and
  then immersed in 500. mL of water in an insulated
  container. The initial temperature of the water
  was 22.0oC. After the Al and water reach thermal
  equilibrium, the temperature of both was 33.6oC.
  What was the temperature of the Al just before it
  was plunged into the water.
• (Al 0.902 J/goC)

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Practice with Units

• The MCL for arsenic is 0.01 mg/L. What is that
  in ppm, ppb, M (moles/L)?

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Problem

• 17) Specifications for lactated Ringers
  solution, used for IV injections, are as follows
  For each 100 mL of solution
• 285-315 mg Na
• 14.1-17.3 mg K
• 4.9-6.0 mg Ca2
• 368-408 mg Cl-
• 231-261 mg C3H5O4-
• Specify the amounts of NaCl, KCl, CaCl22H2O, and
  NaC3H5O3needed to prepare 100 mL of lactated
  Ringers solution.

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The Polyprotics (Multiples)

• http//www.okinawa.usmc.mil/Public20Affairs20Inf
  o/Archive20News20Pages/2003/030131-twins.html

http//www.emory.edu/EMORY_MAGAZINE/spring97/tripl
ets.htmlhttp//www.emory.edu/EMORY_MAGAZINE/spring
97/triplets.html
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H3PO4

• How many acidic protons?
• How many ions in solution?
• Calculate the concentrations of all of the ions
  in a 0.1 M solution of phosphoric acid.
• How many ICE tables will it take?

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Triprotic Acid

• Phosphoric acid has three acidic protons
• Ka1 6.9 x10-3
• Ka2 6.2 x10-8
• Ka3 4.8 x10-13
• What trend do you observe in the Ka's and what is
  the chemical explanation for that trend?

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Titration of H3PO4
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• Ka1 6.9 x10-3
• Ka2 6.2 x10-8
• Ka3 4.8 x10-13

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When pH pKa

• 10 mL 0.1 M H3PO4 add 5 mL 0.1 M NaOH

H3PO4 H2O ? H2PO4- H3O
I C E


x H3O
pKa -log Ka

-logH3O pH
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Shortcuts
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Acid/Base Titration Curves A Closer Look
Plot pH vs. volume of NaOH added.
Equivalence/stoichiometric point ½ equivalence
point
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HA H2O ?? A- H3O
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Are all acid/base titrations the same?
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Titrating Base with Acid

• A weak base (NH3) HCl

pH at Starting line
What governs the reaction until the equivalence
point is reached?
Whats going on at the stoichiometric point?
What happens after the stoichiometric point?
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Titration of Weak Base with Strong Acid
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Buffers

• http//www.fws.gov/r5crc/Habitat/Riparianbuffers.h
  tml

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Acidosis

• Acidosis
• Acidosis is caused by an accumulation of acid or
  a significant loss of bicarbonate
• Kidney and lungs control your bodys pH
• Lungs cant remove CO2 (an acid)
• Kidney not able to regulate bicarbonate
  ingestion of too much acid
• Generation of lactic acid upon breakdown of
  glucose.

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Buffers

• Acid/base equilibria at work!
• If we need an equilibrium, can strong acids/bases
  work as buffers?

• Seeing a buffer in actionhuman buffer simulation

HA H2O ? H3O A- When more acid is added to
this solution H3O    A- ?  H2O   HA When
more base is added, OH- HA ? H2O A-
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Titration Curves and Buffers
Where does pH change the least while base is
added?
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Looking for a specific pH?
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Henderson-Hasselbalch Rules Buffers
HA H2O ? H3O A-
A-H3O

• Ka

HA
pH pKa log (A-) HA
logH3O log (A-) HA
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Image from http//cwx.prenhall.com/bookbind/pubb
ooks/hillchem3/medialib/media_portfolio/04.html
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Question 4

