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2周多了,485还没收到receipt number
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2周多了,485还没收到receipt number# Immigration - 落地生根
c*l
1
【 以下文字转载自 Military 讨论区 】
发信人: gtrr35 (GTR-R35), 信区: Military
标 题: cs用的数学是很高深的
发信站: BBS 未名空间站 (Sun May 18 02:33:39 2014, 美东)
我来简单的说说为什么有人眼中觉得cs的数学简单,物理甚至是ee的数学比cs更难。
用盲人摸象来比方,数学就是头大象,自然科学的各个领域分别摸到的是大象的不同部
位。
比如说物理学,摸的最多的是分析学,最简单的分析学就是微积分,包括单变量多变量
微积分场论常微分偏微分方程,复分析(简单点的叫复变函数),往深了学就是实变函
数(测度Lebesgue积分)和泛函分析。然后摸的是代数学,简单的叫线性代数,难点的
叫高等代数,再深点就是数学系的抽象代数。几何学,微分几何黎曼几何,物理系学过
广义相对论和场论的人多多少少接触过(就是度规联络还有描述空间弯曲程度的张量)
,其实近代的经典力学也引用几何的描述方法。另外物理系学的数学就是概率论和统计
以及数值分析了。总结一下,物理系学的数学就是解各种方程,从代数方程到常微分方
程偏微分方程以及跟布朗运动有关的SDE,所有的学习要么是直接解方程,要么是简化
近似完了解,还有就是求数值解。当然推导公式(作为求解方程的中间步骤)的能力,
是区分物理学得好坏很重要的标准。
说cs数学简单的,很可能是半路出家的码工,他们没有受过cs的正规的教育。cs的核心
是算法和优化,这两者的关键都是数学:离散数学。半路出家的码工可能除了big/
small O,big/small Theta/Omega这类的,其他都不知道。他们在学习估算算法复杂度
的时候也是一知半解,学了个皮毛,以为连微积分都用不上都是初高中的数学。这是大
错特错。计算算法复杂度需要高深的离散数学和统计学的知识,计算的时候会涉及到无
穷级数的求和以及积分。另外,单说离散数学这一个分支,就可以把偏微分方程解得很
溜的人为难得毫无头绪的。要是以下几个计算机本科离散数学的课程没听说的,以后就
不要再谈论cs的难度了:组合论,图论,数理逻辑。另外离散数学会涉及到数论(这个
绝对可以难死人的)古典拓扑等等数学的分支。
所以说,物理和cs在数学的使用程度和难度上,应该很难分高下,它们摸到的是数学的
不通部位。但是化学生物以及各工程学科用到的数学,基本上是物理和cs需要用的数学
的子集。
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a*g
2
According to Common Sense Media, tweens log 4 1/2 hours of screen time a day
, seven days a week, 52 weeks a year. For teens, it's even higher: nearly
seven hours a day. And that doesn't include time spent using devices for
school or in school.
From babies with iPads to Chromebooks in classrooms, digital devices seem
more ubiquitous every year. And one of the hottest issues today in both
parenting and education circles is the proper role of electronic media in
children's lives.
There's research to support both the benefits and dangers of digital media
for developing minds. Plenty of questions remain unanswered.
But those of us raising and teaching children can't afford to wait years for
the final evidence to come in. That's why the American Academy of
Pediatrics plans to update its guidelines on media use later this year.
Current recommendations are to avoid all screens for children under 2, and
to allow a maximum of two hours per day of high-quality material for older
children.
I spoke with David Hill, chairman of the AAP Council on Communications and
Media and a member of the AAP Children, Adolescents and Media Leadership
Working Group, to hear about the upcoming recommendations and to get some
advice on how to use screens wisely.
Why new screen time recommendations now?
The American Academy of Pediatrics routinely updates all of its
recommendations to ensure that they reflect the most current data. We are
hoping to expedite the process for these particular recommendations in light
of the fast-changing landscape of children's media use. We understand that,
as the technologies available to parents evolve, they are looking for
guidance that reflect their current realities. Our goal is to release these
new policy statements in October of 2016.
What are the intentions behind the new guidelines?
The intentions of all of our policy statements are the same: to translate
the best available data on child health and development into recommendations
that help parents, health care providers and policymakers work together to
foster children's optimal well-being.
You made a preliminary announcement this past fall. It mentioned issues such
as the need to carefully regulate content, and the need for parents to put
away their own devices at times. You also suggested certain kinds of
interactive media could be appropriate even for infants and toddlers. What
did you think of the responses?
We were excited and flattered to witness so much interest in our commentary.
At the same time, I personally felt a little frustrated at some of the ways
that certain parties misread our statement.
I think that people on both sides of the debate at times exaggerated the
differences between what we discussed in our commentary and current AAP
policy.
While we acknowledged that mobile and interactive screens have become
ubiquitous in children's lives, we did not advocate for their wholesale
adoption. I suspect that when they do come out, the statements will be
highly conservative, reinforcing much of what we have said in the past about
the known effects of electronic media use on child health and development.
Talking to different researchers and clinicians about digital media and
young people, I get the sense that there is a "harm reduction" camp — many
feel that screen exposure is here to stay, even for infants, so to tell
families to give it up isn't realistic.
I share your perception.
Are you in the harm reduction camp?
We at the AAP have a history of advocating whatever the data support
regardless of public opinion. There was a time when eliminating smoking
indoors, removing lead from gasoline and paint, and restraining children in
cars were all seen as unrealistic recommendations that no one would ever
follow. And yet each of these practices has been widely adopted with
profoundly positive effects on child health.
If our future statements move away from recommending total electronic media
abstinence at any age, it will be because the available data don't clearly
support such a recommendation. The question before us is whether electronic
media use in children is more akin to diet or to tobacco use. With diet,
harm reduction measures seem to be turning the tide of the obesity epidemic.
With tobacco, on the other hand, there really is no safe level of exposure
at any age. My personal opinion is that the diet analogy will end up being
more apt.
What are some positive parenting practices around technology?
First, I would say role-modeling. Demonstrate your own mindfulness in front
of your children by putting down your phone during meals or whenever they
need your attention. Second, make sure they know you appreciate their
behavior when it's something you like. If they color or read or play
basketball or ride their bikes, take some time to ask them about what they'
ve done and why they enjoyed it. These conversations will help them focus on
the joys of the "real" world, and they will notice that their activity
attracts your attention.
Finally, involve them in making rules around media. Ask them what they think
appropriate electronic media use looks like and what sorts of consequences
might be warranted for breaking the agreed-upon rules. You may have to help
guide them in these discussions, but often you'll find that they have
expectations that are not that different from your own.
What do you hope that new research will tell us soon? Where are the biggest
gaps in your opinion?
Just last week we finally had a study that looked at the effects that some "
educational" toys had on young children's development. The results surprised
even the researchers, showing that toys that talk and sing, light up and
play music interfere with learning rather than contributing to it. I would
love to see this study reproduced and to see others exploring what role, if
any, electronic media might play in enhancing or inhibiting learning in
young children.
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c*l
3
如题,12月3号提交485,5号收到。目前还没收到receipt number。正常吗?求祝福顺
顺利利啊!
★ 发自iPhone App: ChineseWeb 7.7
★ 发自iPhone App: ChineseWeb 7.7
★ 发自iPhone App: ChineseWeb 7.7
avatar
g*e
4
你低估了半路出家的码公

