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全部话题 - 话题: sigma
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e*****i
发帖数: 149
1
我其实是搞生物 的,要用到很多小分子化合物做药理实验
sigma卖得贵死
其他卖的也不便宜
据说sigma都是 买国内的便宜货,然后自己有一个很好的纯化系统,过一下纯化系统就
ok了。然后就 卖得死贵。
是这样的吗?
x********3
发帖数: 12
2
我现在在设计一个MASH22 sigma delta modulator.
单个2nd order sigma delta modulator SQNR可以达到70+dB。
但两级合在一起后, SQNR 不但没提高, 还略有下降。
各位高人是否能推荐一篇论文或材料详细讲解MASH22 的设计?
先谢过了!
s***d
发帖数: 15421
3
有关delt sigma adc在rf 系统的应用问题
比如无线系统 突然有个peak power来来agc 不可能在很短的时间内调整
这时候delta sigma adc 被over range的input power 超过来fullscale 震荡了 应该
怎么解决
是不是pga或者if band amp 要限幅度?还是系统根据算法判断ds adc是不是震荡?还
是做个powerdetector,peak power一来 就reset ds adc 系统默认此时adc满量程?
★ 发自iPhone App: ChineseWeb 16
c*********e
发帖数: 119
4
来自主题: Macromolecules版 - 有人考过six-sigma证书吗?
近几年,很多大公司都在开始six-sigma的变革。GE是其中最成功的。所以six-sigma证书
好像挺热的。有没有人去考过? 我想去考一个。能不能拿到证书没有关系,主要是想通过
考试,我能学点东西。
a****r
发帖数: 4965
5
来自主题: Macromolecules版 - 有人考过six-sigma证书吗?
Nod

近几年,很多大公司都在开始six-sigma的变革。GE是其中最成功的。所以six-sigma证书
想通过
f********r
发帖数: 121
6
来自主题: Mathematics版 - Questions on E(1/x) if x~N(mu, sigma)?
if x~N(mu, sigma), what's the expectation of 1/x, 1/x^2?
E(1/x)<1/mu?
E(1/x^2) >1/(mu^2+sigma)?
how to get the exactly value?
thanks a lot
a***s
发帖数: 616
7
来自主题: Mathematics版 - 请教:algebra VS. sigma algebra
Sigma algebra is much more complicate than algebra. So we usually start with
studying algebra and then extend the result to sigma algebra.
In constructing the Lebsgue measure, we want to measure as many sets as poss
ible and also make sure that intervals have measure in the common way, i.e.
[a,b) has measure b-a. (Let's focus on the whole set [0,1) to ,make things s
imple.)
So we start with interval of the form [a,b). Then we can easily extend to fi
nite union of intervals of this form, i.e. [a,
z****e
发帖数: 2024
8
来自主题: Mathematics版 - 请教:algebra VS. sigma algebra
太牛逼了。收藏了先。
您是教授吧?
最后,为什么 the sigma-algebra generated by "C", contains the algebra
generated by "C" 呢?
我怎么觉得凡是sigma-algebra就都是algebra,这样的话,不是反过来了吗?
谢谢。
r*****t
发帖数: 286
9
来自主题: Quant版 - [合集] Two sigma怎么样啊?
☆─────────────────────────────────────☆
fotini (装深沉) 于 (Wed Jan 31 00:54:02 2007) 提到:
网上搜不到什么信息,请大家指点一下。
在搞hedge fund的公司里边,two sigma算什么规模?业绩怎么样?
谢谢!
☆─────────────────────────────────────☆
hbcat (哈巴猫) 于 (Wed Jan 31 01:12:36 2007) 提到:
这事儿应该请 twosigma 同学站出来讲话。

☆─────────────────────────────────────☆
twosigma (Alpha) 于 (Mon Feb 26 11:30:34 2007) 提到:
倒。过了这么多天我才看到。
Two Sigma是一个很好的hedge fund啊,想做stat arb就过来吧。不过这位仁兄好像已
经决定不来了,真可惜。
☆─────────────────────────────────────☆
KuangTer (Kuan
l*********c
发帖数: 22
10
来自主题: Quant版 - Two Sigma 面试该怎么准备?
大家了解Two Sigma的面试流程吗?
面试主要考什么?
貌似大部分面Two Sigma的是CS背景的。 我是计算数学背景,会一点点编程,但是
leetcode那样的问题还是不会做。 请问该怎么应对好呢?
l*********c
发帖数: 22
11
来自主题: Quant版 - Two Sigma面试怎么准备?