• You are given three different aqueous solutions
  and told that they each contain either NaOH,
  Na2CO3, or NaHCO3. You do some experiments and
  gather the following data
• Sample A Phenolphthalein is colorless in the
  solution. Methyl orange is orange.
• Sample B The sample was titrated with HCl until
  the pink color of phenolphthalein disappeared,
  then methyl orange was added to the solution.
  The solution became a pink color.
• Sample C Two equal volumes of the sample were
  titrated with standardized HCl. Using
  phenolphthalein as the indicator, it took 15.00
  mL of acid to reach the equivalence point using
  methyl orange as the indicator required 30.00 mL
  of HCl to achieve neutralization.
• Methyl orange changes colors from pH 3.01 (red)
  to pH 4.4 (orange)
• Phenolphthalein changes color from pH 8 (clear)
  to pH 9 (pink)

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• (a) Orange K2Cr2O7(aq) is about to be added to
  colorless ethanol (CH3CH2OH(aq)) that has been
  acidified with H2SO4. (b) The ethanol solution
  becomes colored due to the Cr2O7-2(aq). (c) After
  the reaction, the solution becomes a pale violet
  color, signifying that the Cr2O7-2(aq) is gone
  and that Cr3 is now present (along with CH3COOH)

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Fuel Cells

• H2 ½ O2 ? H2O
• http//science.howstuffworks.com/fuel-cell1.htm
• A fuel cell converts the chemicals hydrogen and
  oxygen into water, and in the process it produces
  electricity.
• Combustion engines like the turbine and the
  gasoline engine burn fuels and use the pressure
  created by the expansion of the gases to do
  mechanical work. Batteries converted chemical
  energy back into electrical energy when needed.
  Fuel cells should do both tasks more efficiently.
  

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• the pressurized hydrogen gas (H2) entering the
  fuel cell on the anode side. This gas is forced
  through the catalyst by the pressure. When an H2
  molecule comes in contact with the platinum on
  the catalyst, it splits into two H ions and two
  electrons (e-). The electrons are conducted
  through the anode, where they make their way
  through the external circuit (doing useful work
  such as turning a motor) and return to the
  cathode side of the fuel cell.
• Meanwhile, on the cathode side of the fuel cell,
  oxygen gas (O2) is being forced through the
  catalyst, where it forms two oxygen atoms. Each
  of these atoms has a strong negative charge. This
  negative charge attracts the two H ions through
  the membrane, where they combine with an oxygen
  atom and two of the electrons from the external
  circuit to form a water molecule (H2O).
• This reaction in a single fuel cell produces only
  about 0.7 volts. To get this voltage up to a
  reasonable level, many separate fuel cells must
  be combined to form a fuel-cell stack.
• PEMFCs operate at a fairly low temperature (about
  176 degrees Fahrenheit, 80 degrees Celsius),
  which means they warm up quickly and don't
  require expensive containment structures.
  Constant improvements in the engineering and
  materials used in these cells have increased the
  power density to a level where a device about the
  size of a small piece of luggage can power a car.
  

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• Anode side2H2 gt 4H 4e- Cathode sideO2
  4H 4e- gt 2H2O
• Net reaction2H2 O2 gt 2H2O

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• The electrolyte is the proton exchange membrane.
  This specially treated material, which looks
  something like ordinary kitchen plastic wrap,
  only conducts positively charged ions. The
  membrane blocks electrons.
• The catalyst is a special material that
  facilitates the reaction of oxygen and hydrogen.
  It is usually made of platinum powder very thinly
  coated onto carbon paper or cloth. The catalyst
  is rough and porous so that the maximum surface
  area of the platinum can be exposed to the
  hydrogen or oxygen. The platinum-coated side of
  the catalyst faces the PEM.

