p*********w
发帖数: 23432 | 1 维基解密：美国外交文档部分中文翻译zz
from 政府丑闻 by Robert
原始来源：http://www.peacehall.com/news/gb/intl/2010/11/201011291554.shtml
G5在京召开，朝鲜半岛与关塔那摩成主要议题
09BEIJING1247
BEIJING-BASED G-5 CHIEFS OF MISSION ON DPRK, GTMO
2009-05-08 10:10
CONFIDENTIAL 保密等级：机密
Embassy Beijing
于五月八号在北京召开的G5大使常规会议上，法国大使Nicholas Chapuis报告说，
中国国务委员戴秉国告诉法国前总统希拉克，西方世界将在对朝鲜制裁的问题上一无所
获。据报道，戴秉国认为，涉及“（朝鲜）经济发展水平”的议题并无在六方会谈上扮
演何等重要角色，“美韩对话”才是解决问题的有效途径。德国大使Michael Schaefer
说，德国已经将美国要求其接受部分关押在关塔那摩基地的维吾尔人的信息告知中国，
但随后而来的是中国方面的不满和警告——如果德国接受关押人员，那“将对中德双边
关... 阅读全帖 |
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j****c
发帖数: 19908 | 2 前两个天体比较大，所以用的焦距短的小望远镜，astro-tech 65qed
相机是SBIG 8300M，然后颜色是分别拍LRGB来合成的
导星用的SBIG 8300OAG |
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j****c
发帖数: 19908 | 3 最少得五六千
望远镜，这个不需要多大的镜子，口径8cm的就可以了，买折射的APO ED镜。焦距不需
要太长，因为星系星云都是extended object，焦距太长视野就不够了，比如仙女座大
星云的angular size是5°，满月才0.5°，是十个满月那么大。
光圈大点成像快，一般折射的光圈是f/5-f/8。最好的是日本高桥系列的，Takahashi
FSQ 85ED or 106ED，这个要五千。我应该会买个astro-tech 106ED
赤道仪 equatorial mount，这个得买好的。如果只是肉眼看，便宜的赤道仪就行了，
但拍深空就必须要精度高的赤道仪。建议买HEQ5 PRO，带goto功能的。导星用SBIG SG4
成像系统可以先用自己的单反顶替下，买个T-mount就可以接佳能单反了。以后再搞一
个冷冻CCD。用单反有个好处就是携带方便，不需要专门的蓄电池，冷冻CCD需要在搞个
牛逼的蓄电池
在湾区吗？附近的话可以一起玩 |
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k**o
发帖数: 3006 | 4 ☆─────────────────────────────────────☆
juce (juce) 于 (Fri Apr 19 19:51:43 2013, 美东) 提到:
好羡慕，能不能介绍下具体的参数
☆─────────────────────────────────────☆
ShiyiJin (金似衣；今世遗) 于 (Fri Apr 19 19:58:00 2013, 美东) 提到:
长时间曝光。
因为地球在自转，所以有星轨。
☆─────────────────────────────────────☆
tomato0888 (tomato) 于 (Fri Apr 19 20:00:54 2013, 美东) 提到:
这个应该曝光2个小时+
☆─────────────────────────────────────☆
ShiyiJin (金似衣；今世遗) 于 (Fri Apr 19 20:08:41 2013, 美东) 提到:
可以量一下
图上有圆心——北极星，量一下角度
然后 角度数*24/360 就是曝光时间。
☆─────... 阅读全帖 |
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j****c
发帖数: 19908 | 5 入了sbig stf8300 mono ccd，昨晚开光，结果把螺丝拧断在里面了，哭啊。。。 |
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j****c
发帖数: 19908 | 6 no, 不用eyepiece，直接把monoCCD 接到望远镜上的
camera: SBIG STF-8300M with 5 position filter wheel
filter: Baader LRGB filter set |
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j****c
发帖数: 19908 | 7 Globular cluster M5
camera: SBIG STF-8300M
filters R/G/B: 2 x 2min; bin 2x2 |
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D****e
发帖数: 1122 | 8 Leica M monochrome欢迎你
或者拍星空有Sbig |
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j****c
发帖数: 19908 | 9 我所有的器材
望远镜: Celestron EdgeHD 800; SkyWatcher ED80
赤道仪: Celestron CGEM DX; Celestron Advanced VX
导星镜: Orion Shortube 80
相机: SBIG STF-8300M; Canon 450D modified
滤镜: Baader Ha 7nm, LRGB set (36mm diameter)
附件就太多了，不一一列出来了 |
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n******e
发帖数: 623 | 10 by neveruse(neveruseforever)，转载请注明原作者并保留此声明。
随时更新，转载请写明版本（更新日期）。
部分段落引用请至少注明原作者或给出本文连接。
--------目录--------
0. 不便携的选择
1. 概述
1.1 赤道仪
1.2 经纬仪的赤道仪模式
1.3 其他说明
2. 型号列表
2.1 赤道仪
2.2 其他
2.3 国产赤道仪
2.4 自带赤道仪模式的电动经纬仪
2.5 手动经纬仪
3. 参考
--------0. 不便携的选择--------
便携与稳固始终是不可兼得的两个因素，需要权衡，如果更看重后者请参考其他文章。重型赤道仪选择可以参考：
http://www.astropix.com/HTML/I_ASTROP/MOUNTS.HTM