大家了解Two Sigma的面试流程吗?
面试主要考什么?
貌似大部分面Two Sigma的是CS背景的(他们招金融背景的多吗?)。 我是计算数学背
景,会一点点编程,但是leetcode那样的问题还是不会做。 请问该怎么应对好呢?
a*******o
发帖数: 81
12
【 以下文字转载自 JobHunting 讨论区 】
发信人: aeolusloo (aeolusloo), 信区: JobHunting
标 题: 公司烙印在这里查two sigma面经,外挂google翻译。大家尽量用中文+错别字
关键字: 面经
发信站: BBS 未名空间站 (Wed Apr 22 09:09:33 2015, 美东)
公司烙印在这里查two sigma面经,外挂google翻译。大家尽量用中文+错别字
D****a
发帖数: 19
13
【 以下文字转载自 JobHunting 讨论区 】
发信人: Danica (Danica), 信区: JobHunting
标 题: 请教:two sigma onsite后多久有消息?
发信站: BBS 未名空间站 (Wed Jan 27 08:56:53 2016, 美东)
请教板上的大牛,two sigma onsite 后多久有消息?
谢谢!
C******g
发帖数: 2930
14
GameStop has updated its site with a listing for a limited edition of Ninja
Gaiden Sigma 2 exclusive to the retailer. The product page lists the $69.99
premium release as including an 80-page book divided into three sections:
art from the game, a color Ninja Gaiden Sigma 2 comic and a strategy guide.
There's no mention of special packaging for the edition, which is dated for
September 29.
We contacted Tecmo for more info and were told that additional details will
be disclosed within the next two
w*******y
发帖数: 60932
15
Sigma was $2.99 - Rating: 4.00 (839):
http://appshopper.com/games/sigma
A brilliant looking match 3 game of top notch quality. - TouchArcade
New & Noteworthy!
What's Hot!
What We're Playing!
Five-Minute Fixes!
Critics:
Top notch quality. - TouchArcade
It just feels right. - PocketGamer
wonderfully designed. - AppAdvice
Replay value is very good. - AppSmile
An amazing puzzler. - AppSpy
Stunning presentation. - Gamezebo
A real fun experience. - GamersRoute
A newly invigorated gem The iPhone App
w*******y
发帖数: 60932
w*******y
发帖数: 60932
17
Sigma 70-200mm f/2.8 APO EX DG HSM OS FLD Large Aperture Telephoto Zoom Lens
for Canon Digital DSLR Camera
bylSigma
For 949 sold by amazon. Great telephoto lens and build quality from sigma,
I've been watching this lens for a while. Lowest price everywhere else is
1399.00
I know someones gonna come I here talking about the canon 70-200l f2.8. It's
out of my pay grade and this is a hell of a deal. Click on New and search
for the lens sold by Amazon to get it for 949.00. For some reason it's
takin... 阅读全帖
w*******y
发帖数: 60932
w*******y
发帖数: 60932
19
newegg has the SIGMA 30mm F1.4 EX DC HSM Lens For Nikon and Canon for $449.
99 shipped.
This is the lowest price especially for a lens that rarely goes on sale.
With the recent price increase from Sigma, its a great deal at 449. Used
copies goes for around 400 on ebay.
Canon Mount:
http://www.newegg.com/Product/Product.aspx?Item=9SIA04D01D3796&
Nikon Mount:
http://www.newegg.com/Product/Product.aspx?Item=9SIA04D01D3797&
Details:
This large aperture 30mm F1.4 EX DC HSM lens is designed to match t... 阅读全帖
w*******y
发帖数: 60932
20
Heads up. This is the best price that I've seen for this lens:
Sigma 30MM F1.4 EX DC HSM for Canon
$429 - $50 off (Coupon Code: SIGMA50) = $389 w/FS
Coupon Code: SIGMA50
Link:
http://store.uniquephoto.com/e/index.php/sigma-30mm-f1-4-ex-dc-
w*******y
发帖数: 60932
21
Buydig.com has Sigma 17-70 OS HSM lens for Canon and Nikon mounts for $399 -
$10 coupon HolidayBDBux10
Must log in and add to cart to see price.
Link:
http://www.buydig.com/shop/search.aspx?kwd=sigma 17-70&x=0&y=0
w*******y
发帖数: 60932
22
Looks like a great deal for a Sigma 17-50 OS for $599 with free shipping!
The sale is available for Canon, Nikon, Sony, Pentax, Sigma mounts.