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Problems

• H2 sourceHydrogen is difficult to store and
  distribute, so it would be much more convenient
  if fuel cells could use fuels that are more
  readily available. This problem is addressed by a
  device called a reformer. A reformer turns
  hydrocarbon or alcohol fuels into hydrogen, which
  is then fed to the fuel cell. Unfortunately,
  reformers are not perfect. They generate heat and
  produce other gases besides hydrogen. They use
  various devices to try to clean up the hydrogen,
  but even so, the hydrogen that comes out of them
  is not pure, and this lowers the efficiency of
  the fuel cell.
• Some of the more promising fuels are natural gas,
  propane and methanol. Many people have
  natural-gas lines or propane tanks at their house
  already, so these fuels are the most likely to be
  used for home fuel cells. Methanol is a liquid
  fuel that has similar properties to gasoline. It
  is just as easy to transport and distribute, so
  methanol may be a likely candidate to power
  fuel-cell cars.
• In the next sections, we will take a look at how
  fuel cells

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• How stuff works compares efficiencies
• Biodiesel

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A Copper-Zinc battery What Matters?
What occurs at Copper electrode?
What occurs at Zinc electrode?
Zinc is oxidized and dissolves, mass decreases
Copper plates out, mass increases
Prevent direct reduction of copper at Zinc
electrode Force electrons to flow through
external circuit Allows sulfate ions to flow
maintaining charge balance
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Polymer Structure
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Product Monomer units btwn crosslinks Flexibility Strength
Calculator casing 5-10 small very high
Tires 10-20 restricted high
Tire tubes 20-30 moderate moderate
Artificial heart membrane 30-40 moderate moderate
Kitchen gloves 50-80 moderate low
Surgical gloves 100-150 high low
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Synthesis Radical

• Monomers which contain a double bond in between
  two carbon atoms (called a vinyl group.)  

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Radical (Addition) Polymerization

•  A radical is an unpaired electron.  
• An initiator containing a radical is added to the
  vinyl monomer.  
• The radical steals one of the electrons from the
  double bond to form a single bond between the
  initiator and one of the carbon atoms.
• This leaves an unpaired electron on the other
  carbon atom allowing the process to continue.

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Synthesis Condensation

• Do the polymers weigh as much as their monomers?

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Polymer Recycling

• PET - Polyethylene Terephthalate is a transparent
  plastic with good gas barrier properties. It is
  also relatively cheap and strong. This makes it
  especially suitable for producing soft drink
  bottles
• HDPE - High Density Polyethylene is another
  plastic commonly used for drink bottles. It is
  translucent and strong with a good resistance
  against chemicals. Pigments are used to add color
  to HDPE bottles.
• PVC - Polyvinyl Chloride is frequently used for
  drainage pipes because of its superior chemical
  resistance. It also a good insulator and is used
  for cable jacketing.
• LDPE - Low Density Polyethylene is a tough and
  highly flexible plastic that is used for
  producing plastic bags, cable jacketing and
  bottles. Other applications include products that
  can be heat sealed.

Taken from http//www.visionengineer.com/env/plas
tic_recycling_symbols.shtml
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Recycling Continued

• PP - Polypropylene is a strong and light plastic.
  It has a relatively high melting point and is
  used in products exposed to high temperatures.
  These include yogurt and ice cream containers
  that are filled while hot.
• PS - Polystyrene is rather stiff and rigid. In
  this form, it is used in disposable cutlery and
  CD jewel cases. Packing foam is also produced by
  blowing air bubbles into PS while it is still
  setting.
• Other - This designation is used for plastic
  products that do not fall into any of the other
  categories. Further sorting of these items is
  required at recycling centers. An example is
  melamine, which is often used in plastic plates
  an cups.
• Which kinds of polymers does Ann Arbor recycle?

Taken from http//www.visionengineer.com/env/plas
tic_recycling_symbols.shtml
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How are Polymers Recycled?

• One of the keys to recycling is the ability to
  melt a polymer and reform it.  
• Thermoplasts Soften and melt when heated, and
  therefore can be reshaped. (Ex the polyethylene
  used to make a pop bottle)
• Thermosets are harder, stiffer and more rigid
  than thermoplasts.  They are processed at
  temperatures above their melting point.  Once
  they are cooled and become hard they cannot be
  reshaped (hence thermo-"set").. (Ex  epoxy,
  polyester, bakelite, and fiberglass.)  
• Elastomers are very stretchy, pliable materials,
  like anything made out of rubber (Ex rubber
  bands or tires)

From www.risfc.org/ print.php?sid452
69
1998 MMR Vaccine linked to Autism

• From www-student.newn.cam.ac.uk/
  nigma/site6/sc.htm

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Autism

• Isolation (some born with it sometimes it seems
  to develop)
• Many experts argue that improved diagnosis and
  deeper awareness among professionals have led to
  more accurate and earlier identification of the
  problem. Others contend that the absolute number
  of cases is rising, not just medicine's ability
  to find them. In their view, something in the
  environment must be to blame.

