HPS211H1 Lecture Notes - Lecture 6: Mitosis, August Weismann, Anglo-Egyptian War

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rosewalrus493

2 Jun 2012

School

UTSG

Department

History and Philosophy of Science and Technology

Course

HPS211H1

Professor

Chen- Pang Yeang

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Document Summary

Studies of living organisms before late 18th century. Natural history was focused on: fieldwork, observe, collect, classify species. Medicine was focused on form and functions of human body. Studies of animals and plants as by-products. Shift focus from species in wild to the bodies of organisms. Rise of morphology (i. e. cuvier"s comparative anatomy) concerns the study of structure and forms of animals and plants. Museums of natural history as research centers: transformation of life science in the 19th century. Physiology the study of the functions of organs in a body. It emphasizes function (structure vs. function morphology vs. physiology) It became a dominant type of biological studies; replaced natural history, morphology, etc. Emphasis on experimental method, laboratory science (i. e. microscope, vivisection, tissue culture) Coll ge de france: fran ois magendie and claude bernard. University of berlin: johannes m ller, carl ludwig, emil dubois-reymond, hermann helmholtz. Cell was discovered in the 17th century by robert hooke.

Related Questions

For many of us, smartphones have become indispensable, but they have also come under fire
for their impact on the way we think and behave, especially among children. Two of the largest
investors in Apple Inc. are urging the iPhone maker to take action against smartphone addiction
among children over growing concerns about the negative effects of technology. An open letter
to Apple on January 6, 2018 from New York-based JANA Partners and the California State
Teachers’ Retirement System (CalSTRS) stated that the firm must do more to help children
fight smartphone addiction. These two shareholders together control about $2 billion in Apple
stock. The investors’ letter urged Apple to offer tools to prevent smartphone addiction and to
provide more parental options for monitoring children’s smartphone usage. The iOS operating
system for Apple smartphones and tablets already has limited parental controls for restricting
Examiners: Dr. Emmanuel Awuni and Dr. Acheampong Owusu Page 2 of 4
apps, features such as location sharing, and access to certain types of content. The investors
felt Apple needs to do more—for example, enable parents to specify the age of the user of the
phone during setup, establish limits on screen time, select hours of the day the phone can be
used, and block social media services.
The average American teenager who uses a smartphone receives his or her first phone at age
10 and spends over 4.5 hours a day on it (excluding texting and talking). Seventy-eight percent
of teens check their phones at least hourly and 50 percent report feeling “addicted” to their
phones. The investors’ letter cited a number of studies on the negative effects of heavy
smartphone and social media use on the mental and physical health of children whose brains
are still developing. These range from distractions in the classroom to a higher risk of suicide
and depression. A recent survey of over 2,300 teachers by them Center on Media and Child
Health and the University of Alberta found that 67 percent of the teachers reported that the
number of students who are negatively distracted by digital technologies in the classroom is
growing. Seventy-five percent of these teachers think students’ ability to focus on educational
tasks has decreased. Research by psychology professor Jean Twenge of San Diego State
University found that U.S. teenagers who spend 3 hours a day or more on electronic devices
are 35 percent more likely, and those who spend 5 hours, or more are 71 percent more likely,
to have a risk factor for suicide than those who spend less than 1 hour. This research also
showed that eighth-graders who are heavy users of social media have a 27 percent higher risk
of depression. Those who spend more than the average time playing sports, hanging out with
friends in person, or doing homework have a significantly lower risk. Additionally, teens who
spend 5 or more hours a day on electronic devices are 51 percent more likely to get less than 7
hours of sleep per night (versus the recommended 9).
Nicholas Carr, who has studied the impact of technology on business and culture, shares these
concerns. He has been highly critical of the Internet’s effect on cognition, and these cognitive
effects extend to smartphone use. Carr worries that excessive use of mobile devices diminishes
the capacity for concentration and contemplation. Carr recognizes that smartphones provide
many useful functions in a very handy form. However, this extraordinary usefulness gives them
too much influence on our attention, thinking, and behaviour. Smartphones shape our thoughts
in deep and complicated ways, and their effects persist even when we aren’t using the devices.
Research suggests that the intellect weakens as the brain grows dependent on the technology.
Carr points to the work of Adrian Ward, a cognitive psychologist and marketing professor at
the University of Texas at Austin, who for a decade has been studying how smartphones and
the Internet affect people’s thoughts and judgment. Ward has observed that using a smartphone,
or even hearing one ring or vibrate, produces distractions that make it harder to concentrate on
a difficult problem or job. Divided attention impedes reasoning and performance.
A study published in Applied Cognitive Psychology in April 2017 examined how smartphones
affected learning in a lecture class with 160 students at the University of Arkansas at
Monticello. It found that students who didn’t bring their phones to the classroom scored a full
letter-grade higher on a test of the material presented than those who brought their phones. It
didn’t matter whether students who brought their phones used them or not. A study of 91 U.K.
secondary schools, published in 2016 in the journal Labour Economics, found that when
schools ban smartphones, students’ examination scores go up substantially, and the weakest
students benefit the most. Carr also observes that using smartphones extensively can be
detrimental to social skills and relationships. Connecting with “friends” electronically via
smartphones is not a substitute for genuine person-to-person relationships and face-to-face
conversations.

