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Extra Slides
2
Scientific Models and Inquiry
  • Models of atoms, periodic table, bonding, shape
  • Inquiry
  • Hot and cold packs
  • Well Wishes case study

3
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?
4
Model 2 Simplest
From http//acept.la.asu.edu/courses/phs110/si/c
hapter1/main.html
5
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
6
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
7
Model 5 Inquiry Wheel
  • Robinson, W.R. J. Chem. Educ. 2004, 81, 6,
    791-792.

8
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?

9
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??
10
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.
11
Dioxane
12
Ann Arbor Water
Huron
Liberty
7th
Stadium
  • Picture from http//www.hvcn.org/info/srsw/graph
    .JPG

13
Water Treatment
  • Picture from http//www.mlive.com/aanews/special
    /pall/map

14
Algae Blooms
15
Millers Creek
  • Millers Creek
  • Eroding banks
  • Flooding

http//www.aamillerscreek.org/Watershed.htm
16
Finishing Thermochemistry Heat and Phase Change
A
  • Why do we cool down when we sweat?

17
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.
18
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?).

19
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!
20
A
Enthalpies of Vaporization
H2O(l) ? H2O(g) DH gt0
21
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!
22
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.
23
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24
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.

25
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26
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)

27
Practice with Units
  • The MCL for arsenic is 0.01 mg/L. What is that
    in ppm, ppb, M (moles/L)?

28
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29
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.

30
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
31
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?

32
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?

33
Titration of H3PO4
34
  • Ka1 6.9 x10-3
  • Ka2 6.2 x10-8
  • Ka3 4.8 x10-13

35
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
36
Shortcuts
37
Acid/Base Titration Curves A Closer Look
Plot pH vs. volume of NaOH added.
Equivalence/stoichiometric point ½ equivalence
point
38
HA H2O ?? A- H3O
39
Are all acid/base titrations the same?
40
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?
41
Titration of Weak Base with Strong Acid
42
Buffers
  • http//www.fws.gov/r5crc/Habitat/Riparianbuffers.h
    tml

43
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.

44
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-
45
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46
Titration Curves and Buffers
Where does pH change the least while base is
added?
47
Looking for a specific pH?
48
Henderson-Hasselbalch Rules Buffers
HA H2O ? H3O A-
A-H3O
  • Ka

HA
pH pKa log (A-) HA
logH3O log (A-) HA
49
Image from http//cwx.prenhall.com/bookbind/pubb
ooks/hillchem3/medialib/media_portfolio/04.html
50
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)

51
  • (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)

52
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53
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.

54
  • 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.

55
  • Anode side2H2 gt 4H 4e- Cathode sideO2
    4H 4e- gt 2H2O
  • Net reaction2H2 O2 gt 2H2O

56
  • 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.

57
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

58
  • How stuff works compares efficiencies
  • Biodiesel

59
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
60
Polymer Structure
61
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
62
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63
Synthesis Radical
  • Monomers which contain a double bond in between
    two carbon atoms (called a vinyl group.)  

64
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.

65
Synthesis Condensation
  • Do the polymers weigh as much as their monomers?

66
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
67
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
68
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

70
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.

71
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
72
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

73
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)

74
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.

75
  • 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

76
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

77
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.

78
  • 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.

79
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

80
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.

85
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)

92
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.

93
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.)

94
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?
97
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

98
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?
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