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MMR

• Measles (1964) is a virus which causes a rash,
  cough, runny nose, eye irritation, and fever in
  most people, but can also lead to pneumonia,
  seizures, brain damage, and death in some 1 in
  2500 cases.
• Mumps (1967) virus causes fever, headache, and
  swollen glands, but can also lead to deafness,
  meningitis, swollen testicles or ovaries, and
  death in some cases.
• Rubella, (1970) also known as the German Measles,
  is generally a mild disease, but can cause
  serious birth defects in the child of a woman who
  becomes infected while pregnant.

http//www.nlm.nih.gov/medlineplus/ency/article/00
2026.htm
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Measles in the US

• Prior to licensure of the first measles vaccine
  in 1963, virtually every person in the U.S. got
  the measles by age 20. Since the vaccine became
  available, there has been a 99 reduction in the
  incidence of measles. However, measles is still
  being imported from other countries. The most
  recent outbreaks occurred in the U.S. between
  1989 and 1991, resulting in 755,000 cases and 123
  reported deaths.
• From http//www.immunizationinfo.org/vaccineInfo/
  vaccine_detail.cfv?id8

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The Triple Vaccine

• Given 15 months and then again at 4-6 or 11-13
  years
• Mild to moderate side effects
• fever (1 in 6 children)
• rash (1 in 20)
• swollen glands (rare)
• seizure (1 in 3,000)
• Joint pain/stiffness (1 in 4, usually young
  women)
• low platelet count/bleeding (1 in 30,000)
• Severe adverse effects may include
• allergic reaction (less than 1 per million)
• long-term seizure/brain damage/deafness (so rare
  that the association with the vaccine is
  questionable)

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Vaccine Source

• Product M-M-R II Manufacturer Merck Year
  licensed 1971
• (First used in US and Scandanavia 1972)
• MMR is a live vaccine containing measles, mumps
  and rubella viruses that have been modified so
  they do not cause symptoms. It produces an immune
  response sufficient to protect children from the
  diseases.

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• 1988 The MMR (measles, mumps and rubella) triple
  vaccine is introduced in the UK, a year after
  Britain had a measles outbreak which killed 17
  children

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The Wakefield Study

• Ileal-lymphoid-nodular hyperplasia, non-specific
  colitis, and pervasive developmental disorder in
  children
• A J Wakefield, S H Murch, A Anthony, J Linnell, D
  M Casson, M Malik, M Berelowitz, A P Dhillon, M
  A Thomson, P Harvey, A Valentine, S E Davies, J A
  Walker-Smith
• The Lancet, Volume 351, Number 9103 28 February
  1998
• Inflammatory Bowel Disease Study Group,
  University Departments of Medicine and
  Histopathology (and the University Departments of
  Paediatric Gastroenterology Child and Adolescent
  Psychiatry Neurology (and Radiology (Royal Free
  Hospital and School of Medicine, London NW3 2QG,
  UK
• Correspondence to Dr A J Wakefield

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Background

• Evidence gastrointestinal disorders and autism
  are linked.
• Fudenberg16 noted that for 15 of 20 autistic
  children, the first symptoms developed within a
  week of MMR vaccination.
• Gupta17 commented on the striking association
  between measles, mumps, and rubella vaccination
  and the onset of behavioral symptoms in all the
  children that he had investigated for regressive
  autism.