Link:
http://www.adorama.com/searchsite/default.aspx?searchinfo=sg175
w*******y
发帖数: 60932
23
Stopped into academy today to take a look at what they had on clearance. I
came across the Allied Forces Smith and Wesson 9mm Disaster Kit tagged at $
379.88. Once I decided to pull the trigger and cleared background check, it
was a pleasant suprise when it rung up for $358.88!! Out the door price
was $388.49. The Smith and Wesson Sigma 9VE 9mm w/2 hi capacity mags has
sold for $259 after a $50 rebate in the past. This allied forces kit has
sold for as high as $599. Although this may not be... 阅读全帖
w*******y
发帖数: 60932
24
来自主题: _DealGroup版 - 【$】$50 off any sigma lens over $250
Unique Photo is running a promo series of classes on Sigma Lenses and they
gave us all a coupon code good for $50 off any lens over $250. I think this
was only meant for those of us who were at the seminar but my time spent
sitting at a lecture turns into your benefit.
www.uniquephoto.com:
http://www.uniquephoto.com
Link:
http://store.uniquephoto.com/e/index.php/brands/sigma
COUPON CODE: SIGMA50
d**s
发帖数: 920
25
来自主题: Military版 - VIX = 60 是不是说 Sigma σ = 0.60 ?
向大家请教一下:
VIX = 60 是不是说 Sigma σ = 0.60 ?
这里σ就是 implied volatility for SPY for Black-Scholes formula.
我这样理解对不对 ?
我问这个问题的原因是, volatility in Black-Scholes formula 通常都很小, 譬如,
都小于1. 为什么 VIX可以是 60 甚至80 ?
多谢大家。
j********g
发帖数: 23
26
来自主题: Classified版 - [FS] Sigma 8mm f/4 fisheye Canon mount
器材名称
Sigma 8mm f/4 fisheye Canon mount
付款方式(需要其他付款方式请联系卖家)
paypal non-cc or PM
卖家联系方式
PM or email: d**************[email protected]
器材具体描述、价格、运费:
(均为现金/BOA/check/MO或non-cc paypal价,+$5 for echeck)
(其他付款方式引起的价格变动请与卖家联系)
朋友不用给我的,自己两年就用它拍了3张。带盒证,镜头袋,带原厂机身盖。
$600 net to me.
m*****o
发帖数: 2578
27
二手交易风险自负!请自行验证是否合法和一手卡!:
我想卖的物品:
Sigma 50-200mm f/4.0-5.6 DC IF SLD Lens Nikon
单张面值:
96
可接受价格(必须明码标价!):
110
物品新旧要求:
New
邮寄方式要求:
YL
买卖双方谁承担邮寄损失(Required if not code only):
before,after
付款方式说明:
Paypal/boa/bill pay
其他补充说明:
Till gone
广告的有效期:
Till gone
物品来源(Required for All Cards!):
Amazon
我的联系方式:
PM
Warranty期限:
能否证明是合法的一手卡?(Required for All Cards!):
state and zip:
T******9
发帖数: 2222
28
二手交易风险自负!请自行验证是否合法和一手卡!:
我想卖的物品:
Sigma 50-200mm f/4.0-5.6 DC IF SLD Lens Nikon
单张面值:
96
可接受价格(必须明码标价!):
110
物品新旧要求:
New
邮寄方式要求:
YL
买卖双方谁承担邮寄损失(Required if not code only):
before,after
付款方式说明:
Paypal/boa/bill pay
其他补充说明:
Till gone
广告的有效期:
Till gone
物品来源(Required for All Cards!):
Amazon
我的联系方式:
PM
Warranty期限:
b******g
发帖数: 2965
29
二手交易风险自负!请自行验证是否合法和一手卡!:
我想卖的物品:
