“骗子”之我见——与顾英老师商榷

《语文学习》2005年第3期顾英老师的《浅谈语文课堂提问艺术》一文给人以耳目一新的感觉，让人很受启发。在受到启发的同时，我也有些不同意的地方。该文中有这样一段：“我在讲授《皇帝的新装》时，提问‘如何评价课文中的两个骗子？’学生一时难以回答。我就将这一问题分解为：‘骗子针对皇帝的贪图安逸，不理朝政，设下骗局，其出发点是什么’？”

我在淘宝遇到了骗子

现如今,网上购物已逐渐成为一种时尚。在网购快捷、实惠、方便等优势的感召下,我经过四年的努力,成为了淘宝一名货真价实的蓝钻买家。然而几天前的一次购物经历,却差点让我这个网购老手掉进圈套。

为一元钱,成了“骗子”

糟糕!站在街边，我终于回过神来。我把包落在车上了，这可咋办？ 我家在郊区，工作在城区，每天乘坐公司班车上下班。刚才在车上我迷迷糊糊地睡着了，下车就忘记了拿包，现在我口袋里一分钱也没有，手机也在包里。倒不担心丢东西，问题是，这个下车点离我家还有好几里，我得转乘公交车呀!

Revised quantum direct communication scheme with mutual authentication

Based on mutual authentication and dense coding,a novel revised efficient quantum direct communication scheme is proposed.It is composed of two phases：the quantum state distribution process and the direct communication process.The purpose of the former is to authenticate Trent and users to each other,and let the two legitimate users（Alice and Bob）safely share the Bell states.While the latter aims to make direct communication to transmit a secret message between Alice and Bob.In order to prevent from Eve＇s eavesdropping as well as to authenticate each other simultaneously,a decoy photon checking technique is applied.Compared with other analogous protocols,the quantum state distribution process is more simple and feasible and the proposed scheme is more efficient;i.e.,the total efficiency is almost 100%.Security analysis shows that the proposed scheme is secure against the eavesdropping attacks,the impersonation attacks,and some special Trent＇s attacks,including the attacks by using different initial states.

Fluctuation Analysis of Decoy State QKD with Finite Data-Set Size

Decoy state method quantum key distribution (QKD) is one of the promising practical solutions for BB84QKD with coherent light pulses.The number of data-set size in practical QKD protocol is always finite,which will causestatistical fluctuations.In this paper,we apply absolutely statistical fluctuation to amend the yield and error rate of thequantum state.The relationship between exchanged number of quantum signals and key generation rate is analyzed inour simulation,which offers a useful reference for experiment.

北京海淀消协提醒:购买红豆杉种子提防骗子公司

日前，北京海淀区消协发布消费警示提醒市民，邮购红豆杉种予需谨慎。

Evolution of deceit by worthless donations in a nuptial gift-giving spider

Males of the nursery web spider Pisaura mirabil usually offer an insect prey wrapped in white silk as a nuptial gift to facilitate copulation. Males exploit female foraging preferences in a sexual context as females feed on the gift during copula- tion. It is possible for males to copulate without a gift, however strong female preference for the gift leads to dramatically higher mating success for gift-giving males. Females are polyandrous, and gift-giving males achieve higher mating success, longer copulations, and increased sperm transfer that confer advantages in sperm competition. Intriguingly, field studies show that ap- proximately one third of males carry a worthless gift consisting of dry and empty insect exoskeletons or plant fragments wrapped in white silk. Silk wrapping disguises gift content and females are able to disclose gift content only after accepting and feeding on the gift, meanwhile males succeed in transferring sperm. The evolution of deceit by worthless gift donation may be favoured by strong intra-sexual competition and costs of gift-construction including prey capture, lost foraging opportunities and investment in silk wrapping. Females that receive empty worthless gifts terminate copulation sooner, which reduces sperm transfer and likely disadvantages males in sperm competition. The gift-giving trait may thus become a target of sexually antagonistic co-evolution, where deceit by worthless gifts leads to female resistance to the trait. We discuss factors such as female mating rate and intensity of sperm competition that may shape the evolution of male deception, and how ecological factors may influence the evolution and maintenance of worthless gifts as an evolutionarily stable alternative mating strategy by frequency dependent selection

Practical decoy-state quantum key distribution method considering dark count rate fluctuation

Considering fluctuant dark count rate in practical quantum key distribution(QKD) system,a new decoy-state method with one vacuum state and one weak decoy state is presented based on a heralded single photon source(HSPS).The method assumes that the dark count rate of each pulse is random and independent.The lower bound of the count rate and the upper bound of the error rate of a single photon state are estimated.The method is applied to the decoy-state QKD system with and without the fluctuation of dark count rate.Because the estimation of the upper bound of a single photon state's error rate is stricter,the method can obtain better performance than the existing methods under the same condition of implementation.

SARG04 decoy-state quantum key distribution based on an unstable source

A three-state protocol for the SARG04 decoy-state quantum key distribution(QKD)based on an unstable source is presented. The lower bound to the secure key generation rate is derived without using the basic hypothesis of the original decoy-state idea.The three-state SARG04 decoy-state protocol with an unstable parametric down-conversion source is considered in the simulation.The simulation results show that the protocol in this paper with an unstable source gives a key generation rate that is close to that with a stable source,and only slight advantage appears by using a stable source when the transmission distance is long.So the SARG04 decoy-state protocol with an unstable source still can obtain the unconditional security with a slightly shortened final key.