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• Methods 12 children (mean age 6 years range
  3-10, 11 boys) were referred to a pediatric
  gastroenterology unit with a history of normal
  development followed by loss of acquired skills,
  including language, together with diarrhea and
  abdominal pain. Children underwent
  gastroenterological, neurological, and
  developmental assessment and review of
  developmental records. Ileocolonoscopy and biopsy
  sampling, magnetic-resonance imaging (MRI),
  electroencephalography (EEG), and lumbar puncture
  were done under sedation. Barium follow-through
  radiography was done where possible. Biochemical,
  haematological, and immunological profiles were
  examined.
• Findings Onset of behavioural symptoms was
  associated, by the parents, with measles, mumps,
  and rubella vaccination in eight of the 12
  children, with measles infection in one child,
  and otitis media in another. All 12 children had
  intestinal abnormalities, ranging from lymphoid
  nodular hyperplasia to aphthoid ulceration.
  Histology showed patchy chronic inflammation in
  the colon in 11 children and reactive ileal
  lymphoid hyperplasia in seven, but no granulomas.
  Behavioural disorders included autism (nine),
  disintegrative psychosis (one), and possible
  postviral or vaccinal encephalitis (two). There
  were no focal neurological abnormalities and MRI
  and EEG tests were normal. Abnormal laboratory
  results were significantly raised urinary
  methylmalonic acid compared with age-matched
  controls (p0003), low hemoglobin in four
  children, and a low serum IgA in four children.
• Interpretation We identified associated
  gastrointestinal disease and developmental
  regression in a group of previously normal
  children, which was generally associated in time
  with possible environmental triggers.

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Results

• 9-10 of 12 children developed autism parents
  noted behavioral change 24 h to 2 months after
  vaccine (15-21 months old)
• Some (3) autism diagnoses made by non-hospital
  physicians

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Discussion

• Intestinal and behavioral pathologies may have
  occurred together by chance, reflecting a
  selection bias in a self-referred group however,
  the uniformity of the intestinal pathological
  changes and the fact that previous studies have
  found intestinal dysfunction in children with
  autistic-spectrum disorders, suggests that the
  connection is real and reflects a unique disease
  process.
• We did not prove an association between measles,
  mumps, and rubella vaccine and the syndrome
  described.
• If there is a causal link between measles,
  mumps, and rubella vaccine and this syndrome, a
  rising incidence might be anticipated after the
  introduction of this vaccine in the UK in 1988.
  Published evidence is inadequate to show whether
  there is a change in incidence22 or a link with
  measles, mumps, and rubella vaccine.23

81
Conclusions

• We have identified a chronic enterocolitis in
  children that may be related to neuropsychiatric
  dysfunction. In most cases, onset of symptoms was
  after measles, mumps, and rubella immunization.
  Further investigations are needed to examine this
  syndrome and its possible relation to this
  vaccine.

82
Recommendations

• Suspend MMR vaccination until further data is
  collected
• Hypothesis the ultimate culprit for the
  children's autism was measles virus in the
  vaccine

83
More Information

• Other research in PhD dissertation from
  Wakefields lab Results, no live measles,
  mumps, or rubella virus. Conclusion. The results
  do not support previous data implicating
  persistent measles virus infection with the
  aetiology of IBD or autistic enteropathy.
• Funded by funds from a group of parents filing a
  multibillion dollar lawsuit against the vaccine
  companies.
• Most patients in the journal study were not
  routine admissions, but referred by the lawyers
  in the lawsuit.

http//briandeer.com/mmr/wakefield-post.htm
84
Investigation Reveals

• Wakefield filed a string of patents for vaccine
  and products that would only succeed if MMR
  vaccine went down
• Ten of the 13 physicians involved in the original
  report have withdrawn their support
• The Journal editor was a former colleague of
  Wakefields.

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Since the Scare

• The Institute of Medicine in Washington, part of
  the National Academy of Sciences, has compiled 14
  large-scale studies in the United States, Canada
  and Europe that all exonerate the vaccine.
  Wakefield suggests each study has been flawed
  either because of its methodology or because its
  authors massaged the findings to get the answers
  they sought.

86
One Study

• Madsen, K.M., et. al., New England Journal of
  Medicine 2002, 347, 19, 1477-1482.)
• Introduction
• Studies designed to evaluate the suggested link
  between MMR vaccination and autism do not support
  an association, but the evidence is weak and
  based on case-series, cross-sectional, and
  ecologic studies.