Sigma 70-200mm f/2.8 APO EX for Canon $1150
单张面值:
1399
http://www.amazon.com/gp/product/B0
可接受价格(必须明码标价!):
1150
物品新旧要求:
new
邮寄方式要求:
yl, >3 my label
买卖双方谁承担邮寄损失(Required if not code only):
付款方式说明:
BOA, bill pay
其他补充说明:
广告的有效期:
2 days
物品来源(Required for All Cards!):
amazon
我的联系方式:
bbs
Warranty期限:
能否证明是合法的一手卡?(Required for All Cards!):
state and zip:
FL
s**********e
发帖数: 377
30
来自主题: Classified版 - [出售]Sigma 10-20mm 镜头 (佳能)
二手交易风险自负!请自行验证是否合法和一手卡!:
我想卖的物品:
Sigma 10-20mm f/4-5.6 EX DC HSM Lens for Canon Digital SLR Cameras
附加Tiffen 77mm UV镜
Amazon价格:
$479+16.5
可接受价格(必须明码标价!):
$429.00
物品新旧:
Used,no damage, no scrach, works as new
买卖双方谁承担邮寄损失(Required if not code only):
default
付款方式说明:
non-cc paypal
广告的有效期:
till gone
我的联系方式:
站内信
state and zip:
NM 87***
m*********t
发帖数: 295
31
二手交易风险自负!请自行验证是否合法和一手卡!:
我想卖的物品:
Sigma 30mm f/1.4 EX DC HSM for Canon $350
单张面值:
可接受价格(必须明码标价!):
$350
物品新旧要求:
mint/like new Used only couple of times
邮寄方式要求:
YL
买卖双方谁承担邮寄损失(Required if not code only):
default
付款方式说明:
BOA or bill pay
其他补充说明:
广告的有效期:
till gone
物品来源(Required for All Cards!):
Bought it from Uniquephoto last December
我的联系方式:
pm
Warranty期限:
1-Year Worldwide Warranty + 3-Year Extended USA Warranty till 2015
能否证明是合法的一手卡?(Required for All Cards!):
state and zip:
OH
n*****3
发帖数: 514
32
Sigma 24-70mm f2.8 EX DG Macro for Nikon. 原来双休的时候用在D200, 现在只用
canon, lens is in very good condition, woks well. 只有 both caps, 和一个
third-party hood. Ask $350 shipped.
还有三个 430EX II, 一个基本是新的, 买来就只用了两次, 有盒子, 所有的配件。
还有两个是 used but in good condition, shows some scratches, comes with
case, stand, but no box, manual. 带盒子的 $185
shipped. 其他两个 $165 each shipped.
S******n
发帖数: 5022
33
来自主题: Classified版 - 【FS】全新Nikon D7100 、Sigma 35mm 1.4
#1、Nikon D7100 24.1MP(全新 USA版) $1099 + your label
#2、Nikon D7100 24.1MP(全新 USA版) $1099 + your label
#3、sigma 35 /1.4 N+(全新 USA版) $784 + your label
http://www.price.com.hk/product.php?p=147626 港行的价格或约美元$784(1 USD = 7.76 HKD)
buy.com 15X, 899 - 899*0.15*0.85 = 784 也是这个价
所以我就定这个价了,美版的质保是1年国际加3年USA扩展,一共4年
联系方式 站内PM
Payment method: chase quickpay/non-cc paypal
附:
Nikon D7100 主要参数
24.1MP DX-format CMOS Sensor
EXPEED 3 Image Processing Engine
No Optical Low-Pass Filter
1080p Full HD Vid... 阅读全帖
L*********x
发帖数: 2191
34
1. Canon 5D Mark III, 今天的shutter count 是305.
机身没有任何痕迹,全套包装盒,附件和文件,blank service card.
First owner.
$2650+shipping, from boston.
2. Sigma 35mm for Canon
买了大概2个礼拜了。就用了一次,镜头本身没有任何痕迹。
镜头前盖正面被滤镜磨得有两道划痕了。
receipt from adorama.
$740 shipped, from boston.