rubyarmadillo521

Vapor cycles
5EM - Thermodynamics
September 2010
1 The T-S diagram
The temperature-entropy diagram is an alternative to the well knownpressure-
volume diagram. Before using it to analyze different vapor cycles,we need
to understand it properly.
1. Plot the following transformations for ideal gases in a T-Sdiagram
(a) Isothermal expansion
(b) Isobaric expansion
(c) Isometric heating
(d) Reversible adiabatic expansion
(e) Irreversible adiabatic expansion
2. Repeat the last question, but this time do it for a realsubstance,
starting in the compressed liquid1 region and ending in thesuperheated
region, when possible. Indicate the boundaries of eachregion.
3. We know that under certain circumstances the area under theplot
in a P-V diagram represents the work performed during theprocess.
What does it represent in this case? Under what assumptions isyour
answer true? Compare examples 6.1 and 6.2.
2 Thermal machines
We understand by thermal machine a device capable of transformingther-
mal energy (heat) into mechanical energy (work). We already knowthat
these machines have a limited efficiency which, in the two-sourcesmodel, is
obtained by Carnotâs cycle.
(Compressed liquid is sometimes also called subcooled liquid)
2.1 Carnot cycle
This cycle, although efficient, is impractical. To begin with, theextreme
temperatures of the cycle should be within the sources temperaturesfor a
finite heat flow to exist.
1. Given the temperature of the sources, draw the cycle accordingto the
named limitation.
2. Show that this leads to lower efficiency than the theoreticallimit.
3. Assume that heat flow from/to the sources is proportional to thetem-
perature difference between them and the working fluid, anddemon-
strate that a higher power output is related to a decreasedefficiency.
2.2 Rankine cycle
Out of the several practical possibilities, Rankine cycle and itsvariations is
widely used, especially for electric power generation.
1. Draw the basic cycle in a T-S diagram and explain it.
2. What does the efficiency of the cycle depend on? Comparewith
Carnotâs.
3. What are the differences between the ideal cycle and the realone?
4. Describe how it is modified by superheating and/or reheating.Explain
te benefits.
2.3 Problems
After answering the previous questions solve the followingexercises from the
book: 8.2, 8.4, 8.5, 8.13, 8.19, 8.20
3 Frigorific machines
3.1 Reverse Carnot cycle
We have already studied Carnot cycle in detail as the ideal thermalmachine.
Now we will take is as the starting point to understand thecharacteristics
of frigorific machines.
1. Draw the ideal cycle in a T-S diagram and explain it.
2. Show that this cycle has a theoretical efficiency Ã =Tcold/Thot-Tcold
3. What are the difficulties in implementing such cycle in actualdevices?
3.2 Actual refrigerators
1. Why is the turbine replaced by an expansion valve in mostcases?
2. Plot the actual cycle and explain the differences with the idealcase.
3. How do cascade and multistage systems improve the performanceof
the refrigerator?
4. What aspects are important in the choice of a refrigerant fluid?Justify
3.3 Problems
After answering the previous questions solve the followingexercises from the
book: 10.2 10.7, 10.8, 10.9, 10.22, 10.23 10.1D

HPS211H1 Lecture Notes - Lecture 6: Mitosis, August Weismann, Anglo-Egyptian War

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