87
Case series
http//servers.medlib.hscbklyn.edu/ebm/2600.htm
88
Cross-sectional

• Collects data all at one time and one time only
  from a variety of people, subjects, or
  phenomena.  Provides a snapshot of the variables
  at one particular point in time in a
  cross-section of a population.   
• Data on many variables but increased error
• Data from a large number of subjects
• Data from dispersed subjects but increased cost
  with each location
• Data on attitudes and behaviors
• Cannot measure change or establish cause and
  effect
• Good for exploratory research to generate
  hypothesis
• No control of independent variable

http//www.csulb.edu/msaintg/ppa696/696preex.htm
Cross-Sectional20Design
89
Ecologic

• Looks at data on populations or groups of people
  for correlations (this group has high blood
  pressure and high cancer rates therefore there
  might be a link.)
• Dales, L. Hammer, S.J. Smith, N. J. JAMA 2001,
  285, 9, 1183-1185.
• Results Essentially no correlation was observed
  between the secular trend of early childhood MMR
  immunization rates in California and the secular
  trend in numbers of children with autism enrolled
  in Californias regional service center system.
  For the 1980-1994 birth cohorts, a marked,
  sustained increase in autism case numbers was
  noted, from 44 cases per 100000 live births in
  the 1980 cohort to 208 cases per 100000 live
  births in the 1994 cohort (a 373 relative
  increase), but changes in early childhood MMR
  immunization coverage over the same time period
  were much smaller and of shorter duration.
  Immunization coverage by the age of 24 months
  increased from 72 to 82, a relative increase of
  only 14, over the same time period.

90
(No Transcript)
91
Back to the NEJM study

• Study includes all children born in Denmark
  1991-1998 (440,655 received MMR vaccination
  96,648 did not)
• Conclusions No risk in vaccinated versus
  unvaccinated children (adjusted relative risk
  0.92)
• Increase in autism from 2 cases/10,000 (1980s)
  children to 10 cases/10,000 children (1990s)

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Strengths of Study

• Exposure data collected independent of parent
  recall and before diagnosis of autism
• Autism reporting independent of recording of MMR
  vaccine
• Controlled for cofounders (age, sex, calendar
  period, socioeconomic status, mothers
  education, gestational age, and birth weight)
• Checked validity of autism diagnosis high since
  only specialists in child and adolescent
  psychiatry are authorized to code diagnosis of
  autism in the Danish Psychiatric Central Register.

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Study Critiques

• Family history of autism not recorded may have
  chosen not to receive MMR vaccine. (But would
  have expected to see higher risks at beginning of
  study before scare.)

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Ethics
M

• Name a situation in science where an ethical
  decision must be made?

What behaviors/practices in science would you
consider unethical?
95
M

• List all of the ethical issues in the case of
  Millikan?

• List all of the ethical issues in the case of
  Schön?

How are the situations in the two cases similar?
How are they different?
Did Millikan behave ethically in reporting his
data? Why or why not?
Did Schön behave ethically in reporting his data?
Why or why not?
96
M

• If you were faced with a portion of your data
  that "didn't fit" your hypothesis what would your
  options be?

What are the consequences of publishing incorrect
data?
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From 9/12 Masses of Handfuls of Pennies
M

• 42.43
• 42.43
• 43.53
• 47.54
• 50.075
• 67.606
• 67.874
• 100.140
• 132.73
• 170.20

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Mark and Jerry
A

• List the ethical issues in this case

What are the consequences of reporting the data?
What are the consequences of NOT reporting the
data?
Does the fact that Jerry Elrod tells Mark that
anything under 5 unfavorable results is
insignificant relieve Mark of any further
responsibility?

If Mark wonders whether Jerry's 5 standard for
reporting data meets regulatory standards of
acceptability, how might he go about finding out?
99
A

• Under what conditions, if any, do you think it is
  ethical for scientists not to report all data in
  cases related to pollution?