请教大家一个简单的数理经济问题 - 未名空间MITBBS历史存档

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请教大家一个简单的数理经济问题

请教大家一个简单的数理经济问题# Economics - 经济

w*d2010-06-22 07:06

1 楼

A professor in Mechanical Engineering of Wayne State University is seeeking
a PhD student for
his research group.
The candidate should have a Master degree with any backgrounds in
metallurgy, polymer science, mechanical engineering, mechanics (theoretical
and experimental), solid physics, microstructure and deformation,
thermomechanical processing.
The candidates can be from departments of ME, ChE/MSE, ECE etc,ideally in
US right now.
Anybody interested can send the resume TO d****[email protected]

d*a2010-06-22 07:06

2 楼

【以下文字转载自 Immigration 讨论区】
发信人: dingguagua (guagua), 信区: Immigration
标题: I-765 EAD 填表一问
发信站: BBS 未名空间站 (Wed Apr 18 22:37:38 2012, 美东)
I-765 EAD 表中11项问 have you ever before applied to employment
authorization from USCIS 和 result (granted or denied)。我之前申请了OPT EAD
卡，还没批。现在我要递485，兼申请EAD和AP。对于result一问，我的OPT EAD既没有
granted也没有denied，该怎么填？可以填pending吗？
谢谢明白人解疑。

z*m2010-06-22 07:06

3 楼

帅死了，无论哪个方面来说。
http://www.youtube.com/watch?v=V4xzLB5bXdI&NR=1

s*h2010-06-22 07:06

4 楼

就是前端时间买的英文Win7 Home Premium版本
能否用来激活中文版的Home Premium？

F*E2010-06-22 07:06

5 楼

上个帖子问了一个比较naive的问题，其实我现在面临一个很犹豫的选择，真得很想听听别人的意见。我是化学系的computational chemistry PhD，现在是一所大学的postdoc，主要做computational chemistry，一直做下去只要一个乏味的终点：faculty，我对此也完全没有兴趣。但现在刚拿到一个政府机关为期两年的fellowship，虽然也是postdoc，但工作内容将完全是一个大型生物软件的编程及组装(offer上详细写明:Python和C++(boost)，wxPython,openGL,MPI,CVS,RPM...)。我现在有两三万行的C++/Python scientific programming经历，相信把这个软件从头到尾完成后，自己应该能从scientific programmer更接近software engineer。
问题的关键是，如果我选择了这个offer，基本上等于脱离了学术界。这一点我本身并不会觉得遗憾，甚至开心，但唯一的担心是按照我的PhD in computational Chemistry的背景，真的怀疑两年后能不能顺利找到software engineer/scientist的职位。我最近一直在投石问路，试着按自己背景先找找software engineer看，但不知道因为自己简历太superficial了，投了二三十家，一点消息都没有...
不好意思，讲了很多，主要是想听听圈内人的意见，这个政府的programmer postdoc该不该去。已经三十出头了，不能再折腾了。
多谢！

U*e2010-06-22 07:06

6 楼

经济学建模通常有这样的情形：
假设消费者总数为测度1，如果有一个商品定价为1元，每个消费者购买1个。那么厂商
的总收入是多
少？
简单的计算得到总收入是1，但是这个1不等于1元，而是1元＊总人口。
许多文献和教科书都不明确指出这个量纲的区别。虽然很多时候没有太大的影响，但有
时非常误导。
比如，假设厂商是个垄断者，需要投资x元来生产商品。如果直接定义利润为收入减去
成本，这个x元
就不能大于1，否则利润是负的。但实际上不应该发生这个问题。因为投资x的量纲和收
入1的量纲完全
不同。
不知道大家有没有遇到过这样的问题或者看到过相关文献？谢谢指点。

s*t2010-06-22 07:06

7 楼

可以写pending

s*a2010-06-22 07:06

8 楼

I do not believe that is a big deal. After all, everything is normalized.

【在 U*****e 的大作中提到】

: 经济学建模通常有这样的情形：
: 假设消费者总数为测度1，如果有一个商品定价为1元，每个消费者购买1个。那么厂商
: 的总收入是多
: 少？
: 简单的计算得到总收入是1，但是这个1不等于1元，而是1元＊总人口。
: 许多文献和教科书都不明确指出这个量纲的区别。虽然很多时候没有太大的影响，但有
: 时非常误导。
: 比如，假设厂商是个垄断者，需要投资x元来生产商品。如果直接定义利润为收入减去
: 成本，这个x元
: 就不能大于1，否则利润是负的。但实际上不应该发生这个问题。因为投资x的量纲和收

U*e2010-06-22 07:06

9 楼

Thanks for the input.
I used to think so. However, it is not that everything is normalized. In
the example I used, the revenue of 1 is after normalization, but not the
price of 1. So a reader may not sure whether the investment cost is
normalized or not.
If I am the only one gets confused, I can live with that. :)

normalized.

【在 s*****a 的大作中提到】

: I do not believe that is a big deal. After all, everything is normalized.

s*a2010-06-22 07:06

10 楼

I will think of it this way:
fixed cost is not normalized, or naturally normalized; while total variable
cost is normalized as revenue.

【在 U*****e 的大作中提到】

: Thanks for the input.
: I used to think so. However, it is not that everything is normalized. In
: the example I used, the revenue of 1 is after normalization, but not the
: price of 1. So a reader may not sure whether the investment cost is
: normalized or not.
: If I am the only one gets confused, I can live with that. :)
:
: normalized.

U*e2010-06-22 07:06

11 楼

This is constructive.
In light of your suggestions, I agree in the case of monopoly (or
oligopoly), both fixed and total costs should be normalized. In the case
of continuum of firms, then only aggregate fixed or total costs are
normalized, while individual costs must not be normalized.
As there are models about one dominant firm and many price-taking small
firms, things could be worse.

variable

【在 s*****a 的大作中提到】

: I will think of it this way:
: fixed cost is not normalized, or naturally normalized; while total variable
: cost is normalized as revenue.

s*a2010-06-22 07:06

12 楼

When you have a continuum of firms, I believe the costs are not normalized,
but you can still assume the measure of number of firms is 1, as what you
did for consumers.
This technique, I believe, works for an arbitrary number of firms.
Actually think of it this way, in most of the macro models, we talk about
the average variables, like average capital per capita, etc. There we are
doing virtually the same thing: normalize everything so that it corresponds
to only one person, and we are free to t

U*e2010-06-22 07:06

13 楼

normalized,
you
about
are
corresponds
one.
That makes sense. But in micro sometimes we need to look at agents
distinct in their sizes. In this case just talking about everything in
average sense is not enough.

【在 s*****a 的大作中提到】

: When you have a continuum of firms, I believe the costs are not normalized,
: but you can still assume the measure of number of firms is 1, as what you
: did for consumers.
: This technique, I believe, works for an arbitrary number of firms.
: Actually think of it this way, in most of the macro models, we talk about
: the average variables, like average capital per capita, etc. There we are
: doing virtually the same thing: normalize everything so that it corresponds
: to only one person, and we are free to t

s*a2010-06-22 07:06

14 楼

I agree.
That way you don't employ this technique.

【在 U*****e 的大作中提到】

:
: normalized,
: you
: about
: are
: corresponds
: one.
: That makes sense. But in micro sometimes we need to look at agents
: distinct in their sizes. In this case just talking about everything in
: average sense is not enough.