【在 c*********l 的大作中提到】
: 【 以下文字转载自 Military 讨论区 】
: 发信人: gtrr35 (GTR-R35), 信区: Military
: 标 题: cs用的数学是很高深的
: 发信站: BBS 未名空间站 (Sun May 18 02:33:39 2014, 美东)
: 我来简单的说说为什么有人眼中觉得cs的数学简单,物理甚至是ee的数学比cs更难。
: 用盲人摸象来比方,数学就是头大象,自然科学的各个领域分别摸到的是大象的不同部
: 位。
: 比如说物理学,摸的最多的是分析学,最简单的分析学就是微积分,包括单变量多变量
: 微积分场论常微分偏微分方程,复分析(简单点的叫复变函数),往深了学就是实变函
: 数(测度Lebesgue积分)和泛函分析。然后摸的是代数学,简单的叫线性代数,难点的

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l*n
5
该来的总会来的,急啥?还不允许USCIS放个假啥的啊。
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e*a
6
do not confuse software blue-collar worker with computer scientist.
They both belong to two quite different careers.
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l*m
7
过年了,IO们心散了,队伍不好带了
耐心等等会来的
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c*k
8
Coding farmers don't need to know the deep math theory in their daily job...
its just labor...
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t*s
9
不用太担心,holiday seasons。我当时是劳动节后寄到的,两周多才收到receipt.你
是NSC吗?
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r*i
10
我觉得cs用的逻辑系统,正则语法,lambda-calculus,是数学专业也少有涉及的一种
数学。
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c*l
11
谢谢,tsc,已经2周多了

★ 发自iPhone App: ChineseWeb 7.7

【在 t******s 的大作中提到】
: 不用太担心,holiday seasons。我当时是劳动节后寄到的,两周多才收到receipt.你
: 是NSC吗?

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n*n
12
说了半天,就是想说自己牛逼,就是想听别人说自己牛逼。right?
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