http://lambermont.dyndns.org/astro/pe.html
重型经纬仪选择不多。一些自带赤道仪模式的电动经纬仪自重超出本文收录范围，在相应厂商的轻型产品后面备注说明了。手动经纬仪除了本文列出的之外，只有国際光器T-REX具有微动结构并且可接照相三脚架，而自重超出本文收录范围了：
... 阅读全帖 |
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d********r
发帖数: 303 | 11 First I would start by posting a figure on this board.
what is the blue molecule?
and what is the yellow one?
Answer:
Membrane protein is very difficult to crystallize. Therefore, Mackinnon spent
lots of time to get monoclonical antibody against KcsA potassium channel. The
blue molecule is the the Fab fragment and the yellow molecule is the channel.
The amazing thing is only the fab fragment interact each other and mediate the
crystallization. Therefore, the hydrophobic residues on the channel d |
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d********r
发帖数: 303 | 12 The directinality of the channel is a good question.
I do not know. (though I can search for answer)
I say it is imporant becasue it verify the role of the helix term and the
cavity. Based on this principle, I will say the channel should have
directionality. That means, ion can only come out from the cell, not the
opposite, or the stabilization effect will not be there.
I bet ppl has done experiment on it. This is kind of classical
electriphysiology research.
I think dehydration is the the criti |
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s***e
发帖数: 911 | 13 我看了那个图象,通道不对称. cavity在靠近细胞内的一面. 所以我才问方向的
问题. 可如果这完全是单向的,那么最终细胞内K+浓度会减少到很低的水平. 必须
有反向的流动才能维持平衡.
另外,细胞内K+浓度比外面高了30倍.这是靠什么维持的呢? |
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d********r
发帖数: 303 | 14 Cell has a Na/K pump. Basically it used ATP (energy) to pump out Na and pump
in K. Actually cell uses large amount of energy to establish such gradient.
Why need it?
For many reasons.
Example one:
neurons need this gradient for signal transduction.
Example two:
some cell in intestine need this gradient to transport in nutrients.
Generally the ion gradient across membrane is kind of stored energy that are
ready for use by many biological systme.
the ion channels do not generate this gradient. On |
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d********r
发帖数: 303 | 15 http://hebb.mit.edu/courses/8.515/lecture1/img027.jpg
Actually the study of ion channels is kind of biophysics. It is, as I know,
the first example of single molecule research. (see above figure)
basically, researchers use a patch clamp technique to clamp a small membrane
patch, containg very small or even singl number of channels. this kind of
reseach generate the bulk of information about membrane channel. (see below) |
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d********r
发帖数: 303 | 16
pump
gradient.
K*T*Log[100/4],
This is a very good question. i don't know how the pump look like, since no
structure about pump as I know has been solved. I have to say, it is very
likely it has some kind of channel like structure. remeber the potassium
channel? It has two configurations, one for high K and the other for low K. So
I can envision the pump should at least have two configurations.
