Model validation software for classification models using repeated partitioning: MVREP

The process of assessing the prediction ability of a computational model is called model validation. For models predicting a categorical response, the prediction ability is usually quantified by prediction measures such as sensitivity, specificity, and accuracy. This paper presents a software Model Validation using Repeated Partitioning (MVREP) that implements a computer-intensive, nonparametric approach to model validation, which we call the re-partitioning method. MVREP, developed using the SAS Macro language, repeats the process of randomly partitioning a dataset and subsequently performing standard model validation procedures, such as cross-validation, a large number of times and generates the empirical sampling distributions of prediction measures. The means of the sampling distributions serve as the point estimates of prediction measures of the model. The variances of the sampling distributions provide a direct assessment of variability for the point estimates of prediction measures. An example is presented using a mouse developmental toxicity chemical dataset to illustrate how the software can be used for the assessment of structure-activity relationships models.     

Visualization of individual single-walled carbon nanotubes by fluorescent polymer wrapping

Manipulating optical properties of single-walled nanotubes (SWNTs) is necessary for the development of nanoscale optical devices and probes for biomedical research. In life sciences it will make possible the direct observation of SWNTs inside living cells using optical microscopes. In the nanotechnology field it will enable the development of nanosensors with fluorescent reporting. However, the direct fluorescent labeling of SWNTs is obstructed by their strong light quenching qualities. Besides, chemical functionalization of SWNTs needed for the covalent attachment of fluorescent dyes could change favorable properties of nanotubes. Here we report that optical properties of SWNTs can be manipulated without their covalent modification by wrapping them with fluorescently labeled polymer poly(vinylpyrrolidone) (PVP-1300). Fluorescent PVP-1300 forms a monomolecular approximately 2.5 nm thick layer coiling around individual SWNTs and nanotube bundles. PVP casing is fluorescent although it is only several nanometers thick. This makes individual SWNTs observable by a fluorescent microscope. The spare polymer strands left over after wrapping around the relatively shorter nanotubes form junctions between SWNTs tying them together into new configurations, primarily Y- and psi-type junctions. The ability to use a single fluorescent polymer strand to fasten nanotubes together can be useful in assembly of nanotube-made devices. In PVP-covered SWNTs multiple fluorophores are attached to each single nanotube making them unique composite fluorophores attractive as parts of biological fluorescent probes and in the development of the new materials in photonics and nanotechnology.     

Scattering of light by a periodic structure in the presence of randomness. III. Limit of the extended matched filtering method for the detection of weak periodicities

It is known that, for scattering of light by a rough grating, the periodically occurring intensity maxima that are characteristic of the periodic part of the scattering medium get smeared off and hence become undetectable if coherence length r0 of the randomness is much smaller than wavelength A of the periodic part of the grating. It is also known that by conventional intensity measurements the detectability region is r0/lambda > or = 0.33, which can be extended to lower regions by intensity interferometry. It is established here that an extended matched filtering method enables one to detect the periodic part of the medium, even in the presence of higher roughness (i.e., lower r0), and the limit is placed at r0/lambda approximately 0.11 by our numerical experiments.     

“千千静听”当黑客 网吧目录轻松破解

我是一个穷人,没有自己的电脑,所以只能在网吧上网。可恨的是网吧的电脑普遍都对硬盘目录进行了隐藏并进行了严格的限制,这让我不爽之极。举个常见的例子,网吧通常都为大家准备了丰富的音乐以供欣赏,但却只许听不许你动,要将喜欢的音乐转存到自己的MP3播放器中,想都别想!即使你得知了它的存放目录路径,在地址栏中打开时只会毫不客气地出现如图1所示的提示(见图1)。不过我在网吧使用千千静听(网吧通常都安装有这个播放器)时,却偶然发现了一种破解网吧任意文件目录的绝妙方法,从此终于可以将“不爽”抛到一旁了。一、破解音乐文件夹破解网吧…     

安全第一 用好你的SSID

S S I D是“无线网络服务集标识”的简称,它用来标识一个无线局域网,用户想要接入一个无线网络,必须知道S S I D。S S I D为无线网络提供了最低级别的安全访问功能,只有合理设置S S I D,才能增强无线网络的安全,防止黑客的非法入侵。SSID的构成S S I D由一串字符构成,最多可以有32个字符,这些字符可以是字母、数字和符号,并且字母是区分大小写的。无线路由器或无线A P在出厂时,都有一个S S I D初始化值,并且同一型号设备的S S I D通常是相同的,如T P-L I N K无线路由器,它的S S I D初始化值一般为“tp-link”。修改SSID…     

免费拥有 无限QQ秀

“银两,我所欲也,Q Q秀亦我所欲也,怎奈我等囊中羞涩Q Q秀不能买也……”眼见着好友们的Q Q秀形象一个个日益变得光鲜动人时,穷困潦倒的笔者无奈地发出了上面的感叹。难道在虚拟的网络中都非得以“银子”换“面子”了吗?这是什么世道呀?!笔者经过一番苦心钻研终于找到了两全其美的解决方案,从此“银子”与“面子”终于可以兼得了。探究QQ秀文件的秘密不知道大家注意过Q Q2005(包括各个版本)安装目录中的“flashshow”文件夹没有,在其中可以找到“qqshow0～qqshow9”共10个QQ秀文件夹,打开它们就可以看到好友和自己的Q Q秀图片,而且文…     

频繁安装Reader更新,实在没必要

因为安全方面的考量,几乎每隔一段时间,Adobe Reader都会进行一次版本升级。默认设置之下,Adobe Reader会自动在后台下载更新程序,并在系统托盘中提示用户进行安装(如图1)。但由于笔者电脑已经相当陈旧了,而Adobe Reader体积又比较大,每次安装都得花上不少时间,其实现有版本的AdobeReader功能已经足够,频繁升级实在没那么必要。如果你也有这种想法,我们可以通过简单的设置,让     

Gmail邮箱新增还原通讯录功能

人常说,常在河边走哪有不湿鞋。由于笔者经常使用Gmail邮箱,所以里面的通讯录也会常常去用,例如删除或增加通讯录、同步通讯录、导入通讯录、合并通讯录等。但有时因为自己一时疏忽,误删除了某个通讯录,或同步失败了通讯录,这时该如何是好?难道就没有补救措施?别慌,如今Gmail加上了     

关闭QQ邮箱漂流瓶功能

身边不少好友都在玩QQ邮箱中的漂流瓶,在他们耳濡目染之下,我也成为漂流瓶一份子。但我这人对于新鲜事物只有三分钟热度,玩了几次漂流瓶就已索然无味。更伤脑经的是,不管往后再玩不玩漂流瓶,只要你登录了QQ,一旦你QQ邮箱收到了新的漂流瓶,从系统托盘中都会弹出提示窗口,就像收到新邮件一样,烦人啊!假如你想让