J*********n
发帖数: 6974
f****6
发帖数: 4472
36
全新,from an authorized dealer,所有附件都在,从来没用过。你出邮费或者加10
刀。
最后一个Sigma 35了,短期内也不会搞这个头了,大家轻拍。
f****6
发帖数: 4472
37
全新,from an authorized dealer,所有附件都在,从来没用过。你出邮费或者加10
刀。
最后一个Sigma 35了,短期内也不会搞这个头了,大家轻拍。
g**a
发帖数: 2129
38
来自主题: ebiz版 - Sigma DP2S 14MP X3@amazon $559.00
Sigma DP2S 14MP X3 FOVEON CMOS Digital Camera with 24.2mm f/2.8 and 2.5 inch
LCD
c*******h
发帖数: 1096
39
【 以下文字转载自 Quant 讨论区 】
发信人: dl12 (deeplearning12), 信区: Quant
标 题: Two Sigma 的两位老板首次进入福布斯
发信站: BBS 未名空间站 (Thu Oct 15 20:21:07 2015, 美东)
http://www.forbes.com/sites/nathanvardi/2015/09/29/rich-formula
值得一读。一将功成万骨枯,作者的春秋笔法还真不错。
T******9
发帖数: 2222
40
二手交易风险自负!请自行验证是否合法和一手卡!:
我想卖的物品:
Sigma 50-200mm f/4.0-5.6 DC IF SLD Lens Nikon
单张面值:
96
可接受价格(必须明码标价!):
110
物品新旧要求:
New
邮寄方式要求:
YL
买卖双方谁承担邮寄损失(Required if not code only):
before,after
付款方式说明:
Paypal/boa/bill pay
其他补充说明:
Till gone
广告的有效期:
Till gone
物品来源(Required for All Cards!):
Amazon
我的联系方式:
PM
Warranty期限:
b******g
发帖数: 2965
41
二手交易风险自负!请自行验证是否合法和一手卡!:
我想卖的物品:
Sigma 70-200mm f/2.8 APO EX for Canon $1150
单张面值:
1399
http://www.amazon.com/gp/product/B0
可接受价格(必须明码标价!):
1150
物品新旧要求:
new
邮寄方式要求:
yl, >3 my label
买卖双方谁承担邮寄损失(Required if not code only):
付款方式说明:
BOA, bill pay
其他补充说明:
广告的有效期:
2 days
物品来源(Required for All Cards!):
amazon
我的联系方式:
bbs
Warranty期限:
能否证明是合法的一手卡?(Required for All Cards!):
state and zip:
FL
s**********e
发帖数: 377
42
来自主题: FleaMarket版 - [出售]Sigma 10-20mm 镜头 (佳能)
二手交易风险自负!请自行验证是否合法和一手卡!:
我想卖的物品:
Sigma 10-20mm f/4-5.6 EX DC HSM Lens for Canon Digital SLR Cameras
附加Tiffen 77mm UV镜
Amazon价格:
$479+16.5
可接受价格(必须明码标价!):
$429.00
物品新旧:
Used,no damage, no scrach, works as new
买卖双方谁承担邮寄损失(Required if not code only):
default
付款方式说明:
non-cc paypal
广告的有效期:
till gone
我的联系方式:
站内信
state and zip:
NM 87***
k*k
发帖数: 49
43
来自主题: JobHunting版 - questions on two sigma onsite -- 救助
I am going to have an onsite with Two-Sigma (a hedge fund company @ NY) next
week for Java developer position.
各位大侠有过面试这家公司的经历吗? 可以不可以稍微透露一点。。。
我听说他们 quant 的面试非常难。。。 一大堆 brainteaser 和 math... Java
developer 也一样吗?
先 多谢各位大侠了。。。
a*****4
发帖数: 986
44
来自主题: JobHunting版 - FW: six sigma black belt consultants needed
I need consultants with the following competencies
A. Engineering - mechanical, electrical, industrial
B. Willing to travel internationally
C. PMP certified very helpful
D. Certified six sigma black belt
E. 10 or more years corporate experience
F. Ability to facilitate training classes
Right now we need 12 to 22 consultants
Can you link us to your database and have them apply online at www.
pqcinternational.com
a*******g
发帖数: 1221
45
我也只是面到中午两轮就突然告诉我结束了,当时通知我结束的时候我很惊讶。三天后
挂了。我也觉得面得挺好的。。。
lz加油,相信你一举拿下two-sigma
a***o
发帖数: 1182
46
two sigma是nyc office?
j*******h
发帖数: 20
47
vote for Two Sigma
钱景绝对比其他几个好
t*********7
发帖数: 255
48
TWO SIGMA+1
S*****e
发帖数: 229
49
two sigma
先是coding test,题目在glassdoor上有,虽然不难但是也得小心。他们家onsite时间
很长,4个人面一人一个半小时,有很多behavior问题,体力和耐心要好。只说技术题了
第一次onsite:
1. find cubic root of a number
2. 10个硬币,有一个硬币两面都是head,现在随机抽了一个硬币,投了一次发现是
head,问抽到的是坏硬币的概率
3. given a set, find all subsets
4. linear regression, integration of gaussian, max heap insertion and
deletion ….
5. how to design a web server that monitors the usage of backend servers and
display results
6. 记得有个同学说过的题,有两个矿A,B,有2n个工人,每个工人在A和B中挖矿的效
率不同,由两个数组给出。如果必须要有n个工人在A,n个工人在B里面,问如何使效率
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q****x
发帖数: 7404
50
不错。2-sigma居然两次?只说F电面,是去F了?
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