Just suppose there is a potassium pump, it tries to do work against the
gradient, literally by pumpin |
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d********r
发帖数: 303 | 18 http://www.hhmi.org/research/investigators/images/mackinnon_fig1_lg.gif
This is the major figure from Mackinon's classical potassium channel work.
Now it is the trademark of the potassium channel. It will be remembered by
generations of biologists, like watson's double helix image.
But what does it mean?
Look at the left figure.
It reveals the dehyration, transport and rehydration process of the whole
event. The bottom cavity is within the cell. It is water filled and supposed
to overcome membra |
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d********r
发帖数: 303 | 19 Now comes the problem how an ion actually pass through the channel.
We know the membrane is a barrier against ions. Let's quote space's idea:
"consider a plane interface formed by two semi-infinite mediums with
different dielectrics(e1, e2). A charge "q" in medium "e1" at position
z=z1(let's define z-direction as the normal direction toward medium "e1" from
the
intereface) induces a charge distribution on the interface and it feels a
force by the field
generated by the charges on the inter |
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d********r
发帖数: 303 | 20 Finally, Mackinon reveals two configuration of the potassium channel at high
and low potassium concentration. This actually corresponds to the native
configuration of the channel when it is closed or open.
Sorry I cannot find a free figure for this arguement.
One lesson is, how little conformation changes actually take place! Just some
side chain rotations. but it produces two different configuration. This let us
speculate how the Na/K ATPase might work. We know it has different
configurations, |
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d********r
发帖数: 303 | 21 http://www.hhmi.org/news/images/mackinnon5.gif
Now comes the chloride channel.
What is the differnce.
Potassium channel transports potassium, which is a cation, with positive
charge on it.
chlordie channel transports chloride, which is an anion, with negative charge
on it.
This is the difference.
Look at its structure, you will find each monomer of the chloride channel is
an independent channel. The native form is dimer. So you have two channels
within the dimer. This is not the case for potassi |
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d********r
发帖数: 303 | 22 how the channel select the ion? Charge and dimension. yes.
So how about potssium channel?
Look at this figure again.
http://www.hhmi.org/research/investigators/images/mackinnon_fig1_lg.gif
the second pannel of the right figure. The backbone partial negatively charged
carbonyl oxygen atoms actually interact with the postively charged potassium.
Also the partical negative charge from C-term of helices play crucial part.
this is also true for chloride channel, though the geometry of its selective
f |
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d********r
发帖数: 303 | 23 water channel has the similar configuration as chloride channel. That means,
each subunit is an independant channel. But it forms tetramer. So one tetramer
has four channels.
question about water selectivity. No charge this time.
But the problem remains same. That is we need something to "bind" the water
but not too tightly. the channel is designed in such way that most of it is
hydrophobic but has hydrophilic patches on it, which solved both problems.
Another thing need to be addressed is the s |
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d********r
发帖数: 303 | 24 Yesterday, we mostly discussed the ion channels, though I talked a
little bit about water channel - aquaporin.
Let's look at this man.
http://www.the-scientist.com/images/yr2000/jun26/agre.jpg
Dr. peter Agre, the winner of this year's nobel price. What is his major
contribution? This man discovered the water channels, a class of protein named
as aquaporin, in 1980's.
The following table is the distribution and function of aquaporins in
human body.
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d********r
发帖数: 303 | 25 Aquaporin is related to some diseases.
- Mutations in the aquaporin-2 gene cause hereditary nephrogenic diabetes
insipidus in humans.
- Mice homozygous for inactivating mutations in the aquaporin-0 gene develop
congenital cataracts. I don't know whether similar situation exists in human.
- Some people have been identified with severe or total deficiency in
aquaporin-1. Interestingly, they appear clinically unaffected, but have not
been examined under conditions of water deprivation. Mice with t |
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d********r
发帖数: 303 | 26 The structure of aquaporin -1 has been solved. it is a tetramer. But more like
chloride channel, each of its four subunit has an independant pore. So the
tetramer actually is composed by four channels. (see figure below)
The selection problem is solved by arranging three hydrophlic patches along
the
hydrophobic channel wall. This hydrophilic patches contribute four water
binding sites and form the selective filter. Look at the following figure.
Four water molecules (green sphere) are shown here, |
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